| It is still a challenge in geotechnical engineering to cure the expansive soil slopes well.Because of the complicated characteristics of expansive soils,the slope would slide again if treated inappropriate.Flexible reinforced retaining wall possesses both construction convenience and good economy,and it can release expansion pressure of expansive soils through flexible deformation.The curing effect of flexible reinforced retaining wall has been proved in many projects.However,with overloading on the crest,the mechanical characteristics and curing effect of reinforced retaining wall needs further research to confirm.This paper was based on the curing of an expansive soil cutting slope of a railway line in Yanwumian,Yichang Dangyang city,Hubei province.Through the investigation of the research status at domestic and abroad,combined with soil test in the laboratory,field monitoring test and numerical simulation,the characteristics of expansive soils in Yanwumiao,the tensile properties of flexible reinforced materials and mechanical characteristics of the reinforced retaining wall were studied.The main research contents and conclusions were as follows:(1)By XRD diffraction,scanning electronic microscopy,and other soil test,the characteristics of expansive soils in Yanwumiao were acquired.The influence of moisture content and upload to expansive soils’ sheering strength was studied.And the influence of moisture content to soils’ swelling properties was studied as well,which could provide physical and mechanics parameters to the slopes’ treatment in the field.(2)Through tensile test,the tensile strengths and elongations of fiberglass geogrid,plastic geogrid,and gabion net were acquired.Comparing to single reinforced material,the reinforced mesh could increase its mechanical characteristics and maximum elongation.Those research results could provide mechanics parameters to reinforced retaining plan.(3)According to the actual failure of expansive soil slope and the results of inclinometer monitoring,the position and shape of sliding surface was acquired,and the instability of expansive soil slope of Yanyumiao was further analyzed.Combined with the unconfined swelling properties,expansive soils’ characteristics were simulated by finite element method through temperature rising.Based on the simulation method,the two dimensional numerical model of expansive soil slope was established.The simulation results were compared with the slope failure condition measured on site,which verified the reliability of numerical simulation.The influence of overloading and soils’ expansion to displacement of the slope was discussed and the mechanism of the slope’s instability was studied through numerical simulation.(4)Laying apparatus like flexible displacement meter,earth pressure cell,the horizontal earth pressure of the reinforced retaining wall,the vertical earth pressure in the reinforced soil and foundation,and the tensile strain of geogrid were monitored.The net effect of geogrid made the vertical earth pressure of stiffened cushion lower than the calculated value;because of the rain infiltration,expansive soils on the back of the reinforced retaining wall expanded,led to the horizontal soil pressures 3meters below the top of the slope larger than calculated value.(5)Combined with in-site monitoring test,a numerical model of the reinforced retaining wall was established.The monitoring results and simulation results were compared to ensure the accuracy of simulation method.The curing effect of reinforced retaining wall was evaluated.Also,the influence of overloading and soils’ expansion to the reinforced retaining wall was discussed.And safety factors to the reinforced retaining wall was discussed as well.It is suggested that a warning line should be set 5.0 meters from the slope shoulder and mines are prohibited in areas to the right of the warning line.Besides,the load of mines should be less than 140 k Pa.This thesis includes 90 figures,17 tables and 109 references. |
PDF Full Text Request