Failure Characters and Origin of Zhangjiaping Bridge in Wanzhou — Liangping Expressway

Abstract

Zhangjiaping bridge is located in the front of the large ancient landslide, in the section K34+600∼K35+000 of Wanzhou-Liangping expressway. It has been controlled with anti-slide pile and gridiron with prestressed anchor cable. The the first and the second pier column of the first bridge has been cracked. The orificeplate for resistance to earthquakes has been cracked too, after torrential rain for a few days in June 2007, affecting the structure's normal use. A study was made of the failure reason by hydrogeology survey; engineering geology survey; environment geology survey and numerical simulation. The following results were obtained: Zhangjiaping slope is stable as a whole but with local deformation. Root cause of the bridge crack is the down-slide stress arising from slip mass thrust in the middle part of the pier column of the bridge. Terrain between the two rows of anti-slide piles is steep and the distance between the two rows of anti-slide piles is large. The covering layer is made up of noncompact solum and the long-lasting rainstorm after long-lasting drought is the main factor causing the slide. It is a key problem to prevent the deformation of the slide.