Study On The Advanced Forecast And Supporting Techniques For Veritical Karst Cave Filled With Mud In Tunnel Engineering

With the rapid development of China’s economic strength, infrastructure constructions gradually pushed from the Midwest to the mountainous Southwest region. More and more tunnels have been built in the Karst region. However, during the tunnel excavation in karst areas, geological hazards problems such as collapse, gushing water, and sudden infow of mud have happened, which threatened the safety of construction workers and hindered construction process of the tunnel. In the construction process of a railway tunnel, a large number of vertical mud type caves appeared, resulting in geological hazard problems such as a tunnel vault collapse, tunnelfacesudden mud. Therefore, efficient and accurate methods for early identification of advanced prediction of adverse geological body is an important guarantee for the construction safety.In this paper, based on the large railway tunnel as the research object, after on the basic principle of geological radar and working method were studied, then the combination of the practical application of advanced prediction technology, usingfinite difference time method, vertical mud type caves with different moisture contents conduct forward modeling research. In the combination of the FLAC3 D numerical simulation technology, three supporting measurements have been taken to simulate thevertical mud type caves with different moisture contentsfor three supporting effects. The main findings were as follows:(1) Vertical Mud karst karst adverse geological site sampling, measurement of different karst adverse change in dielectric constant moisture geological body to make its water content and dielectric constant of the diagram. For the forward modeling each moisture content in case of bad karst geological it helped.(2) the use of radar forward software for different moisture content karst Mud forward modeling study, summed waveform difference between them. In the tunnel construction site, under the radar waveforms can roughly determine the moisture content of the mud filled karst.(3) by the respective moisture karst Mud direct shear tests, measuring its mechanical parameters. The results of numerical simulation FLAC3 D parameter selection has helped.(4) use FLAC3 D comparative analysis of surrounding rock excavation Mud type vertical cave by different response when the moisture content of a tunnel in three Support Measures(advanced small pipe, pipe roof, ahead of a small catheter tube + studio) features. Supporting effect compared found ahead of a small catheter tube + separate shed more than Forepoling greater than lead small pipe support.(5) found that when the karst Mud moisture content less than 36% at three support measures for tunnel displacement are small. When karst Mud moisture content less than 45%, use Forepoling can make the maximum amount of displacement of less than 10 cm. When karst Mud moisture content of 51%, and only by a small joint branch conduit pipe roof guard shall be effective to control the deformation of the tunnel.The maximum displacement magnitude of 10 cm ~ 12 cm.(6) binding assay results and geological radar FLAC3 D forward to karst Mud water content of the foundation. It summed up a new type of vertical Mud cave forecasting techniques, and to provide appropriate support measures to have geological conditions are forecast.