scholarly journals Resilient Properties of Soil-Rock Mixture Materials: Preliminary Investigation of the Effect of Composition and Structure

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1658 ◽  
Author(s):  
Junfeng Qian ◽  
Yongsheng Yao ◽  
Jue Li ◽  
Hongbin Xiao ◽  
Shenping Luo
Keyword(s):  
Shear Stress ◽  
Stress State ◽  
Triaxial Test ◽  
Resilient Modulus ◽  
Discrete Element ◽  
Modeling Method ◽  
Triaxial Tests ◽  
Crushed Rock ◽  
Bulk Stress ◽  
Octahedral Shear Stress

The physical composition and stress state of soil-rock mixture (SRM) materials have a crucial influence on their mechanical properties, and play a vital role in improving the performance of subgrade. To reveal the resilient behavior and mesostructure evolution of SRM materials, triaxial tests and discrete element method (DEM) numerical analysis have been carried out. In the triaxial test section, the mechanical response of SRM materials was investigated by preparing samples under different stress states and physical states and conducting triaxial tests on samples. Simultaneously, a new irregular particle modeling method was developed and applied to the discrete element modeling process to analyze the mesostructure evolution of SRM materials under cycling loading. First, a cyclic triaxial test of SRM material is performed on the SRM material, and the effects of bulk stress, octahedral shear stress and rock content on the resilient modulus of the SRM material are analyzed. It is revealed that the resilient modulus increases with increasing bulk stress and rock content, and decreases with increasing octahedral shear stress. Based on a new resilient modulus prediction model, the relationships among the rock content, stress state and resilient modulus are established. Then, based on an improved DEM modeling method, a discrete element model of the SRM is established, and the influence of rock content on coordination number and mesostructure evolution of the SRM is analyzed. The results show that in SRM materials, the increase of crushed rock changes the mesostructure of the SRM material. With the increase of rock content, the internal contact force changes from “between soil and rock” to “between rocks”, and the skeleton formed in the rocks gradually develops overall stiffness. Under the condition of low stress, the anisotropy of the SRM material is mainly caused by the shape and grade distribution of crushed rock. The induced anisotropy caused by the change of stress state has little effect on its mechanical behavior, which may lead to the greater dispersion of multiple SRM test results.

scholarly journals Modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control

2014 ◽  
Vol 51 (12) ◽  
pp. 1413-1422 ◽  
Author(s):  
Farhad Salour ◽  
Sigurdur Erlingsson ◽  
Claudia E. Zapata
Keyword(s):  
Stress State ◽  
Moisture Content ◽  
Prediction Model ◽  
Pore Pressure ◽  
Resilient Modulus ◽  
Matric Suction ◽  
Pressure Effects ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Suction Control

The resilient modulus of unbound materials is an important parameter in the mechanistic design of pavements. Although unbound layers are frequently in a partially saturated state, a total stress approach is conventionally used in modeling the material behaviour, and therefore pore pressure effects are not considered. In fine-grained unbound materials, the saturation state can affect their mechanical behaviour due to pore pressure effects. In this study a modified test procedure and a predictive resilient modulus model that takes into account the subgrade soil matric suction as a stress state variable is presented. Two different silty sand subgrade materials were tested in unsaturated conditions using a series of repeated load triaxial tests under controlled pore suction conditions to study its influence on the resilient modulus. The test data were further used to obtain the resilient modulus model regression parameters that account for moisture content variations through the matric suction parameter. Generally, the prediction model could effectively capture the resilient modulus behaviour of the subgrades with respect to changes in the normal stress state and the matric suction. Given the completeness of this method, this prediction model is recommended as an improved approach in capturing the moisture content effects on the material stiffness properties.

A Repeated Loading Triaxial Test Study on Resilient Modulus of Graded Crushed Stone

2012 ◽  
Vol 503-504 ◽  
pp. 280-283
Author(s):  
Sui Yuan Wang ◽  
Zhi Gang Luo
Keyword(s):  
Stress State ◽  
Moisture Content ◽  
Triaxial Test ◽  
Resilient Modulus ◽  
Optimum Moisture Content ◽  
Crushed Stone ◽  
Repeated Loading ◽  
Test Results ◽  
Confining Stress ◽  
Test Study

To investigate the effect of confining stress, deviation stress, moisture content and gradation type on resilient modulus of graded crushed stones, three types of graded crushed stone with three moisture content levels(optimum moisture content and ±2% of the optimum moisture content, respectively ) were used, and repeated loading triaxial (RLT) tests with twenty five stress levels were carried out. The RLT test results demonstrate that resilient modulus of graded crushed stone remarkably increases with decreasing moisture content and/or increasing confining stress; resilient modulus of graded crushed stone slowly increases, or minor decreases at the beginning and then slowly increases with increasing deviation stress at low stress state. Results also indicate that gradation type has a certain impact on resilient modulus of graded crushed stone.

