Abstract
Cutterhead loads are the key mechanical parameters for the strength design of the full face hard rock tunnel boring machine (TBM). Due to the brittle rock-breaking mechanism, the excavation loads acting on cutters fluctuate strongly and show some randomness. The conventional method that using combinations of some special static loads to perform the strength design of TBM cutterhead may lead to strength failure during working practice. In this paper, a three-dimensional finite element model for coupled Cutterhead–Rock is developed to determine the cutterhead loads. Then the distribution characteristics and the influence factors of cutterhead loads are analyzed based on the numerical results. It is found that, as time changes, the normal and tangential forces acting on cutters and the total torque acting on the cutterhead approximately distribute log normally, while the total thrusts acting on the cutterhead approximately show a normal distribution. Furthermore, the statistical average values of cutterhead loads are proportional to the uniaxial compressive strength (UCS) of cutting rocks. The values also change with the penetration and the diameter of cutterhead following a power function. Based on these findings, we propose a three-parameter model for the mean of cutterhead loads and a method of generating the random cutter forces. Then the strength properties of a typical cutterhead are analyzed in detail using loads generated by the new method. The optimized cutterhead has been successfully applied in engineering. The method in this paper may provide a useful reference for the strength design of TBM cutterhead.
Highlights
tunnel boring machine (TBM) is widely used in the construction of various types of hard rock tunnels
1 Introduction TBM is widely used in the construction of various types of hard rock tunnels
The brittle rock-breaking mechanism and the inappropriate operating parameters may result in severe vibration of cutterheads of TBM, which would lead to serious strength failure
Summary
TBM is widely used in the construction of various types of hard rock tunnels. The working performance of cutterhead, which is the key tunneling component of TBM, directly affects the efficiency and safety of construction [1, 2]. With a full-scale rotary cutting machine (RCM), Geng et al [10] investigated the cutting forces of TBM gage cutters and found that the cutting forces of the gage cutter were lower than those of the normal cutter Upon this finding, a design scheme of multi-stage cutterhead was proposed [11]. Due to the neglecting of the great differences of cutting forces on different cutters, these models could only provide a relatively rough estimation of the average loads In addition to these simplified calculation model, the available engineering data were employed for studying the cutterhead loads. A new method is developed to analyze the strength for TBM cutterhead
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