【摘要】 岩溶地区修建公路隧道时,把溶洞的处理和施工监测工作放在首要位置,准确掌握围岩沉降、收敛规律以及支护压力的变化,便于及时调整支护和施工参数。针对隧道穿过特大溶洞边墙的情况,采取上下台阶法施工并施做了支顶结构和临时支撑墙确保在隧道开挖过程中围岩的稳定性及施工安全。通过对白须公特大溶洞隧道的溶洞支顶结构的应力应变以及老虎嘴处临时支撑结构承受上部围岩压力在施工过程时间变化特性分析,探讨不同的隧道开挖方式对围岩的扰动影响,并分析了地下附属结构物的回应。通过对结构物的监测分析可以看出:溶洞对支顶结构的影响主要表现为水平推力,竖直压力较小;老虎嘴上部岩层中软弱夹层对围岩整体稳定影响较小,没有产生过大松动压力。更多还原

【Abstract】 Limestone cave treatment and construction monitoring are critical for highway tunnel construction in karst area.Accurate controlling surrounding rock settlement,convergence regularity and changes of support pressure in the process of tunnel excavation are helpful for timely adjustment of support and construction parameters.In view of the tunnel traversing the side wall of a grand karst cave,the benching tunneling method was applied and the reacting wall as well as the temporary supporting wall were added during excavation to insure the stability of the surrounding rock and construction safety.Analysis on the stress and strain of the reacting wall of Baixugong grand karst cave and the time-varying characteristic of the surrounding rock pressure borne by temporary supporting wall at Laohuzui during construction was performed to discuss the disturbance of the surrounding rock induced by different excavation methods,and the reaction of the accessory structure was also analyzed.The analysis of structure monitoring shows that(1) the effect of karst cave on the reacting wall manifested as horizontal force mainly than vertical pressure;(2) soft intercalation in the upper strate of Laohuzui has little influence on overall stability of surrounding rock,which does not generate too large loosening pressure.更多还原