Study On Prediction Method Of Tunnel Advance Horizontal Borehole Parameters Based On Multiwavelet Analysis And Evidence Reasoning

Advance horizontal drilling parameter prediction is the most direct and effective shortrange tunnel prediction method.This method uses the drilling speed,rotation speed,propulsion pressure,torque and other parameters obtained from horizontal drilling on the palm surface to infer the specific surrounding rock situation in front of the palm surface by using the correlation between the four parameters and the surrounding rock.At present,the division of lithology and structure of surrounding rock is not meticulous in the study of parameter prediction.The result has some errors with the actual surrounding rock,and it can not distinguish lithology and structure more accurately.Based on the parameters obtained in the drilling process of Xiaochuan Tunnel,the power-velocity ratio curve is deeply studied by using the methods of wavelet denoising,multi-wavelet analysis and evidence reasoning,in order to achieve a more accurate division of rock properties and structures in front of the face.The main work is as follows:(1)Wavelet denoising method is used to denoise the parameters curve with noise obtained from field drilling test,which can effectively acquire the characteristics of the curve,and the correlation of the drilling parameters after denoising is used to introduce the powervelocity ratio formula.(2)Through continuous wavelet transform and edge detection method,the powervelocity ratio curve is matched by multi-wavelet,and the lithology and some structures of surrounding rock are divided by combining the results of multi-wavelet matching with face description and drilling parameter curve.The results show that the multi-wavelet matching analysis of work-velocity ratio curve can accurately divide the lithology and some structures of surrounding rocks.(3)In view of the uncertainties and unknowns in the classification of surrounding rock structure by multi-wavelet analysis,an evidential reasoning method with the ability to express them directly is introduced.The structural classification of the uncertain surrounding rock section determined by evidential reasoning has high reliability.Compared with the results of core drilling prediction method and TSP prediction method,the results of this method are better than those of the other two methods.(4)The method in this paper is applied to an engineering example to verify the accuracy and feasibility of this method.Therefore,it can improve the accuracy of prediction results by introducing it into the prediction method of tunnel advance horizontal borehole parameters,which can better serve the tunnel construction and construction,and provide reference for future research.