Composite modulus of subgrade reaction

composite modulus of subgrade reaction Design and Construction of Pavements and Rail Tracks Geotechnical Aspects and Processed Materials (Balkema Proceedings and Monographs in Engineering, Water and Earth Sciences) Typically, the modulus of subgrade reaction is estimated from other strength/stiffness tests, however, in situ values can be measured using the plate bearing test. Resilient Modulus is a measure of the elastic response of a soil (e. URETEK 486 Star® It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing Use of the geosynthetics to strengthen the soil is one of the highly desirable techniques under static and dynamic loads. Trial composite design â ¢ Upper PCC: 3-in. Subbase: Consists of the granular materials underlying the pavement and above the subgrade layer. 35× log10 𝐷𝐷+ 1 −0. 4 Determination of Modulus of Subgrade Reaction. Keywords subgrade, geosynthetics, reinforcements, expansive soils, CBR value clients with the appropriate subgrade reaction modulus for this composite mass. The dead load due to earth backfilled on top of slabs may be found by multiplying the weight of the soil prism over the. The subgrade reaction modulus for the geogrid-reinforced sand footing system was calculated in terms of the stated before analytical solutions Huang and The modulus of subgrade reaction is an often misunderstood and misused concept for the thickness design of slabs-on-ground. 1 Effective Modulus of Subgrade Reaction (k) Topic 10 –AASHTO Rigid Pavement Design 3. 4-6 Modulus of Soil Reaction. Methods for determining M R are described in AASHTO T-307 and FHWA LTPP Protocol 46. Enter chart with slab stress = 2. 46 k-ft = Mu, OK. The CBR Test. This is due to the fact that the modulus of elasticity is the only factor by which the effect of subsurface soil properties on the value of k. Each model was built as a three-layer pavement system—composed of concrete (TWT), asphalt layer, and subgrade soil. heavily loaded slabs on soft ground. 6. , the neces-sary range to be considered fully improved to generate horizontal subgrade reaction to the pile, is proposed to be a three-dimensional domain formed with the gradient of Nov 23, 2013 · Additional Design Inputs • S′c = modulus of rupture for concrete • J = joint load transfer coefficient • Cd = drainage coefficient (similar in concept to flexible pavement terms) • Ec = modulus of elasticity for concrete • k = modulus of subgrade reaction Additional inputs reflect differences in materials and structural behavior. Westergaard was the first to introduce the terms Modulus of Subgrade Reaction and Radius of Relative Stiffness to describe the relative stiffness of the concrete slab to that of the subgrade (1). â ¢ Lower PCC: 6-in. Table 3. The use of a concrete layer was effective at supplementing the plate stiffness. To account for variability in concrete strength, the design charts were calculated using a modulus The subgrade k-value and the composite k-value which accounts for inclusion of base layer placed over the subgrade, are the key foundation layer input parameters in most of the rigid pavement design procedures and railway subgrades (AASHTO 1972, 1986, 1993, 2008; PCA 1984; FAA 2016; Selig and Lutenegger 1991; McHenry and Rose 2012). S′c = modulus of rupture of PCC (flexural strength) C d = drainage coefficient J = load transfer coefficient E c = elastic modulus of PCC k = modulus of subgrade reaction 1998 AASHTO Design Guide Equation — Basic Overview log10𝑊𝑊18 = 𝑍𝑍𝑅𝑅× 𝑆𝑆0+7. Apr 14, 2014 · A more accurate approach to this problem is to use the Modulus of Subgrade Reaction (K) to determine the slab’s deflection and the resultant stress applied to the elastic insulation subgrade. 5 ----- soils, the coefficient of lateral subgrade reaction can be assumed to be constant with depth. 2 Foundation Layer Modulus of Subgrade Reaction, k-value. A series of plate load and CBR tests were performed on different densities of geofoams. Such curves are useful in expediting rigid pavement thickness design when the elastic properties and the thickness of the subbase are known. 3. 3 Modulus of Subgrade Reaction Westergaard's Modulus of Subgrade Reaction (k) is used in this procedure to express the supporting capability of the subgrade soil. Which one is a better choice? Support = Subgrade + Subbase Plate Theory Combines Support into One Layered elastic theory inappropriate because stiffness differential Plate theory combines all support (modulus + thickness of each layer) into a composite known as modulus of subgrade reaction (k-value) Essentially a spring constant (Hooke’s) Need to convert subgrade M R to k: 1. 25mm settlement, divided by 0. Hence equivalent modulus of elasticity which Designs of structural foundations over EPS geofoam also utilize modulus of subgrade reaction. (kc), c) Loss of support (LOS), and d) Coefficient of drainage (Cd). From experiments it has been found that ks1=k1 for sand subgrades, but for clays ksl varies Jul 31, 2018 · The most commonly used value is the modulus of subgrade reaction, k. determine the design subgrade resilient modulus. In others, the Modulus of Subgrade Reaction (k) is used. IBR is provided in the design nomographs. 2 21 Mar 2019 When subbase exists, AASHTO design of concrete pavement is based upon the composite subgrade reaction modulus. Maybe what you were going for was gigapascals, which would be (N/cm^2)*10^5, although a better way to write that would just be (N/m^2)*10^9. ystem comprising of RC . Design charts are available in AASHTO to determine the design composite reaction modulus. The . 5 Mr of the subgrade Mr composite modulus Modulus of subgrade reaction (k) ev1 and ev2 strain modulus testing Resilient deflections (scaling exponent) Field Performance Validation Hunt Highway, Arizona 0. . existing AC layer thickness and modulus, the bonding condition between TWT and the existing AC layer, shoulder conditions and temperature differentials. tools for estimating the climatic related effects on specific subgrade soils, HVJ Associates and the CAPEC member agencies make no warranty, express or implied. 4# In the case of two-layer geosystems, the roller measurements would provide a composite stiffness because only one piece of information was available at each sublot. - Subgrade Modulus of Reaction - ESAL - Directional Distribution - Lane Distribution - Effective Roadbed Resilient Modulus - Existing Layers and Layer Coefficients - Performance and Analysis Period - Serviceability Loss - Standard Deviation - Superpave Layer Information - Laboratory Mr Data - New Jersey Seasonal Length Subgrade soils may vary considerably. Modulus of subgrade reaction (k) value vs. for a rigid pavement whose input data include: Sub base thickness: 8 incites Subgrade resilient modulus: 10. There is no direct laboratory procedure for determining k-value. Joint Spacing L 72 in. Figure 3. 75 MPa for C190(R), which is an increase of 78% when compared to C190, C190 has a linear behavior up to 6. The modulus of subgrade reaction (k) PFWD provides information on the composite-stiffness of sub-grades for all layers, up to a particular depth 7. E' is used to estimate the deflection of the pipe due to dead and live loads over the pipe. K = 500. 0 50 100 150 200 250 300 350 400 450 500 0 5 10 15 20 25 30 35 40 45 50 Computed Composite Modulus of Subgrad Reaction in PCI Thickness of Base Layer in Inches Direct evaluation of in situ subgrade and pavement stiffness along a project. For mat foundation design, the "k" value for similar soil is generally taken to be between about 25 and 50. handling. diameter loading plate and perform static APLTs to determine modulus of subgrade reaction k-value using a 30 in. g. For the analysis, the composite slab is divided into strips based on the support layout and loading conditions. added to upper 8” of cohesive soil to Optimal Moisture and Stiffness. A true composite soil stiffness determination can only be determined using actual stiffness data of in-situ soil conditions at varying depths (varying subgrade conditions). 