scholarly journals Experimental study on permanent deformation characteristics of coarse-grained soil under repeated dynamic loading

2021 ◽  
Author(s):  
Huihao Mei ◽  
Sajjad Satvati ◽  
Wuming Leng
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Permanent Deformation ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Deformation Characteristics ◽  
Permanent Strain ◽  
Coarse Grained Soil

AbstractPractical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading. In this paper, repeated load triaxial tests were performed on coarse-grained soil (CGS), and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed. Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory. A prediction model of permanent deformation considering stress state and number of load cycles was established, and the ranges of parameters for different types of dynamic behaviors were also divided. The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS. The stress state (confining pressure and dynamic stress amplitude) has significant effects on the permanent strain rate. The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function, and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude. The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.

scholarly journals New Structure for Strengthening Soil Embankments

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Fang Xu ◽  
Wuming Leng ◽  
Rusong Nie ◽  
Qishu Zhang ◽  
Qi Yang
Keyword(s):  
Shear Modulus ◽  
Large Scale ◽  
Dynamic Stress ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Additional Stress ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Critical Dynamic

A new prestressed reinforcement device (PRD) consisting of two lateral pressure plates (LPPs) and a reinforcement bar is developed to strengthen soil embankments by improving the soil confining pressure and providing lateral constraint on embankment slopes. The reinforcement effects of PRDs were demonstrated by investigating the beneficial effects of increasing confining pressure on the soil behavior via the performance of a series of large-scale static and cyclic triaxial tests on a coarse-grained embankment soil. The results show that PRDs can effectively improve the soil shear strength, bearing capacity, ability to resist elastic and plastic deformation, critical dynamic stress, and dynamic shear modulus, and empirical methods were also developed to determine the critical dynamic stress and initial dynamic shear modulus of the embankment soil. Moreover, 3D finite element analyses (FEAs) with an LPP width of 1.2 m were performed to analyze the additional stress field in a prestressed heavy-haul railway embankment. The FEAs showed that the additional stress at a given external distance from the border of an LPP first increased to a maximum value and then gradually decreased with increasing depth; the additional stress was transferred to the zones where the subgrade tends to have higher stresses with peak stress diffusion angles of 34° (slope direction) and 27° (longitudinal direction); and a continuous effective reinforcement zone with a minimum additional stress coefficient of approximately 0.2 was likely to form at the diffusion surface of the train loads, provided that the net spacing of the LPPs was 0.7 m. The reinforcement zone above the diffusion surface of the train loads can act as a protective layer for the zones that tend to have higher stresses. Finally, the advantages and application prospects of PRDs are discussed in detail. The newly developed PRDs may provide a cost-effective alternative for strengthening soil embankments.

scholarly journals Experimental Study on Cumulative Plastic Deformation of Coarse-Grained Soil High-Grade Roadbed under Long-Term Vehicle Load

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Zhongming He ◽  
Yaxin Liu ◽  
Haolong Tang ◽  
Yihang Xing ◽  
Hanbing Bian
Keyword(s):  
Moisture Content ◽  
Permanent Deformation ◽  
Correlation Coefficients ◽  
Summation Method ◽  
Coarse Grained ◽  
Test Scheme ◽  
Loading Frequency ◽  
Coarse Grained Soil ◽  
Compaction Degree ◽  
Coarse Soil

According to the change characteristics of the subgrade moisture content and the mechanical calculation of several typical highways, the test scheme of the permanent deformation of coarse soil was formulated. The relationship between the permanent deformation of coarse-grained soil and the stress level, compaction degree, moisture content, and loading frequency was studied by cyclic loading triaxle testing. The results show that the permanent deformation of coarse-grained soil increases with the increase in partial stress and moisture content and decreases with the increase in compaction degree. The experimental data were fitted by the Tseng-Lytton model, and the correlation coefficients were 92%, which indicated that the model could be used to predict the permanent deformation of coarse soil. The relationships between the model coefficient and the moisture content and spring back modulus were obtained by the multiple regression method. Finally, the permanent deformation of the subgrade soil was calculated by using the layered summation method and a typical subgrade pavement structure.

