基坑开挖对运营高铁路基变形影响因素分析

以软土地区某邻近运营高铁路基的基坑工程为例,采用数值分析方法,建立包含基坑及高铁路基在内的三维分析模型,研究降水方案、坑底加固、围护结构插入比以及基坑距路基坡脚距离这4个因素对高铁路基变形的影响。结果表明:与一次性降水相比,分层降水所造成的路基最大沉降和水平位移分别减小3.8%和5.2%;坑底加固对路基沉降的影响较小,但对路基水平位移影响相对较大;围护结构插入比存在一个最佳值,超过该值后继续增加插入比对减小路基变形作用不大;路基最大变形的峰值点出现在基坑距路基坡脚距离为10~15 m处。研究成果可为基坑支护设计和施工及邻近高铁的运营提供参考。

Analysis on Influencing Factors of Foundation Pit Excavation on Deformation of High-speed Railway Subgrade

This study focuses on a foundation pit excavation project adjacent to the subgrade of an operating high-speed railway in soft soil area. Using numerical analysis method,a three-dimensional analytic model incorporating the foundation pit and the subgrade of the nearby high-speed railway is built to study the influences of such factors as dewatering scheme,reinforcement,embedded depth ratio,and the distance between excavation and toe of slope on the deformation of the subgrade. The results show that compared with one-time dewatering,the settlement and lateral displacement of the subgrade induced by multi-layer dewatering are reduced by 3. 8% and 5. 2% respectively. The influence of reinforcement on the settlement of the subgrade is relatively small while that on lateral displacement is relatively large.There exists an optimal value of the embedded depth ratio to minimize the deformation of the subgrade,and any value over the optimal helps little. The maximum deformation reaches its peak when the distance between excavation and toe of slope is between 10 to 15 m. The research results may provide references for the design and excavation of foundation pit as well as the operation of nearbyhigh-speed railway.