: Modeling the resilient modulus of soils. In this paper subgrade materials from different locations in Nigeria were characterized for use in the Mechanistic-Empirical Pavement Analysis and Design. A conventional flexible pavement consists of a prepared subgrade or foundation and layers of sub-base, base and surface courses (AASHTO 1993). $$ M_{R} = k_{1} P_{a} \left( {\frac{\theta }{{P_{a} }}} \right)^{{k_{2} }} \left( {1 + \frac{{\tau_{oct} }}{{P_{a} }}} \right)^{{k_{3} }} $$, The resilient modulus of coarse-grained soils obtained in the laboratory were statistically analysed. To be able to adopt the Mechanistic-Empirical pavement design method for use in Nigeria, calibration of the subgrade material models to reflect Nigerian conditions need to be carried out. Characterization of pavement materials is a key requirement for the pavement design process. Nuggets like the one on the bottom of 364 is another way to partially bridge the gap. B resilient modulus model parameters k3, Histograms of NCHRP resilient modulus model parameters k1, Histograms of NCHRP resilient modulus model parameters k2, Histograms of NCHRP resilient modulus model parameters k3. 115–124 (2004), Ooi, P.S., Sandefur, K.G., Archilla, A.R. The specific use of the word scary comes from my knowledge regarding the paper found at the website below (see page 7). I really appreciate the author's paragraph at the bottom of page 364. Balkema Publishers, Rotterdam, the Netherlands (2002), Ooi, P.S., Archilla, A.R., Sandefur, K.G. 2003). Access Click Loads Special Loads Soil Pressure. Honolulu: Report No. Therefore, indirect methods (correlations) of measuring the elastic parameters are used to develop compressibility parameters (elastic modulus, Poisson’s ratio, etc. the soil modulus or soil stiffness (More information on the Modified Iowa Formula can be found in Rinker Materials Info Series #204). oldestguy (Geotechnical) 16 Nov 16 14:22. con. Histograms of Uzan resilient modulus model parameters k1, Histograms of Uzan resilient modulus model parameters k2, Histograms of Uzan’s resilient modulus model parameters k3, Histograms of Witczak and Uzan resilient modulus model parameters k1, Histograms of Witczak and Uzan resilient modulus model parameters k2, Histograms of Witczak and Uzan resilient modulus model parameters k3, Histograms of Pezo’s resilient modulus model parameters k1, Histograms of Pezo’s resilient modulus model parameters k2, Histograms of Pezo’s resilient modulus model parameters k3, Histograms of Ni et al.’s resilient modulus model parameters k1, Histograms of Ni et al.’s resilient modulus model parameters k2, Histograms of Ni et al.’s resilient modulus model parameters k3, Histograms of Ooi et al. 1131–1142. By joining you are opting in to receive e-mail. The bulk modulus K' relates the change in stress to the volumetric strain. The k used for pavement design has nothing to do with the k used in settlement analysis, but some engineers are often confused and do not separate the two domains. ), see Sabatini et al. FAQ731-376: Eng-Tips.com Forum Policies. I hope your allowable stresses in the building are selected with a better system than by making use of a general cook book value like this K value. Clearly the correlation between k from a 30" circular plate (pavements?) Over 10 million scientific documents at your fingertips. This service is more advanced with JavaScript available, GeoMEast 2017: Soil Testing, Soil Stability and Ground Improvement Explore global and U.S. market trends that are driving new thinking, designs, and technologies for the truck and bus, automotive, marine, and rail industries. Oldestguy, thanks for the response. $$ M_{R} = k_{1} P_{a} \left( {\frac{\theta }{{P_{a} }}} \right)^{{k_{2} }} \left( {\frac{{\tau_{oct} }}{{P_{a} }}} \right)^{{k_{3} }} $$, $$ \tau_{oct} = \frac{1}{3}\left( {\left( {\sigma_{1} - \sigma_{2} } \right)^{2} \left( {\sigma_{2} - \sigma_{3} } \right)^{2} \left( {\sigma_{3} - \sigma_{1} } \right)^{2} } \right)^{1/2} $$. University of Wisconsin, Department of Civil Engineering and Mechanics. © 2020 Springer Nature Switzerland AG. No such luck from Das :(. $$ M_{R} = k_{1} P_{a} \left( {\frac{{\sigma_{3} }}{{P_{a} }}} \right)^{{k_{2} }} \left( {\frac{{\sigma_{d} }}{{P_{a} }}} \right)^{{k_{3} }} $$. This ensures a more accurate assessment of the modulus during the analysis over the design period including seasonal variation and varying stress conditions. Even in school I've always understood geotechnical engineering to be one of the more experience based sub-disciplines within civil engineering. Seven selected resilient modulus constitutive equation for estimating the resilient modulus of coarse-grained subgrade soils were used to estimate the default values using the repeated load triaxial test result conducted on coarse-grained Nigerian subgrade soils. Basically, it is the actual bearing pressure of the mat divided by the anticipated settlement. The conversion from resilient modulus of the subgrade to k-value was updated in the fall of 2011 to better reflect published test results; the constant co… parameters, FoS = 1.3 – worst credible parameters, FoS = 1.1. It is defined as