偏压小净距公路隧道围岩稳定性与对策研究

Study on Rock Stability Surrounding Closely Spaced Bias Highway Tunnel and the Countermeasures

以京昆高速公路曹家庄隧道工程为背景,运用连续介质与非连续介质数值模拟研究了破碎偏压小净距公路隧道围岩稳定性,并给出了相应的施工对策。研究表明:①隧道围岩在重力作用下,将向临空面塌落。根据连续介质数值计算得到围岩保持稳定,然而,由于节理面的存在,围岩将无法保持稳定,隧道的破坏由应力控制变为节理结构面控制;②根据计算分析得到施加锚杆加固后,围岩应力状况得到改善;③针对围岩结构几何失稳的特点,宜采取以轻型支护为主并保护围岩的施工对策。

Taking the Caojazhuang Tunnel of Beijing-Kunming Expressway as the background, the stability of broken rock surrounding closely spaced bias highway tunnel was studied by means of continuous and noncontinuous medium numerical simulation, and then the related construction countermeasures were provided. The result of research shows that, the surrounding rock , under the action of gravity, intends to collapse towards the free face and, according to the numerical calculation of continuous medium, it is solved to keep stable, however, due to the existence of joint plane, the rock is subject to failure, thus the tunnel would be destructed under the control of joint structural plane instead of stress;according to the calculation and analysis, it is found that the stress condition of surrounding rock will be improved after anchor bolts are applied for reinforcement;in relation to the features of geometric instability of the surrounding rock structure, it should be taken to use light support oriented rock protection as the construction countermeasures.