Open-pit Rock Slope Stability Analysis And Excavation To Determine The Angle Of The Slope

Recently, with the construction procedure in mountainous area, railroad, speedway, and the excavation of deep foundation as well as open mine, the practical engineering problems become more and more in the real situation, especially in the large open mine slope stability. The rock slope in one large surface mine is chosen as the engineering background. This paper studies the proper slope angle and the stability of rock slope, by the method of isitu investigation, stability analysis by structure plane in rock mass, laboratory test, limit equilibrium, and numerical analysis, the main contents and conclusions are as follows,(1) The insitu investigation is done, and the following characteristic of rock slope are obtained, such as distribution of rock mass, structural plane characteristic, distribution of underground water; the joint plane and fault near slope have little affect on the stability of slope, so the method of equivalent rock mass parameters can be adopted in the following mechanical stability analysis.(2) The rock samples are made from the insitu filed, and physical-mechanical tests are done as well as the coresponding engineering treatments. Then the parameters for the further stability analysis are obtained from the test, such as the density, tensile strength, compressive strength, cohesion, and internal friction angle.(3) The simplified BISHOP method is adopted to calculate the stability of slope. During calculations, the slope angle changes under two different situations, one is under the dead load of rock mass, the other is under the dead load and seismic load. The analysis results show that, the failure mode of slope is local damage.(4) The numerical analysis model is founded, which is based on the shear strength reduction. The numerical calculations of safety factor and failure mode are done under the slope angle of 65°. The numerical calculation results show that, safety factor is 1.58, which shows the slope is in the stable state. The result obtained by numerical calculation is a little difference in amount (6.47%) with that obtained by limit equilibrium method, which is under bias towards safety. At the same time, the results also show that the potential slip block is under local failure mode. The stress and displacement responses in different areas of slope after excavation are shown in the macroscopic way, which can give some guidance for the practice.