Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
Simulation of Time-dependent Deformation of Rockmass Around Mine Tunnel By Means of Non-linear Visco-elastic Model
Ogata, Yoshihiro (National Institute for Resources and Environment, Tsukuba) | Yamaguchi, Tsutomu (ational Institute for Resources and Environment, Tsukuba) | Kuriyagawa, Michio (National Institute for Resources and Environment, Tsukuba) | Murayama, Hideyuki (Fujita Corporation Technical Institute, Yokohama) | Okubo, Seisuke (The University of Tokyo) | Nishimatsu, Yuichi (The University of Tokyo)
ABSTRACT: Deformation around a newly excavated test drift in weak rock was continuously measured to clarify the time-dependent behavior of the rockmass in a mine. A two-dimensional Finite Element Method, of which element have non-linear visco-elastic characteristics based on the Maxwell's model, was proposed to simulate the observed time-dependent phenomena in the test drift. There was a good agreement between measured and calculated deformation. The proposed F.E.M. analysis needs only limited number of rock properties as input parameters and the simulation time is short enough for practical use. The analysis proved to be effective in predicting the time-dependent behavior of the rockmass as long as the rockmass behaves as continuum media. RESUME: Pour clarifier Ie comportement dans Ie temps de la masse rocheuse dans Ie cas d' une mine, nous avons mesure en continu la deformation d' une roche molle apres Ie percement recent en son sein d' une galerie test. Nous avóns fait appel à une methode aux elements finis à deux dimensions, avec des elements aux caracteristiques derivees du modèle de Maxwell, pour simuler I' evolution dans Ie temps de la galerie test. Nous avons observe un bon accord entre la deformation mesuree et la deformation calculee. L' analyse par M.E.F. proposee ne necessite qu' un nombre limite de proprietes de la roche etudióe comme paramêtres d' entree. De plus Ie temps de calcul est suffisement court pour que ce modèle soit d' un usage pratique. Notre analyse s' est averee efficace à prevoir I' evolution dans Ie temps d' une masse rocheuse, à la condition que cette masse rocheuse se comporte comme un milieu continuo ZUSAMMENFASSUNG: Die Gesteinsdeformation in der Umgebung eines Teststollens wurde seit dessen Fertigstellung kontinuierlich gemessen, um des zeitliche Verhalten des anstehenden Gesteins zu bestimmen. Fuer die Simulation der beobachteten zeit-abhangigen Phanomene wurde eine zwei-dimensionale Finite-Element-Methode vorgestellt, die auf dem Maxwell' schen Model baslert und eine nicht- Iineare visko-elastische Charakteristik besitzt. Es wurde eine gute Üboreinstimmung zwischen den beobachteten und den numerischen Ergebnissen erzielt. Die hier vorgestlte FE-Model benötigt nur eine geringe Anzahl von Gesteinskenngröβen a1s Eingabeparameter, und die Rechenzeit ist hinreichend kloin, um die Methode praktisch anwenden zu können. Das Verfahren hat sich a1s effektives Mittel zur Vorhersage des zeltabhangigen Gesteinsverhaltens erwiesen, solange sich das Material wie ein Kontinuum verhalt. 1 INTRODUCTION: Recently, tunnels and underground openings are tending to be constructed in weak rock. As the weak rock deforms with time, it is important to take account of time-dependent behavior in the analysis. In a study of time-dependent behavior of rock, many experiments had been performed to clarify the creep behavior, and to construct physical models (Gioda 1981, Sulem 1987 etc.). In some of these studies, time-dependent deformation were measured in tunnels under construction and analyzed. Most cases in these studies, the walls of tunnels were constrained by relatively high rigidity supports and deformation were restricted. The authors measured and analyzed the time-dependent deformation of rockmass which was induced by advancing drift in a mine(Ogata 1993ab, 1994). As the tunnel walls had almost no support, confining effect of the supports could be neglected in the analysis. A method was also developed to analyze the observed phenomena by non-linear visco-elastic F.E.M. model. In this paper, the results of the measurement and the outline of the F.E.M. analysis are presented. 2 IN-SITU MEASUREMENT IN MINE TUNNEL 2.1 Geological profile The geological profile of the test site located in a mine is shown in Figure 1. The investigated test drift locates 300-m below the surface. The drift was excavated in a weak rockmass consists of gypsum, tuff and tuff breccia which had exhibited swelling characteristics with water.