Analysis of Resilient Modulus of Dense- and Open-Graded Aggregates

1996 ◽  
Vol 1547 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Andrew G. Heydinger ◽  
Qinglu Xie ◽  
Brian W. Randolph ◽  
Jiwan D. Gupta
Keyword(s):  
Resilient Modulus ◽  
Linear Regression Analysis ◽  
Natural Stone ◽  
Moisture Condition ◽  
Bulk Stress ◽  
Octahedral Shear Stress ◽  
Log Linear ◽  
Moisture Conditions ◽  
Material Gradation ◽  
Two Parameter

The results of analyses of laboratory resilient modulus testing conducted on dense-graded and open-graded aggregates are presented. The testing program included three different aggregate materials (crushed limestone, natural stone, and slag), five different gradation specifications, and three different moisture conditions (dry, moist, and saturated). In addition to the five aggregate specifications, test specimens were prepared so that they would satisfy the lower, central, and upper bounds for the gradations. Resilient modulus tests were conducted as closely as possible according to Strategic Highway Research Program Protocol P-46 (AASHTO T 294-92 I). The test results were analyzed using log-linear regression analysis with two-parameter (bulk stress) and three-parameter (bulk stress and octahedral shear stress) expressions for resilient modulus. The results of the testing indicate that the resilient modulus of aggregates and regression constants vary significantly depending on the type of material and vary less significantly depending on material gradation and moisture condition. The natural stone aggregates had the higher moduli and the slag aggregate had the lowest moduli. The resilient modulus does not vary significantly as the moisture content increases unless the aggregate becomes saturated. The R2 values are consistently higher using a three-parameter expression than a two-parameter expression.

Parameter Determination of Discrete Element Model of Conditioned Soil by Genetic Neural Network

2010 ◽  
Vol 150-151 ◽  
pp. 27-31
Author(s):  
Li Wu ◽  
Tian Min Guan ◽  
Fu Zheng Qu ◽  
Shou Ju Li
Keyword(s):  
Neural Network ◽  
Triaxial Test ◽  
Element Model ◽  
Discrete Element ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Discrete Element Model ◽  
Discrete Element Simulation ◽  
Element Simulation ◽  
Genetic Neural Network

The inversion method combining the genetic neural network and the discrete element simulation of triaxial tests is firstly described for determining the discrete element model parameters of the conditioned soil. The purpose is to make the error of the simulation curves and the laboratory curves of the triaxial test minimum. The solve approach is the parameters identification based on the genetic neural network. The network training sample is provided by the discrete element simulation. The input sample is the simulation curves of triaxial test, and the output sample is the model parameters. The laboratory triaxial test curves of the conditioned soil are used to determine its model parameters. The simulation curves calculated with the inversed parameters match the laboratory curves well, which illustrate that the discrete element model can accurately predict the deformation characteristics and flow patterns of conditioned soils.

scholarly journals An Energy-Based Discrete Element Modeling Method Coupled with Time-Series Analysis for Investigating Deformations and Failures of Jointed Rock Slopes

2021 ◽  
Vol 11 (12) ◽  
pp. 5447
Author(s):  
Xiaona Zhang ◽  
Gang Mei ◽  
Ning Xi ◽  
Ziyang Liu ◽  
Ruoshen Lin
Keyword(s):  
Time Series ◽  
Iterative Process ◽  
Discrete Element ◽  
Jointed Rock ◽  
Modeling Method ◽  
Discrete Element Modeling ◽  
Rock Slopes ◽  
Sliding Surface ◽  
Element Modeling ◽  
Displacement Based

