| Nowadays China has already developed into a country which has the greatest number and largest scale of tunnels, as well as, the fastest growing pace, in the meanwhile, its complicated geological condition and frequent geological disasters have become a great challenge for underground construction period as well. Water inrush brings enormous loss to economy, vital injury to personnel, adverse impact to the society, and irreparable damage to surface and tunnel zone water source and the environment. Advanced forecast theory and technology of water inrush and mud burst disaster source (geological water-bearing structure) have become the key urgent scientific problems, which need to be solved for tunnel construction. To solve the above problems, Advanced forecast theory and technology of water inrush and mud burst disaster source (geological water-bearing structure) have become a key scientific problem which urgently needs to be resolved. To solve the problems above, new multi-isotropic source array and hole-array induced polarization advanced forecast method, which with the core content of relevant theory and method of3D imaging and water forecast for water-bearing structure, has been proposed. Constrained joint inversion ideology has been involved in the theory, which combines with comprehensive advanced forecast method based on constrained joint inversion. Multi-isotropic source array induced polarization advanced forecast comprehensive quantitative recognition method has formed which is for water-bearing structure during construction, and has been applied in physical model test and field engineering. A range of innovative research results have been achieved:(1) According to the problem that traditional induced polarization forecast method may seriously interference the flank and is not available for TBM tunnel construction, new multi-isotropic source array induced polarization advanced forecast method is put forward. Multi-isotropic source mechanism that shielding interference behind and focusing on the front of the tunnel face is revealed. And hole-array induced polarization is also investigated. The response characteristics of typical geological water-bearing structure has been developed, and optimum way of array electrode observation has been revealed. Anti interference and advanced forecast ability are increases, which is suitable for drilling and blasting method and TBM method tunnel.(2) To solve the problem that the linear inversion method is sensitive to initial model and low search efficiency of non-linear method, the least squares inversion method has been put forward based on observational data weighted function and model depth weighted function. At the same time, introducing resistivity smooth constraint and track smooth constraint to the ant colony inversion has improved the latter’s search efficiency, established the method which combines linear and non-linear method, the tough problem that poor depth resolution for narrow tunnel face forecast space inversion, hence, has been worked out.3D inversion imaging of water-bearing structure in tunnel has been realized.(3) To solve the inherent geophysical detection problem of multiplicity of solution, spatial structure constrained inversion method has been suggested, by using the ideology of taking known information as priori constraint. Studying constrained joint inversion model construct method with known priori information, spatial shape and structure constraint inversion method are put forward. By using the deterministic result generated from seismic wave method, electromagnetic method and geological analysis method as known priori constraint information, and adding its result into induced polarization constrained inversion equation, the tunnel comprehensive advanced forecast method on the carrier of induced polarization constrained joint inversion is established. Multiple water-bearing structure boundary identification and3D shape characterization be realized. It provides a practical method to simplify multiple geophysical data information fusion and joint inversion.(4) Induced polarization instrument-GEI comprehensive electric instrument has been successfully developed. Multi-channel high constant current technology and multi-channel synchronous acquisition technology have been realized. Therefore, six-channel high constant current output and eight-channel synchronous data acquisition are realized. Multiple geophysical fields’ similar material is developed. Large-scale comprehensive advanced forecast test device, compatible with a variety of geophysical detection methods, has been developed. Dimensions is17m (length)×8.4m (width)×6.7m (height). This platform can simulate caves, underground rivers and faults etc. multiple geological water-bearing structure detection, and multiple geophysical detection requests can be satisfied, like seismic method, electromagnetic method and electric method.(5) To solve the tough problem of water-bearing structure quantitative detection of water, induced polarization electric field, concentration field, ion flow field coupling equation is established based on the electrochemical and mass transfer kinetics theories. Migration law of ion concentration in pore model is studied, it is revealed that microscopic mechanism of induced polarization water detection based on half-life time difference of the two current. Through carrying out typical water-bearing structure advanced detection physical model test, the relationship between induced polarization attenuation characteristics and water volume of water-bearing structure is revealed. The model and method of water-bearing structure quantitative forecast of water are established based on induced polarization method.(6) Comprehensive induced polarization3D inversion imaging method and water forecast method,3D position and water forecast tunnel technology system is established. Research achievements have been used in Yiba highway Majiapo tunnel, Shimenya tunnel engineering prediction. The feasibility and applicability of the identification method and technology, which is comprehensive advanced forecast for water-bearing structure in tunnel based on induced polarization method, is validated. |
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