KEY TECHNOLOGY FOR CONSTRUCTION OF BRIDGES AND TUNNELS OF YICHANG-WANZHOU RAILWAY

The Yichang-Wanzhou Railway (simplified as the railway) runs in the northeast of the Yunnan-Guizhou Plateau and twice crosses the Yangtze River. The area where the railway travels is full of high mountain peaks and deep valleys, being extremely steep and dangerous. The topography is featured by strongly developed karst. The ground surface Karst is of multiple types and different shapes. The underground Karst caves can be seen everywhere. Underground rivers are grand and intensely distributed. The area is one of the most developed and typical Karst areas of China. The Engineering construction conditions are so hard, difficult and dangerous that they are rarely seen in railway histories of our country and even the world. The railway covers 159 bridges and 159 tunnels. In this paper, 3 representative special structure bridges were introduced. The Yichang Yangtze River Bridge was built of the 130 m + 2 x 275 m + 130 m continuous rigid-frame flexible-arch structure, adopting five items of new technology. The Yesanhe Bridge was built of the asymmetric parallel double rib composite tubular steel concrete truss arch structure with the 124 m long span main arch, adopting 3 items of new technology. The Luobuxi Bridge was built of the double track concrete arch structure with stiff skeleton and 178 m long main span, adopting 3 items of new technology. Referring to Karst tunnel treatment, applicable conditions and technical measures were studied for application of the technology of grouting, cavity protection and reinforcement, passing over of tunnel bottom, karst water drainage and detouring of a cavity. The technology of information grouting and energy release pressure reduction was mainly introduced.