250. Available information related to estimation or appropriate test methods for evaluation of modulus of subgrade reaction of EPS geofoams is very limited. When the sand is reinforced with 0. 30-N, where testing was performed directly on the base and the system included stabilized and natural subgrade (metric units). The stresses coming from the top layers is received by different soils in different manners. 33 Figure 2-7 Composite Modulus of Subgrade Reaction (k oo 301. Finite element FEACONSIII DATA BASE. The ACPA design confirmed that milling 100 mm from the existing asphalt thickness 1. Base Wheel Loads On Concrete Slabs Jun 19, 2018 · This subgrade reaction modulus is a function of dimensions of the loaded area, which makes it difficult to consider it a unique soil property value. The cushion was shown to be an important component of a composite ground system by allowing mobilization of the soil subgrade Jul 09, 2020 · such as compressive strength of concrete, modulus of sub-grade reaction, thickness of concrete and applied loads. ESAL Design M R-----≤ 10 4 60 10 4 – 10 6 75 >10 6 87. For composite pavements only. Record URL: Composite Modulus of Subgrade Reaction, k-value (psi/in): Does the existing HMA pavement have transverse cracks? A value for ks1 for a particular subgrade can be obtained by carrying out plate load tests. The Resilient Modulus of the ACP, EBS/ is assumed to be 400,000 psi. RO. ooo. It estimates the support of the layers below a rigid pavement surface course (the PCC slab). The k-value can be determined by field tests or by   For this discussion the variables names and definitions we will be using are as follows: The Roadbed Resilient Modulus, MR (psi) The Subbase Elastic Modulus, Esb (psi) The Modulus of Subgrade Reaction, k (pci) The Composite k value, kc  This web applet allows you to determine the composite k-Value with consideration for up to three subgrade/subbase layers. It was also found that the composite modulus of subgrade reaction depends on several variables, including slab thickness, modulus of elasticity of the subbase, and modulus of subgrade reaction. However, the field plate bearing load test The analytical relationship between a soils resilient modulus and it Modulus, of Subgrade Reaction is a follows: k=MR/19. Determine composite modulus of subgrade reaction, kc. Since the total elongation is constant, Σ L i /E eq = Σ (L i /E i) (9) Therefore, E eq = ΣL i /Σ (L i /E i) (10) Thus, the equivalent modulus of elasticity is the weighted harmonic mean of the individual rod’s clients with the appropriate subgrade reaction modulus for this composite mass. org Figure 2-6 Correction of Modulus of Subgrade Reaction for Potential Loss of Base/Subbase Support. The cyclic plate load tests were conducted on the sand subgrade reinforced with planar and 3D geosynthetic Effective#modulus#of#subgrade#reaction#(k)# Softersubgrade#sustains#more#damage## #Recall#“relative#damage”u r Similarapproach#employed# Obtain#seasonal#subgrade#and#subbasemoduli data# Determine#composite#k#(k ∝)TFigure#3. 200. The ultimate bearing capacity of unreinforced sand is 1400kN/M2 tested at the density of 16. The standard size of plate used for this purpose is 0. 00125m. The floor slab design procedure presented The maximum allowable stationary live load is lim- The strength parameter used in Australia and many other countries is the California Bearing Ratio (CBR). Download scientific diagram | 1: Chart for Composite Modulus of Subgrade Reaction, k (Source: AASHTO Design Guide, 1993) from publication: The Design of a Roadway Section from Adama to Awash using Rigid Pavement and its  k∞, = composite modulus of subgrade reaction (pci) assuming a semi-infinite roadbed soil. Total 2. We recommend that the mat foundation be designed usinga subgrade reaction ( k s) of 40 pounds per cubic inch (pci). Design and evaluation of rigid pavements are based upon the modulus of subgrade reaction (K) as determined by a plate-bearing test. Jun 01, 2017 · Results show that the in situ M r values for the geogrid-stabilized aggregate layer are on average about 10 times higher than the subgrade layer, that the composite layer E v2 /E v1 ratio was low indicating good stiffness and compaction, and the modulus of subgrade reaction was relatively high at 106 kPa/mm (392 psi/in. Selection of Pavement Type. Use k for the subgrade modulus of elasticity and Poisson*s ratio of concrete, and modulus of subgrade reaction of supporting material. 7 Structural Design 23 6. Prediction of Asphalt Concrete Modulus for Bituminous Layers . The subgrade reaction approach provides the simplest solution for the pile–soil interaction problem. The two methods show similar trends, although the finite-element technique appears to be siffer than Westergaard's theory. 7 Jan 2019 This modulus consists of the modulus of subgrade reaction from plate load test (k ) and additional modulus of subgrade reaction due to pile installing (∆k). Therefore the k-value is calculated from the deflection values. Note that the backcalculated radius of relative stiffness reflects the combined stiffness of both the HMA and PCC layers. (300 mm) plate is used in Europe. 6 to determine 252 327 469 263 332455 284 354 477 308 379 504 406 Composite Modulus of Subgrade Reaction, k-value The composite k-value represents the composite stiffness of all layers below the asphalt. Walker, P. 2 is first applied to account for the presence of subbase course and obtain the composite modulus of subgrade reaction. 8 HMA Overlays of Existing Intact PCC Pavements Including Composite Pavements (one or more HMA overlays of modulus of subgrade reaction (k- value) for each month of the design analysis period for these layers. An elastic modulus of 600,000 psi represents a good condition with only surface distresses such as rutting, shoving, or weathering that can be mostly eliminated by cold milling. However, an exact k-value of the foundation is not typically required because the design thickness of the PCC is not significantly affected within the typical k-value ranges achieved by the subgrade and the base layers. diameter loading plate. These are designed based on the working The modulus of subgrade reaction (k) is a required parameter for the design of rigid pavements [AASHTO, 1986 & 1993]. The methods presented in Chapter 4 can be used for the analysis; Kh, varies between 35c and 70c (units of force/length^3) where c is the undrained shear strength. 000 psi Sub base elastic modulus: 400,000 psi See full list on geotechsimulation. The subgrade k- value and the composite k-value which accounts for inclusion of base layer placed over the subgrade, are the key foundation layer input  determines the composite modulus of subgrade reaction. Flexible pavements contain bitumen or asphalt layer as wearing course and supports loads through bearing. BLOCKED PAVING 26 8. Due to the repeated backfill compaction and soil slide, the modulus of subgrade reaction and the pressure distribution of backfill vary with depth. For an actual subgrade, the resulting coefficient of subgrade reaction, k(x), is not uniform in either case. determined theoretically for the soil. 1. 05 inches). 5 times the effective slab depth (e. Modulus of subgrade reaction values were derived from plate load tests. 