北京地铁九号线(军事博物馆—白碓子段)卵砾石粒径调查研究

Grain size survey of gravels in the section from Military Museum to Baiduizi for the programming Line No.9 of Beijing Metro

拟建北京地铁九号线(军事博物馆—白碓子段)区间隧道及车站主体结构主要位于第四纪砂卵石地层及第三纪砾岩地层中。卵砾石颗粒级配、最大粒径、大粒径卵砾石含量以及母岩强度对地铁盾构隧道、基坑围护桩施工均有很大影响,而常规勘察手段难以查明这些要素。本文结合工程实践,采用钻探法、探井法、既有基坑调查法及工程类比法等多种手段进行综合分析,以提供更为接近实际的含大粒径卵砾石地层描述,为地铁盾构隧道及基坑围护桩设计和施工提供依据。同时借鉴前人研究成果,阐述了全套管取样法的优缺点和适用性。

The main structures of the tunnel and station in the section from the Military Museum to Baiduizi for the programming Line No.9 of Beijing Metro mostly locate in the sand and gravel layers formed in the quaternary deposit and in the conglomerate layers formed in the tertiary deposit. The gradation, the biggest grain size, the content of the bigger size gravel of the gravels and the strength of the parent rock heavily affect the construction of shield tunnel and the retaining piles for foundation pit, but these factors couldn＇t be well found out by the conventional exploration methods. Combining the engineering examples, some methods such as drilling, excavating test pit, surveying the existent pit, and engineering analogism to describe the veracious gravel stratum are offered, which provide the basis for the design and construction of the tunnel and the retaining piles. Based on the research results from predecessors, the advantages and shortcomings of the full-casing sampling method are discussed.