Study on Compression Deformation Characteristics of Coarse-Grained Soil in High Filled Subgrade

2013 ◽  
Vol 438-439 ◽  
pp. 1089-1092
Author(s):  
Qun Liu ◽  
Xiang Bo Deng
Keyword(s):  
Moisture Content ◽  
Uniaxial Compression ◽  
Coarse Grained ◽  
Compressive Deformation ◽  
Uniaxial Compression Test ◽  
Coarse Particles ◽  
Deformation Characteristics ◽  
Railway Construction ◽  
Compression Deformation ◽  
Coarse Grained Soil

Coarse-grained soil is widely used in railway construction, and it is of great significance to take research on how compression deformation characteristics affect deformation of coarse-grained soil in high filled subgrade. To analyze compression deformation characteristics of coarse-grained soil under different moisture content and different grain compositions conditions, influence pattern of moisture content and grain compositions was researched through uniaxial compression test. The result indicates that compressive deformation is in logarithm relation with time; moisture content and grain compositions are important factors that affect the characteristics of compressive deformation of sandy slate coarse-grained soil and it is better to control subgrade settlement with dry or saturated coarse-grained soil which contains 70% coarse particles.

The Deformation Characteristics of Soft Clay under Cyclic Loading

2012 ◽  
Vol 446-449 ◽  
pp. 1709-1712 ◽  
Author(s):  
Yong Zhang ◽  
Li Wan ◽  
Xiong Wei Li
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Elastic Strain ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Soft Clay ◽  
Dynamic Elastic Modulus ◽  
Deformation Characteristics ◽  
Cycle Number ◽  
Critical Type

Through the undrained dynamic triaxial experiment, the deformation characteristics of saturated soft clay under cyclic loading are investigated. The cyclic loading was simplified as sine wave. It is found that under different dynamic stress, the deformation patterns of specimen in this experiment can be divided into three kinds, such as dense compressed, tensile break-up and shear failure type. In the process of vibration, the deformation forms of samples can also be divided into three types by dynamic stress amplitude, such as stable, destructive and critical type. The dynamic stress amplitude corresponding to the critical type is called critical dynamic stress. With the dynamic elastic strain increasing gradually, the dynamic elastic modulus decreases and rigidity softening occurs. Furthermore, dynamic elastic modulus and dynamic elastic strain curve decrease while the cyclic number is increasing. Finally, to establish the equation of the relationship between dynamic elastic modulus and dynamic elastic strain, the factor of cycle number should be considered.

Deformation characteristics of coarse-grained soil with various gradations

2014 ◽  
Vol 21 (6) ◽  
pp. 2469-2476 ◽  
Author(s):  
Fei Meng ◽  
Jia-sheng Zhang ◽  
Xiao-bin Chen ◽  
Qi-yun Wang
Keyword(s):  
Coarse Grained ◽  
Deformation Characteristics ◽  
Coarse Grained Soil

Study on Particle Breakage of Coarse-Grained Soil Based on Large-Scale Triaxial Test

2014 ◽  
Vol 937 ◽  
pp. 585-589
Author(s):  
Fu Yong Chu
Keyword(s):  
Power Function ◽  
Triaxial Test ◽  
Large Scale ◽  
Confining Pressure ◽  
Particle Breakage ◽  
Plastic Work ◽  
Coarse Grained ◽  
Earth Dam ◽  
Relationship Of ◽  
Coarse Grained Soil

Using large-scale shearing device, isotropiclly consolidated-drained triaxial test under different confining pressures are performed for overburden material of ShuangJiangKou earth dam which relative density is 0.8. The relationship between particle breakage of coarse-grained soil and input plastic work under loading and between particle breakage and confining pressure and between particle breakage and strength of coarse-grained soil. The results show that the particle breakage of coarse-grained soil and the input plastic work under loading is closely related. The particle breakage of coarse-grained soil increase with the input plastic work and there is a relationship of power function between Bg andWp. the increase of confining pressure will lead to the increase of particle breakage of coarse-grained soil, and there is a relationship of power function between Bg and. the increase of particle breakage of coarse-grained soil will lead to the decrease of strength of coarse-grained soil, and a relationship of linear between Bg andφ.

