旱塘坡隧道口斜坡变形分析及防护措施研究

Deformation Analysis and Study of Protective Measures of Slope Located on the Exit of Hantangpo Tunnel

研究目的：旱塘坡隧道出口开挖时，斜坡体地表出现了局部开裂，多条裂缝呈弧形分布于开挖段隧道右侧（靠山侧）50m范围内，缝宽0．1～5cm，最大长度约30m，可见最大深度约0．45m。为了确保隧道工程安全，本文结合现场变形观测数据及现场调绘，对斜坡体和隧道进行不同工况下数值模拟分析，并研究不同防护措施下斜坡体及隧道变形规律，为隧道开挖防护设计提供科学依据。研究结论：（1）该隧道为断层破碎带内浅埋偏压隧道，斜坡体变形开裂原因主要是隧道开挖初支后，由于隧道偏压及围岩破碎等因素导致洞身变形延伸至地表；（2）后续隧道施工防护方案推荐采用加强隧道洞身衬砌支护强度，斜坡坡脚采用回填反压措施，若后续施工过程中隧道变形继续发展，则在隧道左侧增设埋设桩防护，经专家评审后，采用加强洞身衬砌支护强度和坡脚反压综合防护措施，隧道变形得到有效控制，确保了后续隧道工程的施工安全；（3）本研究成果可应用于铁路、公路及水电等其他行业隧道工程，可为类似处于断层破碎带范围内浅埋偏压隧道工程的防护设计提供参考或借鉴。

Research purposes： In the excavation of the exit of Hantangpo tunnel, local cracking appeared at the surface of the slope, many cracks appeared in a curved distribution within 50 meters on the right side of the tunnel （ the side near the hill）. The width of the crack is 0.1 - 5 cm, the maximum length is about 30 meters and the maximum visible depth is about 0.45 meter. For the safety of the tunnel engineering, this article makes numerical simulation analysis of slope body and tunnel under different conditions based on field deformation observation data and field mapping, and then studies the deformation characteristics of tunnel and slope under different protective measures, which can provide design basis for the subsequent protective measures of tunnel excavation. Research conclusions： （ 1 ） The Hantangpo tunnel is a shallow bias tunnel located in fault fracture zone. After the preliminary support of excavation, the deformation of the tunnel extended to the surface because of the tunnel bias and the broken rock mass, causing the surface cracking on the slope. （2） For the subsequent protective measures, the tunnel lining support strength should be improved and the backfill measures should be taken at the toe of the slope. The piles should be set at the left side of the tunnel if the deformation continues to develop in the subsequent construction process. After expert review, the measures of strength support and toe backfill can effectively control the deformation of tunnel and ensure the construction safety. （3） The research results can be applied to railway, highway, hydropower and other industries tunnel projects which can provide design basis for the protective measures of those similar shallow bias tunnels in fault fracture zone.