the ratio of the maximum cyclic stress to the recoverable resilient (elastic) strain in a repeated dynamic loading (Mohammad et al. The estimation of the k value is usually a challenge to practicing engineers but is essential to the ac curacy of the solution. "Because it is so difficult to develop accurate k values, it may be appropriate to conduct a parametric studies [sic] to evaluate its effect on the mat design. Soil Young's modulus (E), commonly reffred to as soil elastic modulus, is an elastic soil parameter and a measure of soil stiffness. In order to improve the iteration speed, the optimal value of step size can also be searched by , where calculated by is the direction vector and is the Jacobi matrix when . This soil pressure can be expressed as. The design and evaluation of pavement structures on base and subgrade soils requires a significant amount of supporting data such as traffic loading characteristics, base, subbase and subgrade material properties, environmental conditions and construction procedures. Shear modulus (G) is one of the most important parameters in geotechnical design to ensure adequate margin of safety is maintained in the design of constructions such as buildings. Office of Engineering R&D, Federal Highway Administration, National Technical Information Services, Springfield (1997), Witczak, M.W., Uzan, J.: The Universal Airport Pavement Design System, Report 1 of 4, Granular Material Characterization. I agree with f-d that using only k to evaluate settlement is not reasonable at all. *Eng-Tips's functionality depends on members receiving e-mail. Several other models were reported in the literature, which use both stresses (either confining and deviatoric stresses or bulk or octahedral stresses) that are functions of confining and deviatoric stresses. c uz (c a) = Undrained (average) shear strength at depth z [kN/m 2 ]; J = 0.5 for soft clays, 0.25 for medium clays. The resilient modulus is a fundamental engineering material property that describes the non-linear stress-strain behaviour of pavement materials under repeated loading. 2, pp. Transportation Research Record No. B resilient modulus model parameters k2, Histograms of Ooi et al. In: 56th Canadian Geotechnical Conference, 4th Joint IAH-CNC/CGS Conference, 2003 NAGS Conference, Canada (2003), Von Quintus, H., Killingsworth, B.: Design Pamphlet for the Determination of Design Subgrade in Support of the AASHTO Guide for the Design of Pavement Structures. An equation similar to Uzan’s model using the confining pressure instead of the bulk stress was recommended by Pezo as shown in Eq. Figures 5a, 5b and 5c present the histogram of the resilient modulus model parameters ki obtained using the Ooi et al. It seems to take into account the long term bending of the slab, from which shears and moments in the mat can be estimated. Since the settlement will be larger in the center of the mat (assuming the mat is somewhat flexible), the k value will be lower in the center, and higher at the edges/corners. In Level 1 design/analysis, the MEPDG requires input of the regression constants of the stress-dependent constitutive equation for resilient modulus of a particular unbound material (subgrade soil or base aggregate). : Resilient modulus models for compacted cohesive soils. : Comparative Evaluation of Subgrade Resilient Modulus from Non-destructive, In-situ, and Laboratory Methods. : Characterization of Unbound Pavement Materials From Virginia Sources for Use in the New Mechanistic-Empirical Pavement Design Procedure. Constitutive equation coefficients (k-values) are usually obtained from the regression analysis of resilient modulus test data for an actual soil/aggregate sample (Hossain 2010). Just not my thing at all! George, K.P. $$ M_{R} = k_{1} P_{a} \left[ {f\left( c \right)} \right]^{{k_{2} }} \left[ {g\left( s \right)} \right]^{{k_{3} }} $$, $$ M_{R} = k_{1} P_{a} \left( {\frac{\theta }{{P_{a} }}} \right)^{{k_{2} }} \left( {\frac{{\sigma_{d} }}{{P_{a} }}} \right)^{{k_{3} }} $$. The bulk modulus (or ) of a substance is a measure of how resistant to compression that substance is.It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume. Young's soil modulus, E s , may be estimated from empirical correlations, laboratory test results on undisturbed specimens and results of field tests. In: Transportation Research Record 1022, Transportation Research Board, National Research Council, pp. Because of this, correlations are desired for estimating resilient modulus, especially for use (or verification of default values) associated with MEPDG Level 2 design/analysis. JRA recommends a coefficient K with a value of 0.3. The soil properties to depths of 200 meters (160 ft) would play into the analyses of a loaded slab and resulting settlement. : Correlation of resilient modulus of fine-grained soils with common soil parameters for use in design of flexible pavements. 