Method For Slope Reliability Analysis Considering Uncertainty Of Reinforcement Measures

Uncertainty of soil parameters has a significant effect on the reliability of reinforced slopes.In addition,reinforcement measuressuch as backfill compaction of excavations,reinforced retaining wall,anchor reinforcement,struts reinforcement are also subjected to uncertainty because they are limited by the skill level of the builders and the surrounding geological conditions.This paper focuses on the influence of slope reliability considering uncertainty of reinforcement measures.In this paper,Slope/W module of Geo-Studio software is batched based on Win-Batch^TM and the slope stability of reinforced retaining wall or anchor reinforcement is analyzed separately.Next,accumulation state of unstable slopes under raising the height of the retaining wall is simulated with SPH.Furthermore,the reliability of reinforced slopes is analyzed with Monte Carlo.Finally,the slope reliability of struts reinforcement is studied using multi-response surface method.The main contents are as follows:For reinforcement measures of excavation and backfill,the uncertainty of reinforcement measures is considered through varying the coefficient of variation of the backfill soil.The relative relationship between the height of the retaining wall and the displacement of sliding soil is analyzed,constructing new function functions analysis slope reliability before and after hightening retaining walls.The method proposed described above has been applied in the slope reinforcement of Ha-jia railway line.The research results show that:improving the construction quality can distinctly reduce the failure probability of the reinforced slope;strict control of the construction quality to reduce the coefficient of variation of soil parameters during the construction process can effectively reduce the failure probability of the reinforced slope;increasing the height of the retaining wall can effectively prevent the sliding soil from sliding to the railway line and significantly reduce the failure probability.When slopes reliability of anchor reinforcement are analyzed,the uncertainty of anchors is considered through the following two approaches One is to assume that friction force on the unit surface of the contact surface between the anchor and the anchor solid is a log-normal distribution variable,and the other is to introduce the attenuation coefficient of the friction force on the unit surface of the contact surface between the anchor and the anchor solid to consider the uncertainty of the anchor during construction and maintenance.The limit equilibrium method and Monte Carlo sampling method are used to calculate and compare the variation curve of failure probability of the reinforced slope under two approaches.Finally,the effectiveness of the proposed method is validated against an example of the slope retaining project of Laoshan,Qingdao.The results show that the failure probability of the reinforced slope increases gradually with the increase of the coefficient of variation of unit surface friction on the contact surface between the anchor and the anchor solid under the same soil statistical parameters,and the increase extent is between 18.03%and 41.90%for the first approach.For the second approach,the failure probability of the reinforced slope increases rapidly with the decrease of the attenuation coefficient of the anchor ranging from 1.0 to 0.0,and the increase extent is between 55.64%and 124.90%.Under the same attenuation coefficient,the failure probability of reinforced slope increases with the increase of the number of attenuation anchors.When slope reliability of foundation pit is analyzed,a Monte Carlo simulation method of foundation pit excavation support system reliability analysis based on multi-response surface method is proposed.The specific calculation steps are given,a failure probability calculation program for multiple failure modes of foundation pit excavation support system based on multi-response surface method is written using software,the reliability of pit systems considering multiple failure modes is systematically investigated against an example of a foundation pit project in Licang,Qingdao.The results show that the proposed method can quickly and effectively analyze the reliability of foundation pit excavation support system considering the variability of soil parameters and multiple failure modes of foundation pits,verified correlation between primary failure mode and other failure modes.In order to reduce the failure probability of foundation pit system,problems that lead to a high failure probability in a single failure mode are analyzed,struts reinforcement are prestressed reasonably.