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Soft rock engineering is involved in many important engineering fields such as mining, hydraulic engineering, transportation and national defense. With the increase of mining depth and the development of tunnel engineering, a large number of tunnels and roadways need to pass through soft rock formations, in which the problems such as high geostress and broken and weak surrounding rocks are prominent. Large deformation disasters of soft rocks pose serious threats to engineering safety and cause enormeous economic losses. In this paper, the research progress on soft rock support in China is first reviewed, and the research status quo of technology for soft rock control for large deformation hazards is summarized in the following aspects: (1) passive support methods represented by improved rigid support, retractable support and compound lining; (2) reinforced active support technology using high-strength bolts and cables; (3) soft rock modification technology using grouting; (4) soft rock reinforcement with pressure relief as the core idea; and (5) compound support methods. Furthermore, the development of different supporting technologies and methods is elaborated, and the applicable conditions, advantages and disadvantages of different supporting methods are analyzed. It is usually difficult to meet the demand of large deformation control of soft rock relying on a single support method. Therefore, it is urgent to solve the problems of the prevention and control of large deformation disaster of soft rock to realize the efficient collaborative control among different supporting measures and achieve the real-time accurate monitoring of deformation and stress fields. Finally, based on the above research results, the development tendency of support technology for soft rock with large deformation hazards is prospected and the countermeasures are proposed.

The accurate prediction of rock breaking forces of disc cutters is especially significant for the design and tunneling of TBM. Normal thrust of disc cutter plays a leading role in rock breaking through analyzing the motion of disc cutters. Calculation formulas for rock breaking forces of CCS disc cutters were derived based on the assumption of contact pressure distribution between cutter ring and rock, and the accuracy and applicability of the formulas were verified by linear cutting test data of multiple rock of different strength. Based on analysis of relative error between computed results and test data, the contact pressure distribution index was updated by means of least squares principle, and the prediction accuracy was improved. The contact pressure distribution index varies with the penetration of disc cutters according to the exponential law. Research results provide a guidance for the design and application of TBM in tunnel excavation. [ABSTRACT FROM AUTHOR]