粉质黏土隧道支护体系力学特性试验研究

An Experimental Study of the Mechanical Characteristics of the Support System for Tunnels in Silt Clay

隧道穿越稳定性较差且构造节理发育的粉质黏土的施工过程中支护体系力学特性较为复杂,通过开展杨家岭1#隧道粉质黏土段支护体系现场试验,研究粉质黏土段隧道初期支护中的围岩压力、钢架应力、喷混凝土应力及支护变形规律。结果表明:由于隧道左右两侧地质条件的不同(即粉质黏土的不均匀性),初支上的围岩压力存在一定偏压情况,且围岩压力较大;喷混凝土应力及钢架应力值均较大,说明该段粉质黏土隧道围岩的稳定性较差,若初支仅考虑对围岩的封闭作用采用较小的喷混凝土厚度且不施作钢架,隧道的施工和结构安全存在较大风险;对于本工程,虽然偏压会对衬砌受力形成一定的不利因素,但是变更后的初期支护能够保证施工期间的安全。

When a tunnel goes through the silt clay stratum which is poor in stability and developed in joint, the mechanical char- acteristics of a supporting system for tunnels will be comparatively complex. Through the site experiments on the support sys- tem for the 1 # tunnel at Yangjialing in the silt clay stratum,the changing laws of the pressure of the surrounding rock mass in the initial support period, the stresses of the steel frame, the stresses of the shot concrete, and the deformation of the support are studied in the paper. The results show that unsymmetrical pressure exists in the surrounding rock because of the different geo- logical conditions on the two sides of the tunnel,and the pressure is quite large;the values of the stresses of the steel framework and shot concrete are rather large,which show that the stability of the surrounding rock mass is poor;if,during the initial sup- port period, only the sealing function of the surrounding rock mass were taken into account,a relatively thin layer of concrete were shot and no steel frame were provided,greater risks would exist in the tunneling construction and the safety of the tunnel structure. However,as far as this project is concerned,the improved initial support is strong enough to ensure the safe construc- tion of the tunnel, although the unsymmetrical pressure does exert some unfavorable effects on the shot lining.