Generally large cavern excavation will be selected in better geological conditions of the area. In the past of Taiwan, most of large caverns is also located at the site of better rock mass .The following large cavern was located at the right bank of Tachia River, which was into hillside about 50m. The dimensions of cavern was 49.0m in length, 19.6m in width, 18.0m in height, and the overburden shown about 70m. According to geological survey, the regional slate bedrock was develop 2~3 sets of joint. The rock quality designation (RQD) value was mostly less than 20, and existing local fracture zone. Overall, the rock mass classification of RMR Bieniawski (1976) should be IV~V in excavation area. Based on site monitoring data, the article described how to ues Barton Q-system empirical method and numerical analysis method to do feedback design. The steel fiber reinforced shotcrete, rock bolt, tendon and temporary steel support were adopted to maintain the strength around the cavern and conformate the rock arch.
斷層錯動位移對於傳統自來水管影響很大，為降低斷層錯動位移破壞重要自來水幹管而影響正常供水，自來水公司對於跨過斷層的重要自來水幹管採用管中管設計，即以潛盾隧道及軟弱填充材包裹保護著自來水鑄鐵管(DIP，Ductile Iron Pipe)，必要時於自來水鑄鐵管內設置多處柔性接頭，以吸收斷層錯動的大變位。自來水幹管的管中管斷面近似於複合材料其變位行為相當複雜。本文以大度路1200mm輸水管潛盾工程為例，探討自來水管中管斷面受到斷層錯動位移的變位行為。大度路輸水幹管係以近似正交方式跨過山腳斷層，斷層錯動位移對於自來水輸水幹管的影響係屬三維問題，本文採用ANSYS程式數值模擬探討斷層錯動位移對於大度路1200mm輸水管的影響，並藉由數值計算結果，提出如何決定柔性接頭的數目及配置以吸收斷層錯動位移。
Fault movement has a great influence on the displacement of the water pipe. To reduce the impact of fault displacement on the ordinary water supply. A pipe-in-pipe has been designed to absorb the fault displacement when the water pipe crosses a fault. The pipe-in-pipe has been composed of lining of shield tunnel, weak stuff and DIP cast iron pipe. If necessary, multiple flexible joints will be installed in the DIP cast iron pipe to absorb a large deformation caused by fault movement. The cross-section of pipe-in-pipe is similar to a composite material in which the deformation behavior is usually quite complicate. In this paper, a case study on the deformation behavior of pipe-in-pipe subjected to a fault displacement has been explored. The water pipe-in-pipe of ψ1200mm at DaDu road is in nearly orthogonal way across the SanJiao Fault so that fault displacement affecting on the water pipe is a typical three-dimensional problem in the numerical analysis. The well-known FEM software ANSYS is adopted to study the influence of the fault rupture displacement on ψ1200mm water pipe at DaDu road. From the conclusion of calculation, a suggestion of how to determine the number and configuration of the flexible joints installed at DIP(Ductile Iron Pipe) to absorb the fault rupture displacement has been proposed. It is expected that the conclusion described in this paper would be helpful for engineer in gaining the ability of the analysis so that more effective design can be developed for such problem in the future.
For uncontrollable rockfall monitoring and prevention issues, rigid techniques such as rock shed acts as the main design solution in Taiwan nowadays, to absorb the high rockfall energy from the great falling distance. However, the reinforced concrete structure results in bulk designed volume, huge labor, and material costs due to the immaturity absorption technique, which reveals that rockfall techniques in Taiwan still got room for improvement. Japan has similar geological conditions with Taiwan, and flexible rockfall techniques have developed for years. By Japanese reference review, flexible techniques could be co-operated with rigid techniques, or have them independently set. Thus, the application of flexible technique: Beads ringer net (BRN), is mentioned in this paper. Setting at the position nearby the source of falling rocks, which receives relatively less energy owing to the short falling distance. Besides, feature of wire net, wire rope, and energy absorber makes better energy absorbing capacity. Furthermore, BRN considers rockfall prevention with the concept of whole life cycle, and it possesses advantages such as short construction period, economy, long duration, simply maintenance, environmental friendly, and natural landscape integration.
BRN technique has been widely used in Japan, it could be suitably apply to most conditions due to the support of series of complete theory, standard established, numerical simulation, and full scale tests. Introducing the BRN technique by design and construction aspects, and the adaptation in Taiwan, this article is expected to be helpful in developing the new engineering techniques and new construction materials in the future.
