有载冻融作用对深部重塑黏土抗剪强度影响的试验研究北大核心CSCD

深厚表土层冻结法凿井工程中,深部土体由于经历了高压冻融作用,导致其工程性质变化,认识冻融作用对其强度与变形影响,对于冻融病害防治有一定意义。本文通过室内试验对深部重塑黏土进行了有载冻融,并对不同干密度、围压、冻结温度和融化温度条件下的深部冻融重塑黏土进行三轴剪切试验,探讨有载冻融作用下深土重塑土抗剪强度的变化规律。研究结果表明:冻融作用使深部重塑黏土的偏应力-应变关系由软化型转变成硬化型;同时,经冻融作用后其抗剪强度与割线模量都产生了一定的下降,在本试验条件下,抗剪强度最高下降了48.8%,割线模量E_()最大下降了72.0%。通过对各影响因素的显著性分析,发现初始干密度对抗剪强度和割线模量影响最为显著,围压对两者的影响最弱。

Experimental study on shear strength of deep remolded clay under freeze-thaw loading

For freezing sinking in deep alluvium， the deep clay experiences freeze-thawing under high ground stress due to the formation and thawing of the frozen wall， which can lead to changes in its engineering properties. In this paper， loaded freeze-thaw tests were conducted on deep remodeled clay by indoor tests， and triaxial shear tests were conducted on deep freeze-thaw remodeled clay under different conditions of dry density， surrounding pressure， freezing temperature and thawing temperature to explore the changes of shear strength of deep remodeled clay under the effect of loaded freeze-thaw. The results showed that the freeze-thaw effect changed the bias stress-strain relationship of deep remodeled clay from soft type to hardened type； meanwhile， the shear strength and cut-line modulus both decreased to a certain extent after the freeze-thaw effect， and the maximum shear strength decreased by 48.8% and the maximum cut-line modulus E_0.5 decreased by 72.0% under the present test conditions. Through the significance analysis of the influencing factors， it was found that the initial dry density had the most significant effect on the shear strength and the cut line modulus， and the perimeter pressure had the weakest effect on both.