Technology On Reconstruction And Expansion Of Highway In Mountainous

In order to solve the problem, based on the Wenshan to Dulong renovation and expansion project, using the method of on-site investigation, theoretical analysis and numerical analysis, the subgrade deformation characteristic, slope stability and the corresponding control technology in renovation and expansion of typical sections are studied. The mainly research content and results are as follows:1) Based on field investigations and the existing research results, the various factors that affect the availability of the old subgrade are analyzed and the evaluation index set of the subgrade’s availability is selected. Then the availability level division standard of the subgrade is studied, and the fuzzy comprehensive evaluation mathematical model of the available evaluation of the different old subgrades is constructed. The method is put into the evaluation of the investigated old subgrades successfully.2) Through numerical calculation, the deformation behavior of typical fill and excavation widening subgrade in construction period, operation period and overload conditions is studied, respectively. The rebound deformation is closely related to the unloading width and the properties of the rock or soil. The greater the excavation amount, the greater the amount of rebound deformation. The amount of rebound deformation caused by the rock excavation is far less than the content of rebound deformation caused by the soil excavation.3) For the high fill widening subgrade in steep slopes, when using retaining structures, the failure modes include:slipping along the potential sliding surface between the new and old subgrades; sliding out of the top of the retaining wall; whole slipping along the bedrock overlay caused by the whole loads of the renovation and expansion of the subgrade. When the widening subgrade excavation slope is soil, the slope failure probability is large. The failure modes mainly include the sleek sliding and the collapse of the local soil in the slop surface. When the excavation slopes are composed of broken rock mass and bedding rock, the phenomenon of slope failure may also occur and the failure mode is generally the fold line or planar linear sliding.4) Setting geotechnical grille in the fill widening subgrade can effectively improve the stability factor of the broaden subgrade. This method increases the stability of the embankment slope.5) The stability control measures of the subgrade of renovation and expansion can be divided into three categories:a) improving the drainage system of the widening subgrade; b) enhancing the slope protection of widening subgrade; c) reinforcing the widening subgrade.