滑坡-隧道斜交体系稳定性案例分析及综合治理——以云南大关至永善高速公路椿坪2号隧道出口段为例

Case Analysis and Comprehensive Treatment Evaluation of Lands lide-Tunnel Oblique System:a Case Study of Exit Section of Chunping No.2 Tunnel of Daguan-Yongshan Expressway in Yunnan,China

为解决滑坡处隧道进洞难的问题,以云南大关至永善高速公路椿坪2号隧道出口段为依托,结合场区工程地质条件,开展滑坡成因和治理前稳定性分析,据此提出针对坡体-隧道斜交体系的综合治理措施,采用数值模拟分析滑坡治理效果,评价隧道结构安全性。得到以下结论:1)隧道洞口处坡体在天然或暴雨状态下安全性较低,“反压回填+抗滑桩+锚索”的滑坡治理措施具有综合效益。2)采用“反压回填”治理后,滑坡体在天然工况下稳定,但暴雨工况下不稳定;继续采用“抗滑桩+锚索”治理后,滑坡体在暴雨工况下稳定。3)采用桩基并注浆、双层超前大管棚的预处理措施可确保明洞施工安全性,滑坡对隧道出口段结构主要影响范围为20 m。

It is difficult to construct a tunnel in landslide area.As a result,a case study is conducted on the exit section of the Chunping No.2 tunnel of the Daguan-Yongshan expressway in Yunnan,China,and the causes of landslide and the stability before treatment are analyzed according to geological conditions.Based on this,the comprehensive treatment measures for the slope-tunnel oblique intersection system are proposed,and the effect of landslide treatment is analyzed by numerical simulation,so as to evaluate the safety of tunnel structure.The results show the following:(1)The slope at the portal of the tunnel has low safety under the condition of nature or rainstorm.The landslide control measures of"reverse pressure backfill+anti-slide pile+anchor cable"are comprehensively beneficial.(2)After backfilling treatment,the landslide body is stable in natural condition,but unstable in rainstorm condition.After treatment of antislide pile+anchor cable,the landslide body can remain stable under the rainstorm condition.(3)The pretreatment measures of pile foundation and grouting and double-layer advance large pipe shed can ensure the safety of open-cut tunnel construction.The main influence range of landslide on the tunnel exit section structure is 20 m.