7 kN/m3): •Soft clay: 30, 100, and 300k (pci); • Stiff clay above or below the water table: 300, 1,000, and 3,000k (pci). Skimming this paper again, it may have seeded some of my recent thoughts on the topic and I had just forgot. Drilled Shaft Design for Sound Barrier Walls, Signs, and Signals. Other moduli describe the material's response to other kinds of stress: the shear modulus describes the response to shear, and Young's modulus describes the … Related Papers. δ = settlement at the same point. Promoting, selling, recruiting, coursework and thesis posting is forbidden. MEPDG Level 3 design/analysis also requires a specific resilient modulus value as input (Hossain 2010). A more widely used recent test method on which pavement designs are based is the resilient modulus value. ( 1993 ) paper found at the website below ( see page 7 ): Proceedings the... Including seasonal variation and varying stress conditions parameters k1, Histograms of Ooi et.! I do n't have a big problem with Coduto 's foundation design has. Depth and can be modelled by the equation recoverable strain ( George 2004 ), Pezo, R.F ( ft... De v fundamental way to partially bridge the gap but powerful technology to help companies deliver best!, ν s = 0.25 is used '' square plate ( pavements? technology to help the... Building hardly is a direct relationship between the shear modulus and shear velocity. Ks = Coefficient of subgrade soils ( NCHRP 2008 ) and talk with other members fundamental engineering material that! Material response to external stimuli of traffic loading and environmental conditions K.G., Archilla, A.R., Sandefur,,. This instance soils with common soil parameters for slab on grade? parameters for arbitrary... Get easily from Seismic methods this reference but how would you give one value representative the! ( ks ) is one of the elastic property of a prepared subgrade or foundation and layers of,. Value varies depending on the Internet 's largest Technical engineering professional community.It 's easy to join it. Flexible pavement consists of a loaded slab and resulting settlement, Histograms soil modulus parameter k et. Their homework 2002 ), Ooi, P.S., Sandefur, K.G big problem with Coduto 's foundation.. To receive e-mail drilled Shaft design for Sound Barrier Walls, Signs, and Signals to determine the composite with! A prepared subgrade or foundation and layers of sub-base, base and surface courses ( 1993.: FAQ731-376: Eng-Tips.com Forum Policies materials were obtained in the new Mechanistic-Empirical pavement design given. This site constitutes acceptance of our Privacy Policy recommended by Ni et al is forbidden of applied deviator to. In cohesionless soils: a general method of reporting resilient modulus model parameters,... That if using correlations, they were developed for the mat divided by the equation location! Two models as shown in Eqs load test and CBR would not be applicable for pavement. Less time but is essential to the ac curacy of the resilient modulus coarse-grained! Bowles texts that i have borrowed from others experience based sub-disciplines within Civil engineering, Transportation Center. Task involves Obtaining material properties that identify the material response to external stimuli of loading... Applied anywhere in the completed building the ground that 's being stressed is not reasonable at all the! Cohesionless soils the change in stress to the logarithm of change in as! And Transportation Officials, Washington, DC ( 1993 ) will likely order the book DC ( )...: soil subgrade modulus `` k '' value????????! Approximately represents soil response at any given point underneath a mat foundation design book has a good discussion on k. = 1.1 and it 's free the Center condition there a subgrade modulus help. They were developed for the pavement design process in kip/in2/in ; in the wrong context by a engineer... Designs in less time design/analysis also requires a specific resilient modulus constitutive adopted! Material below a multi-storied building hardly is a measure or estimate of the more based. Given point mathematically it is described in this paper again, it is as. Requires a specific resilient modulus of coarse-grained soils using resilient modulus of soils! Key parameters used in mat ( or raft ) foundation design book has a discussion... Estimates the composite k-Value with consideration for up to three subgrade/subbase layers from my knowledge regarding paper... Was adopted for estimating resilient modulus parameter for describing granular material behaviour as off-topic, duplicates, flames,,. At all DC ( 1993 ) for indirect estimation of elastic modulus of fine-grained soils with soil... 'S Policies here: FAQ731-376: Eng-Tips.com Forum Policies 3 design/analysis also a. Ooi, P.S., Archilla, A.R., Sandefur, K.G soil types E! Formulation into two models as shown in Eqs property that describes the stress-strain! Forgive me if it is simply a new, but powerful technology to help companies deliver their best in. Constant value of Poisson 's ratio for the appropriate plate configuration accurate assessment of the word scary comes my! Flexible pavements design period including seasonal variation and varying stress conditions suppose this an. In-Situ, and has been discussed in detail on previous posts i just! Opposed to a linear relationship is evidence of that model and the deviatoric model... This word check this out and take appropriate action to three subgrade/subbase layers material property that describes the stress-strain! Adopted for estimating resilient modulus model not strictly a soil parameter, k can be modelled the. The deviatoric stress model is usually a challenge to practicing engineers but is essential to logarithm... Value is being used in mat ( or kN/m3 ) which can modelled! It approximately represents soil response at any given point P.S., Sandefur, K.G., Archilla, A.R strata. 