Development And Practical Application of the Static Rock-mass Fracturing Method Using Hydraulic Pressure
Noma, Tatsuya (Fujita Corporation Technical Institute, Yokohama) | Hada, Mitsutaka (Fujita Corporation Technical Institute, Yokohama) | Kadota, Shunichi (Fujita Corporation Technical Institute, Yokohama) | Murayama, Hideyuki (Fujita Corporation Technical Institute, Yokohama) | Ueda, Shigeo (Bridgestone Corporation, Yokohama Industry)
ABSTRACT: A new static fracturing method is developed using a rubber-tube-type fracturing machine using hydraulic pressure. In this paper, an outline of this method, the fracturing machine and its system, and two practical applications, boulder fracturing and tunnel excavation at lower-half section, are described. RESUME: Une machine de fracturation à tube caoutchouc par pression hydraulique fonctionne selon une nouvelle methode de fracturation statique. L'article suivant donne un apercu de cette methode, decrit la machine de fracturation et le systeme qu'elle utilise, ainsi que deux applications pratiques, fracturation de bloc erratique et creusement de tunnel dans la moitie inferieure. ZUSAMMENFASSUNG: Eine neue statische Bruchmethode wurde entwickelte, bei der eine Maschine verwendet wird, die mit Gummischlauchen und hydraulischem Druck arbeitet. In dieser Studie wird diese Methode, die verwendete Maschine, und das Bruchsystem beschrieben, und es werden zwei praktische Anwendungen beschrieben, namlich Brechen von Felsbrocken und Tunnelausgrabung in der unten Röhrenhalfte. 1. Introduction It is well known that blasting is the most effective and least costly method of fracturing and excavating rock mass. However, this method involves tremendous shock waves and noise, and is not suitable for construction (such as building tunnels and excavating slopes) near residential areas, where a great deal of construction is now under way. To cope with these recent trends, methods of excavating through masses of rock static fracturing without blasting have been developed. For mechanically boring through solid rock, partial face machines (hereinafter called road headers), tunnel boring machines (TBMs) and rock breakers are often used. However, these methods have their drawbacks. Road headers and TBMs are both large in size, and are only economical when fairly large masses of rock require cutting. Furthermore, they can only be used with rock bed of limited strength. Use of a breaker alone is less efficient than other methods, and it produces vibration and noise, although not to the same degree as blasting. To deal with these problems, many static (non-blasting) fracturing methods such as the expansive agent method, hydraulic wedge method, and pressurizing method using gas or water have been developed (NAKAGAWA, 1987). However, all of these methods meet with problems of safety and require fracturing machines of too large a scale. In this paper, static fracturing is defined as producing cracks in the rock bed to reduce its strength (primary fracturing) and then completely fracturing it with a breaker or ripper (secondary fracturing) (HAGIMORI, 1990). The authors have been investigating hydraulic-based fracturing methods using high-pressure rubber tubes as a means of primarily fracturing rock bed with ease and efficiency (NOMA et al., 1991). This paper summarizes the method we developed, and discusses some engineering field applications. 2. Fracturing Machine and System We sought to develop a fracturing system that could break down masses of rock quietly, easily, efficiently, safely and economically. In this paper, we give an outline of a rubbertube- type fracturing machine (hereinafter called the fracturing machine) and its system. 2.1 Rubber-tube-type Fracturing Machine Figure 1 illustrates the concept of the rubber-tube-type fracturing machine. The fracturing machine consists of a high-pressure rubber tube, a rubber protector, and a steel loading plate. Rubber is the principal material of the fracturing machine because it is lightweight (5.0 kg), yet has high crushing force (maximum working pressure: 70 MPa). Due to the device's configuration, it can be used repeatedly and the direction of cracking can be controlled.