综合勘探手段在砂卵石地层勘察的应用

Application of Comprehensive Exploration Method in the Investigation of Sand Gravel Layer

砂卵石层作为地基持力层具有压缩性低、承载力高的优势,然而砂卵石地层又具有稳定性差、无黏聚力、渗透性强、硬度高、级配差异大等特点,地铁勘察、施工难度较大。以北京地铁19号线一期工程为依托,介绍钻探、探井、物探、原位测试、室内试验、现场抽水试验、地下水流向流速测定等综合勘探手段在查明砂卵石地层的密实度、颗粒级配、地层强度等特征以及地下水的赋存状态的应用,为隧道设计、施工提供依据,同时也为砂卵石地层勘察提供借鉴。

As the bearing layer of foundation,sand gravel layer has the advantages of low compressibility and high bearing capacity.However,the stability of sand gravel layer is poor,which has the characteristics of no cohesion,strong permeability,high hardness and great difference in gradation,so it is difficult to survey and construct the subway.Based on the first phase project of Beijing Metro Line 19,the comprehensive exploration method of drilling,artificial exploration well,geophysical exploration,in-situ test,indoor test,on-site pumping test and underground water flow velocity measurement and other exploration methods were conducted,which were used to find out the characteristics of sand gravel layer,such as density,particle gradation,sand gravel layer strength and the occurrence of groundwater.This study could provide the basis for the design and construction of tunnel,and also provides a reference for the investigation of sand gravel layer.