| Shield machine encounters a variety of different strata of earth like silt clay, sand, soft rock, hard rock and so on when it is pushed down into the ground. In this process, cutting tools, such as radial cutters and disc cutters, are mainly used to crush and strip rock-soil. The cutters need to endure the mutation load and shock caused by cutting, and its condition of breaking rocks has direct relation to the tunneling efficiency and accuracy. The study on dynamic mechanism of the interaction between cutters and rock-soil and change rules of stress field in the process of excavating plays an important role in establishing a perfect stress forecasting model of cutters, guiding the design of cutters and improving the efficiency of entry-driving machine. Based on the background above, related to a great number of materials at home and abroad, this paper makes an in-depth study on the dynamic response characteristic of rock-soil under the effect of cutters through a combined way of simulation of particle flow code and experimental research from a mesoscopic angle of rock-soil to create a new thinking way to solve the problem rising in rock-breaking mechanism. The results of this research and primary contents are as follows:1. According to fundamental theory of rock-soil mechanics of granular materials, simulated specimen of rock mass generated from particle flow code has been used. The experiment of biaxial compression of particle flow code and Brazilian tensile strength test have been carried out to match the micro parameters of particle and the macro parameters of material.2. Based on the reasonable simplification of the actual condition, in this paper the numerical model of the interaction between the cutter and rock has been established through the method of particle flow code to statistically analyze the influences of configuration parameter, work parameter and cutting mode of cutters on cutting. What’s more, fragmentation problems under the condition of cutting in succession with cutters or cutting in optimal space with the double hobs have been discussed. Thus, the dynamic response mechanism of the rock and soil under the effect of cutters has been revealed in a microscopic view. 3. Through rotary shield cutter cutting test-bed, researches of radial cutter and a disc cutter cutting the soft rock have been made respectively. The macro destruction phenomenon of rock-soil under the effect of cutting tools has been analyzed; the cracking and forming processes of fragments of the rock have been captured. What’s more, this paper makes a reasonable explanation of the dynamic response characteristics of rocks under the effect of cutters, based on the statistical analysis of the related experimental data and the analysis of the simulation process of cutter breaking rock. |
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