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

Zhangjiaping bridge locate in the front of the large ancient landside, in the section K34+600∼K35+000 of Wanzhou-Liangping expressway. It has been controlled with anti-side pile and gridiron with prestressed anchor cable. The the first and the second pier column of the first bridge has been cracked, 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. Make a study of failure reason by hydrogeology survey; engineering geology survey; environment geology survey and numerical simulation. Results were obtained: Zhangjiaping slope is stable as a whole but local deformation; Root cause of bridge crack is the down-slide stress arise from slip mass thrust the middle part of the pier column of bridge. Terrain between the two rows of anti-slide piles is steep, distance between the two rows of anti-slide is large, covering layer is made up of incompact solum and the long-playing rainstorm after long-playing drought is the main factor to cause the slide. It is a key problem to prevent the deformation of the slide.