软土区基坑预降水引起支护墙侧移的典型参数影响研究

发布时间：2018-09-18 15:00

【摘要】：基于天津地区透水层和弱透水层交替出现的场地水文地质条件,通过大量数值计算与工程实测对比,结合非线性回归分析,研究了预降水时间t、预降水深度H_d、基坑长宽L,基坑宽度b等参数对基坑预降水过程中支护墙侧移发展的影响规律。随t延长,最大支护墙侧移δ_(hm)呈增长速率不断减小的非线性增长,在预降水刚开始的几天内,支护墙侧移即可占据其预降水过程中稳定侧移的很大比重。其次,H_d对δ_(hm)及支护墙悬臂侧移深度H_c的发展有重要影响,总的来说,δ_(hm)及H_c均随H_d增大而增大,具体地,当H_d达到场区第2透水层前(后),δ_(hm)随H_d的线性增长比例较小(大),当H_d达到场区深厚弱透水层厚度一半之前(后),H_c的增长接近于(明显快于)H_d的增长。另外,对于同一宽度b基坑,当基坑长度L达到一定程度后,预降水引起的基坑长度方向边角效应总是发生在基坑两侧距离坑角某一确定范围之内,在预降水过程中,若支护墙变形需要严格控制时,可通过布置横隔墙,使得相邻横隔墙间距S_(cw)与b之比在4以内,或S_(cw)/H_d在3.7以内,利用基坑边角效应减小预降水引起的最大支护墙侧移。
[Abstract]:Based on the hydrogeological conditions of the site where the permeable and weakly permeable layers alternately occur in Tianjin, a large number of numerical calculations are compared with the engineering measurements, and a nonlinear regression analysis is combined. The influence of parameters such as pre-precipitation time (t), pre-precipitation depth (H _ d), foundation pit length and width (L) and foundation pit width (b) on the lateral displacement of retaining wall in the process of pre-dewatering is studied. With the extension of t, the lateral displacement 未 _ (hm) of the maximum retaining wall increases with a decreasing nonlinear growth rate. During the first few days of pre-precipitation, the lateral displacement of the retaining wall can take up a large proportion of the stable lateral shift in the pre-precipitation process. Secondly, Hd has an important influence on the development of 未 _ (hm) and the depth of cantilever shift of retaining wall. In general, 未 _ (hm) and Hac increase with the increase of Hd, specifically, When Hd reaches the second permeable layer (after), the linear increase of 未 _ (hm) with HSCD is small (large), and the growth of HSCC is close to (obviously faster) that of Hd before (after) Hd reaches half thickness of deep weak permeable layer in the field. In addition, for the same width b foundation pit, when the foundation pit length L reaches a certain degree, the side angle effect of foundation pit length caused by pre-dewatering always occurs within a certain range of distance between the two sides of the pit, and during the pre-dewatering process, If the deformation of supporting wall needs to be strictly controlled, the ratio of S _ (cw) to b of the adjacent transverse partition can be within 4, or S _ (cw) / H _ d is less than 3.7, the maximum support wall lateral displacement caused by pre-dewatering can be reduced by using the side angle effect of foundation pit.
【作者单位】：湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室;天津大学滨海土木工程结构与安全教育部重点实验室;广西大学工程防灾与结构安全教育部重点实验室;
【基金】：国家自然科学基金项目(No.51308209,No.51578164,No.51708206,No.11602083) 滨海土木工程结构与安全教育部重点实验室开放课题(No.2017-KF03) 湖南省自然科学基金项目(No.2016JJ6044) 湖南省教育厅项目(No.15C0557)~~
【分类号】：TU753

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