木寨岭隧道大战沟斜井高地应力软岩大变形施工技术

Case Study on Large Deformation Control of Dazhangou Inclined Shaft of Muzhailing Tunnel in Soft Ground with High Ground Stress

高地应力软弱围岩段施工不可避免地产生大变形,为合理选择支护措施,有效控制软岩隧道变形,进行专门的研究试验是非常必要的,为解决大变形问题,结合专家意见并根据现场实际采用9个试验段来探索变形施工技术,由试验段可知高地应力软岩大变形施工应放抗结合。随着斜井埋深的增加、地应力的增加,初期支护强度、刚度应相应增加,否则容易出现坍塌;二层支护(套拱)的方法能有效控制变形;超前小导洞,超长水平大钻孔高地应力释放技术的应用,有一定效果。

Large deformation is inevitable during the construction of tunnels in soft ground with high ground stress. It is of great necessity to perform dedicated studies and tests so as to select reasonable reinforcement measures and to effectively bring the deformation under control. During the construction of Dazhangou inclined shaft of Muzhailing tunnel, 9 trial sections are established on basis of the site conditions so as to investigate on the deformation control technology. The test indicates that the combination of stress resistance and stress releasing should be adopted to control the large deformation in soft ground with high ground stress. As the cover of the inclined shaft increases, the ground stress increases. Therefore, the strength and rigidity of the primary reinforcement structures should be increased, otherwise collapse may occur. The secondary lining of the inclined shaft can effectively bring the deformation under control. The pilot tunnel and the super-long large-diameter horizontal boreholes installed are favourable to the releasing of the high ground stress.