scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

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.

FRACTAL CHARACTER OF GRAIN-SIZE DISTRIBUTION OF EXPANSIVE SOILS

Fractals ◽  
1999 ◽  
Vol 07 (04) ◽  
pp. 359-366 ◽  
Author(s):  
YONGFU XU ◽  
SONGYU LIU
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Mass Distribution ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Fractal Character

Fractal mass distribution of expansive soil grains is studied in this paper. It is found that there is different fractal mass distribution exponent of the grain-size distribution for different genesis of expansive soils. The expansiveness, physical properties and mechanical properties of expansive soils can be quantitatively described by the fractal mass distribution exponent of grain-size distribution of expansive soils. In consolidated tests, the fractal mass distribution exponent increases with increases in consolidated pressure, as well as increases in confining pressure in triaxial tests.

scholarly journals Strength Characteristics and Slope Stability Analysis of Expansive Soil with Filled Fissures

2020 ◽  
Vol 10 (13) ◽  
pp. 4616 ◽  
Author(s):  
Zhangjun Dai ◽  
Jianhua Guo ◽  
Hongming Luo ◽  
Jian Li ◽  
Shanxiong Chen
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Modular Design ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Triaxial Tests ◽  
Sliding Surface ◽  
Inclination Angles ◽  
North Water ◽  
The Stability

Fissured expansive soils were widely distributed in the South-to-North Water Transfer Project. Most of the fissures were filled with clay, which controlled the stability of the slope. With the method of layered filling—bevel cutting—refilling and a modular design idea, the sample with a filled fissure preparation device for triaxial test was designed. After setting the filled fissures of gray-green clay in the expansive soil, triaxial tests were carried out for the samples with no filled fissures and with filled fissures with inclination angles of 15°, 30°, and 45°. Then, considering the spatial distribution and the strength of the filled fissures in the slope, the stability analysis method for the expansive soil slope with filled fissures was proposed. The stability of a typical slope in Nanyang was analyzed. The results show that the c of expansive soil with filled fissures was about 12 to 15 kPa and the φ was 3° to 6°. Filled fissures had an attenuation effect on the strength of the expansive soil. The larger the inclination of filled fissures, the more significant the effect of soil strength attenuation. The fissured slope stability was controlled by the filled fissures. The sliding surface was affected by the vertical fissures on the top of the slope and the slow-inclined long-large fissures in the slope, and the shape of the sliding surface was a broken line, which was basically consistent with the actual landslide.

DEGRADATION EFFECT OF SEAWATER ON THE LONG-TERM DYNAMIC BEHAVIOR OF ARTIFICIALLY CEMENTED SAND

2013 ◽  
Vol 07 (04) ◽  
pp. 1350031 ◽  
Author(s):  
BO LI ◽  
YUANQIANG CAI ◽  
XIANGWU ZENG ◽  
LINYOU PAN
Keyword(s):  
Shear Modulus ◽  
Dynamic Behavior ◽  
Tap Water ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Resonant Column ◽  
Cyclic Triaxial Tests ◽  
Cemented Sand

The dynamic behavior of lightly cemented sand under long-term seawater attack was evaluated in this study. Resonant column and cyclic triaxial tests were employed to investigate the evolution of the shear modulus and damping ratio of cemented sand with respect to soaking period (SP), confining pressure, and cement content (CC). The results of this study show that the cementation of the sand is affected by soaking in seawater to a greater extent than by soaking in tap water. The shear modulus of the cemented sand soaked in seawater was smaller than that of the cemented sand soaked in tap water. The damping ratio increased significantly, as the SP increased and was greater for the cemented sand soaked in seawater than for the cemented sand soaked in tap water. The dynamic behavior of nonhomogenous specimens was examined. Crystallization of salts could be clearly observed and probably explains the evolution of the dynamic behavior of the cemented sand. Finally, the shear modulus was fitted using Rollins' Law [Rollins et al., 1998], which demonstrates that the parameters used in the equation can be reasonably fitted linearly over a range of SPs.

