Research On The Probability For The Shengmu-Weinan Coal Transfer Pipe Crossing Weihe River By Directional Drilling Technique

Directional drilling technology has been widely used and made more achievements inthe oil and gas pipelines practices, but this project is the first time used in the coal pipelinefield. It has important theoretical significance and reference value to research crossing ofcoal pipeline deeply.This study basing on the sector of Shenmu-Weinan coal conveying pipelines crossingWeihe carried on the analysis,according to field investigation,we have cleared up theengineering geological conditions of the crossing Weihe section;taking advantage ofin-doors tests and field tests, we have acquired basic physico-mechanical index、shearstrength index、compressibility index、permeability coefficient,etc,to provide the parametersfor numerical analysis;considering the basic principle and influence factors of directionaldrilling,we have established three-dimensional numerical analysis model of the directionalcrossing Weihe section and analyzed maximum principal stress and the displacementchange of formation in the directional drilling crossing condition ofcurve type and lineartype.the analysis result shows that: due to the long underground pipes of curve directionalcrossing method, the big principal stress and displacement will appear on the tunnel wall anda maximum value occurs in the middle of tunnel during crossing; oppositely, althoughmaximum displacement occurs also in the middle of the tunnel, the principal stress anddisplacement of straight directional crossing method is relatively smaller because of shortunderground pipes, and the main stress is distributed fluctuantly along the crossing direction.Thus, straight method is better from the stress analysis. But, straight method must excavate20m from ground at first before tunnel construction, it has the disadvantages of high cost,easy to damage local ecology and pollute the deep underground water. Compare with straightmethod, curve method has the advantages of small ground occupied, low cost andwell-rounded construction technology. As the result of the contrast, the curve directionalcrossing method is advised as the optimal construction technology.