土岩组合地层深基坑变形规律研究

Research on the Deformation Law of Deep Foundation Pit in Soil and Rock Combination Stratum

研究目的:随着城市建设的快速发展,软土地区城市近年来涌现大量土岩组合地层基坑。然而针对此类基坑的受力性状及变形规律的理论研究较少,且尚未有实测研究。为探究此类基坑的变形特点,本文以杭州至富阳城际铁路工程典型土岩组合深基坑为例,结合工程监测数据进行分析研究。研究结论:(1)土岩组合基坑开挖过程中,岩层段开挖引起的基坑侧向变形量较小;(2)由于岩层的约束限制,基坑整体变形量较小,统计结果显示基坑最大侧向变形出现在0.4~0.65倍坑深位置;(3)基坑的侧向变形随着岩面上抬而减小,最大变形出现位置也随之上移;(4)经实测值与设计值对比,基坑的实测变形明显小于设计值,常规设计方案偏安全,建议对土岩组合大型深基坑工程可采取更有针对性的分析研究,以兼顾安全性与经济性;(5)本研究成果可为类似土岩组合地层深基坑工程设计及优化提供参考。

Research purposes:With the rapid development of urban construction,a large number of foundation pits in soil-rock combination stratum have emerged in cities of soft soil areas in recent years.However,there are few theoretical studies on the force behavior and deformation laws of such foundation pits,and there is hardly any actual measurement research.In order to explore the deformation characteristics of this type of foundation pit,the typical soil-rock combination deep foundation pits of Hangzhou-Fuyang intercity railway project are taken as an example,and engineering monitoring data is used for analysis and research.Research conclusions:(1)During the excavation of the soil-rock combination foundation pit,the lateral deformation of foundation pit caused by the excavation of the rock section is small.(2)Due to the restriction of rock strata,the overall deformation of the foundation pit is small.The statistical results show that the maximum lateral deformation of the foundation pit occurs at 0.4 to 0.65 times the depth of the pit.(3)The lateral deformation of the foundation pit decreases with the uplift of the rock surface,and the position of maximum deformation also moves upward.(4)After comparing the measured value with the design value,the measured deformation of the foundation pit is obviously smaller than the design value,and it means the conventional design scheme is conservative.It is suggested that more targeted analysis and research should be adopted for large-scale deep foundation pit engineering with soil-rock combination,in order to take into account both safety and economy.(5)The research results can provide references for the design and optimization of similar deep foundation pits in soil-rock combination strata.