冻融作用下伊犁原状黄土水力特性劣化规律与微观机制  

DETERIORATION LAW AND MICROSCOPIC MECHANISM OF HYDRAULIC CHARACTERISTICS OF UNDISTURBED LOESS IN ILI UNDER FREEZE-THAW ACTION

作　　者：李业彤 杨更社[1] 叶万军[1] 李敬娜 王根龙[2] 王佳运[2] LI Yetong;YANG Gengshe;YE Wanjun;LI Jingna;WANG Genlong;WANG Jiayun(College of Architecture and Civil Engineering,Xi an University of Science and Technology,Xi an 710054,China;Xi an Center of Geological Survey,China Geological Survey,Xi an 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]中国地质调查局西安地质调查中心,西安710054

出　　处：《工程地质学报》2023年第4期1261-1268,共8页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:42072319);南疆兵团师市规划建设区资源环境综合地质调查项目(资助号:DD20201119);陕西省自然科学基础研究计划(资助号:2022JQ-307).

摘　　要：新疆伊犁地区冻害严重,尤以滑坡灾害最显著,主要体现在冻融作用下原状黄土的水力特性劣化方面,然而其水力特性的劣化规律和微观机制目前并不明晰,因此本文开展了冻融前后伊犁原状黄土的水力试验和微观试验研究。结果表明:冻融作用使得黄土内部的胶结性和结构完整性遭受破坏,在原位有效应力施加于冻融后的原状黄土,后续加上水分浸泡后,黄土会产生更大变形,因而冻融后原状黄土的自重湿陷性系数增加和孔隙比减小。冻融作用会使得原状黄土内部产生大裂缝和大孔径,渗流过程中水分会从大裂缝和大孔隙流失,因而冻融后原状黄土的渗透系数增加。冻融循环中的冻胀作用使得原状黄土内部自由水变成冰体,产生膨胀作用,其会破坏原状黄土的胶结性和结构完整性,同时产生大裂缝和大孔径,最终造成原状黄土的剪切强度和黏聚力降低。反复的冻融使得土颗粒发生破坏、移位,形成较为复杂的接触形式,从而使得内摩擦角减小并不显著。The freezing damage in Ili area of Xinjiang is serious,especially the landslide disaster is the most significant,which is mainly reflected in the deterioration of hydraulic characteristics of undisturbed loess under freeze-thaw action.However,the deterioration law and microscopic mechanism of hydraulic characteristics are not clear at present.Therefore,this paper carries out the hydraulic test and microscopic test of undisturbed loess in Ili before and after freeze-thaw.The results show that the cementation and structural integrity of loess are destroyed by freeze-thaw action.The effective stress in situ is applied to the undisturbed loess after freeze-thaw,and the loess would produce greater deformation after subsequent water immersion.Therefore,the self-weight collapsibility coefficient of undisturbed loess increases and the void ratio decreases after freeze-thaw.Freeze-thaw action would cause large cracks and large pore size inside the undisturbed loess,and water would be lost from large cracks and large pores during seepage,so the permeability coefficient of undisturbed loess would increase after freeze-thaw.The frost heaving effect in the freeze-thaw cycle makes the free water inside the undisturbed loess become ice,resulting in expansion,which would destroy the cementation and structural integrity of the undisturbed loess,and produce large cracks and large apertures,resulting in the shear strength and cohesion of the undisturbed loess.Repeated freeze-thaw makes soil particles damage,displacement,forming a more complex form of contact,so that the internal friction angle is not significantly reduced.

关 键 词：伊犁原状黄土 冻融作用 力学特性 自重湿陷性系数 渗透系数 内部裂缝 

分 类 号：P642.3[天文地球—工程地质学]