Engineering Geological Research About Double-track Bridge On The Nanpan River Of Qiubei Of The New-built Yungui Railway

With the increase of the amount of railways built in the mountains, and with the experience of constructing being gathered, technology being matured, constructing railways over200km/h in the mountains has already been imperative. Various engineering problems have been widely developed in those areas, based on the experience of constructing railways in the southwest of China, such as landslide, rock falls, debris flows, karst landform and land subsidence, worked out section, harmful gas, high stressed areas and problems soils-red clay, rock salt, expansive soil (rock) and soft soil are also very common. Each of them would endanger the security of the railways, thus bring much inconvenience to the construction of the railways. So it is very necessary to delve into the geological engineering conditions for the construction of grand bridge for railways in the canyon field, especially with the development of faults.This paper takes the Engineering Geological conditions of Double-track Bridge on the Nanpan River of Qiubei for research object and makes an appraisement on the engineering geological conditions of the bridge through field investigation, collecting and verified the engineering geological data, analyzing the result in situ test and construction status, and makes an analysis about the major engineering geological problems encountered during the investigation and construction of the bridge which can fall into four part:(1) Depending on t field investigation and laboratory test results, this thesis pointed out the geological engineering problems likely to be encountered during the designing and construction, and come up with corresponding control measures.(2) This thesis analyses the geological engineering features in schemes of different bridge sites, and demonstrates the rationality of the current schemes of bridge location.(3) The stability of the bank slope, which can influence that of the bridge, has been studied by stereographic projection and finite element numerical analog analysis technique, and a series of problems about testthe design and construction which should be paid attention has been pointed out.(4) Based on the analyze of result of Plate Load test, this thesis points out that the5#pier’s natural foundation suffers an inadequacy of bearing capacity because of the influence of faults.Through the research and analysis about these problems above, profound understanding on the engineering geological conditions about the Double-track Bridge on the Nanpan River of Qiubei is expected, providing instruction for design and construction.