ABSTRACT:

One of characteristics of city construction recent years is the increase of construction near the existing building, and the construction condition is becoming more and more complex and abnormal trend. Based on finite element numerical simulation software, Midas GTS, and the practical engineering, this paper studied the influence of different approach distance excavation to bridge pier, and the deformation characteristic of foundation pit supporting. Studies show that an adjacent bridge will have a significant impact on subsidence characteristics and mechanical behavior of the foundation pit wall; with the increasing of excavation depth, the settlement of bridge pier would increase; with approach distance decreasing, the settlement of bridge pier showed a trend of decrease after the first increase; for adjacent excavation, the effect to bridge pier can be ignored when the adjacent distance is greater than 2 times the base width, when the adjacent distance is less than I times the base width, the piers probably have transfinite subsidence and tilt phenomenon.

1 INTRODUCTION

With the Urbanization developing, the land using of Urban Construction is getting intensive in China. New building constructed close to existing buildings is becoming more and more common. Such construction is known as "adjacent construction". For Core region in big cities, the adjacent construction has been normalized. Many foundation pit engineering is very close to the existing urban public facilities. For bridge, the structure which extremely sensitive to environmental influences, adjacent construction would cause bridge pier generating transfinite settlement and tilt easily. In addition, adjacent construction would increases the displacement of foundation pit retaining wall and even cause the foundation pit accident. In recent years, adjacent construction accidents emerge in endlessly: In Hangzhou, a foundation pit supporting broken near intersection of Wenyi west road and Huajiang road cause surrounding building tilt, as is shown in Figure 1; In Wuhan, Hubei province, a foundation pit excavated over 10 m depth cause an abnormal subsidence of Huyue bridge piers, the maximum reached 16.98 mm; In Lanzhou, the subway tunnel crossing Hua Linping bridge cause the bridge foundation sinked.

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