Analysis And Prevention Of The Slope Stability Of The Xinfazhai Bridge Foundation In Shiping County, Yunnan Provinc

Yunnan Xinfa Zhaite Bridge is one of the regional road networks of highway network construction planning in the 13 th Five-Year Plan of Yunnan Central City Economic Circle,and is a key project in the medium-term planning of “All County Access to Highway” program proposed by Honghe Prefecture,as well as is an important improvement and supplement to the national highway network.Due to its location near the village,complicated geological environment and influence by various uncertain internal and external factors,it makes the stability analysis of the bridge very complicated.In order to analyze its stability comprehensively,a series of comprehensive analysis tools are needed during the research.In this paper,taking the slope of the abutment with small pile number and the slope of the abutment with large pile number of Xinfa Zhaite Bridge as an example,on the basis of on-site geological survey and indoor data research,the stable slope angle of the slope of the abutment with small pile number and the slope of the abutment with large pile number in the natural state are calculated,and the slope map of the analyzed slope is compared with the stable slope angle by using ARCGIS software to call ASTER-DEM data to carry out a preliminary stability analysis on the slop.Then,the relationship between the attitude of rock and the natural abutment slope was further analyzed by using the stereographic projection theories,and further the qualitative stability was obtained.Subsequently,MIDAS GTS software was applied to establish the three-dimensional models of the slope of the abutment with small pile number and the slope of the abutment with large pile number,and the stability of the two slopes under the self-weight condition,bridge loading condition,storm condition and earthquake condition were studied respectively,as well as the quantitative analysis of the safety factor,displacement,stress,plastic zone and maximum shearing strain of the simulation results were carried out.On the basis of the stability conditions of the slope of the abutment with small pile number and the abutment with large pile number under different conditions,the simulation studies were carried out after adopting prestressed anchor bolt support and slope reduction support forms for the two slopes respectively.The main findings and conclusions of this paper are as follows:(1)The slope cloud map obtained based on the calculation of natural stable slope angle by applying ASTER-GDEM data.It is found that both the slope of the abutment with small pile number and the slope of the abutment with large pile number are both in a stable state under the natural working condition.In the Stereographic Projection Analysis,the combination of the dominant joint surface and attitude of rock of the two slopes also does not affect the overall stability of the slopes under natural working conditions.(2)From the simulation results before giving the support,it can be seen that the safety coefficients of the slope of the abutment with small pile number under self-weight condition,bridge load condition,storm condition and earthquake condition are 1.60,1.50,1.10 and 1.00 respectively.At the same time,it is found that the slope of the abutment with small pile number is in stable condition only under natural condition,and it is in unfavorable basic stable condition and unstable condition under storm condition and earthquake condition respectively.The safety coefficients of the slope of the abutment with large pile number under self-weight condition,bridge load condition,storm condition and earthquake condition are 1.50,1.45,1.17 and 1.10 respectively.At the same time,it is found that the slope of large pile bridge foundation is in stable condition only under natural condition,and it is in unfavorable basic stable condition under storm condition and earthquake condition respectively.(3)From the simulation results after giving the support,it can be seen that the safety coefficients of the slope of the abutment with small pile number with prestressed anchor support reach 1.65 and 1.66 under storm condition and earthquake condition,respectively,which are all in a stable condition.The safety coefficients of the slope of the abutment with large pile number with prestressed anchor support and slope reduction under the natural storm condition and earthquake condition are 1.80 and 1.80 respectively,which are also in a stable condition.