成都地铁4号线二期盾构隧道漂卵石专项勘察分析

Special Survey and Analysis of Boulders and Pebbles of Shield Tunnel of Phase Ⅱ of Chengdu Metro Line No.4

为探索漂卵石地层地质勘察方法,查明成都地铁4号线二期工程西延段漂石分布、含量、粒径、强度等工程特性,通过现场井群降水、人工大口径探井开挖、钢筋混凝土护壁、井下地质编录和漂石的量测、现场K30试验、密度试验、取样和水文地质试验等综合方法,查明了漂石的空间分布、含量、粒径大小、形状、强度等特征以及漂卵石土的机床系数、天然密度、水文地质特性。从地质条件、周边环境、工程经验等综合考虑,分析了地铁隧道工法的选择、隧道埋深、盾构选型,预测施工中可能出现的岩土工程问题,并提出针对性的工程措施建议以及漂卵石地层勘察方法的选用建议。

In order to learn the distribution,content,diameter and strength of boulders and machine tool coefficient,nature intensity and hydrogeological characteristics of boulders and pebbles met on west extended section of Phase Ⅱ of Chengdu Metro Line No. 4,a series of methods,i. e. in-situ well group dewatering,manual excavation of largediameter exploratory well,reinforced concrete retaining wall,underground geological compilation and measuring,site K30 test,intensity tests,sampling and hydrogeological tests of boulders,are carried out. The construction method selection,tunnel buried depth and shield type selection are analyzed; the potential geotechnical issues occuring during shield tunneling are predicted. Finally,some countermeasures and surveying method for boulders and pebbles are suggested.