Hydromechanical behaviour of expansive soils with different suctions and suction histories

2016 ◽  
Vol 53 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Junran Zhang ◽  
De’an Sun ◽  
Annan Zhou ◽  
Tong Jiang
Keyword(s):  
Expansive Soils ◽  
Volumetric Strain ◽  
Expansive Soil ◽  
Experimental Results ◽  
Triaxial Tests ◽  
Test Results ◽  
Soil Water Retention ◽  
Suction Control ◽  
Vapor Equilibrium ◽  
High Suction

This paper presents a number of experimental results of suction-controlled triaxial tests on a compacted weakly expansive soil with different suctions and suction histories. In terms of suction control methods, the high suction level (from 3.29 to 38 MPa) was realized by the vapor equilibrium technique and the low suction level (from 0 to 800 kPa) was controlled by the axis translation technique. Results of the triaxial tests indicate that the specimen with higher suction shows higher strength and lower contractive and higher dilative volumetric strains, and the average skeleton stress ratio (q/p′) at failure decreases with increasing suction in the high suction range (3.29∼38 MPa). Given that suction during shearing is constant (e.g., 200 kPa), the specimen dried to a higher suction and the history shows higher strength and lower contractive volumetric strain. Experimental results also show that high pre-applied suction (i.e., the maximum suction in the history) can lead to peak strength, post-peak softening, and shear dilation. Three different methods (pressure plate, filter paper, and vapor equilibrium) were employed to study the soil-water retention behaviour of the unsaturated expansive soil. Test results indicate that by combining these three different methods, it is possible to determine the SWCC in the entire suction range (0∼367 MPa). Test results of the expansive soil also show that the void ratio keeps decreasing with increasing suction in the entire suction range.

Permeability of Expansive Soils Modified/Stabilized with lime (Review Paper)

2021 ◽  
Vol 14 (2) ◽  
pp. 129-140
Author(s):  
Muwafaq Awad ◽  
Ibrahim Al-Kiki ◽  
Amina Khalil
Keyword(s):  
Expansive Soils ◽  
Expansive Soil ◽  
Pozzolanic Reaction ◽  
Curing Temperature ◽  
Curing Time ◽  
Short Term ◽  
Coefficient Of Permeability ◽  
Review Study ◽  
Time Periods

The aim of this paper was to review the mechanism of the expansive soil-lime reactions: short term and long-term reactions in both lime modification and lime stabilization. The focus of the study was the effect of curing time for a certain centigrade 25C curing temperature in both lime modification / stabilization-expansive soils on the coefficient of permeability. Peer reviewed articles published between 2000- and 2019 were collected and relevant data were extracted. Results of this review study showed that the coefficient of permeability of expansive soils modified with lime increased during the first 7 days of curing time at curing temperature 25C and it remains constant or slightly decreased for longer curing time periods. However, for expansive soils stabilized with lime, it was found that the coefficient of permeability increased during the first 7-day curing time at curing temperature 25C, then decreased during the longer curing time periods (pozzolanic reaction). It is also noted that even though the coefficient of permeability decreased during pozzolanic reaction, it remains higher than that of the untreated soils

scholarly journals Study on Creep Characteristics of Expansive Soil in High-Fill Channel of South-to-North Water Transfer Project

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Jianhua Guo ◽  
Zhangjun Dai ◽  
Shichang Li ◽  
Nadeem Muhammad ◽  
Hui Gao
Keyword(s):  
Moisture Content ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Water Transfer ◽  
Load Level ◽  
Dry Density ◽  
Creep Characteristics ◽  
North Water ◽  
Consolidation Coefficient ◽  
Unsaturated Expansive Soil

In the Nanyang section of the midroute of the South-to-North Water Transfer Project, the expansive soil is often used as a filler for high-fill channels. After the channel is stabilized, the expansive soil undergoes creep deformation over time. Studying the creep characteristics of expansive soils in different environments is particularly important for evaluating the safe operation of high-fill channels. In the current study, the creep test of expansive soil under different moisture content and dry density was carried out. It is proposed that the slope of the fitted straight line in the compression curve of the expansive soil can be used to represent the secondary consolidation coefficient of unsaturated expansive soil, and the variation law of the secondary consolidation coefficient under different environmental factors is obtained. The modified Bjerrum calculation method considering the influence of additional load and lateral deformation yields the postexpansion soil settlement curve model to determine the control index range of the project site. Moreover, it is also observed that the secondary consolidation coefficient of unsaturated expansive soil increases with the increase of moisture content and decreases with the increase of dry density. The coefficient of secondary compression of unsaturated expansive soil is linearly related to dry density and moisture content. After the preconsolidation treatment of the expansive soil, when the load level is less than the preload, the secondary consolidation coefficient is smaller, otherwise the secondary consolidation coefficient is larger.

scholarly journals The mechanical behavior of an expansive soil due to long-term seasonal rainfalls

