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.

Study on Test of the Influence of Moisture Content on Creep Property of Sandy Slate Coarse-Grained Soil

2013 ◽  
Vol 405-408 ◽  
pp. 1733-1738 ◽  
Author(s):  
Qun Liu ◽  
Xiang Wang ◽  
Xiao Dong Song
Keyword(s):  
Moisture Content ◽  
Creep Test ◽  
Creep Property ◽  
Coarse Grained ◽  
Creep Model ◽  
Moisture Contents ◽  
Compression Creep ◽  
Moisture Conditions ◽  
Coarse Grained Soil

Coarse-grained soil is widely used in subgrade engineering, creep property of which is the important factor that affects long-term settlement of fill embankment. The creep property of sandy slate coarse-grained soil under different moisture conditions is analyzed through uniaxial compression creep test on influence rule of moisture content on creep of coarse-grained soil. Relations between moisture contents and creep parameters are studied on the basis of H-K Creep Model. It turns out that moisture content is the important factor that affects creep property of sandy slate coarse-grained soil and using dry or saturated coarse-grained soil is able to decrease long-term settlement of embankment.

scholarly journals A frost heave model of unsaturated coarse-grained soil considering vapour transfer

2020 ◽  
Vol 195 ◽  
pp. 02017
Author(s):  
Jianlong Liu ◽  
Jidong Teng ◽  
Sheng Zhang ◽  
Daichao Sheng
Keyword(s):  
High Speed ◽  
Coarse Grained ◽  
Frost Heave ◽  
Test Results ◽  
Proposed Model ◽  
Laboratory Test Results ◽  
Frost Depth ◽  
Lens Formation ◽  
Coarse Grained Soil ◽  
Coarse Soil

Substantial frost heave has been observed in coarse fills in high-speed railway embankments. These coarse fills have low fine contents and very low water content. The groundwater table is located below the coarse fills. The coarse fills were considered not susceptible to frost heave. Recent experimental results in the literature showed that vapour transfer has a considerable influence on the frost heaving of unsaturated coarse-grained soil. But vapour transfer has been rarely considered in the modelling of frost heave. This study presents a new frost heave model with considering vapour transfer and its contribution to ice formation. The rigid ice theory is applied to initiate an ice lens formation in the frozen fringe. An updated computer programme PCHeave is developed by considering the vapour transfer. The results of the proposed model are compared with laboratory test results, which show reasonable agreement. The prediction of the model agrees well with the measured frost heave and frost depth, which indicates that the proposed model can reasonably reflects the process of frost heave in unsaturated coarse soil.

scholarly journals Deformation Behavior of Coarse-Grained Soil as an Embankment Filler under Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhong-Ming He ◽  
Da Xiang ◽  
Ya-Xin Liu ◽  
Qian-Feng Gao ◽  
Han-Bing Bian
Keyword(s):  
Cyclic Loading ◽  
Deformation Behavior ◽  
Soil Samples ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Loading Frequency ◽  
Macroscopic Deformation ◽  
Internal Mechanism ◽  
Coarse Grained Soil ◽  
Internal Evolution

This study aims to examine the deformation behavior and internal mechanism of coarse-grained soil as an embankment filler under cyclic loading. Numerical dynamic triaxial tests were performed on coarse-grained soil using the discrete element software PFC3D. The numerical model was verified by comparing the numerical results with the experimental data. Afterward, the changes in the porosity, force chain, and particle movement of coarse-grained soil samples were analyzed, and the mesoscopic deformation behavior of coarse-grained soil under cyclic loading was investigated. The research results show that with the increase of the deviatoric stress amplitude, moisture content, and loading frequency, the deformation of the soil increases and the ability to resist deformation decreases at the same loading cycles. Due to the inhomogeneous distribution of particles with different sizes, the velocity and displacement of the sample vary in different directions, exhibiting mesoscopic anisotropy. The contact force is relatively even in the downward direction while dispersed near the edge of the sample. This means that the particles at the bottom are less affected by loads and the internal evolution of soil samples conforms to its macroscopic deformation behavior during cyclic loading.

scholarly journals Shear Properties and Mechanism of Freeze-Thaw Interface in Unsaturated Coarse-Grained Soil from Qinghai-Tibet Plateau

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yonglong Qu ◽  
Wankui Ni ◽  
Fujun Niu ◽  
Yanhu Mu ◽  
Jing Luo ◽  
...  
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Coarse Grained ◽  
Tibet Plateau ◽  
Dry Density ◽  
Direct Shear ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Qinghai Tibet Plateau ◽  
Coarse Grained Soil

Freeze-thaw interface in unsaturated coarse-grained soil (CGS) is a weak plane which can cause slope failures in cold regions. This study presents a series of large-scale direct shear tests on freeze-thaw interface in CGS through a temperature control system. The tested soil was taken from a high slope in the Qinghai-Tibet Plateau. It was remolded with three dry densities (1.9, 2.0, and 2.15 g/cm3) and three moisture contents (9.0%, 11.5%, and 14.0%). With testing results, direct shear curves mainly performed as hardening deformation, and they were affected considerably by specimen conditions. The shear strength increased with both the increasing dry density and normal stress, but it was opposite with moisture content changed. The cohesion and internal friction angle increased with the increase in dry density but decreased with the moisture content. The particle movement and water migration of freeze-thaw interface in CGS during the test were significant, and they had close relations with the shear properties of specimens. And, an empirical model was produced to express the effect of pore ice on the shear strength of interface during the shear test. The tests and analysis in this study may provide useful references for CGS slope stability analysis in high cold regions.

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 Study on the Mechanical Properties of Chlorine Saline Soil under the Interaction of Multiple Factors

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Anhua Xu ◽  
Pengcheng Wang ◽  
Jianhong Fang
Keyword(s):  
Elastic Modulus ◽  
Moisture Content ◽  
Mechanical Characteristics ◽  
External Environment ◽  
Confining Pressure ◽  
Dynamic Elastic Modulus ◽  
Dynamic Strain ◽  
Saline Soils ◽  
Loading Frequency ◽  
Failure Strength

The distribution of chlorine saline soils is extensive in Haixi region of Qinghai Province in Northwest China. Its natural and geographical conditions are unique, and the external environment varies greatly. To study the effects of variable external environment on the mechanical characteristics of chlorine saline soils, a number of unconsolidated undrained (UU) dynamic triaxial tests under different confining pressure, moisture content, and loading frequency were carried out. The dynamic stress–dynamic strain, failure strength, dynamic elastic modulus, and parameter of shear strength were analyzed. The triaxial test results demonstrated that the stress–strain curves of the soil were strain-hardening. The failure strength and dynamic elastic modulus increased with the increasing of confining pressure; the law with moisture content and loading frequency were inconsistent. The dynamic cohesion and dynamic friction angle increased with the increasing of loading frequency, but decreased with the increasing of moisture content. Besides, the significance analysis theory was used to analyze the effect degree of different factors. It found that the effects of confining pressure, loading frequency, and the interaction between confining pressure and frequency on mechanical characteristics were significant, but the moisture content had less effect.

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