Application Of Earthquake Refracted Wave Method In Tunnel Forecast

Based on the geological forecast on tunneling, changefully geological conditions, fragmentized rock-strip, faulting, karst, water-rich terrane, and so on, with a slight, it will cause landslides, subsidence, the sudden mud, g ushing-water, and supporting the structural deformation, resulting in harm to personnel and equipment and so on, then serious impact on the progress of the construction and engineering image. So predict the bad geological location in front of working face, surrounding rock structure and the integrity of the surrounding rock, not only that it can do a good job, a reasonable construction plan optimization provides a basis, and to maximize the prevention of Water Tunnel, landslides and other disasters incidents, for the safety and scientific construction, improve the efficiency of construction, and provide a cost savings investment protection is of great social and economic benefit.At present there are many technical methods on tunnel forecasts. The TSD technology is different from the traditional ground geophysical prospecting method. The tunnel forecast mainly to solve the problem of the existence of the belt such as adverse geological factors and the surrounding rock changes in the nature of the law and other issues in front of the working face. The TSD is a new test method which is based on the classical elastic wave theory, and it has borrowed some ideas from the vertical seismic profiling (VSP) of petroleum seismic survey and multi-wave seismic prospecting.The research of data acquisition system is the key problem of the entire tunnel forecast, it mainly aim at the special requirements of the environment of construction and the characteristics of the test data, make use of collecting apparatus and sensor, The Source Excitated is giving birth to the earthquake wave, at the same time, the data acquisition system begin collecting data. The sensor adopts three-component velocities mode so that it can be arranged inside the bare holes coupled with water, thus could greatly reduce the cost and complexity of the field operating. The parameter's setting of data collection consists of excitation modes, seismic energy, blast holes'distance, number of recording channels, sampling rate, recording length, the minimum migrating distance and spacing of the channels. Based on the parameters of the theoretical analysis, put forward basing on the different geological conditions choosing the different observation coefficients parameter.Choose different observing system parameter acquisition parameters will affect the results.This paper described the process of conducting forecast observing system parameter selection, and through the TSD in Chongqing Yuxiang Yingzuiyan highway tunnel (the tunnel rock types for dolomitic limestone) works in practical applications, further details the method in practice feasibility. Main areas are as follows:(1)Comprehensive analysis and evaluation of the tunnel ahead of the current geological prediction method, pointed out that the current method of the tunnel geological prediction of the status and development trends, the application of earthquake refracted wave method as a more efficient, high reliability prediction methods generally used in the actual project.(2)In this paper, the method used was TSD forecast system. The research of data acquisition system is the key problem of the entire tunnel Forecast. Based on the source, detector, offset, sampling rate, sampling length, and spacing, the choice of the theoretical analysis, explain that the observing system parameters should be based on actual geological conditions.(3)This paper mainly aimed at the application of earthquake refracted wave tunnel Forecast process method apply in the areas of dolomitic limestone, the selection of the observing system parameters and the effect on the practice.At present, the TSD technology already carried on the experiment in dozens of tunnels, the preliminary result showed: This system is simple to operate and its interpretation is accurate. With the further improvement and development, this technology is expected to replace the existing traditional methods and become the main method of tunnel prediction technology.