Abstract: Crossing by Horizontal Directional Drilling (HDD), characterized by short construction period, high quality and little impact on environment, is widely used in pipeline crossing engineering. Deviation between the practical and theoretical exit point, where the bit unthreads, is difficult to control. Excessive deviation could not only cause unconformity of requirement, but also expand the correction and make re-drilling more difficult. In sum, accurate controlling of the drilling direction is the key to the success of the crossing. Fortunately, ...
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