Based On The Geological Statistical Model Of Rainfall Condition Slope Reliability Analysis

The traffic construction such as highways and railways is developing fast inChina from the beginning of the twenty first century. A number of slopes due tocutting excavation are inevitable when the path is planned to pass through suchcomplex topography as mountainous areas and river valleys, thus brings about avariety of problems relating to slope stability. It is critical to give the infiltrationstability analysis for post-rain slopes as the book “Typical Landslides in China”reveals that most of slope failures were observed in rainy season among the listedninety landslide cases in the book, nearly ninety five percent of failures were closelyrelated to the rainfall and infiltration. Because of the uncertainty and randomcomplexity for the soil properties, a single factor of safety is unable to describe theslope stability state correctly. It will benefit much to introduce the reliability theory todemonstrate the slope stability state and can evaluate the slope safety in quantity morecompletely and objectively.Based on the deeply-excavated and highly-filled slopes along the path ofHengGui highway, this work devoted into the reliability analysis of the post-rain softsoil slopes and provided the guidelines to the risk prediction and protection for theseslopes. The achievements in the present study can be summarized as follows:(1) When performing the slope reliability analysis, the derived performancefunction is complicit and it is difficult to give an explicit solution. The interpolationprediction approach in geological statistics model is introduced to the Spencer methodin LEM to make the performance function explicit and possible to be solved for thereliability index.(2) The commonly used designing method in geological statistics model is theLatin hypercube test design that can “permeate the full space”, i.e. it can interspersethe samplings uniformly in the whole test space. The stratified test design is able tosample according to the real distribution of the variables. Combining the twoabovementioned designing methods into the geological statistics model can yieldmore accurate model results.(3) A slope along the HengGui highway is selected to be the case example, andan infiltration analytical model for this post-rain slope is established by using thefinite element software Geostudio and cooperating with the strong rainfall investigation of2012in Hunan. Given the total rain height to be consistent, differentrainfall styles are set up to analysis the distribution of the pore water pressure for thepost-rain slope soil and the reliability variation for varied times, thus demonstrate thesafety change of the post-rain slopes. The variation of pore water pressure and thevolumetric water content can be presented in detail by installing observation points onthe slope model.(4) The reliability of post-rain stability for the two slope sections along theHengGui highway is investigated to predict the safety of the decomposed andweathered soft rock over time. This recognition of the safety variation for the softrock slope with different weathered depths can provide guidelines for the slopeprotection.(5) Ecological protection is applied to guarantee the slope safety along path ofthe HengGui highway and the effect for improving the slope stability is verified bythe field measurements. It can be used as a reference for other slope protectionprojects.