滇中红层深埋软岩隧洞支护措施研究

Study on Supporting Measures of Deep Buried Soft-rock Tunnel in Red Bed of Central Yunnan

以滇中红层某软岩隧洞为研究背景,针对不同围岩级别下马蹄形断面形式的软岩隧洞模型进行数值计算分析,研究表明:对Ⅳ类围岩,岩体物理力学参数偏低,破坏区范围较大,建议采用台阶法分部开挖,控制开挖过程中对围岩的扰动,开挖完成后及时施加一次支护;对Ⅴ类围岩,围岩自稳条件较差,建议采取超前支护措施预加固围岩后采用台阶法分部开挖,严格控制开挖的循环进尺,同时建议在台阶法开挖过程中预留核心土,做好超前灌浆加固;此外,隧洞开挖过程中需加强断面变形监测,根据实际变形监测结果和地质条件及时调整方案,以保证不同围岩级别下深埋软岩隧洞的安全。

Taking a soft rock tunnel in the red bed of central Yunnan Province as the research background,the numerical calculation and analysis of the soft rock tunnel model with horseshoe cross-section under different surrounding rock grades are carried out.The results show that:for class IV surrounding rock,the physical and mechanical parameters of rock mass are low,and the scope of failure area is large.It is suggested that the bench method be used to excavate separately to control the disturbance to the surrounding rock during the excavation process,and the primary support should be applied in time after the excavation.For class V surrounding rock,the self-stability condition of surrounding rock is poor,so it is suggested to adopt advanced support measures to pre reinforce surrounding rock,and then adopt bench method to excavate separately,strictly control the excavation cycle footage,at the same time,it is recommended to reserve core soil in the process of bench excavation,and do well in advance grouting reinforcement;in addition,it is necessary to strengthen section deformation monitoring during tunnel excavation,according to the actual deformation monitoring results and geological conditions Conditions should be adjusted in time to ensure the safety of deep buried soft rock tunnel under different surrounding rock levels.