钻孔咬合桩在复合地层中的应用研究 ——以杭州地铁3号线工业大学站为例

钻孔咬合桩多用于软土地层,采用全套管钻机软切割法施工,但在上软下硬的复合地层中,全套管法成孔困难,无法保证桩体的垂直度,以致于咬合效果达不到设计要求。为了解决此类工程问题,依托杭州地铁3号线一期工程工业大学站基坑工程,研究了钻孔咬合桩在上软下硬复合地层中的适应性及应用情况,并与其他围护方式在可实施性、安全性、经济性、施工效率等方面进行了综合比较。研究结果表明,在复合地层中采用旋挖钻机硬切割法施工咬合桩,成孔效率高,桩体垂直度高,止水效果好,能产生更好的工期效益、社会效益和经济效益。并且钻孔咬合桩能够很好地适应复合地层,经济性好,施工效率高,解决了复合地层中钻孔咬合桩的施工工艺和设备选型问题。研究过程及结果可为复合地层中的基坑工程施工提供借鉴与参考。

Study on the application of bored interlocking pile in composite strata: A case study of ZJUT station in Hangzhou Metro Line 3

The bored interlocking pile is mostly used in soft soil, employing soft cutting method with full casing drilling machine. However, there are difficulties for composite strata in the process of hole forming by using full casing drilling technology, which can not guarantee the verticality of the pile in upper-soft and lower-hard soil horizon, so that the occlusion can not meet the design requirements. In order to solve this kind of engineering problems, the study of the adaptability and application of bored interlocking pile in upper-soft and lower-hard soil horizon was carried on in this paper based on the excavation engineering of ZJUT station in Hangzhou Metro Line 3 phase one, and the comparison between bored interlocking pile and other supporting methods in feasibility, safety, economy and efficiency were investigated. The research shows that rotary drilling rig hard cutting method in composite strata has created better efficiency of time limit of project, social benefits and economic benefits due to the high hole completion efficiency, high pile verticality and good water sealing effect. And the bored interlocking pile can adapt to the composite strata well, with good economy and high construction efficiency, which solves the problem of the selection of construction technology and equipment. The research process and results can provide reference for the construction of foundation pit in composite strata.