2020 ◽  
Vol 195 ◽  
pp. 02019
Author(s):  
Kai LI ◽  
Liang Kong ◽  
Hossein Nowamooz ◽  
Cyrille Chazallon
Keyword(s):  
Mechanical Behavior ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Direct Determination ◽  
Model Parameters ◽  
Continuous Change ◽  
Step Method ◽  
Steady Solutions ◽  
Unsaturated Expansive Soils

Expansive soils, susceptible to be affected by the environmental conditions, expand when water is added and shrink when they dry out. This continuous change in soil volume is able to cause structures built on them to move unevenly and crack. To investigate the hydro-mechanical behavior of unsaturated expansive soils, many laboratory tests on these materials have been carried on and numerous models have also been proposed with a relatively large number of parameters. In this study, a simplified model based on Zarka method has been developed for unsaturated expansive soils. The direct determination of the steady solutions in Zarka analysis is able to replace classic step-by-step method and needs less model parameters. In this context, this paper presents a Zarka-based model to predict the volume change in unsaturated expansive soils under seasonal drought and rainfall cycles and the proposed model is implemented in the finite element code to simulate long-term behavior of a 2D structure consisting of expansive soils and subjected to successive drought and rainfall cycles. Finally, the numerical calculation defines the plastic strain field and the inelastic displacement field of the studied structure.

scholarly journals Using Fine Silica Sand and Granite Powder Waste to Control Free Swelling Behavior of High Expansive Soil

2020 ◽  
Vol 15 (1) ◽  
pp. 53
Author(s):  
Manal O. Suliman ◽  
Abdulrazzaq Jawish Alkherret
Keyword(s):  
Expansive Soils ◽  
Expansive Soil ◽  
Critical Issue ◽  
Soil Samples ◽  
Silica Sand ◽  
Swell Index ◽  
Subgrade Soil ◽  
Free Swell ◽  
Granite Powder

Many researchers have been interested in studying the effect of adding local natural materials or construction waste on the properties of poor subgrade soil. However, changes in size and strength of expansive soils can cause extensive damage to the geotechnical infrastructure. This damage is often repeatable and latent in the long term, and is a critical issue in highway subgrade engineering. This paper examines the effect of adding both Fine Silica Sand (FSS) and Granite Cutting Powder Waste (GPW) materials on the welling characteristics of expansive soils. Atterberg limits, free swell index, and rate of swell of the mixtures were used as a key to assess properties of a group of expansive soil samples after adding different percentages of the mentioned materials. The rates of additions were 10%, 20%, 30%, 40%, 50%, 60 and 70% of the weight of the soil samples. The test results showed that FSS and GPW significantly affect the expansive soil properties. However, adding 70% of both FSS and GPW reduced the swelling index from 58.3% to 6.6% and from 58.3% to 11% after 7 days of curing, respectively. This study suggests that the Fine Silica Sand and Granite Powder Waste can be used as stabilizers for expansive highly plastic soils.

scholarly journals Influence of Humidity State on Dynamic Resilient Modulus of Subgrade Soils: Considering Repeated Wetting-Drying Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Gongfeng Xin ◽  
Anshun Zhang ◽  
Zijian Wang ◽  
Quanjun Shen ◽  
Minghao Mu
Keyword(s):  
Resilient Modulus ◽  
Confining Pressure ◽  
Service Performance ◽  
Triaxial Tests ◽  
Road Engineering ◽  
Groundwater Level Fluctuations ◽  
Subgrade Soils ◽  
Deviator Stress ◽  
Complicated Conditions ◽  
Satisfactory Prediction

The service performance of subgrade depends on the dynamic resilient modulus (MR) of subgrade soils. Meanwhile, due to complicated conditions such as rainfall infiltration, high temperature evaporation, and groundwater level fluctuations, it can be safely said that the humidity state and repeated wetting-drying (WD) cycles affect the MR of subgrade soils. The object of this study is to conduct a series of dynamic triaxial tests after WD cycles to investigate the characteristics of the MR under various factors. The main results are as follows: (i) the MR decreased with the increase of deviator stress and rose with the growth of confining pressure; (ii) the humidification effect caused by the increase in moisture content attenuated the MR; (iii) the accumulation of WD cycles damaged the MR; however the decline rate was gradually retarded until it was stable with WD cycles 5 times; (iv) the satisfactory prediction model for the MR of subgrade soils considering WD cycles was proposed and verified. It is expected that the findings can provide valuable contributions for road engineering.

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