软土地层顶管法地下通道近接桥梁施工保护方案研究

为顶管施工中既有桥梁结构的保护提供合理可行的方案,以昆明市轨道交通4 号线菊华站地铁车站过街通道矩形顶管近接高架桥施工为背景,采用数值模拟的方法,对软土地层顶管法地下通道近接桥梁施工的地层注浆预加固及不同触变泥浆减摩等保护方案的应用效果进行研究。研究结果表明: 1)对桥桩桩侧土进行预加固可以明显减小顶管施工过程中桥桩的水平横向变形,减小比例达34%; 2)采用超灌触变泥浆减摩方案,可有效降低顶管顶进时管土摩擦力对桥桩的影响,其中桥桩纵向变形的最大值在采用超灌触变泥浆减摩方案时,相较于常规触变泥浆减摩方案减小28%; 3)采用桥桩桩侧土预加固结合超灌触变泥浆减摩的方案,可保证顶管施工过程中近接桥梁结构的安全。

Protection Schemes for Pipe Jacking Construction of Underpass Adjacent to Bridge in Soft Soils

In order to provide rational and feasible schemes to protect the safety of the existed viaduct, the applicable effects of the ground grouting pre-reinforcement scheme and the antifriction schemes using the thixotropic muds with different grouting volumes which are adopted in the rectangular pipe jacking construction of the underpass of Juhua Metro Station on Kunming Rail Transit Line No. 4 in soft soils on protecting the existed adjacent viaduct are studied by numerical simulation. The analytical results show that: (1) The grouting pre-reinforcement of soils between viaduct piles and the jacking pipe can significantly reduce the transverse deformation of viaduct piles during the pipe jacking construction, and the reduction magnitude can reach 34%. (2) The influence of the pipe-soil friction on viaduct piles can be effectively reduced by using the over-grouting scheme of the thixotropic mud in the construction process, and the maximum longitudinal deformation of viaduct piles can be reduced by 28% compared with that when the normal-grouting scheme of the thixotropic mud is adopted. (3) The simultaneous adoption of the pre-reinforcement of soils between viaduct piles and the jacking pipe and the over-grouting scheme of the thixotropic mud can ensure the safety of the viaduct structure during the construction of the jacking pipe.