大面积基坑开挖前预降水对支护墙变形的影响研究

发布时间：2018-01-16 19:03

本文关键词：大面积基坑开挖前预降水对支护墙变形的影响研究　出处：《岩土工程学报》2017年06期 　论文类型：期刊论文

【摘要】：首先基于工程实测,研究了大面积宽基坑土方开挖前群井预降水对支护墙变形的影响,实测到基坑开挖前降水引起的最大支护墙侧移达到15 mm,约为该基坑变形报警值的47.6%;并发现对于排桩支护墙,在支护侧布置降水井,可以起到减小坑内降水引起支护墙侧移的作用;然后开展了35个常见工况的三维流固耦合有限元数值计算,研究了基坑宽度对支护墙变形的影响规律及其机理。结果表明,宽度较大基坑在同一预降水时间和深度条件下将发生更大幅度支护墙侧移,而在通常的预降水深度(0~20 m)条件下,对于宽度为20~40 m的地铁基坑,降水引起的支护墙最大变形及其增量均对基坑宽度的变化十分敏感,而对于宽度大于40 m的基坑,在同一降水深度条件下,支护墙最大侧移仅有较小的差别。而引起上述规律的机理可用降水过程中基坑中轴两侧土体侧移的叠加效应强弱来解释,基坑宽度越小,降水过程中坑内土体侧移叠加效应越明显,最大支护墙侧移就越小。
[Abstract]:Firstly, based on the engineering measurement, the influence of pre-dewatering on the deformation of retaining wall is studied. The maximum displacement of supporting wall caused by dewatering before excavation is up to 15 mm. It is about 47.6 of the alarm value of the foundation pit deformation; It is also found that for the supporting wall with piles, the dewatering wells on the supporting side can reduce the displacement of the supporting wall caused by the precipitation in the pit. Then 35 common cases of three-dimensional fluid-solid coupling finite element numerical calculation is carried out, the influence of foundation pit width on the deformation of retaining wall and its mechanism are studied. The results show that. Under the condition of the same pre-dewatering time and depth, the retaining wall will shift sideways more greatly in the larger width foundation pit, but under the normal pre-dewatering depth of 0 ~ 20 m). For the subway foundation pit with a width of 20 ~ 40 m, the maximum deformation and increment of the retaining wall caused by dewatering are very sensitive to the variation of the width of the foundation pit, but for the foundation pit whose width is more than 40 m. Under the condition of the same depth of precipitation, the maximum lateral displacement of the retaining wall is only slightly different, and the mechanism of the above law can be explained by the superposition effect of the lateral displacement of the soil on both sides of the shaft of the foundation pit in the process of dewatering. The smaller the width of foundation pit, the more obvious the superposition effect of soil lateral movement in the dewatering process, and the smaller the lateral displacement of the maximum supporting wall.
【作者单位】：湖南科技大学土木工程学院;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;天津大学建筑工程学院;
【基金】：国家重点基础研究发展计划(“9 7 3”计划)项目(2010CB732106) 国家自然科学基金项目(51308209,11602083) 湖南省自然科学基金项目(2016JJ6044) 湖南省教育厅项目(15C0557)
【分类号】：TU753
【正文快照】： 0.1基坑支护墙初始变形的探讨在过去,基坑支护墙变形施工监测绝大多数是从基坑即将开挖时才开始,即,基坑开挖前支护墙初始变形被视为0,过往关于基坑变形的文献基本是以此为基础进行的报道[1-4]。而对于高水位地区基坑工程,在基坑开挖前,需要进行降水井洗井、试抽水、疏干抽水(

【相似文献】