地铁车站围护结构侵界处理方案比选

Comparison and Selection of Treatment Schemes for Boundary Invasion of Subway Station

地铁车站基坑普遍存在侵界情况,侵界较小时,通过凿除围护结构钢筋保护层解决;侵界大时,须凿除部分侵界围护结构,并对原围护结构进行补强,适当减小主体结构侧墙厚度、加强结构配筋。该站侵界尺寸及范围较大,地墙侵界部分凿除后影响围护结构受力,且地墙接缝处已形成渗漏通道,拟采取3种围护结构补强方案。考虑钻孔灌注桩支护刚度大、钻孔及吊装所需场地小,高压旋喷桩在粉砂层中施工深度较大时止水效果难保证,MJS旋喷桩桩长大、在粉土粉砂层中成桩质量有保证且止水效果好、可实施性强等优点,最终考虑采用钻孔灌注桩及MJS旋喷桩的补强方案,事实证明本方案切实可行。

The boundary invasion is common in the foundation pit of subway station.If the boundary invasion is small,it can be solved by chiseling out the reinforcement protective layer of retaining structure.When the boundary invasion is large,the retaining structure shall be reinforced,the thickness of the side wall of the main structure shall be appropriately reduced and the structural reinforcement shall be strengthened.The station has a large boundary invasion size and range.The stress of the enclosure structure is affected after the ground wall is chiseled,and a leakage channel has been formed at the ground wall joint.Three enclosure structure reinforcement schemes are proposed.Considering the advantages of large support stiffness of bored cast-in-place pile,small site required for drilling and hoisting,long MJS rotary jet grouting pile,guaranteed pile quality in silty soil and silty sand layer,good water stop effect and strong practicability,the reinforcement scheme of bored cast-in-place pile and MJS rotary jet grouting pile is finally considered,which proves that this scheme is feasible.