Abstract: In order to improve the manufacturing level and feasibility of homemade pipe jacking machine to composite strata, the key technologies of hard rock slurry balance pipe jacking machine for composite ground are studied by taking the sewage project at Yongning District, Nanning for example. The research content includes: (1) A compact cutterhead structure suitable for the composite ground is studied, and the combination form of cutters is optimized. (2) Based on the commonlyused rock breaking method, a kind of variable position shear secondary crushing mechanism is designed. (3) By means of eccentric overbreak of cutterhead, setting stone powder diversion channel and injecting clay into the outer side of the shield, the problem of easy jamming of shield and pipe in hard rock stratum is solved. (4) The double structure of "slurry chamber + air cushion chamber" is designed; and through the rapid and accurate measurement of mud water pressure and the modular automatic control of valves, the low disturbance driving is realized. (5) The targeted design of cutter replacement under pressured condition and atmospheric condition is carried out to realize safe cutter replacement in a narrow space. (6) The antiblocking measures for mud water circulation system are proposed by combining with the transformation of various modes of mud water circulation system and the rational arrangement of self flushing and high pressure water flushing positions. The developed hard rock slurry balance pipe jacking machine for composite ground has a good performance and strong geological adaptability in the practice.

Key words: composite ground, hard rock slurry balance pipe jacking machine, secondary crushing, settlement control, cutter replacement