复杂边界条件下富水深基坑变形控制研究

城市地铁的迅速发展,车站基坑工程的安全性愈发受到重视。为研究在地下水丰富、周边环境复杂的工况下基坑不同支护方案的安全性,为类似工程设计施工提供指导及参考,运用三维有限差分计算软件FLAC3D对基坑工程施工过程进行数值模拟,对基坑开挖过程中支护结构的水平位移、建筑不均匀沉降及管廊竖向位移进行研究。结果表明:采用钻孔灌注桩(Φ800 mm@1 500 mm)+内支撑及桩间旋喷形式,基坑围护桩水平变形超过安全允许值,且周边建筑物不均匀沉降较大;若采用地连墙(厚800mm)+内支撑的支护形式可有效控制基坑及周边构筑物的变形,使结构处于安全状态。

Selection and Optimization of Deep Basement Supporting Structure Under Complicated Environment

With the rapid development of city subway,the safety of foundation pit project in subway stations is becoming more and more important.To analyze the safety of different supporting schemes for foundation pit under the working condition with abundant groundwater and complex surrounding environment as well as provide guidance and reference for similar engineering design and construction,we use the 3D finite difference calculation software FLAC3D to carry out numerical simulation during the construction process of the foundation pit project and calculate the horizontal displacement of supporting structure,uneven sedimentation of building and the vertical displacement of pipe track during the excavation process.Results show that by adopting the form of bored pile (Φ800 mm@1 500 mm) plus inner support and jet grouting between piles,the horizontal deformation of supporting pile of foundation pit exceeds allowable safety value and the uneven sedimentation of surrounding buildings is obvious.If the supporting form of diaphragm wall (thickness of 800 mm)plus inner support is used,it could effectively control the deformation of foundation pit and surrounding buildings so as to keep the structure in safe condition.