应变率与含水率对冻土单轴压缩特性影响研究

通过对泥浆制样法制备的冻结粉质砂土的单轴压缩试验，系统地研究了冻结砂土在一个宽泛应变率以及含水率范围内的单轴压缩破坏应变特性和线弹模量特性。结果表明：随着应变率的增加，当含水率为12.0%，破坏应变逐渐增大；当含水率在16.7%～24.0%范围内时，破坏应变先增大后减小；当含水率大于等于30.6%时，破坏应变逐渐减小，3种情况下破坏应变最终都逐渐趋于稳定。破坏应变随含水率增加而先急剧增大到一个最大值，然后急剧减小，当含水率超过41.5%时，基本趋于冰的破坏应变。线弹模量先随着应变率的增大而非线性增大到一个最大值，然后应变率的继续增大使线弹模量逐渐减小，线弹模量与应变率的关系满足二次抛物函数规律。在温度为 2.0 ℃，应变率小于4.67×10-3 s-1的条件下，线弹模量随着含水率的增大而非线性增大，直至最后趋于冰的线弹模量；而在大于等于该应变率的条件下，随着含水率的增大，线弹模量先增大到一个最大值，然后减小趋于冰的线弹模量。当温度为 5.0 ℃时，类似的应变率临界值为1.00×10-2 s-1。

Effects of strain rate and water content on uniaxial compressive characteristics of frozen soil

Based on a mud method of preparation sample, some uniaxial compressive tests are conducted on the frozen silty sand samples prepared with the mud sample preparation method. The failure strain and linear elastic modulus characteristics of frozen silty sand under uniaxial compression are investigated systemically in a wide range of strain rate and water content. The experimental results show that with rise of strain rate, failure strain increases gradually when water content is 12.0%; failure strain firstly increases and then decreases with growth of stain rate when water content is between 16.7% and 24.0%; when water content is greater than or equal to 30.6%, with increasing strain rate, failure strain decreases gradually; for the above three cases, the failure strain always tends gradually to be stable in the end. With increasing water content, failure strain firstly increases to a maximum sharply and then decreases dramatically. The failure strain tends to the failure strain of ice after water content is beyond 41.5%. Linear elastic modulus increases nonlinearly to a peak with increasing water content and then further rise of water content makes it lower, which can be described by a quadratic polynomial model. At 2.0 ℃, when strain rate less than 4.67×10-3 s-1, with increase of water content, linear elastic modulus increases nonlinearly and then tends to the linear elastic modulus of ice; when strain rate greater than or equal to 4.67×10-3 s-1, linear elastic modulus firstly increases to a maximum and then decreases to the linear elastic modulus of ice with increase of water content. When temperature is at 5.0 ℃, the similar critical value of strain rate to 4.67×10-3 s-1 is 1.00×10-2 s-1.