Stability Evaluation And Support Optimization Design Of Soft Rock Cutting Slope In Mountainous Area

The stability study of high cutting slope in mountainous area is a very important geotechnical engineering problem.In recent years,with the rapid development of China’s economy and the accelerating process of infrastructure construction,many slope projects are gradually carried out in mountainous areas.In the early stage of mountain highway project construction,the common phenomenon of slope instability occurs,especially in soft rock cutting high slope under heavy rainfall operation,which brings serious losses to people’s lives and property.Based on the S238 Anhua Dongping to Qujiang highway cutting high slope engineering,through theoretical analysis and numerical simulation and field monitoring and other research methods,the stability of the selected slope is calculated and analyzed.On the basis of the analysis and evaluation of the original design support scheme,the parameters and layout of the anchor are optimized,which can provide some reference for the design,construction and reinforcement of the cutting high slope.The main research work and results are as follows:(1)Based on the relevant literature and field investigation,the influencing factors of soft rock slope instability in mountainous areas are summarized and analyzed,and the failure types and deformation failure characteristics of soft rock slope instability in mountainous areas are summarized.Before the construction,the construction safety risk assessment of the slope relying on the project is carried out,and the risk level of each slope is determined.The soft rock slope with the highest risk value is located in K7+720-K7+780,which can be selected as the later research object.(2)With the help of numerical software,the stability of the slope before and after rainfall is simulated and analyzed.The stability coefficients are 1.152 and 0.971,respectively.It can be judged to maintain primary stability under natural conditions,and it is easy to lose stability once affected by a rainstorm.According to the relevant parameters of the prestressed anchor frame beam in the original scheme,the numerical model of the slope after reinforcement is established.The analysis shows that the stability of the slope under two working conditions is significantly improved,and the displacement is significantly reduced after support,which verifies the feasibility of the prestressed anchor frame beam support measures.(3)To ensure the effectiveness,safety,and economy of the optimized supporting structure,the slope model under different bolt parameters is established,and the variation law of slope stability coefficient and displacement value with parameter adjustment is analyzed.The stability coefficient is proportional to the anchorage angle and the length of the anchorage section and inversely proportional to the vertical spacing of the anchor,and the change rule of the displacement value is opposite.(4)Combined with the calculation results of the range and variance of each factor in the orthogonal test scheme,the sensitivity of the anchorage parameters was comprehensively ranked as follows:bolt spacing>anchorage length>anchorage angle,and the optimal anchorage parameters were determined as follows:anchorage angle 20°,bolt spacing 3m,and anchorage length 8m.Finally,the displacement of the optimized slope support is evaluated by monitoring measurement.The monitoring data show that the horizontal displacement near the foot of the slope is the largest,which is 8.81mm.The vertical settlement displacement of the top of the slope is the largest,which is 6.58mm.The displacement of the slope is greatly reduced compared with that before optimization.