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

Abatract The paper firstly introduces the designing principle of a new-type alloy-diamond bit for the gravel stratum, secondlyexplains briefly the mechanism of matrix composition for the new-type bit.

Drilling in gravel stratum is one of present difficulties in drilling area with low drilling speed,short service life of bit and high drilling cost.

For the construction of the running tunnels of Chengdu Metro in sandy cobble ground,the shield machine is required to have the capability of performing long-distance boring in sandy cobble ground,crushing the large boulders and cobbles and prevention and control of mud bursting.

The first stage project of line 1 of Chengdu Metro mostly passes through water-rich sandy cobble ground,which contains a small amount of large boulders.