风积沙地层隧道洞口边坡稳定性分析

Stability Analysis of Tunnel Entrance Slope in Aeolian Sand Stratum

雅鲁藏布江流域日喀则地区堆积了广泛的风积沙,高速公路路线规划时不可避免地需要穿越风积沙地层,这对隧道洞口边坡的稳定性提出了更高要求,隧道洞口边坡开挖时受雨水冲刷侵蚀,导致隧道洞口段边坡容易发生滑坡等边坡变形破坏问题。拉日高速公路仁布隧道洞口位于风积沙地层,洞口边坡开挖后存在边坡失稳的风险,通过建立有限元数值分析模型,对隧道洞口边坡稳定性进行分析。分析表明风积沙地层边坡潜在失稳型式为牵引式滑坡失稳类型。针对该潜在的滑坡类型提出了隧道洞口边坡采用延长明洞的加固设计方案,并对边坡加固方案进行了有限元数值分析,分析结果表明边坡加固后安全系数提高,加固后边坡处于稳定状态,证明了方案的可行性。

Extensive aeolian sand is accumulated in the Shigatse area of the Yarlung Zangbo River Basin, and it is inevitable to cross the aeolian sand stratum during the planning of the highway route, which puts forward higher requirements for the stability of the tunnel entrance slope. The slope at the tunnel entrance is eroded by rainwater during excavation, which makes the slope at the entrance of the tunnel prone to landslides and other slope deformation and damage problems. The entrance of the Renbu Tunnel on the Lhasa-Shigatse Expressway is located in aeolian sand, and there is a risk of slope instability after the slope of the entrance is excavated. The stability of the tunnel entrance is analyzed through establishing a finite element numerical analysis model. The analysis shows that the potential instability type of the aeolian sand stratum slope is the traction type landslide instability. Aiming at the potential landslide type, a reinforcement design scheme of extending the tunnel at the entrance of the tunnel is proposed, and the finite element numerical analysis of the slope reinforcement scheme is carried out. The analysis results show that the safety factor is improved after the slope is reinforced, and the slope is stable after reinforcement, which proves the feasibility of the scheme.