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With the application of TBM in the construction of tunnels, increasing simulations are taken on TBM tunnels. This paper first proposes the concept of utilizing Block Theory to simulate TBM tunnels in discontinuous rock masses and analyze the stability of surrounding rock blocks in TBM tunnels. Therefore, block classification for TBM tunnels is set up according to the main differences between TBM tunnels and tunnels using traditional methods, which has laid the foundation of simulating a TBM tunnel. What' more, the identification of Influenced Block and the simulation procedure of a TBM tunnel are both illustrated in flowchart. Also, a simple example of a double shield TBM tunnel excavation is implemented based on BLKLAB and the corresponding removable blocks are analyzed. Moreover, a representative excavation step is picked out to illustrate the removable blocks around the TBM, which meets the block classification for TBM tunnels.
As one type of complex discontinuous medium, rock masses in nature are split into rock blocks by finite and infinite discontinuous geological planes. Recently, the block theory  has developed rapidly as a stability analysis method of discontinuous rock masses. Applying the block theory, researchers have carried out various analyses on the stability of blocks in the excavation of slopes, caverns and tunnels, from which reliable results have been achieved as well [2-7].
Compared with traditional approaches of D&B (Drilling and Blasting) method and NATM (New Austrian Tunneling Method) in tunnel excavation, TBM method has the following advantages of fast heading rate, short construction period, favorable working environment, eco-friendliness and high comprehensive benefits, making it become the preferred choice at home and abroad. In recent years, researches on the simulation of TBM tunnels mainly focus on FEM  and FDM , while the block theory has not ever been applied in the simulation of TBM tunneling.
Copyright 2006, ARMA, American Rock Mechanics Association This paper was prepared for presentation at Golden Rocks 2006, The 41st U.S. Symposium on Rock Mechanics (USRMS): "50 Years of Rock Mechanics - Landmarks and Future Challenges.", held in Golden, Colorado, June 17-21, 2006. This paper was selected for presentation by a USRMS Program Committee following review of information contained in an abstract submitted earlier by the author(s). Contents of the paper, as presented, have not been reviewed by ARMA/USRMS and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of USRMS, ARMA, their officers, or members. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of ARMA is prohibited.
Li, J. Y. (North China University of Water Resources and Electric Power) | Xue, J. (University of Chinese Academy of Sciences) | Xiao, J. (University of Chinese Academy of Sciences) | Yuan, G. X. (North China University of Water Resources and Electric Power) | Dong, J. Y. (North China University of Water Resources and Electric Power) | Huang, Z. Q. (North China University of Water Resources and Electric Power)
ABSTRACT: The classical key block theory is mainly used for the convex blocks on the roof, floor or the walls, and is not applicable for the non-convex blocks. From the view of combinatorial theory, recent advances in block theory are discussed in this paper. Especially the intersecting ways and combination relationships between the free planes of the rock blocks are analyzed generally. Therefore, the convex blocks in the classical block theory can be extended to the non-convex blocks which include the concave intersections between the free planes. Viewing a non-convex block as a combination of several convex blocks, the identification criteria of finiteness and removability for non-convex blocks can be established through analyzing the relationships between the combined block and its sub blocks. Aiming at the redundancy in the combination algorithm of exhaustive enumeration method, a new symbolic representation of blocks can be established. Then a cutting algorithm for the residual block is designed. Finally, the optimized combination analysis for the non-convex block can be realized.
In the process of excavation for rock engineering, a frequently encountered problem is the stability of rock mass. The essence of studying the stability is to study the change mechanism and the stress distribution of rock mass after excavation. Block theory is a kind of rock mass stability analysis method based on limit equilibrium theory. But geometric analysis by the occurrence of joint planes is a major feature of it. Block theory has the advantages such as strict mathematical basis, less input parameters, fast calculation and practical results. And it has been widely applied in many large-scale projects like Three Gorges Project.
The publication of the paper “Stereographic projection method for the stability analysis of rock mass” (Shi, 1977) in Chinese by Gen-hua Shi at Scientia Sinica in 1977 marks the preliminary formation of block theory. And then a rigorous mathematical proof was made for it (Shi, 1982). In 1985, the publication of the book, “Block Theory and Its Application to Rock Engineering” (Goodman and Shi, 1985), which is written commonly by R. E. Goodman and Genhua Shi, marks the formal formation of the system of block theory. Since the block theory proposed, many scholars including Dr. Shi himself have put forward some new development, which is considered from the geometric and the physical characteristics of joint planes (Shi, 2006), mechanical behaviors of blocks combined with the modern mathematical methods. These developments can be summarized as six kinds of methods [4-7], that is, discontinuous deformation analysis (Shi, 1988), numerical manifold method, stochastic network simulation (Zhang et al., 2007), key group method, fractal geometry and stereo-analytical method, elastic-viscous-plastic method (Li et al., 2010).
The geometrical design of optimum cutting is the first task in natural stone quarries. The largest trade blocks (quboits) are the most desired, but they are limited by several geological drawbacks, including one of the most important, discontinuities in rock mass. Rock blocks in mass that formed naturally may range from very small to a few meters with different shapes and orientations. Most trade blocks are chosen and cut from intact rock that bounded discontinuities. Therefore, a discontinuity-based economical analysis should be done in many phases, especially in pre-evaluating deposits and during the cutting operations.
There are many modelling methods related to discontinuities. These methods have been used successfully as one of the main tools in many mining and civil engineering applications such as stability, blasting, and fluid flow. Nevertheless, discontinuity-based assessments and economical analyses related to them have not adequately progressed in the natural stone industry. The analyses and assessments in natural stone quarries generally are still done with human perception. Furthermore, it causes the loss of a large amount of natural resources as an inevitable result of low technology.
The general aim of this study is to compare the current and optimal conditions of productions in active dimension stone quarries as well as pre-evaluations of natural stone deposits. Therefore, we suggested a new perspective comparing the distribution curves of blocks (polyhedrals and quboits) from in in-situ deposit to the final product. This paper also made several theoretical comments about distribution curves.
All rock masses contain various discontinuities. An adequate knowledge of the discontinuity geometries within any rock mass is essential for the optimal design of rock engineering works that are to be done inside. Quarrying dimension stones is one of technical areas where accurate insight into the presence of discontinuities is necessary to establish planning strategies for rock block exploitation. In addition, excessive amounts of waste and broken rock should be avoided as much as possible. Therefore, it is very important to understand the role of in-situ rock mass geometry in terms of block sizes in the application of natural stone productions. Generally with rock masses in a quarry, discontinuities will be formed in different sizes and dimensions due to different forces acting on the earth’s crust. As a result of discontinuities with free surfaces, natural rock blocks may form from a very small size to a few meters with several shapes and orientations.