| China is one of the countries with the most serious geological disasters in the world,because of the special topography and physiognomy,and under the different natural conditions in Southern and Northern Shaanxi,Shaanxi province has developed typical Qinba Mountains and loess geomorphology which belong to the high incidence areas and easy-happening areas of geological disasters.According to incomplete investigation and statistics,there were more than 200 landslides with obvious signs of instability during the construction of the Shaanxi expressways,in spite that engineering management measures mainly of anti-slide pile has been adopted,the phenomenon of some landslide activity after treatment is still occurring,which poses a great threat to the safe operation of roads and the people's lives and properties.Therefore,it is of important theoretical and practical significance to carry out the research of design theory,and early-warning prediction of anti-slide pile for landslide.The paper relies on "Key technology research on landslide monitoring and warning system of expressway",the research project(13-28K)of Department of Transportation of Shaanxi Province,mainly aims at anti-slide pile retaining system,carries out deeply systematic research from two aspects of design theory and early-warning prediction.Main achievements are as follows:(1)Improve the formula of conventional landslide thrust,and verify the rationality of the improved formula by numerical simulation method.(2)Analyze the formation conditions of soil arches which are behind and between piles,propose a computing method of single pile landslide thrust considering the soil arch effect.(3)Establish a formula to calculate the maximum spacing of anti-slide pile,based on the soil arch effect between piles and the soil arch effect behind piles,and verify the reliability of the formula by taking the engineering examples.(4)Numerical simulation analyzes the evolution law of the soil arch effect under the condition of different pile spacing,and further verifies the reasonability and correctness of the calculation method of the maximum pile spacing of the anti-slide pile which is proposed in the paper.(5)Put forward a method of early-warning prediction of the pile shaft stress in the anti-slide pile retaining system for the landslide,according to the comparative analysis of the bending moment of the pile shaft obtained by inverse calculation which is based on the monitoring result of the pile shaft stress of the anti-slide pile for landslide from the designed computing one.(6)Based on the calculation method of elastic pile and rigid pile,respectively establish the early-warning model of pile top displacement.That is the relationship between anti-slide pile top displacement and the maximum bending moment,anchorage length,cantilever length,foundation coefficient along with size of pile section.Therefore,it can obtain the maximum displacement of the anti-slide pile top by inputting the related parameters of the specific landslide,and can realize the timely early-warning to the anti-slide pile through comparing with the actual monitoring results of the pile top displacement.(7)The GMD numerical model of K32+690 to K32+840 left slope of Weinan-Yushan expressway is set up,then the whole process from excavation to instability to retaining by anti-slide pile of the slope is analized through numerical simulation.The results are in good agreement with the actual situation.Meanwhile,by comparing the numerical simulation results with the maximum displacement of the pile top which is calculated by the early-warning model,further verify the reliability of the early-warning model. |
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