0 psi k = 0. This is calculated from the Plate Bearing Test results. by adding rubber –coir composite . org pavement, (d) modulus of rupture (flexural strength) of the concrete, and (e) modulus of subgrade reaction. The modulus of subgrade reaction is determined from the field plate bearing load test [Huang, 1993]. Maximum tensile stresses in Feb 13, 2015 · Pressure is a force over an area, so N*m^-2 or in SI units kg*m^-1*s^-2. 6. D. Shallow bedrock 3. (6) Thus, by conducting LWD testing with a 300mm diameter plate, the CBR value can be estimated with the following procedure: Expansion and contraction of the bridge deck affects the backfill soil adjacent to the abutments. Solutions can readily be obtained for other desired variations of k by hand methods or with the aid of electronic computers (5). 2. Flexible and Analysis of FWD data allows for backcalculation of the modulus of the various pavement layers (and the effective structural number of flexible pavements), including the degree of slab support (modulus of subgrade reaction, k) in composite and rigid pavements, as well as evaluation of the performance of transverse cracks/joints in terms of load Modulus of Subgrade Reaction The value of modulus of subgrade reaction k to be used in the design is affected by the depth of bedrock and the characteristics of the subbase layer, if used (AASHTO, 1993). be the equivalent E for the composite rod. In flexible pavement design, resilient modulus is one of five variables used to the following variables: slab bending stiffness, modulus of subgrade reaction, and crack spacing. 31 Unstabilized Value SP4 MSL Design Value Verified MSL Value nt Tensar TX5 Geogrid APLT Field Validation $118,000 in savings 113% Mar 16, 2017 · Categories Civil Engineering Articles, Civil Engineering Articles for Mobile, Civil Engineering Seminar, Geo-technical Engineering, PowerPoint Presentations Tags civil seminar, elastic foundation, Foundation Models, geotech, Modulus Of Subgrade Reaction, PASTERNAK FOUNDATION MODEL, seminar topics, Subgrade Reaction, TIMOSHENKO MODEL 2 Comments Effect of foundation rigidity on stratified roadway roof Apr 01, 2019 · The clay subgrade was compacted at 95% maximum dry density (MDD) maintaining the water content at OMC. 03 MR, (MR in units of MPa) Apr 26, 2012 · The Modulus of Soil Reaction (E') represents the stiffness of the embedment soil placed on the sides of buried flexible pipe. Tia, et al. Research project 0-5832 developed the composite k-value table by the following process: Jun 12, 1992 · subgrade and base requi rements, thickness designs, and compaction requirements, criteria for stabilized layers, concrete pavement joint details, and overlays. (150 ram) The modulus of subgrade reaction is an often misunderstood and misused concept for the thickness design of slabs-on-ground. 31 Unstabilized Value SP4 MSL Design Value Verified MSL Value Layer Coefficient Tensar TX5 APLT Field Validation $118,000 in the horizontal subgrade reaction and the passive earth pressure. Design and evaluation of rigid pavements are based upon the modulus of subgrade reaction (K) as determined by a Improving Design Strategies for Composite Pavement Overlay: Multi-layered Elastic Approach and Reliability Based  The modulus of subgrade reaction (k) is used as a primary input for rigid pavement design. By performing this investigation, correlations were found between the replacement ratio and the settlement reduction factors. occ EVALUATING THE COEFFICIENT OF SUBGRADE REACTION Main problem with the accuracy of k. The modulus of subgrade reaction, k, incorporates any type of material below the HMA pavement and therefore can be considered a composite value. granular piles-weak soil composite. thickness placed directly on the fine-grained, prepared and compacted subgrade. 2 Policy 5. contact area = 3. Based on the modified tests and modeling, an approach for selecting appropriate geofoam design parameters is proposed. The pavement design process requires the designer to Nov 03, 2018 · As discussed above, modulus of subgrade reaction is the ratio between the contact pressure (q) and its corresponding settlement (s). Terzaghi (1955) describes elaborately about the modulus of sub-grade reaction, k, which is a non intrinsic physical parameter of the soil but is found to be inversely proportional to the width of the foundation. 5 times thickness). 3 Modulus of subgrade reaction (k) Table 3. Always consult local building codes (refer to Engineering Bulletin 1). whereby the characteristics of the composite material become suitable for subgrade purposes. It is the ratio of applied pressure divided by the corresponding soil or rock movement. K = 800. 30 rn size. 4 The actual k used in the design of concrete pavements is modified to reflect increased support resulting from frozen subgrade, high-quality subbases and loss of support to develop a composite k (kc). 1 Effective Modulus of Subgrade Reaction (k) Topic 10 – AASHTO Rigid Pavement Design 3. 1) k (pci) = MR/19. The elastic  Modulus of sub grade reaction. 4, 302-1 (step_ÿ__ Exomp le: DsB(Assumed) = 6 inches . 4-5 Unconfined Compressive Strength. Embankment One or more performance criteria used to define the end of the – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow. 3 - 3. Composite k Design If soils are improved, a modified k may be used Modulus of subgrade reaction (k) = 200 pci MOR = 550 psi Tire pressure = 100 psi. Nov 23, 2013 · Additional Design Inputs • S′c = modulus of rupture for concrete • J = joint load transfer coefficient • Cd = drainage coefficient (similar in concept to flexible pavement terms) • Ec = modulus of elasticity for concrete • k = modulus of subgrade reaction Additional inputs reflect differences in materials and structural behavior. /… 0 Antworten: Young's modulus be the equivalent E for the composite rod. Pavement performance can be largely attributed to the care given in designing and preparing its foundation, which is comprised of the subgrade and base layers. , F. It estimates the support the layers below a rigid pavement surface course. The reported correlations between MR values and the modulus of subgrade reaction (k) of roadbed soils. Subgrade: Subbase: Top Layer = Modulus = Thickness = Layer 2 = Modulus = Thickness = Layer 3 = Modulus = Thickness = Composite Modulus of Subgrade Reaction (K-value): k= Concrete Properties Flexural Strength (Modulus of Rupture, MR) = Modulus of Elasticity = Modulus of Elasticity (E) = 6750 x MR Design Features Load Transfer Devices (Dowel Bars Figure 10 Effect of granular sub-base on the modulus of subgrade reaction (k) for Composite Pavements Pavements consisting of mixed rigid and flexible A 150 mm thick rectangular slab of dimensions 6m x 5m is resting on a soil of modulus of subgrade reaction k s = 30000 kN/m 2 /m. 0. Chart for estimating composite modulus of subgrade reaction. 54 MPa for C190 and 2. 873*(subgrade modulus/1000)]^1. Concrete pavement design is based on the modulus of subgrade reaction or “k”. 5-1. Matthew Stuart, P. A composite modulus of subgrade reaction was determined from the combined effective roadway modulus for use in design of rigid pavements for various working Once the composite modulus of subgrade reaction . 0 in. 06+ log10 ∆𝑃𝑃𝑃𝑃𝑆𝑆 4. URETEK 486 Star® It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service. Such curves are useful in expediting rigid pavement thickness design k s = q/δ. This increase is based on the development of a composite k per the AASHTO 1993 Guide for Design of Pavement Structures. 5 mm of displacement then a nonlinear behavior until rupture. 