Rsearch Of Safety Monitoring In Construction And Inversion And Application Of Design Parameter Of Expressway Slope

In order to accomplish the important strategy of national poverty alleviation and perfect the national transportation infrastructure,the increasing number of expressway projects in mountainous areas,it will inevitably encounter the high slope and landslide geology with complicated geological conditions and environmental conditions.There are many types of rock and soil mass in mountainous road slopes,of which the properties vary greatly.Among them,the silty clay containing breccia is a kind of special rock and soil body with stones in the soil.The physical and mechanical properties under the original conditions are better,and the physical and mechanical properties are greatly reduced after being disturbed.The design parameters of the soil can not be determined by conventional indoor geotechnical test.The design adopts the empirical method to estimate the parameters conservatively,which can not guarantee the safety of the slope and the economic effect is poor.Therefore,it is of great practical value to study expressway slope with silty clay containing breccia.In this paper,safety constructionmonitoring and design parameters inversion and applied research are carried out based on the project of high slope on the right side of 3b bid K86 + 700 ~ K87 + 130 of Changan Expressway.(1)In order to ensure the safety of slope construction,basic data such as slope geology and topography are analyzed and studied in detail.Monitoring points are arranged in the excavation section of the local slope to monitor the slope displacement and groundwater level.Obtaining and statistical analyse of the slope monitoring data during the construction process and studing the physical and mechanical properties of soils to provide training basic data for the back analysis of the parameters of the silty clay.(2)The sensitivity analysis of slope stability was used to determine the main inversion parameters of soil by using two models of homogeneous slope and non-homogeneous slope.The in-situ measurement data of the 3# monitoring point was substituted into the inversion system for parameter inversion,and the slope model at the 4#monitoring point was established based on the inversion result.And the data calculated was compared with the data of the 4# monitoring point.The analysis shows that the maximum error between the prediction result and the actual measurement result is 7.53%,which is less than 10%.It indicates that the parameters of the silty clay containing breccia obtained through inversion are reasonable and can be used as the parameters forpredicting and analyzing the stability of the slope.(3)The soil parameters obtained by inversion analysis are used to analyze the model of the unexcavated section of the slope.According to the results of slope stability evaluation,it is recommended to use the slope excavation sequence,that is,from top to bottom,step by step,and add anti-slide piles after the completion of the second-grade slope excavation,and then carry out one-step slope excavation.It is suggested that the size of rectangle anti-sliding piles should be two meters in length,one and a half meters in width,and the distance between anti-sliding piles should be four meters.The width of the slope steps is recommended to be two meters.For slope excavation,it is recommended to adopt the ratio of the first grade slope is 1:0.75,the ratio of the second grade slope is 1:1,the ratio of the third grade slope is 1:1.2.In the construction excavation,it is recommended that the height should be eight meters for the first grade,ten meters for the second grade,and ten meters for the third grade of the slope.