Abstract:  To clearly identify the fullsection geological information of the tunnel with long distance and large burial depth before construction, the TKSQ215 largediameter horizontal borehole coring is developed based on the vertical drilling and coring technology and the characteristics of horizontal coring. Special coring technology is implemented, which successfully implement 1 900m longdistance horizontal drilling and coring operation, 2.31m coring advance, 2.2 m coring samples, and 95% coring rate. The results show that a horizontal drilling hole along the tunnel direction arranged can collect the fullface tunnel geological information when using longdistance horizontal coring technology, which does not use vertical and multiple shaft construction, thus it is simple and efficient.

Key words: tunnel engineering, geological investigation; horizontal directional drilling, coring tools, diamond bit