降雨对软土基坑支护结构影响实测及机理研究  

Measurement and mechanism of influences of rainfall on supporting structures of foundation pits in soft soils

作　　者：刘畅[1,2] 季凡凡[1] 郑刚 刘涛[1,4] 刘永超[3] LIU Chang;JI Fan-fan;ZHENG Gang;LIU Tao;LIU Yong-chao(School of Civil Engineering,Tianjin University,Tianjin 300072,China;Key Laboratory of Coast Civil Structure Safety,Ministry of Education,Tianjin 300072,China;Tianjin Pile Foundation Technology Engineering Center,Tianjin 300301,China;Beijing Longhu Zhongbai Real Estate Co.,Ltd.,Beijing 100020,China)

机构地区：[1]天津大学建筑工程学院,天津300072 [2]滨海土木工程结构与安全教育部重点实验室,天津300072 [3]天津市桩基技术工程中心,天津300301 [4]北京龙湖中佰置业有限公司,北京100020

出　　处：《岩土工程学报》2020年第3期447-456,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家重点基础研究发展计划(“973”计划)项目(2010CB732106);国家自然科学基金项目(51108312)。

摘　　要：降雨通常易导致土质边坡的滑动、失稳,降雨对基坑特别是软土条件下的基坑的影响研究较少。针对天津市某基坑展开实测,开挖结束后在没有其他施工条件下,连续3 d 247 mm降雨导致基坑支护桩顶水平位移增加13.75 mm,因此研究降雨入渗诱发软土基坑变形的机理具有十分重要的意义。首先进行降雨的入渗深度及对非饱和黏土物理力学性质影响室内试验,在此基础上结合工程实测,采用Plaxis2D有限元分析软件建立二维软土基坑模型,分析了降雨对软土基坑支护结构变形的影响机理,主要对比了降雨强度、降雨时长、降雨量对基坑支护结构变形的影响,以及开挖深度、桩顶初始位移、支护形式不同对降雨的敏感程度。结果表明:降雨对软土基坑支护结构变形影响主要因素为坑外杂填土重度增加、坑内土体软化、渗流作用,降雨量是对基坑支护变形影响较大的因素;降雨产生的支护结构位移增量受支护结构初始位移影响最大,而基坑开挖深度对相同降雨条件下支护结构变形增量影响差异不大。Rainfall is usually easy to cause sliding and instability of soil slopes. At the same time, it also has a great influence on foundation pits, especially for those in soft soils. In the absence of other construction, after three days of rainfall of 247 mm deep, the horizontal displacement of supporting structures of a foundation pit in Tianjin increases by 13.75 mm. Therefore, it is of great significance to study the mechanism of deformation induced by rainfall of foundation pits in soft soils. Firstly, the experiments on the influences of rainfall on relevant model are conducted by using Plaxis2 D. The influence mechanism of rainfall on the deformation of supporting structures of the foundation pit in soft soils is analyzed. The influences of intensity, duration and amount of rainfall on the deformation of supporting structures are analyzed, and the sensitivities of the excavation depth, the initial displacement of pile top, the form of supporting structures to rainfall are studied. The main factors affecting the deformation of supporting structures are the increase of the residual soils outside the pit, the softening of the soils in the pit and the fluid-solid coupling. The amount of rainfall is a factor to have a large influence on the deformation of the supporting structures of the foundation pit. The displacement increment of the supporting structures caused by rainfall is most affected by their initial displacement, while the depth of foundation excavation has small influences on their deformation increment under the same rainfall conditions.

关 键 词：降雨 软土 基坑 支护结构 

分 类 号：TU447[建筑科学—岩土工程]