Comprehensive Treatment Study On High Slope A7 Of TANGTUN Expressway

High slope A7 of Expressway TANGTUN is located near Tangkou interchange from station number of AK3+690 to AK3+888. And down the route of Hefei-Tonglin-Huangshan, the interchange is the only way to the South Gate of Huangshan Scene Area, which is famous in the world. There are two already completed bridges of expressway main route at the foot of High Slope A7. A continuous arc tension crack appeared along the outside of slope top when the 2nd step of the slope was excavated. According to the monitoring results, it was very possible for the slope to become unstable if there were no effective support measures to be used on time. As a result, nearly 240km~3 rock mass or soil mass would slide down. Not only would pecuniary losses be huge, but also the society impact would be very bad.Based on the systemic engineering geology investigation on high slope A7 in situ, firstly rock mass structure type and its formation mechanism, as well as combination trait of discontinuities and slope surface was studied in detail. Secondly the formation and failure mechanism of the high slope was deeply researched through both Flac-3D simulation and the analysis of engineering geology conditions. Furthermore, the stability of slope was systemically evaluated with the specified evaluation method of slope stability on the basis of deformation theory and strength theory. In the end, comprehensive treatment scheme including the emergency measure and the long-term measure was put forward, according to the analysis of engineering geology and slope stability of slope A7. The emergency measure consisted of prestress cable and drainage measure, which controlled the slope deformation, and made it in the permission scope of engineering geology. Sequentially, anchor anti-slide pile was used. Afterwards, synthetic treatment measures of anchor cable framework, bolt framework and drainage measure were adopted. Monitoring data showed that the high slope kept stable after two rainy seasons.The author of this paper led and took part in the overall process of the comprehensive treatment for slope A7. To save time, the rescue work had a match with rainy season. Eventually, high slope A7 kept stable from continuous deformation, which ensured the safety of the engineering.