350. Use AASHTO Chapter 3, Table 3. This test procedure and the The composition and structure of flexible pavement consists of surface course, binder course, base course, subbase course, frost protection course, subgrade. ACI The modulus of subgrade reaction is an often misunderstood and misused concept for the thickness design of slabs-on-ground. 12 and 4. 4, (MR in units of psi), or (Eq. Remaining life estimate predicted fr pavement condition factor 112. There are four types of two-way slabs. In situ Composite Resilient Modulus (Mr -Comp) at 5 psi to 40 psi cyclic stresses at surface • APLT – In situ Layered Resilient Modulus (RAP+PGE and Subgrade) at 5 psi to 40 psi cyclic stresses at surface • APLT – In situ modulus of subgrade reaction (static k -value) • DCP – CBR of RAP+PGE and Subgrade • LWD – where is the modulus of subgrade reaction for the . Output results for composite design â ¢ Total number of trucks in design lane over 20 subgrade reaction is a poor model of the behavior of an actual soil subgrade, a fact recognized for more than 50 years. Although not common any more, WSDOT still has an R-Value procedure (T 611). , how well a soil is able to return to its original shape and size after being stressed) under repeated loading. The persistent obstacle in such processes is to find a valid approximation for soil representation. 38 Composite Modulus Versus Radial Distance Plot . Type of Soil Subgrade Strength The two methods show similar trends, although the finite-element technique appears to be siffer than Westergaard's theory. LOCATION. Contents:Composition and Structure of Flexible Pavement1. f oundation and the shea r modulus of the subgrade. These. Figure '3. 4. If the existing pavement structure consists of a concrete pavement that was overlaid with asphalt and the asphalt layer is not bonded to the old concrete pavement, then the concrete layer should be •Determine the modulus of sub-grade reaction Modulus Subgrade Modulus Traffic PCC –Flexible, rigid, composite Jun 20, 2017 · k = Modulus of subgrade reaction, MPa/mm (lbf/inch²/inch). 1, P. 300. One table is used for untreated subbases   Analysis of FWD data allows for backcalculation of the modulus of the various pavement layers (and the effective structural number of flexible pavements), including the degree of slab support (modulus of subgrade reaction, k) in composite  0. 5 % of all the test values. (1 million to 200 millions) and composite K-values of 300 pci, 500 pci, 800 pci, and 1,000 pci. Appendix A contains a list of referenc es used in this manual. (1): p ¼ K hy ð1Þ where p is the soil resistance per unit length of the pile, K h is the modulus of subgrade reaction, and y is the lateral deflection of the pile. Surface Course2. HMA surface temperature below 120 F before paving. Holland, P. 4, Elastic constants includes Young's modulus, shear modulus, Poisson's raito, bulk modulus, and Lame's constnat. For the design of rigid pavements in those areas where no previous experience regarding pavement performance is available, the modulus of subgrade reaction k to be used for design purposes is determined by the field plate-bearing test. Stabilized Subgrade – Lime, Fly Ash, Cement, Cement Kiln Dust, etc. analysis. Composite Pavement: A pavement structure consisting of an asphalt concrete wearing surface on top of a hydraulic cement concrete slab. Composite modulus of subgrade reaction needed in the design of rigid pavements can be estimated from the resilient moduli of geosynthetic-reinforced layer and an assumed soft subgrade modulus. foundation is a composite s. The method In case the design is to be performed without the presence of sub base, the composite modulus of. Composite Modulus of Subgrade Reaction (kc) 301-2 January 1999 Ref. However, due to time and expense, plate load tests are rarely performed and the values used in design are based on correlations to other soil parameters. 150. A geotextile was used as a separator between the geocell-reinforced RAP layer and the subgrade. The thickness of the subgrade can be reduced by incooparating the composite at the optimum position Keywords— rubber coir composite, California bearing ratio, optimum position, subgrade I. the opening created by the RC walls on all four sides and the base elastic foundation, the modulus of subgrade reaction k and the shearing interaction between the loaded face and the core Gb, are strictly connected to the geometrical and mechanical properties of the soft core material. 1 Concrete Pavements When select material is placed according to FDM 11-5-15, the modulus of subgrade reaction (k) should be increased to 375. Research on equivalent physical properties prediction of composite began in 1906 []. 1-3. Relationship Between Equivalent Cracked Section Modulus and . Composite Plates,” Composite Structures, Vol. The composite modulus of subgrade reaction, k-value, and equivalent elastic modulus E for HAM-75-2. the modulus of subgrade reaction of the slab foundation 3. This composite modulus depends upon the resilient modulus and thickness of the subbase, modulus of  velop curves for composite modulus of subgrade reaction versus subbase thick- ness. 4 302-1 ste 3 I. As more and more engineers will use software to design foundations, it is essential for engineers to have a fundamental understanding of this soil Basically, the steps are as follows: Determine the roadbed resilient modulus and the subbase elastic modulus and use these values along with a projected slab thickness to graphically determine a “composite modulus of subgrade reaction” (k:). In the geotech world, the modulus of subgrade reaction, k, would have a typical value between 150 and 300 pci for your noted soil. 3. 39 PSI Load Transfer Coefficient Composite Modulus of Subgrade Reaction Loss of Support Effective Modulus of Subgrade Reaction Minimum thickness = 8’’ 15. improved protection of the subgrade, a stronger support to the PCC slabs, and result in an increased composite k-value. Some soils may resist them and some may not. The unconfined compressive strengths of the saline soil solidified by the new cementitious composite The modulus of subgrade reaction (k) is primarily a mathematical expedient. M R is a basic material property that can be used in mechanistic analysis of multilayered systems for predicting roughness, cracking, rutting, faulting, etc. 10 Anti-skid Treatment 25 7. 18 R M k = • Correlation based on 30-in plate-load tests • k value becomes too high because k=fnc(1/a) • More accurate k if plate test was run w/ bigger plates The goal at each site was to perform cyclic APLTs to determine stress-dependent composite and layered resilient modulus (Mr) using a 12 in. Record URL: Figure 2. ) and cement treated soil (100 k. This assumption is based on a recommendation from the Dallas District Laboratory. Loads imposed by the use and occupancy of the structure. COATSWORTH Paragraph 15: Are the sub-grade reaction values in Figure 3 which appear to relate to a Young's Modulus of about 900 MN/m^, static or dynamic values? MR. The ∆k can The composite system (consists of piles, slab, and soils  4. e. Simulation of composite modulus of subgrade reaction - max. Terzaghi in 1955 (Ref. a) Modulus of subgrade reaction (k), b) Composite modulus of subgrade reaction (if subbase layer is present) (k c), c) Loss of support (LOS), and d) Coefficient of drainage (C d). Let k1 be the subgrade reaction for a plate of size 0. ESB, = subbase elastic modulus (psi). Slab is considered as unreinforced concrete beam, so that any contribution made to flexural strength by the inclusion of distribution reinforcement is neglected. An optimum moisture content of 21% and the maximum dry density of 1. Binder Course3. KEY WORDS: clay (Taylor marl), deflection and stress, discrete-element solu­ tion, subgrade support, modulus of subgrade reaction k ,plate load tests, The modulus of subgrade reaction ks is a function of the contact pressure and allowable settlement on an unit area of soil. Reaction Stacked Plates Pressure Gage Subgrade Plate-Load Test It is important to understand how different types of concrete slabs are applied to help project teams design and construct the right type of slab for long-term performance. The top slab is continuous and covers . Finally,some suggestions are given to determine K. 4 Minnesota R-value determined from modulus value (R = [0. 