托洛旋扭构造带隧道工程地质特征分析

Analysis of Geological Characteristics of Tunnel Engineering in Tuoluo Rotational Tectonic Belt

研究目的:西南某铁路隧道穿越托洛旋扭构造带,为查明其砥柱及旋回层的铁路隧道工程地质条件,本文通过野外地质调查、钻探、物探、室内试验等综合勘察手段,对其基本特征、成因机制及应力特征进行探讨,在此基础上划分三个区域结合隧道施工实际情况验证分析并探讨该旋扭构造带内隧道工程地质特征。研究结论:(1)托洛旋扭构造带为向西南方向收敛的顺时针旋扭,主要由环形砥柱和两个旋回层组成;(2)根据“无限平板集中力偶”理论,推测该旋扭构造带旋卷应力场影响范围约为65.3 km;(3)该旋扭构造带发育于红层软岩中,砥柱岩体完整性略好,物理力学性质总体优于旋回层,但岩体结构类型无明显的分布差异规律;(4)旋回层隧道施工更易遭遇涌突水、软岩大变形、高地温、放射性及采空区等工程地质问题;(5)表生不良地质发育主要受旋扭构造环形断层及撒开断层控制;(6)本研究成果可为穿越类似构造发育地区的铁路、公路地质选线以及隧道工程勘察设计提供参考和借鉴。

Research purposes:A railway tunnel in the southwest passes through the Tuoluo rotational tectonic belt.In order to identify the geological conditions of the railway tunnel engineering in its pillar and rotation layer,this paper explores its basic characteristics,genetic mechanism,and stress characteristics through comprehensive exploration methods such as field geological investigation,drilling,geophysical exploration,and indoor testing.Based on this,three areas are divided and combined with the actual situation of tunnel construction to verify and analyze the geological characteristics of the tunnel engineering within the rotational tectonic belt.Research conclusions:(1)The Tuoluo rotational tectonic belt is a clockwise knob converging towards the southwest direction,mainly composed of a circular pillar and two cyclic layers.(2)According to the theory of"infinite plate concentrated force couple",it is speculated that the influence range of the spiral stress field in the rotational tectonic belt is about 65.3 km.(3)The rotational tectonic belt is developed in the red soft rock layer,and the integrity of the pillar rock mass is slightly better.The overall physical and mechanical properties are better than those of the spiral layer,but there is no obvious distribution difference in the rock structure type.(4)The construction of spiral layer tunnels is more prone to encountering engineering geological problems such as water inrush,large deformation of soft rock,high ground temperature,radioactivity,and goaf.(5)The development of adverse geological conditions on the surface is mainly controlled by rotary structure circular faults and spreading faults.(6)The research results can provide reference for geological route selection and tunnel engineering survey and design of railways and highways crossing areas with similar geological structure.