| The problem of slope stability relates to many engineering fields such as highway,railway,water conservancy,construction and resource development,which directly affects the quality,safety and cost control of engineering construction.With the development of infrastructure,the engineering geological environment is becoming more and more complex and has a tendency of deterioration.The slope stability problem has become one of the main geological disasters.A practical highway cutting slope is analysis in this paper,which is located entrance section of Yangjia Bay tunnel at Chongqing Fengxi expressway.The engineering situation,hydrogeology and climatic environment are investigated at the location of the cutting slope through field exploration.The main causes are analyzed for the cutting slope.Based on the finite element strength folding method,the software of Midas-GTS is used to calculate the stability of the cutting slope.Combined with the actual situation in field and numerical results,the effective reinforcement measures are proposed.Finally,the related construction technology is explained in detail.The main conclusions are as follows:(1)Through consulting literatures,the common calculation methods of slope stability are expoured in detail,including traditional limit equibrium method,limit analysis method and finite element numerical method.Comparing with the advantages and disadvantages of these methods,the finite element reduction method is adopted to analyze the stability of the cutting slope.This method can not only get the the stability safety factors of slope,but also analyze the distribution of deformation,stress and strain of the whole slope.(2)Through field investigation,the slope soil layers of the cutting slope mainly consists of silgy clay,gravel and stone mixed accumulation at the top layer and silty sandstone marl layer at the lower layer.The development of internal cracks in the slope provides infiltration and enrichment channels for rainfall and surface water.The filtration of precipitation not only increases the weight of the slope but also greatly reduces the physical and mechanical properties of the soil,which is the main reason for the failure of the cutting slope.(3)The stability of the slope under natural conditions is analyzed by using the finite element strength reduction method.The safety factor is only 0.375,the slope is unstable,and the displacement and deformation of the foot retaining wall of the cutting slope are very large.The fracture surface is mainly located near the interface between the soil and gravel mixed accumulation and the lower rock.(4)According to the field investigation and numerical calculation results,the reinforcement and treatment scheme of prestressed anchor cable anti-slide pile is adopted in this paper because of the large downward thrust of the slope,the steep slope behind the landslide and the thin surface soil-rock mixed pile.Finite element method is used to calculate the slope after treatment.The safety factor of the cut slope after treatment is 1.725,which meets the requirement of slope stability.Through the analysis,it is found that the prestressing anchor cable anti-slide pile is enough to resist the downward thrust of the upper slope,and it also plays a good role in protecting the retaining wall at the foot of the cutting slope.This treatment scheme is sufficient to ensure the long-term stability of the cutting slope.(5)Finally,the construction technology requirements,matters needing attention,engineering test and slope engineering monitoring scheme are expounded in detail. |
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