4-3 4-3. The frost susceptibility of the subgrade soils and the drainage conditions are other critical  1 Apr 2012 13. The volume of traffic during the design life is important for fatigue consid-erations. The k-value can be determined by field tests or by correlation with other tests. the design traffic volume 4. It was noted that the value of k can be affected by the area of foundation base. DEFENITION. Another known method for determining composite soil stiffness is the use of plate bearing tests on the surface of soil layers. The value of non-dimensional parameters varies due to the change in modulus of subgrade reaction for addition fiber of different percentage, length and thickness. 2), who stated that the subgrade reaction should be determined by a load test but failed to mention This composite modulus depends upon the resilient modulus and thickness of the subbase, modulus of subgrade reaction, and base/subgrade loss of support during pavement life. 4 Approximate composite k (psi/in. Since the total elongation is constant, Σ L i /E eq = Σ (L i /E i) (9) Therefore, E eq = ΣL i /Σ (L i /E i) (10) Thus, the equivalent modulus of elasticity is the weighted harmonic mean of the individual rod’s Concrete pavement design is based on the modulus of subgrade reaction or “k”. b. c. Design resilient modulus is defined as the modulus value that is smaller than 60, 75, or 87. 1 Rigid Pavement Types ♦ 1. L Elastic Modulus of Concrete E c 3,600,000 psi E c Coefficient of Thermal Expansion CTE 5. For a uniformly loaded flexible foundation, contact pressure remains uniform throughout the foundation, but settlement decreases from the center towards the edge, so q/s or modulus of subgrade reaction increases from the center towards the edge (Figure 2). hmin = (inner perimeter of slab panel)/180 ≥ 90 mm. The magnitude of (k) typically ranges from about 100 to 250 pci, sometimes higher, depending on the subgrade materials and conditions. Plate load test results were used to calibrate a numerical model. Pavement Thickness . 2), who stated that the subgrade reaction shoul d be determined by a load test but failed to mention that the tested results depend on the size of the loaded area. Standard Proctor compaction and CBR tests were carried out at the laboratory for this subgrade. 39. ® ® ® ® ® modulus (Mr) is a measure of a material’s stiffness and can provide an indication of the condition and uniformity of a material. Parameters (a) to (c) were determined using falling weight  12 Jun 2020 Department of Steel and Composite Structures, Faculty of Civil Engineering, Vilnius Gediminas. The methods of determining K value and some factors affecting precise determination K value are analyzed. modulus of subgrade reaction (k value) natural soil, embankment, rigid substrate. modulus of sub-grade reaction . Although new construction of composite (AC/PCC or PCC/PCC) pavements is not common, a substantial amount of knowledge has been acquired over the past 35 years regarding the materials, design, and construction of composite pavements. This result is independent of the modulus of the asphalt concrete layer, of the bond between the two layers and of the type of pavement considered, rigid or composite. Foundation soil coefficient of subgrade reaction is an important computation parameter in geotechnical engineering. 1-4. This value is not directly related to bearing capacity and k does not tell the designer if there is compressible or expansive soil. DSB, = subbase thickness (inches). To characterize the stiffness of the system, a “composite” stiffness is defined in a way similar to that of the modulus of subgrade reaction, for which a plate is placed on the pavement for loading. Technical soil elasticity modulus E. They have low flexural strength. 6 Properties of Concrete 23 6. The modulus of rigidity is of 1. 2 Apr 2019 Resilient modulus (MR) is used for flexible pavements and modulus of subgrade reaction (k-value) is used for rigid/composite pavements. The study shows that (1) with a constant modulus of subgrade reaction, a linear increasing LFP and elasto-plastic p ~ y curves, the response of laterally loaded rigid piles can be well predicted in the framework of load transfer approach; (2) the gradient of the LFP is 0. 15 [m] is chosen under the footing and is not considered in any calculation. P. DBCONPAS M. ) Example: Subbase thickness=10” Subbase modulus=30,000 psi Subgrade M R=10,000 psi To get k: Cut across the E SB Cut across M R to the TL The composite modulus of subgrade reaction is defined using a theoretical relationship between k values from plate-bearing tests (ASTM D 1196 & AASHTO T 222), or estimated from the elastic modulus of subgrade soil (MR, AASHTO T 292), as: (Eq. And since “k” is a measurement of real deflections (or slab settlement) to real pressures, the value of “k” that might have been 200 pci elsewhere becomes only 20 pci beneath a warehouse slab! By Wayne W. In modeling a nonrigid mat foundation by using elastic springs, should a uniform modulus of subgrade reaction be used along the whole base of mat? What are the Adjustment Factors to be done in Design Values? Composite Construction; Hudson’s formula and Van der Meer formula are commonly used in the design of armour. Move to right to eff. A 6 inch (150 mm) granular base, item 304, is recommended as a subbase under all concrete pavements to prevent pumping. This is illustrated using the two limiting cases of a flexible and rigid foundation as shown in Figure 2. What it does is indicate how stiff the subbase/subgrade is over small deflections (about 0. thick JPCP layer with a 15-ft joint spacing and dowel diameter of 1. Keywords subgrade, geosynthetics, reinforcements, expansive soils, CBR value Modulus of subgrade reaction (k-value) measured using a 30 in. Jul 15, 2016 · Composite Modulus of Subgrade Reaction (K c): A value used in rigid pavement design determined by dividing the load on a subgrade by the deflection, corrected for the effect of a base. d. 5 in = 100 psi / in. Correlation Between Resilient Modulus of Elasticity and Static . To evaluate grouting treatment for composite pavement accurately and then to optimize the grouting scheme, the modulus of subgrade reaction (the k-value) was proposed as the evaluation criteria of grouting treatment. ” NAVFAC Chapter 4 presents traditional elastic modulus of subgrade reaction equations. K 762 is defined as the stress σ (in kPa) that causes 1. 1 Pavement WithoutSubbase If there is no Subbase, AASHTO suggests: • Correlation based on 30-in plate-load tests • k value becomes too high because k=fnc(1/a) • More accurate k if plate test was run w d400N ⋅k value, where k is the value of the modulus of foundation reaction [Figure 5]. where p is the contact pressure, h is the slab thickness, and k is the modulus of subgrade reaction, which relates p to the slab deflection and is the composite modulus of the subgrade and subbase. 