Reliability Analysis And Risk Assessment Of Landslides In The Three Gorges Reservoir Area Based On Unscented Transformation

As one of the frequent geological disasters in the world,landslides have serious restrictions and impacts on the safety of peoples lives and properties.Research on the prevention and control of landslide risks in the Three Gorges Reservoir area is important for ensuring the safety of lives and properties of residents in the reservoir area and the golden waterways of the Yangtze The normal operation,etc.,has important scientific and practical significance.Slope reliability analysis is an important issue in geotechnical engineering research,as well as an important content of landslide risk assessment.The traditional safety factor method cannot take into account the uncertain factors in the slope,and the calculated results cannot accurately reflect the slope.Continuous improvement and enrichment of slope reliability analysis methods to achieve efficient risk identification and evaluation of slopes has been a hot and difficult issue in recent years.In this paper,the failure probability calculated by common slope reliability analysis methods(Monte Carlo method,First-order second-moment method,Response surface method)is used as the reference value,combined with the variability and correlation of the parameters,the introduction of strong nonlinear processing capabilities The odorless transformation of the proposed reliability analysis method through a comparative analysis with the benchmark value demonstrates the rationality,applicability and efficiency of the proposed reliability analysis method.Combining rock and soil mechanics,engineering geology,statistics and reliability theories,based on the Muyubao landslide in Shazhenxi Town in the Three Gorges Reservoir area,the landslide reliability analysis and risk assessment are carried out by analyzing the geological conditions and induced characteristics of the landslide.Among them,based on the landslide Failure probability and landslide disaster intensity,carry out hazard analysis under different working conditions(natural working conditions,rainfall working conditions,earthquake working conditions);carry out the identification of disaster-bearing bodies in the study area,and determine the disaster-bearing probability of different types of disaster-bearing bodies to carry out value estimation and carry out landslide vulnerability analysis;Finally,based on the risk analysis and vulnerability analysis,the landslide risk assessment is carried out,and the total risk value under different working conditions and different methods is obtained,and landslide prevention suggestions are put forward.Get the following conclusions:(1)The slope reliability analysis based on the unscented transformation can be efficiently used in the slope reliability analysis.However,due to the different acquisition methods of sigma points,the results of unscented transformation and symmetric point set unscented transformation are very different.For unscented transformation,the parameter?also has a significant effect on the result.Unscneted transformation(?=10^-1)more suitable for slope reliability analysis.(2)The correlation and variability of the shear strength parameters c and?have a certain influence on the reliability analysis results.For different correlation coefficients,symmetric unscented transformation and the scaled unscented transformation(?=10^-2 and?=10^-3)will overestimate the failure probability,resulting in a conservative design plan,while variable-scale and tasteless transformation(?=10^-1).It is more suitable for the correlation value of shear strength parameters commonly used in actual engineering,which also highlights its better applicability.In addition,for the case where the average point of the soil shear strength parameters c and?is above the limit state line,when the coefficient of variation gradually decreases,the difference between the calculated result of the scaled unscented transformation(?=10^-1)and the reference value The relative error is gradually increasing,but in actual engineering,researchers pay more attention to problems with greater uncertainty.(3)For the functional function with n main control variables,the slope reliability analysis based on the symmetric point set unscented transformation requires(2n)calculations,and the slope reliability analysis based on scaled unscented transformation requires(2n+1)times Calculation.Under the same calculation conditions,compared to the Monte Carlo method(20,000 times)that can meet the convergence condition with the least sampling times,the scaled unscented transformation(?=10^-1)can save more than 50%of the time,the calculation efficiency of the unscented transformation is improved more significantly.(4)According to the process of single landslide risk analysis and evaluation,the risk analysis of Muyubao landslide in the Three Gorges Reservoir area is carried out.After calculations,the landslide will produce different risk values under different working conditions.Among them,under rainfall working conditions,it will produce a greater risk value,and it belongs to the five-level high risk category under different working conditions.Once a landslide occurs,it will cause great harm.At the same time,based on the Muyubao landslide disaster risk assessment results,a single landslide risk management strategy is proposed,including:Engineering treatment measures,biological measures,and strengthening the construction of investigation and monitoring systems to improve the emergency response capabilities of landslide disasters.