兰渝铁路杨家坪隧道1号横洞工区大变形成因机制探析

通过分析成兰铁路杨家坪隧道1号横洞工区的地层岩性、地质构造、地应力场、工程地质条件及工程设置、施工组织顺序等的基础上,研究1号横洞工区大变形产生的成因机制。结果表明:杨家坪隧道1号横洞工区大变形的产生是各种影响因素共同作用的结果;复杂的地质构造及高地应力条件和软弱破碎的地层岩性条件为其大变形客观成因,而岩层结构面与洞轴线的不利组合、小间距隧道结构和不合理的施组顺序及左右线不对等的支护措施等不利条件为其主观成因。与大变形的主客观成因相对应,其力学机制主要呈现为应力扩容型的构造应力机制和结构变形型的结构面型机制的混合机制。

Analysis of Cause and Mechanism of Large Deformation in No. 1 Cross-tunnel Area of Yangjiaping Tunnel of Lanzhou-Chongqing Railway

Based on the research of strata,lithology, geological structure, geostress,engineering geology, engineering design and construction organization plan,the paper analyzes the cause and mechanism of larger deformation inNo. 1 cross-tunnel area of Yangjiaping tunnel on Chengdu-Lanzhou railway. The results indicate that the larger deformation in No. 1 cross-tunnel area of Yangjiaping tunnel is the end product of all such objective factors as the intricate geological structure,high geostress,weak and broken lithology and such subjective factors as adverse combination of rock structure surface along the tunnel,short distance between double track tunnels,unfavorable construction organization plan,different supporting measures between left and right lines of double track tunnel. Due to the objective and subjective factors of larger deformation in No.1 cross-tunnel area of Yangjiaping tunnel,a mixed mechanism is presented of geotectonic stress expansion and structural surface deformation.