摘要
钢板桩以其整体刚度大、打拔桩容易和施工速度快等优点被广泛应用于基坑工程中,但钢板桩在拔除后,土体极易留下孔隙,从而造成地面以及邻近建构筑物开裂。从钢板桩施工特点入手,采用数值模拟方法,对软土地层条件下钢板桩拔除后产生40,100,150,200 mm 4组孔隙宽度时对既有隧道位移和受力影响,以及地表变形等问题进行了分析。结果表明:孔隙宽度越大,既有隧道位移和受力也越大,在孔隙宽度为150 mm时,拉应力增量为4.65 MPa,大于拉应力增量容许值的4.5倍;既有隧道邻近钢板桩侧的位移和受力较远离钢板桩侧要大得多;钢板桩拔除后产生的孔隙对其周边10 m范围内的土体影响显著。由此提出优化拔桩顺序、减小拔桩带泥量、周边土体加固以及加密监测等工程措施,对类似地质条件下钢板桩拔除时邻近建构筑物的保护具有一定的借鉴意义。
Due to the advantages of large integral stiffness,easy installing and removing and high construction speed,steel sheet piles are widely used in the excavation of foundation pits.When the steel sheet piles are removed,however,voids may be created in the soil strata,which may cause cracks of the ground surface and the neighboring buildings.In this paper,the influence of 4 void widths,i.e.,40 mm,100 mm,150 mm and 200 mm,produced by steel sheet pile removing on the displacement and stressing of the existing tunnel and the ground surface settlement are analyzed by means of numerical simulation and on basis of study on the construction characteristics of the steel sheet piles.The results show that：1）The displacement and stress of the existing tunnel increase as the void width increases.When the void width is 150 mm,the tensile stress increment is 4.65 MPa,which has exceeded the allowable tensile stress increment by 4.5 times;2）The displacement and stress of the existing tunnel close to the steel sheet piles are much larger than those of the existing tunnel far away from the steel sheet piles;3）The void produced by steel sheet pile removing has significant influence on the soil mass within the scope of 10 m around the void.In the end,countermeasures,including optimization of the steel sheet pile removing sequence,reducing the mud produced when steel sheet piles are removed,consolidation of surrounding soil mass and strengthening the monitoring,are proposed.The paper can provide reference for the protection of neighboring buildings when steel sheet piles are removed in similar soil conditions.
出处
《隧道建设》
北大核心
2015年第6期527-534,共8页
Tunnel Construction
关键词
软土地层
钢板桩拔除
既有隧道
数值模拟
soft soil
steel sheet pile
removing
existing tunnel
numerical simulation