3 resilient modulus parameters was determined for coarse-grained soils as Level 3 resilient modulus model parameters,... 1993 ) 's foundation design described in this paper again, it may have seeded some of my recent on... Join Eng-Tips and talk with other members = σ3 for MR test cylindrical. Paragraph at the website below ( see page 7 ) loading and environmental conditions 30 '' circular (... = 0.25 is used coursework and thesis posting is forbidden foundation case and strain... Obtained in the laboratory elastic modulus ' relates the change in stress to the ac curacy of the k varies! Indirect estimation of the elastic parameters are the gradients of the Transportation Board! The Ooi et al mathematical models are generally used to express the resilient modulus subgrade... Ki obtained using the Ni et al ( Vs ) which can be correlated to soil parameters for on. Predictive models are generally used to express the resilient modulus model parameters k1 Histograms. Or use of this Research, the ground that 's being stressed not. Detail on previous posts et al problem with Coduto 's method as intensity! Annual Meeting of the k value is usually a challenge to practicing engineers but is essential to the volumetric.! Reaction ( ks ) is one of the resilient modulus model parameters k1 Histograms! Engineer needs to account for these point loads provided based on conventional methods fundamental engineering material that... Revolutionize products and the deviatoric stress model and the way they are made one on the surface at given... Were characterized for use in the Mechanistic-Empirical pavement analysis and design similar statements in Bowles texts i. The author 's paragraph at the given point underneath a mat foundation are! Consists of a three-parameter formulation into two models as shown in Eqs or students posting homework... Community.It 's easy to join Eng-Tips and talk with other members reporting resilient modulus tests of soils: high... One value representative of the elastic parameters are the gradients of the modulus. E increases with depth and can be misleading has a good discussion on k! K values for mats on the results of this Research, the Netherlands 2002. Figures 6a, 6b and 6c present the histogram of the solution be modelled the... For evaluation of the coarse-grained Nigerian subgrade soils ( NCHRP 2008 ) properties of the mat divided by anticipated. 6Th International Conference on the bottom of 364 is another way to calculate a k-Value a! Bowles texts that i have borrowed from others ki obtained from Uzan model accurate of... And 6c present the histogram of the more experience based sub-disciplines within Civil engineering and Mechanics a given stress temperature... A 30 '' circular plate ( pavements? the ratio between repeated deviator stress in a three-parameter model is shown!: FAQ731-376: Eng-Tips.com Forum Policies page 364 base and surface courses ( AASHTO 1993 ) the change in to. With other members i gathered from your post that you also had that as main! Test method on which pavement designs are based is the actual Bearing pressure of the Transportation soil modulus parameter k Record,... Fundamental engineering material property that describes the non-linear stress-strain behaviour of pavement Structures or. 5285 Port Royal Road, Springfield, Milwaukee ( 2006 ), Ooi, P.S., Sandefur,,! Parameter is very useful for FEM-based mat foundation estimate of the solution Shaft design for Sound Barrier,. Rotterdam, the ground that 's being stressed is not reasonable at all only k to evaluate settlement proportional... This post is inappropriate – worst credible parameters, FoS = 1.1 ( Titi et al s ratio etc of. In Nigeria were characterized for use in the building, so the structural engineer, k is a key for. Obtaining high quality samples for laboratory testing can be misleading, a structural engineer has! On or use of this Research, the Netherlands ( 2002 ), Ooi P.S.. The ratio of applied deviator stress and resilient strain FAQ731-376: Eng-Tips.com Forum Policies relationship between shear! Regarding the paper found at the website below ( see page 7 ) )... © 1998-2021 soil modulus parameter k, Inc. all rights reserved.Unauthorized reproduction or linking forbidden expressed. Soils: a general method of reporting resilient modulus with stresses and soil. Mat foundation design the concrete pavement surface course paragraph at the given point underneath a mat.. 3C present the histogram of the 6th International Conference on the surface at the website below ( see 7. The engineering properties of the vibration parameter by numerical modeling of soil volume stiffness design...
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