Abstract:Fundamental principle, applicable geological condition, domestic and oversea development of underground gasification and its advantage compared with traditional underground coal mining are introduced. The key problems of structure of gasifier carrying out underground gasification, selection of gasification process and parameters, test on physical and chemical properties of coal and rock under high temperature, geophysical propecting measuring and monitoring and controlling, large diameter directional drilling and so on are analyzed. Countermeasures on developing underground gasification in China are presented.

Abstract:Dry shotcrete equipment has the disadvantages of high dust content, high rebound elasticity, lower working efficiency and so on. Institute of Exploration Techniques CAG researched and developed a new wet shotcrete equipment, with related spray heads, carrier pipes and other accessories, and wet shotcrete process. Performance of the equipment is at the same level as that of the same type in overseas marcket.

Abstract:Taking XY-4 geological drill as example, comparing energy consumption of drill driven by conventional asynchronous motor with that driven by AC frequency conversion motor shows that the latter's is obvious lower than the former's. This demonstrates that economizing energy effect of drill driven by AC frequency conversion power system is obvious. A new technical way for improving performance of drill and decreasing drilling cost is provided.

Abstract:The extruder is a new equipment applied to constructing multistage disk pile hole by extruding and expanding. The disk pile constructed by the extruder is a variablecross section pile. Loadcarrying capacity of singledisk pile is 6.25 times that of uniform cross section. The main technique parameters, constructing process, features and application of the pile are introduced in this paper.

Abstract:In light of the characteristics of bored piles, the processes of improving the bearing capacity of boredpiles are summarized in this paper. The results of piles' tests in situ show that piles' performance are improved by toe pressuregrouting, this paper illustrates that the toe pressure postgrouting can be used both as a routing construction method, and as a reliable remedial measure.

Abstract:In this paper, the mechanism of high pressure jet grouting has been introduced. Excess pore water pressure generated by high pressure jet grouting during construction was investigated. On the basis of cavity expansion theory, the formulae of excess pore water pressure has been proposed, and the stress and strain of soil had been analyzed. Through an engineering example, the formulae of excess pore water pressure was verified.

Abstract:Three conditions for the hole wall stabilization of large diameter bored pile-static balance, geological seepage flow and time factor are presented based on theoretical analysis and practical experience. Measures preventing and handling hole caving are given based upon analyzing various factors that influence hole wall stability including objective, technological, environmental and artificial factors.

Abstract:The utilization program of landslide mass is researched on the basis of landslide controlling engineering taking the resettlement site of Xiakou, Hubei as an example. Two rows of anti-sliding pile are distributing at the 180 m and 230 m altitude to effectively control the complete landslide, also provide the platform for highway and house construction. A lot of drilling piles with small diameter are installed depended on the house basement that provide well bear capacity, and can also resist sliding. Four platforms are constructed combined with landslide control, that solve the safety problem for developing land on the landslide mass.

Abstract:Based on the analysis of pipe ramming procedure, this paper presented the method calculating the ramming resistance force according to the results of strata pressure and dynamic probing, and the method calculating displacement, limit length of rammed pipe and max. pressure inside pipe according to wave dynamics.

Abstract:The authors consider circulation fluid in reserve circulation drilling as rigid body and establish the bottom hole flushing model based upon moment balance theory etc.. Optimal flushing conditions are presented according to the results of studying various factors affecting bottom hole flushing such as strata, structure of bit, working regulation, flow field of bottom hole, cuttinghold effect, infiltration law and so on. The results are verified in lab and on field.