The discrete element method (DEM) can be effectively used in investigations of the deformations and failures of jointed rock slopes. However, when to appropriately terminate the DEM iterative process is not clear. Recently, a displacement-based discrete element modeling method for jointed rock slopes was proposed to determine when the DEM iterative process is terminated, and it considers displacements that come from rock blocks located near the potential sliding surface that needs to be determined before the DEM modeling. In this paper, an energy-based discrete element modeling method combined with time-series analysis is proposed to investigate the deformations and failures of jointed rock slopes. The proposed method defines an energy-based criterion to determine when to terminate the DEM iterative process in analyzing the deformations and failures of jointed rock slopes. The novelty of the proposed energy-based method is that, it is more applicable than the displacement-based method because it does not need to determine the position of the potential sliding surface before DEM modeling. The proposed energy-based method is a generalized form of the displacement-based discrete element modeling method, and the proposed method considers not only the displacement of each block but also the weight of each block. Moreover, the computational cost of the proposed method is approximately the same as that of the displacement-based discrete element modeling method. To validate that the proposed energy-based method is effective, the proposed method is used to analyze a simple jointed rock slope; the result is compared to that achieved by using the displacement-based method, and the comparative results are basically consistent. The proposed energy-based method can be commonly used to analyze the deformations and failures of general rock slopes where it is difficult to determine the obvious potential sliding surface.

scholarly journals A Methodology for Determination of Resilient Modulus of Asphaltic Concrete

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
A. Patel ◽  
M. P. Kulkarni ◽  
S. D. Gumaste ◽  
P. P. Bartake ◽  
K. V. K. Rao ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Triaxial Tests ◽  
Asphaltic Concrete ◽  
Empirical Relationships ◽  
Cyclic Triaxial Tests ◽  
Electronic Circuitry ◽  
Quality Check ◽  
R Value ◽  
Vast Variation

Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV), give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements), was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

The strength and dilatancy of sand

1992 ◽  
Vol 29 (3) ◽  
pp. 522-526 ◽  
Author(s):  
Y. P. Vaid ◽  
S. Sasitharan
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Friction Angle ◽  
Stress Path ◽  
Triaxial Tests ◽  
Confining Stress ◽  
Peak Friction Angle ◽  
Loading Direction ◽  
Dilation Rate ◽  
Unique Relationship

The effects of stress path and loading direction in the triaxial test on strength and dilatancy of sand are investigated. It is shown that the unique relationship observed between peak friction angle and dilation rate at peak in conventional triaxial tests is followed regardless of stress path, confining stress at failure, relative density, and the mode of loading (compression or extension). Key words : sand, peak friction angle, dilatancy, stress path, triaxial test.

scholarly journals Influence of Gradation on Resilient Modulus of High Plasticity Soil-Gravel Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chuang Liu ◽  
Tian-Zeng Ren ◽  
Rui Zhang ◽  
Qian-Feng Gao ◽  
Jian-Long Zheng
Keyword(s):  
Resilient Modulus ◽  
Economic Benefits ◽  
Construction And Demolition Waste ◽  
Triaxial Tests ◽  
High Plasticity ◽  
Demolition Waste ◽  
Gravel Content ◽  
Coarse Aggregates ◽  
Mixing Method ◽  
Skeleton Structure

Because of low resilient modulus, high plasticity soil is often not allowed to fill road subgrades and is discarded as construction and demolition waste (CDW). To make use of the CDW, this study explored the possibility of improving high plasticity soil with gravel and examined the effect of gravel gradation on the resilient modulus of the soil-gravel mixture. A series of dynamic triaxial tests, tests of voids in coarse aggregate, and X-ray CT scans were carried out on high plasticity soil-gravel mixtures of different gravel contents and gravel gradation types. The test results show that there is a critical gravel content, that is, 44.1%. When the gravel content is less than 44.1%, the mixture shows a dense suspended structure and its modulus increases slowly with increasing gravel content. When the gravel content is greater than 44.1%, the mixture exhibits a dense skeleton structure and the modulus increases rapidly as the gravel content rises. Moreover, as the gravel gradation tends to the lower type, coarse aggregates increase in quantity and contact each other to form a dense skeleton; thus, the modulus increases accordingly. As the gravel gradation approaches the upper type, coarse aggregates decrease in quantity and tend to suspend in the soil, so the modulus decreases. With the increase in contact number, the skeleton structure is continuously improved, and thus the modulus is enhanced progressively. The results indicate that the gravel mixing method with a gravel content of 40%–45% can effectively improve high plasticity soil and shows great environmental and economic benefits.

Sign in / Sign up

Export Citation Format

Share Document