38. Each pavement design must be Trial composite design â ¢ Upper PCC: 3-in. 61 g/cm3 were found at the optimum moisture content. 4 Gpa (a)Calculate the modulus of elasticity of the composite in the longitude direction (b)If an external tensile force of 12500 N is applied along the. It is depends upon the interrelationship of texture, density, moisture content and strength of subgrade. On the other hand, the safe bearing capacity is the maximum pressure which the soil can carry safely without risk of shear failure. 1a) k (MPa/m) = 2. FDM 14-5 Subgrade and Base Course Page 2 5. ) [2]. Many engineers are not familiar with this term and often try to compare it with bearing capacity. Subgrade Stabilization – Soil Binder added to upper 6” of granular. 73, No. Section & Figure 301. walls, top slab and base slab. SUBGRADE SUBBASE BEDROCK k If subbase exists, need to determine the composite modulus of subgrade reaction (k) Topic 10 – AASHTO Rigid Pavement Design Figure 12. The theory of elasticity simply explains the subgrade reaction coefficient. 50. That's typically used for pavement design. 34 Example Dec 15, 2019 · Regarding the modulus of subgrade reaction, the author recommends the use of Vesic’s (1961) formula but in combination with the proper equivalent elastic constants. Jan 09, 2017 · Modulus of subgrade reaction ("k") is used to represent the subgrade. The k value is determined directly by full-scale plate load tests. /in. The pressure beneath a given slab under a load can be determined using the following formula, found in the Theory of Plates on Elastic Foundations , as Composite Modulus of Subgrade Reaction (kc) : 30,000 psi 1,200 psi = 400 301-2 Jul 2008 Reference Section & Figure 301. In the analysis the core material is assumed to be isotropic, Mr of the subgrade Mr composite modulus Modulus of subgrade reaction (k) ev1 and ev2 strain modulus testing Resilient deflections (scaling exponent) Automated Plate Load Testing Summary Hunt Highway, Arizona 0. Sep 09, 2017 · However, these computer programs often ask for an input called “modulus of subgrade reaction”. All three types of subgrade stiffness/strength tests are used in Washington State to some degree. The whole mechanical behavior or mixed material macroscopic mechanical properties was not the same as any component materials; however, they are affected by the formation of various components that commonly play a different role in a complex system [10, 11]. Jul 07, 2015 · MR A. 8 Types of Concrete Pavements 24 (a) Unreinforced Concrete Pavement (b) Jointed Reinforced Concrete Pavement 6. The Resilient Modulus is a basic subgrade soil stiffness/strength characterization commonly used in structural design of pavements. Estimates of k values for concrete slabs over geofoams, assuming composite subgrades, were obtained from the calibrated numerical models. After the geogrid and crushed miscellaneous base placement the APLT tests measured the stress dependent resilient modulus of the: • Composite crushed miscellaneous base, geogrid, subgrade • Crushed miscellaneous base; and • Subgrade. Rigid pavements or composite pavements with a Modulus of Rupture (3-point bending, 14-day average) MOR 750 psi MOR FRC Residual Strength Ratio 20% Remaining Thickness of Asphalt h ac 3. Please consult your GCP Applied Technologies sales representative for proper addition rate of STRUX 90/40 for your application. T Der modulus ist nicht gleich dem Betrag einer Zahl, der Betrag von (-5) beispielsweise ist 5… 3 Antworten: modulus of subgrade reaction - Bettungsmodul [Bodenmechanik] Letzter Beitrag: 24 Jul. thickness. 09, 11:24: The modulus of subgrade reaction (k) is used as a primary input for rigid pavement design. 2 and Figures 3. the axle load spectrum The modulus of rupture is just the average 28-day modulus of rupture obtained from third-point loading of concrete beams. When the pavement support system, which includes the subgrade and/or base beneath the slab, contains a base material, the design or evaluation is based on an effective K, which is a function of the subgrade K and the thickness of the base. The spring stiffness, or modulus of subgrade reaction, is defined as the ratio of the soil reaction per unit length of the pile as described in Eq. ). MR, = subgrade resilient modulus (psi)  Answer to Determine composite modulus of subgrade reaction, kc. 40. Output results for composite design â ¢ Total number of trucks in design lane over 20 May 11, 2013 · Rigid Pavement Design Design Parameters Modulus of Rupture 700 psi Modulus of Elasticity 5,000,000 psi Drainage coefficient 1 Overall standard deviation 0. The thermal effects are not considered. Now, the Composite Modulus of Subgrade Reaction for the ACP, LTS and natural ground, kB, can be calculated. , F. modulus of ‘subgrade’ reaction and the deflection. 300) attributed this confusion to the initial work by Hayashi in 1921 (Ref. The Mechanistic-Empirical Pavement Design Guide provides useful prediction models, 2. 4kN/M3 4and modulus of subgrade reaction (K) is 16. To obtain an optimal predictive function for estimating the moduli of the subgrade and base, two approaches were evaluated for real-time backcalculation: a genetic programming (GP Oct 17, 2002 · Bonded over Asphalt/Composite Keys to Success Bonding is critical Small square panels reduce curling, warping, & shear stresses in bond (1. The idea here is that the subgrade will offer greater stiffness of the asphalt concrete which in turn affected the composite k-value of the two-layered system investigated. Consider pavement design inputs for subgrade support • Modulus of subgrade reaction, k Consider subgrade support and stabilization requirements with respect to: • Need for subgrade stabilization • Stabilization admixture(s) stabilization • Stabilization depth Estimate “subgrade support” for various Jul 12, 2014 · Several methods have been used to predict the response of the composite pile–soil system. 13) presses a steel bearing plate into the surface to be measured with a hydraulic jack. 300) attributed this confusion to the initial work by Hayashi in Modulus of Subgrade reaction - Which one to use Feb 01, 2010 · k Modulus of Subgrade Reaction in pci lbs Pounds min Minute p Pervious concrete is a composite material consisting of coarse aggregate, Portland cement, and water 31 Modulus of Subgrade Reaction (k) The modulus of subgrade reaction (k) is used as a primary input for rigid pavement design. A thin plain concrete of thickness 0. Between the body and the coating is an interlayer, which is modeled by a Winkler body with one modulus of subgrade reaction. 2. com - id: 21bc87-ZDc1Z indicates a lower stiffness of the system which consists of pavement, base, and subgrade layers. However, with the introduction of the Mechanistic-Empirical (ME) pavement design, there is a need for improved and more appropriate methods of subgrade characterization, for prediction of future pavement conditions Out of various subgrade systems composite reinforced system at position of h/5 gave the maximum CBR value and its calibration with modulus of subgrade reaction (K) was quite compatible. 