下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工技术研究及应用

RESEARCH AND APPLICATION OF MJS PRE-REINFORCEMENT CONSTRUCTION TECHNOLOGY FOR SHIELD PASSAGE IN WATER-RICH SAND STRATUM THROUGH UNDERGROUND STRUCTURE GROUP PILES

下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工技术包括技术原理、实施思路和具体施工步骤,其由密布群桩富水砂层水平引孔、富水砂层水平引孔砂土流失控制、常规水平MJS注浆加固3个环节组成。技术采用引孔机钻杆+外套管进行水平引孔,实现立柱桩和高强度管桩的穿越,以及富水砂层中的长距离成孔,引孔过程中通过双液注浆对注浆线路进行一次加固,同时利用洞口安装的法兰盘+止回阀来进行砂土流失控制,减少引孔对地下构筑物和周边环境的影响,引孔完成后,进行常规MJS注浆加固,达到预加固目标,并形成具体的下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工步骤指导施工,大幅减少对地下构筑物和周边环境的影响,减少泥浆浪费,提高施工效率,经济社会效益较好,具有较好的推广应用价值。

The MJS pre-reinforcement construction technology of shield passage through water-rich sand layer of underground structure group piles includes technical principles,implementation ideas and concrete construction steps.It is composed of three links:horizontal pilot hole of dense pile group,sand loss control of horizontal pilot hole of water-rich sand layer,and conventional horizontal MJS grouting reinforcement.The technology uses pilot drill pipe+outer casing to carry out horizontal pilot holes to realize the crossing of column piles and high-strength pipe piles,as well as long-distance hole formation in water-rich sand layer.In the process of pilot holes,double liquid grouting is used to reinforce the grouting line once.Meanwhile,flange plate+check valve installed at the hole is used to control the sand loss and reduce the influence of pilot holes on underground structures and surrounding environment.After the completion of the pilot hole,the conventional MJS grouting reinforcement is carried out to achieve the pre-reinforcement target,and the concrete MJS pre-reinforcement construction steps are formed to guide the construction of the shield channel under the underground structure group pile with water-rich sand layer,which greatly reduces the impact on the underground structure and the surrounding environment,reduces the waste of mud,improves the construction efficiency,has good economic and social benefits,and has good popularization and application value.