膨胀土临界状态强度特性及其模型拟合

摘要

According to Mengzi expansive soil,consolidated drained tests and undrained tests are carried on under the saturated and remolded condition.The stress-strain characteristics of saturated soil are researched systematically under different consolidation pressure,initial dry density,initial water content,shearing rate and drainage condition.The inherent unity of diversity of shearing strength for the same samples is measured by different experimental methods and is indicated according to the normalization of critical state test results.The failure lines in p′-q -νspace of remolded saturated expansive soil under consolidated drained and undrained condition are attained.The hyperbolic curve model can fit well the inferior hardening stress-strain curve.The exponential curve model can fit the inferior soft stress-strain curve.The test results can provide technical parameters and theoretical help for shearing strength variation of slope during rainfall and strength state of soil structure in normal water level.%针对蒙自地区膨胀土，进行了饱和重塑条件下的固结排水（CD）与固结不排水（CU）试验，系统研究了饱和土在不同固结围压σ3、初始干密度ρd、初始含水量ω0、剪切速率υ、排水条件下的应力应变特性。通过对临界状态试验结果的归一化处理，揭示了不同试验方法对同一土样抗剪强度量测差异的内在统一性，得到了重塑饱和膨胀土在固结排水与不排水条件下p′－q －ν空间内的破坏线。利用双曲线模型较好地拟合了弱硬化型应力应变曲线，用指数曲线模型拟合了弱软化型应力应变曲线，为模拟边坡在降雨条件下的抗剪强度变化及构筑物土体处于正常水位时的强度状态等工况提供了技术参数与理论支持。