杭州感知谷项目临河基坑设计与分析研究

Design and Research on"Ganzhigu"Project Foundation in Hangzhou Pit Beside River

研究目的:基于杭州滨江区感知谷基坑工程,结合现场施工实测数据及有限元模拟结果,对典型软土地区临近河道基坑施工对周边环境影响以及河道对基坑支护影响进行深入分析。通过对现场实测数据、有限元分析数据、基于半无限空间理论计算数据进行对比、分析,验证周边存在河道等构筑物情况下采用半无限土理论基坑计算的可行性,研究基坑受力及变形规律;确定合理基底加固措施,研究不同因素对基坑周边河堤等建(构)筑物变形的影响。研究结论:(1)本基坑位于软土地区,基坑开挖时围护结构深层水平位移曲线呈“鼓肚”状抛物线,围护桩最大水平位移发生在基坑底部4~5 m处;(2)通过数据对比可知,河道侧支护桩深层水平位移、土体沉降明显小于远离河道侧;(3)通过多软件计算结果分析可知,临近河道侧土体坡度较小且河道距离基坑大于1倍基坑深度时,采用半无限土理论计算得到的支撑轴力、基坑变形等结果依然可应用于工程设计;(4)通过总结分析,提出了增大河堤刚度可有效减小临近河道侧地表沉降、河堤变形;(5)通过对本项目设计与分析研究,可为类似软土地区临河复杂基坑工程设计及施工提供参考。

Research purposes:Based on the"Ganzhigu"foundation pit project in Binjiang District of Hangzhou,the interaction effects of the foundation pit construction and the structures including the bank is deeply analyzed in this paper with the data monitored in-situ and finite element analysis.Based on the data and semi-infinite soil theory,the stress deformation theorem of foundation pit is studied,the reasonable base reinforcement measures are determined,and the influence of different factors on the deformation of the river embankment and other structures around the foundation pit is studied.Research conclusions:(1)During the excavation of the foundation pit,the deep horizontal displacement of the retaining structure is a"belly"shaped parabola,and the maximum horizontal displacement of the retaining pile occurs at about 4~5 m from the bottom of the foundation pit.(2)Through data comparison,it can be seen that the deep horizontal displacement and soil settlement of the supporting pile at the river side are significantly smaller than those far away from the river.(3)Through the analysis of the calculation results of multiple software,it can be seen that when the soil slope near the river is low and the distance between the river and the foundation pit is larger than one time as the depth of the foundation pit,the results obtained by calculating the axial force of the support and the deformation of the foundation pit by using the semi-infinite soil theory can still be applied to engineering design.(4)Through summary and analysis,it is proposed that increasing the rigidity of the embankment can effectively reduce the surface settlement and embankment deformation.(5)Through the analysis of the project,this paper can provide references for the design and construction of complex foundation pit near the river in soft soil areas.