综合考虑沉降与基坑安全的综合管廊地基处理方案研究

Study on Foundation Treatment Scheme of Utility Tunnel with Comprehensive Consideration of Settlement and Safety of Foundation Pit

基坑坑底被动区土体加固能够有效减小综合管廊运营过程中沉降超限问题。基于对现有构筑物沉降标准的探讨,进而提出综合管廊沉降控制要求,结合工程实例从地基承载力和管廊沉降两个角度研究坑底搅拌桩加固方案的合理性。结果表明:在高压缩性土体中,需结合管廊实际长度计算容许沉降量差异,以此作为沉降控制要求;从沉降和承载力角度均要求坑底加固桩体打穿软土层,且具有一定嵌固深度,需要综合分析桩体置换率对坑底加固影响,进行合理取值;沉降缝设置枕梁能减小综合管廊的不均匀沉降,研究可为相近工程提供参考。

The problem of settlement overrun can be effectively alleviated during the operation of utility tunnel by the soil reinforcement in the passive zone at the bottom of foundation pit.Based on the discussion of the existing structure settlement standards,the settlement control requirements of utility tunnel are put forward.Combined with the engineering examples,the rationality of reinforcement scheme of mixing pile at the pit bottom is studied from two angles of foundation bearing capacity and utility tunnel settlement.The result shows that,the allowable settlement difference should be calculated with the actual length of utility tunnel in the high compressibility soils as the settlement control requirements.The reinforced pile at the pit bottom is required to drive through the soft soil from the angles of settlement and bearing capacity,and has a certain built-in depth.It is required to analyze the influence of replacement rate of pile on the reinforcement at pit bottom.A reasonable value is taken.The differential settlement of utility tunnel can be reduced by the setup of pillow beam in the settlement joints.The study can be referred for the similar projects.