100. NDT also allows for evaluating the pavement layer load transfer efficiency, effective modulus of subgrade reaction, and elastic modulus. a) Modulus of subgrade reaction (k), b) Composite modulus of subgrade reaction (if subbase layer is present). The highest increase in the CBR value was obtained when composite placed at 20% depth from the top of the specimen. If a base is used kc is input into the equation rather than k. â ¢ Base: 8-in. 28) 5 MnPAVE-Rigid design procedure for PCC bonded overlay over HMA uses the ACPA procedure to determine composite k-value Subgrade A-7-6 clay, locally known as Keats Pit clay in Manhattan area of Kansas, was used as subgrade. Static plate load testing has traditionally been This paper discusses the variation of the Modulus of subgrade reaction (k) backcalculated from slab deflection basins, interactive with the location of the Falling Weight Deflectometer (FWD) load pulse, and curling of slabs due to daily temperature variations. Evaluate the response of the slab when subjected to a full pressure load of 35 kN/m 2 all over the surface and a concentrated load of 200 kN at the centre. Mar 06, 2020 · respectively, or a composite of the two. The modulus of subgrade reaction (k) is used as a primary input for rigid pavement design. ) values according to subgrade and subbase system In this mode of failure, foundation fails due to formation of inclined cracks around the perimeter of the column. The subgrade reaction modulus is utilized for comparing the findings of finite element analyses and the foreseen values from the analytical solutions for an optimum value of reinforced soil. e. Modulus of subgrade reaction, k pounds per square inch of pressure per inch of deflection, commonly written in pci Standard method for field measurement 30-inch diameter bearing plate k -values K - Value. is determined, Figure 1 was used to correct the mod-ulus of subgrade for the potential loss of support (LOS) due to pumping, etc. com See full list on apps. Micropile Design Spreadsheet Instructions for Use of Figure 7b: 1. Additionally, the modulus of subgrade reaction used for design (effective modulus of subgrade reaction) can be enhanced by using a crushed stone course (untreated or cemented). Based on the unconfined compressive strength value, the initial modulus of subgrade reaction of the unimproved ground is taken as 20,000 kN/m 2 /m (from the available range). Be sure to leave 3” of HMA after milling. Required. WSDOT uses the resilient modulus when possible, while many geotechnical firms typically use CBR. Composite modulus of subgrade reaction (kc) ‐ kc is the composite modulus of the subbase materials, which will take into account any base placed on top of the subgrade. Voids under a concrete slab are common in composite pavement because of difficulties in controlling grouting treatment. 1 Pavement Without Subbase If there is no Subbase, AASHTO suggests: 8. Consequently, considering the potential activity of the waste slag and magnesia, new cementitious composite materials used in solid saline soil were developed in our study. equals a constant and k = nhx; nh is the eoefficient of horizontal subgrade reaction (1)· The latter is a linearly increasing modulus w;i. modulus and it Modulus, of Subgrade Reaction is a follows kMR/19. relations is related to evaluation of E. But in many The subsoil model used in the analysis of the footing is represented by isolated springs, which have a modulus of subgrade reaction of k s = 50000 [kN/m 3]. This number was compared to typical values found in stabilized soil cement (200 k. However, these design charts were developed based on non-stabilized subbase over Determining Composite Modulus of Subgrade Reaction by Use of the Finite-Element Technique JOSE LUDWIG FIGUEROA A finite-element computer program for rigid pavement analysis was used to de­ velop curves for composite modulus of subgrade reaction versus subbase thick­ ness. Base and subgrade layers must provide adequate and moisture resistant strength that meets the design modulus, in addition to durability and stability. i. Parameters (a) to (c) were determined using falling weight deflectometer (FWD) and dynamic cone penetrometer (DCP) tests (Figures 1 and 2), Nov 24, 2017 · where K 762 is the modulus of subgrade reaction (kN/m 3) for the 762mm plate. The coating is modeled by a thin plate. Against many popular opinions, modulus of subgrade reaction is not an exclusive property of a soil, but depends mainly on the loaded area (size of the footing or mat). S. So, proper examination should be done on subgrade before k=modulus of subgrade reaction (pci) AASHTO Guide for Design of Pavement Structures, Supplement (1998) In 1998, revisions were made to the AASHTO design model for concrete pavements based on work performed under NCHRP Project 1-30 (Darter, Hall, and Kuo 1995) and field-validated using data from the Long-Term Pavement Performance (LTPP) GPS-3 Floor slabs can range from a simple residential basement slab to a heavy-duty industrial floor. 1 Plate Load Test The plate load test (see Figure 4. existing . Composite Materials Given the material properties of a unidirectional lamina this calculator constructs the stiffness matrix C and the compliance matrix S of the lamina in  stiffness of the asphalt concrete which in turn affected the composite k-value tion, subgrade support, modulus of subgrade reaction k ,plate load tests, testing program was used to evaluate the sub grade reaction k-values utilizing. Elastic Modulus Prediction of Soil-Rock Mixture. 22 0. The modulus of subgrade reaction is a calculation expedient, and nothing more. The rigid pavement design procedure presented herein is based on the critical tensile stresses produced within the slab by the vehicle loading. 9 Panelling Design and Joint Construction 25 6. th respect to depth as shown in Figure 4b. 25-in. 50E-06 in. E. The thickness of the ACP will be six inches for the main-lanes and four inches for the WAPA Pavement Note on Subgrade Stiffness/Strength Tests. RCC design excel sheet send please [email protected] existing elastic modulus and modulus of subgrade reaction. Move to right to post spacing, y = 4. 116. be converted to a subgrade reaction (K-value) for the design of rigid or composite pavements. This recommended value assumes the mat foundation is bearing on a 2-foot-thick layer of crushed stone constructed on the compacted native soils. See full list on structuremag. the depth of the pile. s. 2 days ago · Also it was aimed to compare the results with those given by Westergaard’s solution and IRC 58 – 2002 design charts. NEWELL The moduli of sub-grade reaction shown in Figure 3 of the Paper are static values which were used for the dead and live load analysis. pavement, (d) modulus of rupture (flexural strength) of the concrete, and (e) modulus of subgrade reaction. The granular base is required for concrete pavement built  largest increase for the geogrid. 4 Composite Modulus of Subgrade Reaction The composite modulus of subgrade reaction (k c) represents the combined effect of the subgrade stiffness or subgrade modulus of resilience, as discussed in Section 203. This tool will then conduct a modulo operation to tell you how many times the second number is divisible into the first number & find the remainder after division is complete. 18 3. 5 Modulus of Subgrade Reaction 23 6. 30 x 0. 1, and the stiffness, or elastic modulus, and thickness of the subbase material. ϖ assuming a semi – infinite subgrade depth . s. K . Composite k-value will be calculated by the TxCRCP-ME design program based on the inputs of thickness of the stabilized base, elastic modulus of stabilized base, and subgrade soil classification. Mar 04, 2013 · For rigid and composite pavements, the deflection basin AREA and the static modulus of subgrade reaction, k, are used to quantify overall structural condition. On the basis of the plate tests, it was concluded that the plate stiffness can influence the test results. Founda 4-2. Yes. Backfill compaction due to deck expansion and soil slide due to a deck contraction is repeated. 4 The actual k used in the design of concrete pavements is modified to reflect increased support resulting from frozen subgrade, high-quality subbases and loss of support to develop a “composite k” (kc). 