Numerical analysis is getting popular in the design of geotechnical engineering and rock engineering due to the development of computers. The popular numerical methods include finite element method, finite difference method, boundary element method, and discrete element method. Since the discretization and elements are limited on the boundary of the domain, the problem is simplified and can be more efficiently calculated. Also, it is very suitable for the finite and semi-infinite domain problem which is popular in geotechnical engineering and rock engineering. In addition, the weak planes which is very common in rock engineering, can be treated by special boundary elements, i.e., displacement discontinuity element or crack tip element.
In this study, the most common indirect boundary element method, applying fictitious stress element and displacement discontinuity element, were applied for the analyses of 2D and 3D rock engineering problems. The typical problems, including the tunnel-slope interaction, the analysis of active fault system, the analysis of tunneling through a weak plane, and the analysis of fraction zones adjacent to the tunneling face, were adopted and analyzed. The results reveals the applicability and efficiency of the boundary element. However, new developments with new components, e.g., stochastic theory and in-time visual capability, for the complicated rock engineering problems are possible and suggested.
This paper presents the newly developed research achievements of the DDA (Discontinuous Deformation Analysis) method for engineering in jointed rock masses. The first achievement is to introduce principle of simulating the behavior of rock fracture using DDA and its applications. The second achievement is to conduct the simulation of Brazil test using the newly developed DDA program. In order to simulate the fracture behavior inside a rock masses, the fracturing function of an isolated block was initially developed and then followed by the one of sub-block as a result of the distribution inside the block composed of sub-blocks obtained. The new developed DDA, therefore, is capable of simulating the fracture propagation in rock masses. The analysis and application to the engineering problems including rock-fall, glacier movement, and slope failure using the newly developed DDA program were introduced next. Finally, the newly developed DDA program was also employed to conduct the analysis of stress and crack propagation in rock masses of Brazil test. The analytical results appear good match with the experiment measurements.
The major difference between rock engineering and soil engineering is the presence of joints in rock. Joint distribution, strength and deformation parameters dominate the engineering behavior. Considering that the geological structure and joint distribution of each site are different, and theoretical formulae are always based on ideal assumptions such as rock is homogeneous or rock layers are perfect horizontal. Design and analytical results cannot be completely imitated from case to case. Tools and methods of design and construction to simulate the practical characterization of rock engineering are needed. To combine numerical analysis with empirical concepts is worldwide adopted for investigation, design, and monitoring instrumentation at present. The paper presents what we learned from numerical simulation of rock engineering in the past decade in NTUST, and hope to obtain expert comments.
Concerning the importance of seismic behavior on underground structure due to more frequent risk of earthquake in Taiwan, soil-structure interaction is required to analyze/design for such situation. Comparing with current conventional method of forced-displacement-analysis to solve this complicated structure-soil interaction in practice, this paper intends to study seismic response of open-cut tunnel with two methods: (1). Simply quasi-static pushover analysis, which is familiar to engineers having a better understanding of structural nonlinearity, was introduced by transferring ground displacement to structure through equivalent soil spring element ; (2). Time history analysis of the finite element model by modifying numerical open source of OpenSEES. The amplification of seismic wave from rock to ground surface as well as structural response of tunnel was conducted. In addition, a simplification model was then proposed and analytical results obtained were compared with those of time history analysis. The result shows the proposed pushover analysis gives engineers not only a straightforward insight of seismic behavior for underground tunnel but also a rapid and appropriate analysis. The result obtained form this paper can benefit engineers in seismic design of practical engineering.
It has become the global trend to reduce the carbon dioxide emission in the construction industry. However, most of the geotechnical engineers in Taiwan are still not familiar with the carbon dioxide emission resulted from the process of geotechnical practice. This paper is to demonstrate the way to calculate the carbon dioxide emission from the activities and the materials used in the construction of diaphragm wall. Since most of the carbon emission is embodied in the material (mainly the concrete and steel) used in the diaphragm wall, it is crucial to keep the dimension of diaphragm wall down. The RIDO program which is commonly used by the geotechnical engineers in Taiwan is adopted to carry out the parametric study on the effect of changing diaphragm wall dimension on reducing carbon emission and wall deflection for a top-down basement construction project. Finally, diagrams are prepared for estimating the carbon dioxide emission of diaphragm wall based on the basement depth, wall dimension, and wall deflection.