Analysis And Treatment Of Landside Accident In Sigou Tunnel Exit

In construction of highway tunnels, especially in the excavation of the portal section because of many reasons such as the design and geology, the slope instability may be often happen during excavation. Therefore, it need to judge accurately the stability of the slope and take effective treatment measures promptly.In this thesis the problems in the tunnel exit construction of Sigou Tunnel of Shibai Highway are studied. The reasons and process of the collapse have been analyzed. Meanwhile, the reasonable measures aimed the complicated geometrical conditions at the tunnel exit have been taken. The contents are as follows.1. Based on the related references, the present methods of judgments and treatments for the slope stability are summarized. Combined with the special geological conditions in Sigou Tunnel exit, the process and reasons of the landside in the tunnel exit have been analyzed.2. Based on the geological materials and special situation, the related treatment measures have been proposed. As the landside is not completely stable after first phase of governance by the anti-slide wall, the intrinsic reasons have been analyzed by the translating factor method. The measured data show that the treatment plan has not satisfy the requirement of the safety and stability.3. After a complementary analysis, a supplementary treatment plan is formulated, i.e., the anti-slide pile joint governance landslide is provided. According to the mechanical characteristics of the retaining wall and the anti-slide piles and based on the safety and economic consideration, a combined mechanical model of the retaining wall and the anti-slide piles is proposed. In the study, the rational space between the piles are calculated. The measured data show that the slope stability requirement has been satisfied by the requirement plan.4. The finite difference method software, FLAC3D, is used to analyze the treatment scheme of the tunnel exit. The plastic strain regions have been calculated. Comparing the numerical simulation, theoretical results and the site monitoring, the rationality and safety of the treatment is demonstrated.The results have been referred in the undergoing construction of the highway tunnel. At the same time, they can be referred in the similar situations of excavation of other tunnel portals.