The Study on Dynamic Mechanical Response under Staged Loading

2014 ◽  
Vol 501-504 ◽  
pp. 115-119
Author(s):  
Fei Luo ◽  
Zhan Yuan Zhu ◽  
Lin Zhi Cui ◽  
Gao Min Li ◽  
Yi Ting He
Keyword(s):  
Energy Dissipation ◽  
Residual Strain ◽  
Dynamic Stress ◽  
Mechanical Response ◽  
Stress Amplitude ◽  
Testing Machine ◽  
Morphological Characteristics ◽  
Confining Pressure ◽  
Dynamic Mechanical ◽  
Microscopic Damage

Based on MTS-810 type vibration testing machine, morphological characteristics of hysteretic curves of frozen clay are quantitatively studied, and dynamic mechanical response are analyzed consisting of stiffness, viscosity, degree of microscopic damage, residual strain and energy dissipation. The studies have shown that the higher vibration frequencies are, the greater the stiffness is, while the smaller viscosity, the degree of microscopic damage, residual strain and energy dissipation are. Stiffness, viscosity, degree of microscopic damage, residual strain and energy dissipation are less affected by confining pressure. With increasing dynamic stress amplitude, stiffness decreases gradually, while viscosity, degree of microscopic damage, residual strain and energy dissipation increase gradually.

Influence Factor on Dilatancy of Coarse-Grained Soil Based on Large-Scale Triaxial Test

2014 ◽  
Vol 919-921 ◽  
pp. 687-692 ◽  
Author(s):  
Fu Yong Chu
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Large Scale ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Earth Dam ◽  
Triaxial Shear Test ◽  
Overburden Material ◽  
Confining Pressures ◽  
Coarse Grained Soil

Abstract：Using large-scale shearing device, K0 consolidated-drained triaxial test and isotropiclly consolidated-drained triaxial test under different confining pressures are performed for overburden material of ShuangJiangKou earth dam which relative density is 0.9. And meanwhile, isotropically consolidated-drained triaxial test under different confining pressures are also performed for overburden material of ShuangJiangKou earth dam which relative density is 0.8. The difference of strength and deformation between under under K0-consolidation condition and isotropic consolidation condition and between under different relative density, and the influence of confining pressure, relative density and consolidation condition on the dilatancy of coarse-grained are analyzed. The results show that the strength of K0 consolidated-drained triaxial shear test is slight greater than that obtained by isotropically consolidated-drained test. The strength of coarse-grained soil increases with increase of relative density.The volume strain value of isotropically consolidated-drained triaxial shear test is bigger than that of K00 consolidated-drained test, and the volume strain value decreases with the decreases of relative density. The dilatancy of coarse-grained soil decreases with the increase of confining pressure, and increases with the increase of static lateral pressure coefficient.

scholarly journals Undrained Dynamic Behavior of Reinforced Subgrade under Long-Term Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Min Geng ◽  
Debin Wang ◽  
Peiyong Li
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Dynamic Behavior ◽  
Vibration Frequency ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Confining Pressure ◽  
Reinforced Soil ◽  
Dynamic Elastic Modulus

To study the dynamic behavior of reinforced subgrade, a series of undrained cyclic triaxial tests of reinforced soil (the specimen a height of 50 cm and a diameter of 20 cm) were performed in this paper. The specimens were tested by varying confining pressure, vibration frequency, dynamic stress amplitudes, and reinforced layers. Orthogonal experiment is a better way to optimize the process of experiment. Impact on dynamic behavior of the reinforced soil specimens is discussed through orthogonal design of experiments in four factors and three levels. This study has demonstrated that the order of dynamic elastic modulus of reinforced soil is influenced by dynamic stress amplitude, frequency, reinforced layer, and confining pressure within changing in factor level. The dynamic stress amplitude has great influence on the dynamic elastic modulus of reinforced soil. The bearing capacity and dynamic elastic modulus of reinforced subgrade decrease slightly with the increase of dynamic strain. Frequency has an influence on the dynamic elastic modulus. It is shown that the cumulative strain of reinforced soil is related to the vibration frequency. The test results also exemplify the reinforced subgrade restrict lateral displacement of subgrade and reduce settlement of subgrade under long-term cyclic loading.

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