Optimization Of Slope Anchoring Parameters And Evaluation Of Support Scheme

In this paper,the existing slope support design is relatively conservative and may cause material waste.The three aspects of anchor parameter setting,strength material parameters attenuation form and constitutive model selection are explored.The length and anchorage of the bolt are optimized based on orthogonal experiment.The anchoring parameters and design schemes such as angle and prestress value are used to discuss the material attenuation in the process of strength parameter reduction.Based on the Drucker-Prager model,the non-equal ratio based on the Drucker-Prager series criterion(referred to as the D-P series criterion)is derived.In addition,the realization process of the non-equal scale reduction method in the D-P series criterion is briefly described,and the support scheme optimized by the anchor parameters is evaluated based on the Drucker-Prager model.The research work and main achievements of the thesis include the following aspects:(1)Determine the orthogonal test scheme and analyze the relationship between the effective bolt length and the optimal anchoring angle by numerical simulation.The results show that there are different effective anchor(cable)lengths and optimal anchoring angles at different positions of the slope.When the anchoring position of the anchor is fixed,the optimal anchoring angle appears with the increase of the length of the anchor(cable).There is a negative correlation between the two.(2)The relationship between the prestressing value of the anchor cable and the reinforcement effect of the slope is analyzed by applying prestressed anchor cables of different sizes.The results show that when the prestressing value increases to a certain extent,the reinforcement effect of the slope begins to weaken.The main reason is that the active force characteristics of the prestressed anchor cable change the original plastic failure zone of the slope,and then increase the prestressing value.It does not change the fact that the slope has been partially destroyed.(3)Compared with the original support scheme,the total bolt usage of the new support scheme was reduced by 8.9%,the amount of anchor cable was reduced by 31.2%,and the total amount of prestress was reduced by 16.7%.The numerical simulation results show that the new support scheme has the same slope reinforcement effect.(4)Establish a three-dimensional model for the unsupported slope excavation of Xiaguanfang,and analyze the slope stability based on the D-P series criteria.The results show that the slope stability evaluation based on the D-P series criterion is obviously different.The slope safety factor value obtained based on the DP1 criterion is the largest,and it is increased by about 16% compared with the M-C strength criterion,The DP4 criterion is the closest to the M-C strength criterion,with a maximum difference of only 1.2%.(5)In order to study the influence of the non-equal strength reduction method derived from the paper on the reinforcement effect of the slope,based on different strength criteria,the calculation results under the action of two different strength reduction methods are compared and found,based on the M-C strength criterion and the DP4 criterion.The value of the slope safety factor obtained by the non-equal scale reduction method is smaller than that of the traditional strength reduction method,while the critical instability displacement value is too large.The results obtained by the non-equal scale reduction method derived in this paper are more conservative.