Study On The Process Stability Of High Slope Construction Of Highway Expansion Project

With the rapid development of economy in our country, many existing roads cannot meet the increasing traffic demand, therefore, it is necessary to rebuild and extend some of the existing roads. During the high cutting slope construction process in the road rebuild and extension, it is bound to give a secondary excavation to the original slope, and the original supporting structure should be demolished before the secondary excavation So how to avoid the slope being instability after the supporting structure being removed and during the secondary excavation has became an urgent problem that need to be solved in the engineering.In this paper, the K1431+380 high slope in the highway rebuild and extension engineering of Guilin to Liuzhou to Nanning highway was took as an example, firstly, using the sensitivity and orthogonal experiment method to give a sensitivities analysis to the influence factors of slope stability, secondly, through the numerical simulation by FLAC 3D, gave a systematic study to the process stability during the secondary excavation, finally proposed some reasonable construction technology which are suitable for the slope. The main research content and conclusions are as follows:(1) Based onthe orthogonal experiment designing, got the factors sensitivity to the safety factor that affect the stability of K1431+380 high slope, it concluded that the sensitivity relations beyond this factors which affect the slope stability is:The average slope inclination angle>The stope height>Geotechnical average angle of internal friction>Geotechnical average severe>The classification number of slope excavation>Geotechnical average cohesion.(2) Through the numerical simulation of different excavation proportions and depths, it concluded that the slope stability is more sensitive to slope excavation proportion; The safety factor Fs reached the maximum at the each level excavation depth of 10m; Finally concluded that the safety factor and each level excavation depth are not simple linear relationships, but exiting an optimum excavation depth that the slope stability can achieve the best.(3) Through the numerical simulation to the excavation, considered that the slope stability can achieve the best when supported in a timely manner after the third excavation step. The final conclusion is that it has a best time when the support measures should be done, which is the most critical step. At this critical step, the support measures and the slope stability can achieve the best degree.