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Shear strength characteristics at different temperatures of Shenshuo Railway subgrade filling(PDF)


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Shear strength characteristics at different temperatures of Shenshuo Railway subgrade filling
ZHANG Zhi-chun LI Xu TIAN Ya-hu WEI Chao-xiong ZHANG Guo-guang
1. Shenshuo Railway Branch, China Shenhua Energy Co., Ltd., Yulin 719316, Shaanxi, China; 2. School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; 3. Jinan Railway Bureau, Jinan 250000, Shandong, China
subgrade engineering subgrade filling direct shear experiment shear strength characteristic shear dilatancy displacement
With the increase of axle load, the instability failure of heavy haul railway subgrade is becoming more and more prominent. In order to obtain the shear strength of the subgrade filling of Shenshuo Railway at different temperatures, a series of direct shear tests were conducted by the large direct shear apparatus, which was developed in the Frozen Soil Laboratory of Beijing Jiaotong University. The subgrade filling is low liquid limit silt, the optimum moisture is 14.5%, which was selected as the moisture content of samples, and the compaction coefficient is 0.95. Three temperature levels of positive temperature, -3 ℃ and -5 ℃ were set up, and four different vertical pressures were selected to be tested. Based on the test results, the changes and regulations of various characteristics, such as shear stressdisplacement, internal fiction angle, cohesion and shear dilatancy, were analyzed. The results show that the cohesion of subgrade filler is strongly influenced by the cooling temperature. Cohesion of subgrade filling at -3 ℃ is over 500 kPa than that at positive temperature, and is 95.5 kPa less than that at -5 ℃. With the temperature decreasing from positive temperature to -5 ℃, the internal friction angle increases from 19.6° to 33.8°. Under the conditions of different temperatures and different vertical pressures, curves of shear stress-displacement are basically the same, which can be divided into consolidation stage, partial shear stage and failure stage. The shear strength of subgrade filling of Shenshuo Railway is significantly affected by cooling temperature. In frozen state, the maximum increase of shear strength is more than 400% compared with the unfrozen state. Even if they are all frozen at negative temperature, the shear strength also increases with the decrease of cooling temperature. The subgrade filling in frozen state shows obvious shear dilatancy. With the increase of vertical pressure, the shear dilatancy becomes decreasing. However, it has no obvious change with the cooling temperature.



Last Update: 2017-07-17