摘要
[目的]现有土压力理论计算方法未考虑卵石地层孔隙度大、结构松散等离散性特点,计算结果与实际土压力有所偏差,需要研究适用于成都地区卵石地层的土压力计算方法。[方法]以成都轨道交通7号线为依托,分析卵石地层深基坑土压力与朗肯土压力理论值的差别,并建立深基坑开挖土压力计算方法。采用离散元数值模拟和数据统计分析,获取围护结构平动、围护结构绕墙顶转动和围护结构绕墙底转动三种基本变位模式下静止土压力、被动土压力和主动土压力的分布特征。与朗肯土压力理论计算结果进行比较,得到不同变位模式下三种土压力的修正系数,并建立深基坑土压力修正计算方法。进一步与现场实测数据比较,对比验证所提出的土压力计算方法。[结果及结论]主动土压力和被动土压力分布形式具有强烈的非线性,可采用双折线进行描述,交点分别位于埋深8 m和9 m处。静止土压力修正系数分布在0.91~0.96之间,在使用时不需要修正;主动土压力修正系数分布在0.33~0.78之间,被动土压力修正系数分布在0.52~0.91之间,在使用时应予以修正。所提出的卵石地层深基坑土压力计算结果与现场实测结果吻合较好,可为类似轨道交通工程提供参考。
[Objective]The existing theoretical calculation method of earth pressure does not take into account the discrete characteristics of pebble stratum such as large porosity and loose structure,and the calculated results are different from the actual earth pressure.Therefore,it is necessary to study the earth pressure calculation method suitable for pebble stratum in Chengdu area.[Method]Based on Chengdu Rail Transit Line 7,the differences between the earth pressure in deep foundation pit of pebble stratum and the theoretical Rankine value are analyzed,and an earth pressure calculation method for deep foundation pit excavation is established.Using discrete element numerical simulation and statistical data analysis,the distribution characteristics of static earth pressure,passive earth pressure and active earth pressure under the three basic displacement modes of the enclosure structure translation,rotation around the wall top and rotation around wall bottom are obtained.By comparing with the calculation results from Rankine earth pressure theory,the correction coefficient of the earth pressure under three different displacement modes are obtained,and the calculation method of earth pressure correction for deep foundation pit is established.The proposed earth pressure calculation method is verified by further comparison with the on.site measured data.[Result&Conclusion]The distribution of active earth pressure and passive earth pressure shows strong nonlinearity,which can be described by double fold lines,and the intersection points are located at the buried depth of 8m and 9m respectively.The static earth pressure correction coefficient is distributed between 0.91 and 0.96,not need for correction in use.The active earth pressure correction coefficient is distributed between 0.33 and 0.78,and the passive earth pressure correction coefficient is between 0.52 and 0.91,should be corrected in use.The calculated results of earth pressure in deep foundation pit of pebble stratum are in good agreement with the on.site measured results,providing a reference for similar rail transit projects.
作者
李姝
闫胜
张霄
杨恒洪
LI Shu;YAN Sheng;ZHANG Xiao;YANG Henghong(Sichuan Water Conservancy Vocational College,Resources and Environmental Engineering,611231,Chengdu,China;Southwest Jiaotong University of Civil Engineering,610031,Chengdu,China)
出处
《城市轨道交通研究》
北大核心
2024年第6期172-177,184,共7页
Urban Mass Transit
关键词
地铁隧道
卵石地层
基坑
土压力
离散元
metro tunnel
pebble stratum
foundation pit
earth pressure
discrete element
