基坑降水对临近地面沉降规律的影响研究

RESEARCH ON INFLUENCE OF FOUNDATION PIT DEWATERING ON ADJACENT GROUND SETTLEMENT

近年来,伴随着城市化进程的不断加快,人类对地下空间的利用也在不断加强,同时也出现了各种各样的问题,各种地质灾害频频发生,其中,临近基坑地面的沉降是最为常见的问题。根据广州广佛环线项目明挖基坑的现场情况,结合相关资料,对现场监测情况和理论计算进行对比分析,得出如下结论:(1)基坑深度为15 m,在基坑2倍范围内,地面沉降变化情况为由近及远逐渐变大,然后减小,最大位置位于距离20 m左右,大约1.5倍基坑深度,最大沉降25~30 mm,地面沉降总体趋势垂直基坑方向呈现勺型;(2)基坑周围地表沉降变化情况和基坑降水深度维持在同一频率,同时下沉,在第二次混凝土支撑建设后出现变化减缓,但仍保持下降趋势;(3)在基坑降水过程中,土体也发生了侧向位移,方向为基坑一侧,也是导致距离基坑较远处地面沉降较大的因素之一。

In recent years,with the accelerating process of urbanization,the use of underground space is also constantly strengthened.At the same time,there are a variety of problems.A variety of geological disasters and disasters occur frequently.Among them,the settlement of the ground near the foundation pit is the most common problem.According to the field situation of Guangzhou Foshan ring road project open cut foundation pit,combined with relevant data,this paper compares and analyzes the field monitoring situation and theoretical calculation,and draws the following conclusions:(1)The depth of the foundation pit is 15m.Within the double range of the foundation pit,the change of land settlement gradually increases from near to far,and then decreases.The maximum position is about 20m away,about 1.5 times the depth of the foundation pit,and the maximum settlement is 25~30mm.The overall trend of land settlement is vertical to the direction of the foundation pit,showing a spoon shape;(2)The surface settlement around the foundation pit and the dewatering depth of the foundation pit maintain the same frequency and sink at the same time.After the second concrete support construction,the change slows down,but still keeps a downward trend;(3)In the process of foundation pit dewatering,the soil also has lateral displacement,and the direction is one side of the foundation pit,which is also one of the factors leading to large ground settlement far away from the foundation pit.