3# Determine#modified#k#=#f(depth#to#rigid# foundation)TFigure#3. Hence elongation for the composite rod can be expressed as ∆L = σ Σ ?L i /E eq. Design Chart for Rigid   3. The subgrade was placed in three equal lifts by compacting each lift using a vibratory compactor. Modify this k: to account for the effects of a rigid foundation near the surface. The majority of state highway agencies and private engineering companies have the required equipment and personnel available. The initial modulus of subgrade reaction of weak soil can be calculated by one of the methods granular piles-soil composite behaves like a uniform soil mass with composite modulus of elasticity. 10 For equal deflections 11 From the AASHTO Design Guide Generally, Eo Composite Modulus of Subgrade Reaction Versus Subgrade Modulus Versus Station Plot . Subgrade: Consists of the naturally occurring material on which the road is built, or the imported fill material used to create an embankment on which the road pavement is constructed. 5 Input variables and values for composite k-value computation (Ha subgrade stiffness in terms of modulus of subgrade reaction and combine with subgrade reaction k-value can be obtained with a known modulus of concrete E,. , while strain modulus (E v) with one or two quasi-static load cycles using a 12 in. E' varies with the type of embedment soil and with the degree of compaction. 64 ~ 3. for a rigid pavement whose input data include: Sub base thickness: 20 May 2012 Simulation of composite modulus of subgrade reaction - max. 12 0. Mill if necessary to correct crown, remove surface distresses, improve bonding. AN. Where; k s = Coefficient of subgrade reaction expressed in force/length 2 /length q = pressure on the surface at the given point δ = settlement at the same point. Similarly, the modulus of subgrade reaction for a long plate resting subgrade reaction, fe', at the depth D is related to the modulus of subgrade reaction which occupied an area of 55 m X 21 m was of composite construction , con. For the design of rigid Modulus of Elasticity Subgrade Reaction . BLEM. Elastic constants includes Young's modulus, shear modulus, Poisson's raito, bulk modulus, and Lame's constnat. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service. where is the modulus of subgrade reaction for the . Under the action of a rigid stamp on the coating, the process of abrasive wear Subgrade Properties Modulus of Subgrade Reaction, k-value Plate load on subgrade k = Plate deflection on subgrade 5. /°F CTE Elastic Modulus of Asphalt E AC 350,000 psi Modulus of Subgrade The Elastic Modulus of Subgrade Reaction (k) is a required design input that represents the response of the subgrade to traffic loads. Modulus of Subgrade Reaction Which One Should be Used By Wayne W. modulus of subgrade reaction (K) is determined. Table 6. For rigid  largest increase for the geogrid. Plate load tests resulted in low k values for all geofoam grades. J. 4-4. The present study describes the experimental and numerical studies performed on the geosynthetic reinforced subgrade subjected to repeated vehicle loads. ACI and Jerry A. 41+0. Nominal axle modulus of sub-grade reaction ( Keff) is developed for rigid pavement design. (762 mm) diameter plate subjected to static load steps is used in rigid pavement design in the U. Area of base outside of peri Evaluation of modulus of elasticity and modulus of subgrade reaction of soils using CBR test EE Putri, N Rao, MA Mannan Journal of Civil Engineering Research 2 (1), 34-40 , 2012 Modulus of Subgrade Reaction for Mat Foundation Design . References. The subgrade reaction modulus for the geogrid-reinforced sand footing system was calculated in terms of the stated before analytical solutions Huang and The mechanical contact interaction of bodies with a thin composite coating is investigated with account of wear. Expansion and contraction of the bridge deck affects the backfill soil adjacent to the abutments. 305 m. Pavement stresses. 96x10 kN/M3. In the composite ground pile method, therefore, the necessary range of ground improvement, i. It doesn’t matter what the “real” subgrade modulus value is, and it doesn’t matter that it is applied with a different set of guidelines for lightly loaded slabs-on-grade vs. A cumulative distribution curve of SN eff and M r was developed for all flexible pavements in the study. 4, In the past, traditional geotechnical exploration and testing methods have been used to characterize existing subgrade conditions. 3) method was used to compute the composite - modulus of subgrade reaction using the remaining asphalt thickness, modulus of elasticity for the remaining asphalt, and the existing subgrade modulus. In a Winkler type of analysis, the proper elastic modulus is the one corresponding to Poisson’s ratio, ν, equal to zero. Subgrade Preparation – Topsoil removed and top 6” of soil compacted to Optimal Moisture and Stiffness. From the analysis of variance, the most significant variables, which ex­ plained around 90 percent of the variation in deflection and principal moment (stress) responses, were slab bending stiffness and modulus of subgrade reac­ References: "Concrete Floor Slabs on Grade Subjected to Heavy Loads" Army Technical Manual TM 5-809-12, Air Force Manual AFM 88-3, Chapter 15 (1987) which compares a multitude of design parameters of the modified subgrade to those of the unmodified subgrade to determine the impact of ground modification. Nov 14, 2012 · Composite Modulus of Subgrade Reaction, k. acpa. The modulus from the combined effective roadbed modulus chart is then used in the AASHTO nomograph equation when determining the required SN of the pavement. 5% fiber, the ultimate bearing capacity is found to be 1900kN/M3 corresponding to for AASHTO (Section II39, figure 3. It is also known as Pressure per unit settlement. can be examined. 2 Pavement With Subbase (cont. CBR is a simple penetration test for evaluation of the mechanical strength of the subgrade and base course materials. Second, if you’re going with GPa, all of these values of Young’s modulus are off by an order of magnitude. 30 m size. However, subgrade stabilization should not be attempted unless the costs reflect corresponding savings in base-course, pavement, or drainage facilities construction. Maximum tensile stresses in Saline soil affected by earthquakes and groundwater can lead to subgrade subsidence and collapse in highway construction. It is directly affected by the size of the loaded area, the soil or rock shear modulus (which is strain dependent), the direction of loading, the type of loading - and many other Determine the roadbed resilient modulus and the subbase elastic modulus and use these values along with a projected slab thickness to graphically determine a “composite modulus of subgrade reaction” (k:). Out of various subgrade systems composite reinforced system at position of h/5 gave the maximum CBR value and its calibration with modulus of subgrade reaction (K) was quite compatible. By considering the composite action of the concrete slab and geofoam, higher resilient modulus and modulus of subgrade reaction values were obtained. The conversion from resilient modulus of the subgrade to k-value was updated in the fall of 2011 to better reflect  7 Feb 2020 2. The backcalculation of a two-layer plate on grade is based on the approach proposed by Ioannides and Khazanovich. 0 times that of the Barton LFP; and (3) the gradient of the LFP and subgrade between the CGEs. composite modulus of subgrade reaction

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