构造破碎带深路堑地质核查方法研究

Study on Geological Verification Method of Deep Cutting in Structural Fractured Zone

为查明某新建高速铁路深路堑施工开挖后基底及边坡工程地质条件,采用调查、补充勘探、动力触探等方法,对路堑基底及边坡进行地质核查,结合既有勘察资料,查明了构造破碎带、膨胀性岩土的工程性质和空间分布。根据路堑边坡工程地质条件,将边坡分为16部分,选取岩土类型、结构面类型、边坡高度、边坡坡率、降雨5个影响因子,将影响因子指标进行量化,利用层次分析法确定影响因子权重,将路堑边坡危险性分为危险、较危险、一般危险和较安全4个等级,并对原设计方案进行危险性分析。根据不同边坡条件,提出放坡、“锚杆框架+桩板墙”和增加桩长等防护措施。结果表明:构造破碎带深路堑地区地质核查宜采用综合勘察技术,将路堑基底与边坡综合分析并平面化展示,增加了勘察成果可信度,其危险性评价结果及防护措施建议可为设计优化提供地质依据。

In order to find out the engineering geological conditions of the base and slope after the excavation of a new high-speed railway deep cutting construction,methods of investigation,supplementary exploration and dynamic penetration are adopted to check the cutting base and slope.Combined with the existing survey data,the engineering properties and spatial distribution of structural fracture zone and expansive rock and soil are found out.According to the engineering geological conditions of cutting slope,the slope is divided into 16 parts.Five influencing factors of geotechnical type,structural plane type,slope height,slope rate and rainfall are selected to quantify the influencing factors.AHP is used to determine the weight of influence factors,and the cutting slope risk is divided into four grades:dangerous,relatively dangerous,general dangerous and relatively safe,and the original design scheme is analyzed.According to different slope conditions,some protective measures are put forward,such as slope setting,“anchor frame+pile sheet wall”and increasing pile length.The results show that the comprehensive survey technology should be adopted in the geological verification of deep cutting area in the structural fracture zone,and the cutting base and slope should be comprehensively analyzed and displayed in plane,which increases the credibility of the survey results.The risk assessment results and protective measures can provide geological basis for design optimization.