Abstract:The root pile is unique in foundation reinforcement and deviation correction for the existing building and will result in obvious effect. The design principle,construction processand bearing capacity of the root pile are described with analysis of the field cases.

Abstract:To construct the compound pile diaphram using bored piles and jet -grouted piles,and related techniques is an important approach to reinforce the pit wall and protect the building. The structural design,construction techniques and quality control of the bored/jet-grouted compound pile diaphram are described in regard to the field cases.

Abstract:In curtain grouting in thick overburden, good grouting results can be achieved with leak age prevention and bearing cap acity of the over burden improved through use of high grouting pressure and groutwith excellent rheology,and control of the grouting process.

Abstract:Based on the study on the electric conducting mechanism and electric properties of foam, the quantitative model for the on-line testing of the gas/liquid ratio of foam has been established; hence, an on-line gas/liquid ratio tester which is suitable for use in the field been designed and developed. The technical performance and wide adaptability of the tester is analyzed.

Abstract:The comprehensive formula for the optimizd design of the planetary gear train of the hoist on drill rig is described. The optimum gear tooth matching can be easily carried out for each part of the planetary gear train by means of this method.

Abstract:Based on analysis of the rock bit bearing wear mechanism,it is proposed that an effective approch to increasing the service life of the bearing be to improve the frictional surface of it. With analysis of the mechanics and frictional properties, it is verified that tungsten carbide can be used as the frictional surface of the rock bit slide bearing,with the solution to the brittleness of the tungsten carbide put forward.

Abstract:Based on the analysis of "bit walk" in drilling, a concept of using weak diamond -holding matrix to get rid of "bit walk" is introduced. This paper describes the basic principle and use of the bit with weak holding and high wear resistant matrix.

Abstract:根据TOPSIS法原理，提出一种同时考虑“理想方案”和“负理想方案”的金刚石钻头综合评价灰色关联分析法。结合φ60mm绳索取心金刚石钻头评价，说明了该方法的具体应用，并与用其它方法评价的的结果进行了对比。

Abstract:Through study on the fluid velocity at the hole bottom in large diameter reverse circulation rotary drilling with flat-bottom bits, the law that the tangential, radial and resultant velocities, and bit rotary speed and flowrate control the fluid velocity at the hole bottom are found out in the modelling condition.

Abstract:The paper describes the rock breaking test of the PDC bit in mudstone under different downhole pressure conditions(from 0 to 5000m). The results indicate that the.cutting force needed for breaking the rock increases with depth (confining pressure); meanwhile, the cutting efficiency is influenced to some degree by the cutter shape of the bit and the bit configuration. Therefor, the cutter shape and the bit configuration should be designed according to the well depth and the rock characteristics so as to increase the penetration rate.

Abstract:Some technical measures to increase the tunnelling efficiency are described with new ideas presented in conjunction with the particular cases.