隧道工程岩体完整性新的评价参数及方法

A New Coefficient and Method to Appraise Tunnel Rock Mass Integrity

研究目的:隧道围岩分级是隧道勘察设计中的重要参数,以往工作中主要通过地质调查法、钻探法、物探方法定性判识隧道岩体完整程度,物探法主要以弹性波速度作为岩体完整性评价的参数,但针对深埋隧道,由于埋深大,难以直接从地表获得隧道洞身岩体的波速值,使得围岩等级的划分缺少依据。本文建立层状岩体模型,通过研究分析岩体几何参数与电性参数的相关关系,拟提出一种新的围岩完整性评价参数及方法。研究结论:(1)基于层状岩体模型电阻率计算公式,推导出岩体几何参数与电性参数的相关关系,提出了一种新的表征岩体完整性的参数——岩体完整性系数Kr;(2)Kr表征完整岩石在单位岩体中所占的比例,Kr值越大,岩体越完整;(3)通过钻孔综合测井试验,论证Kr可以作为评价岩体完整程度的量化指标,初步统计得出Kr与岩体完整程度量化关系表;(4)Kr评价岩体完整性方法可用于铁路隧道勘察设计阶段,也可用于其他地下工程勘察设计阶段。

Research purposes： The classification of tunnel surrounding rocks is an indispensable parameter in the tunnel survey and design stage, which was mainly determined by geological survey, drilling and geophysical methods before. The geophysical method mainly use the P- wave velocity to evaluate rock mass integrity, and the P -wave velocity can be usually obtained via shallow seismic reflection method, which renders it hardly applicable to deep buried tunnels since it cannot be directly acquired at the depth of the tunnel. In this paper, the author established a layered rock mass model to study the relationship between the geometric parameters and the electrical parameters, attempt to find a new method to appraise the rock mass integrity of the surrounding rocks of the tunnel. Research conclusions： （ 1 ） Based on the resistivity calculation formula of layered rock mass model, the relationship between the geometric parameters of rock mass and the electrical parameters of rock mass is derived, and a new rock integrity coefficient Kr is brought. （2） Kr represents the proportion of intact rock in the unit rock mass, and the larger the Kr value is, the more complete the rock is. （3） The comprehensive logging experiments results show that Kr can be used as a quantitative index to evaluate the integrity of rock mass. Through the statistics the quantitative relationship between Kr and rock mass integrity is got. （4） Kr can be used in the railway tunnel survey design stage, and can also beused for other underground engineering survey and design stage.