Tong Liyuan

Application of Analytic Hierarchy Process in large span and shallow buried highway tunnel construction risk recognition

Recently there has been rapid development of large-span and shallow-buried highway tunnel construction and considerable risk appear, the urgent issues are that how to identify effectively risk factors which in the process of tunnel construction. With the review of disadvantages of risk recognition methods, the risk hierarchical structure for construction of the tunnel was established using the Analytic Hierarchy Process in a tunnel construction site, the synthesis weights of each basic risk event and weights of factors which cause these basic risk events were calculated. A risk recognition model of large-span and shallow-buried highway tunnel construction was established.

Prediction of deformation and back-analysis m value on deep pit construction

Based on the elastic foundation beam method, m values for deep excavation were back-analyzed by using a constrained no-linear optimization method in MATLAB. The horizontal displacement of diaphragm wall during excavating was used in back-analysis procedure. The case studies in Suzhou subway showed that the presented method is simple and feasible. The m values obtained can reflect the actual situation and predict displacement of next working stage accurately.

Notice of Retraction Effect of compaction grouting reinforce on deformation of deep foundation pit in metro station in active Zone

Adopting Hardening-Soil finite element model based on unloading ,the improvement of grouting strengthening rear soil on deformation of the pit is studied. The results show that the reinforce influence on lateral deformation increases with the increasing of the excavating depth, the final lateral deformation reduces 13.6% than without reinforce, the displacement of pile top reduces 40.66%, but the displacement of pile bottom increases 13.27%; the uplift in bottom soil can be control in the area 6.00m near the wall, the range reduces 7.21% than without reinforce; It is conspicuous to reduce the soil settlement in the area 20.00m behind the retaining structure, the maximum settlement reduces 7.96% than without reinforce, the same as the lateral deformation of the soil in the area 20.00m~30.00m behind the retaining structure, the maximum lateral deformation reduces 45mm, relative 26.45%. Therefore, grouting strengthening rear soil based on difference geological conditions and deformation requirements to improve the reinforced soil intensity to devised result, which can guarantee the pit safety and environment influencing, as well as enhance the anti-permeability capacity.