膨胀性辉绿岩隧道修建主要工程问题及对策分析

Difficulties in Construction of Tunnels in Swelling Diabase and Their Countermeasures

为分析在建高速公路某隧道出口膨胀性辉绿岩地段台阶法施工过程中的主要工程问题,并提出相应对策。通过现场监测数据和理论计算分析,研究了膨胀性辉绿岩隧道在施工期间的主要工程问题,分析表明:全风化至强风化辉绿岩亲水性矿物高岭石含量高、吸水膨胀、失水收缩、易崩解、易扰动及岩体裂隙发育等工程特性会给穿过该地层的隧道带来初期支护受力不均、喷射混凝土出现开裂剥落、易失稳破坏、洞室及地表严重变形、塌方频繁的工程问题;解决上述工程问题的关键措施是控制初期支护变形,做好排水,减少膨胀性辉绿岩与水的接触。

A tunnel passes through completely-weathered-to-intensely-weathered diabase, which is a kind of swelling rock mass. The difficulties in the construction of the tunnel located in the swelling diabase are studied by means of site monitoring and theoretical calculation. Conclusions drawn are as follows： 1 ） The weathered swelling diabase has such properties as containing a large amount of kaolinite, swelling when water is absorbed, shrinking when water is lost and being subject to spalling; 2 ） The tunneling may encounter such difficulties as uneven stress on the primary support, spalling of the primary shotcrete, serious deformation, failure and collapse; 3 ） Countermeasures to overcome above- mentioned difficulties include controlling the deformation of the primary support, keeping good drainage conditions and preventing the diabase from contacting water.