Abstract
At present, disc cutters of a full face rock tunnel boring machine are mostly mounted in the traditional way. Practical use in engineering projects reveals that this installation method not only heavily affects the operation life of disc cutters, but also increases the energy consumption of a full face rock tunnel boring machine. To straighten out this issue, therefore, a rock-breaking model is developed for disc cutters’ movement after the research on the rock breaking of forward-slanting disc cutters. Equations of its displacement are established based on the analysis of velocity vector of a disc cutter’s rock-breaking point. The functional relations then are brought forward between the displacement parameters of a rock-breaking point and its coordinate through the analysis of micro displacement of a rock-breaking point. Thus, the geometric equations of rock deformation are derived for the forward-slanting installation of disc cutters. With a linear relationship remaining between the acting force and its deformation either before or after the leap breaking, the constitutive relation of rock deformation can be expressed in the form of generalized Hooke law, hence the comparative analysis of the variation in the resistance of rock to the disc cutters mounted in the forward-slanting way with that in the traditional way. It is discovered that with the same penetration, strain of the rock in contact with forward-slanting disc cutters is apparently on the decline, in other words, the resistance of rock to disc cutters is reduced. Thus wear of disc cutters resulted from friction is lowered and energy consumption is correspondingly decreased. It will be useful for the development of installation and design theory of disc cutters, and significant for the breakthrough in the design of full face rock tunnel boring machine.
Highlights
Tunnel boring machines (TBMs) are currently utilized on a large scale in mining and civil engineering projects
When the wedge edge of disc cutter is pressed into rock surface by large thrust exerted, a small crushed area comes into being under the disc cutters, which is further compacted [1]
The main research on mechanism of rock indentation and cutting started in the 1970s, among which are those mentioned as follows: Teale [2] observed that penetration is the essential rock cutting parameter
Summary
Tunnel boring machines (TBMs) are currently utilized on a large scale in mining and civil engineering projects. Moon and Oh [19] used discrete element method analysis to simulate a multi-indentation to study the optimal rock-cutting phenomena in terms of the interaction of the spacing to penetration ratio with intact rock properties. These achievements were all based on the research with disc cutters traditionally installed, while after the long-term research we discovered the mechanics law of interaction between disc cutters installed slantingly outward and rocks [20,21], and hereafter we found that the disc cutter installed slantingly can generate a better mechanical effect [22,23]. This is a new attempt to probe the mechanical features of the interaction between disc cutters and rocks
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