Deformation characteristics and shakedown behaviors of frozen silty clay under complex cyclic stress paths
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摘要: 复杂循环应力路径下冻土的变形特性与安定性行为研究对寒区工程的长期稳定性具有重要作用。为分析不同复杂循环应力路径对冻土变形特性与安定性行为的影响,设计不同温度同一水平下的5种循环应力路径,即三轴循环应力路径(TCSP)、定向循环应力路径(DCSP)、圆形循环应力路径(CCSP)、椭圆循环应力路径(ECSP)和心形循环应力路径(HCSP),分析了粉质黏土的轴向累积塑性应变,同时利用3种安定性评价准则对结果进行评估。研究结果表明:不同温度5种循环应力路径下的轴向累积塑性应变满足DCSP > ECSP > HCSP > CCSP > TCSP。安定性评价结果表明,定向循环应力路径对土体的安定性行为影响最大,在3种准则下都属于增量破坏。在-15℃时,心形循环应力路径与椭圆循环应力路径试验结果在Chen-准则评估下也属于增量破坏。Abstract: The deformation characteristics and stability behaviors of frozen soil under complex cyclic stress paths play an important role in the long-term stability of cold region engineering. To analyze the influences of different complex cyclic stress paths on the deformation characteristics and shakedown behaviors of frozen soil, five cyclic stress paths are designed at the same level, namely triaxial cyclic stress path (TCSP), directional cyclic stress path (DCSP), circular cyclic stress path (CCSP), elliptical cyclic stress path (ECSP) and heart-shaped cyclic stress path (HCSP). The axial cumulative plastic strains of the samples are analyzed, and the results are evaluated by three shakedown evaluation criteria. The axial cumulative plastic strains under five cyclic stress paths at different temperatures satisfy the following: DCSP > ECSP > HCSP > CCSP > TCSP. The directional cyclic stress path has the greatest influences on the shakedown behaviors of the soil, and the failure belongs to the incremental one under the three criteria. At the temperature of -15℃, the results of the HCSP and ECSP tests also belong to the incremental failure under the evaluation of Chen criterion.
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表 1 试验土体基本物理性质
Table 1 Physical properties of test soil
最大干密度ρdmax/(g·cm-3) 最优含水率wopt/% 饱和含水率wsat/% 液限wL/% 塑限wP/% 塑性指数IP 1.84 17.51 20.12 31.17 17.20 13.97 表 2 试验方案
Table 2 Test schemes
试样编号 温度/℃ CSR 应力路径 TN1~5 -1.5 0.875 TCSP, DCSP, CCSP, ECSP, HCSP TN6~10 -6 1.750 TCSP, DCSP, CCSP, ECSP, HCSP TN11~15 -15 1.750 TCSP, DCSP, CCSP, ECSP, HCSP -
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