Tracing Design Method of Pectinate Directional Borehole of Tunnels in Underground Mine

In order to drain gas fast and effectively from surrounding rock mass of successive tunnel in the soft seam, combining the performance of the directional kilometer drilling machine, the long pectinate directional borehole with "horizontal" or "vertical" layout form was presented to pre-pump gas from surrounding rock mass of successive tunnel in a long distance. The design principles of borehole trajectory were summarized according to characteristics of coal tunneling face and the design flow of long pectinate directional borehole. And drawing on the theory of directional well design and calculation, the three-segment incline planar method was proposed to design the long pectinate direction borehole, which defined the relationship among point, line, and plane of spatial position of drilling trajectory, simplified and optimized design parameters of drilling trajectory, and reduced the risk of drilling construction. Finally taking a successive tunnel of Yuwu Coal Mine as an example, the design method of the incline planar was introduced in detail. The analysis showed that the design method of three-segment incline planar of the long pectinate directional borehole meets the engineering accuracy, reduces the workload of design and improves the working efficiency.