控制气压条件的非饱和粘性土固结沉降特性研究  

Study on consolidation and settlement characteristics of unsaturated clay soil under the air pressures controlled condition

作　　者：李晓宁[1] 王林[1] 徐静 LI Xiao-ning;WANG lin;XU jing(School of Civil Engineering and Architecture,Southwest University of Science and Technology,Mianyang 621010,China;Southwest Jiaoda Civil Engineering Design Co,Ltd,Chengdu 610031,China)

机构地区：[1]西南科技大学土木工程与建筑学院,四川绵阳621010 [2]四川西南交大土木工程设计有限公司,四川成都610031

出　　处：《高原科学研究》2019年第3期28-34,共7页Plateau Science Research

基　　金：国家自然科学基金项目(51348003);绵阳市科技计划项目(2017YFNY009)

摘　　要：气压条件是影响土体非饱和特性的关键环境,是青藏高原土体工程设计需要考虑的重要因素。文章开展基于改装的GDS动三轴仪的控制气压条件的非饱和土一维固结试验,分析非饱和粘性土在各级大气压力下的沉降规律,分析试验中非饱和土试样沉降过程及其主固结、次固结和总固结沉降规律。结果表明:①非饱和粘性土在控制恒定气压在100 kpa、200 kpa和300 kpa时,土样均排出孔隙水,导致固结试验开始时各个土样的饱和度分别随控制气压的增大而减小;②当恒定气压较大时,固结沉降主要靠孔隙气体体积变化贡献,土体固结速率较大;当恒定气压较小时,固结沉降主要靠孔隙水的排出贡献,固结速率相对较小;③控制气压较大会导致非饱和土体内部结构有效应力增大,土体固结沉降量较小时便可达到一个稳定的土体结构来抵抗荷载,且有利于高原非饱和土体长期工程力学特性的强化。Atmospheric pressure condition as the key environment affects on the unsaturated characteristics of soil,and it is an important factor to be considered in soil engineering design of Qinghai-Tibetan Plateau.In this paper,one dimensional consolidation test of unsaturated soil was carried out under the air pressure controlled condition based on modified GDS dynamic three axis apparatus,the settlement law of unsaturated clay soil was analyzed at different atmospheric pressure.The settlement process,and the law of main consolidation,secondary consolidation and total consolidation of unsaturated soil specimen were analyzed as well.The results showed that:①when the constant atmospheric pressure was controlled at 100 kpa,200 kpa and 300 kpa,the unsaturat?ed clay soil samples discharge pore water leading to saturation degree of each soil sample decreased with the in?crease of constant atmospheric pressure at the beginning of consolidation test,②when the constant atmospheric pressure was large,consolidation settlement was mainly contributed by the volume change of pore gas and the consolidation rate of soil was relatively large,in contrast constant atmospheric pressure was small,the consolida?tion settlement mainly depended on the discharge of pore water with relatively small consolidation rate,③higher atmospheric pressure controlled will lead to the increase of the effective stress of the internal structure of the un?saturated soil,and the consolidation and settlement of the soil can reach a stable soil structure to resist the load,and is beneficial to the strengthening of the long-term engineering mechanical properties of the saturated soil on the Plateau.

关 键 词：非饱和土 固结试验 主固结沉降 大气压力 青藏高原 

分 类 号：TU411.5[建筑科学—岩土工程]