摘要
土体和岩体对基坑围护结构的组合作用,使得土岩组合基坑的设计和施工具有不确定性和复杂性。一般情况下,岩体的物理力学性质要明显优于土体。因此将岩体简化为土体考虑,根据地勘报告中的岩体结构面抗剪强度指标——黏聚力和内摩擦角,采用支护结构设计软件对地铁车站深基坑围护桩的嵌岩深度进行了数值模拟分析。通过模拟计算可知,在满足深基坑围护桩侧向最大位移允许值、坑外地表沉降允许值、基坑各项安全系数的情况下,可以得到趋于稳定的围护桩体内力值。该内力值随着嵌岩深度的加大变化极微小,此时嵌岩深度的最小值即为嵌岩深度的最优值。根据围护桩最优的嵌岩深度值设计的桩长,后期深基坑围护桩侧向位移和地表沉降监测值与计算值误差在10%之内。该数值模拟研究可为土岩组合基坑支护设计提供一定参考。
That composition action of soil and rock masses on the retaining structure makes design and construction of soil-rock composited foundation pit uncertain and complex.In general,the physical and mechanical properties of rock mass are obviously better than that of soil mass.Therefore,the rock mass is simplified as soil mass.According to cohesive force and angle of internal friction which are the shear strength index of rock joints in geological survey report,the rock-socketed depth of retaining piles in deep foundation pit in subway station are simulated and analyzed by retaining structure design software.By simulation calculation,the internal force value of retaining pile will tend to be stable on condition that the maximum lateral displacement allowable value of deep foundation pit retaining pile,allowable value of surface settlement outside the pit and various safety factors of foundation pit are met.The internal force value changes very little with the increase of rock-socketed depth.The minimum value of rock-socketed depth is the optimal.When the pile length is designed by the optimal depth,error between the monitored value and the calculated value of lateral displacement and surface settlement of the retaining pile in the later stage of deep foundation pit is within 10%.The numerical simulation can provide reference for similar projects.
作者
蔡兴华
Cai Xinghua(Shanghai Tunnel Engineering Co.,Ltd.,Shanghai 200032,China)
出处
《市政技术》
2021年第7期188-192,共5页
Journal of Municipal Technology
关键词
深基坑
围护桩
嵌岩深度
土岩组合
deep foundation pit
retaining piles
rock-socketed depth
soil-rock composite
