The application of pipe-jacking in sand-pebble layer of Chengdu Leshan sewage control engineering is introduced,including equipment selections and construction techniques,and the reason of pipe-jacking with upward-deflection is analyzed.

By the analysis of present drilling ways,and according to the characteristics of gravel strata,application feasibility is put forward for DTH hammer concentric simultaneous casing drilling tool in gravel strata,and analysis are made on the structure principle and characteristic of drilling tool.

Through applying downhole hammer concentric simultaneous casing drilling method,the difficulties that drill in gravel strata are solved out fundamentally,the authors consider downhole hammer concentric simultaneous casing drilling is an effective way for gravel beds in combination with a case of rock-soil engineering survey in Duyun Cit