泉太隧道围岩破碎带施工方法可行性研究

Feasibility Study on the Construction Method for the Surrounding Rock Fractured Zone of Quantai Tunnel

以泉太隧道为依托工程,通过Midas/GTS数值模拟软件对围岩破碎带处采用台阶法和CD法2种开挖方法进行三维数值模拟,并与现场监测数据进行了对比分析。研究结果表明:在采用台阶法或CD法开挖时,均表现为在隧道拱脚、拱腰部位围岩应力集中、水平位移最大,拱顶和仰拱处竖直位移最大。相比于台阶法,CD法开挖条件下围岩应力、衬砌受力、围岩变形更小,但2种开挖方法均能满足隧道受力及变形要求。综合考虑施工难度、施工成本、施工工期等因素,可优先采用台阶法进行开挖,若实际开挖过程中发现隧道变形过大时,应及时换用CD法开挖。现场监测的水平收敛位移和拱顶沉降变化规律与数值模拟结果趋势相同,但变形稍大于模拟值,在施工过程中应加强监测。

Based on the Quantai Tunnel project,three-dimensional numerical simulation was carried out for the bench method and CD method to excavate the surrounding rock fractured zone with Midas/GTS numerical simulation software,and the simulation results were compared and analyzed with the field monitoring data.The results show that,when applying the bench method or CD method for excavation,the concentration of stress and horizontal displacement are maximum in the surrounding rock in tunnel skewback and haunch area,and the vertical displacement is most at the vault and inverted arch.Compared with the bench method,the CD method can result in lower level of surrounding rock stress,lining cutting force,and surrounding rock deformation,but both of excavation methods can meet the tunnel force and deformation requirements.Taking into account the difficulty of construction,construction costs,construction duration and other factors,we can use the bench method as a priority for excavation and switch to CD method,if the tunnel deformation is excessively large during the actual excavation process.The change law of horizontal convergence displacement and vault settlement monitored on site is identical to the numerical simulation results,but the deformation is slightly larger than the simulation value and should be paid attention to during the construction process.