Optimization of Zhenqing two standard K29 450 to K29 900 paragraph excavation slope stability analysis and reinforcement
|School||Kunming University of Science and Technology|
|Keywords||Slope excavation Stability analysis Numerical simulation FLAC3D Reinforcement optimization|
Nowadays highway slope stability has become a global concern and it is a hot topic to evaluate the stability of slope and choose the optimal reinforcement.The Zhenqing (Zhenxingqiao-Qingshuihe) roadway, the key construction road in Lincang City, is one of 52 secondary highway plans in Yunnan Province and its length is 156km. The highway which mainly consists of subgrade excavations and bridges is built along Nanting River. Throughout the whole project, there are 120 slopes among which one forth holds the height beyond 50m.Based on the shapes of slopes、geological characteristics and the types of slope failure, the study is conducted on the Zhenqing K29+450～K29+900 section with the typical high steep slope. Basically, this paper consists of the following studies:1、Based on the topographic and geologic conditions of slope, the geological patterns of slope was determined by drilling and geophysical (high-density electrical) and. combining a numerical study, the depth and scope of the sliding surface was determined. The slope was characterized as a medium-sized gravel soil-bedrock landslide and its mechanical property was traction.2、using numerical simulation method to analyze the stability of slope excavation Under normal and rainfall conditions. The simulation results showed that the slope was in an unstable state with a safety factor of 1.12 with wide plastic zones. Especially when raining. the slope deformation is large and the safety factor is only 1.05. Therefore, the impact of rainfall must be taken into accounts during the choice of slope.3、As for instable slope, optimization of three kinds of reinforcement methods, cutting load shedding, piles and anchor-sash supporting beam has been carried out. Using FLAC3D, and analyzing the stress distribution, deformation (displacement) features, the distribution of plastic zone, safety factors and other characteristics, it is shown that all the three options can play the effect of slope. Coupling with technical and economic comparison of three options, the final optimization method of slope reinforcement, cutting load shedding, which is technically feasible and economically reasonable was determined.4、According to the slope reinforcement, eight displacement observation points, intervals of 10-15m, were laid in the second and fourth step above embankment. They were mainly used to observe the reinforced slope displacement. The results showed that the slope is stable and the slope reinforcement measure is reasonable.