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Collaborating Authors
11th ISRM Congress
Influence of Chemical Attack On Physical And Mechanical Properties of Some Dimension Stones From Brazil
Bastos, Messias De Paiva (Departamento de Engenharia Civil, Universidade Federal de Vicosa) | Marques, Eduardo Gomes (Departamento de Engenharia Civil, Universidade Federal de Vicosa ) | Moreira Sossai, Fabiano Jeronimo (Departamento de Engenharia Civil, Universidade Federal de Vicosa)
ABSTRACT This work presents part of the results of a comprehensive technological test campaign of 21 rock types from Espรrito Santo state, Brazil, used as dimension stones. From this initial group, 12 rock types were selected to be submitted to chemical attack throughout cycling with four different reagents: hydrochloric acid (HCl โ 18% V/V), diluted detergent (20% V/V) and distilled water. Mechanical and physical properties were determinated both previously and after chemical attack for all rock types, in order to evaluate long time behavior and influence of chemical weathering. Results show that all rocks tested presented sensitive visual changes such as stain spots, bleeding, clouding and mineral oxidation. Some of the rocks were completely weathered by chemical attacks. Unexpectedly, despite of those severe changes over visual aspects of rock samples, the influence of chemical attack over its physical properties was not clear for some of the studied properties. Although, it can be noted an average reduction of specific weight and an average increase for porosity and saturated water content. Point load strength results show a strength reduction of 25% for HCl, 24% for detergent, 27% for KOH and 13% for distillated water, characterization chemical weathering influence on mechanical properties of those rocks. 1 INTRODUCTION In general, a rock is selected to be used as dimension stones because of its beautifulness, which is given by minerals colors and rock texture. Yet, it is the specific properties of each mineral which determinates rock hardness, durability, color and structure which will more adequate use of such rock as a dimension stone (Aires-Barros, 2001). In recent years, mainly because of its high durability quality, rocks turn back to be used as an important facing material with great architectural effects (Frazรฃo & Farjallat, 1995 and 1996). It is important to a good physical, chemical and mechanical characterization of rocks used as dimension stones, as they are subjected to several different stress and strength loadings as well as climate agents such as sun, acid rain, temperature variations and wind. 2 OBJECTIVES The main purpose of this paper is to present the results obtained by Sossai (2006) and Bastos (2006) on the study of the influence of rock weathering on physical and mechanical properties for some of the most common dimension stones from Espรrito Santo State, Brazil. The effect of weathering was simulated throughout cycling tests using three different substances: distilledwater, detergent, chloride acid and potassium hydroxide. 3 MATERIALS AND METHODS Twelve rock types were submitted to chemical attack for the substances and concentrations presented on Table 1. Tests procedures followed Brazilian standards (ABNT 1992a, 1992b, 1992c and 1997) for water-oven cycling, physical properties determination, uniaxial compression strength, and chemical attack, respectively. Ten samples for each rock type and for each chemical substance were tested. Average values were calculated discarding both two highest and lowest values for each test.
- Geology > Rock Type (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.68)
ABSTRACT The paper deals with the interpretation of laboratory drying tests on a partially saturated argillite for the determination of its permeability, by an inverse method. The drying test consists in measuring the transient weight loss of a partially saturated sample when submitted to a decrease of relative humidity, imposed by saline solution in a hermetic chamber. The kinetic of variations of weight and deformation is linked to the permeability. Both hydromechanical coupling and presence of gas result in a highly non linear coupled diffusion process in the partially saturated media. The non linear problem is solved with a finite element method, considering 2D finite element calculations under the hypothesis of axisymmetry, allowing to account for the 3D effects due to the geometry and dimensions of the sample. The finite element code Aster (Electricite De France) has been used to model the drying test. The constitutive model chosen is the non linear thermoporoelastic model due to Coussy, and various coupling effects are taken into account. 1 INTRODUCTION The principle of the determination of the permeability in the partially saturated domain is based upon measures of weight loss and deformation of a sample during a drying test. The kinetic of variations of weight and deformation is linked to the permeability. The presence of gas, aswell as the hydromechanical couplings in rocks such as argillites, results in a highly non linear coupled diffusion process in the partially saturated domain. Numerical methods such as finite element have then to be used to solve the direct problem (Chavant et al. 2002). An identification method based on 1D linear and non linear modelling of these tests has been presented by Giraud et al. (2006). In the present paper, the non linear hydromechanical behaviour, as well as 3D effects due to both the geometry and the finite dimensions of the tested samples, is taken into account. The finite element code Code_Aster (Chavant et al. 2002) has been used to model the drying test. The constitutive model chosen in this paper is the non linear thermoporoelastic model developed by Coussy (2004). Various coupling effects due to the presence of liquid, gas, surface tension of the capillary interfaces and the phase change between liquid and vapour are accounted for. 2 COUPLED HYDROMECHANICAL MODEL FOR PARTIALLY SATURATED POROUS MEDIA Let us consider a porous medium, composed of a deformable matrix, and partially saturated by a compressible liquid (subscript l) in equilibrium with its vapour (subscript v), while the vapour forms an ideal mixture (subscript g) with another gas (dry air, subscript a). 3. MODELLING OF THE DRYING TEST 3.1 Presentation of the drying test The experimental apparatus developed at the laboratory for the drying test is shown on figure 1. The kinetic of variations of weight is linked to the permeability. A cylindrical sample of radius R and height L of a partially saturated rock is introduced inside a hermetic chamber in which the relative humidity is maintained constant with a saline solution.
Geotechnical Properties In an Alteration Profile of the Granite of Covilha
Cavaleiro, V.M. (Department of Civil Engineering, University of Beira Interior) | Almeida, P.G. (Department of Civil Engineering, University of Beira Interior ) | Riscado, J.F. (Department of Civil Engineering, University of Beira Interior )
ABSTRACT In the area of Covilhรฃ the granite is on of the more abundant lithologies. The superficial alteration, controlled by the fault system, leads to the formation of alteration horizons in the vertical direction, which, on the geotechnical point of view, change their properties. This article presents some preliminary results of the accomplished study, that tries to establish correlations between weathering degree and mechanical properties. 1 INTRODUCTION The geomechanical properties of rocks vary fundamentally in function of the rock type, tectonics, fracturing degree and weathering. The alteration degree is, of the referred factors, probably the most important in engineering, since its variation affects the dynamic behavior of the rocks, and so conditioning their aptitude characteristics, like rock mass if excavability, the bearing capacity or the behavior of materials in work along the time. This phenomena has been study by several authors, based on weathering, compressive wave velocity or uniaxial compressive strength aiming on proposing a classification. The main objective of this study is to evaluate, through sampling accomplished along ten boreholes, how the weathering mechanisms and the different geomechanical parameters vary in depth. Laboratory testing accomplished on the samples bodies (bulk volume weight, open porosity, water absorption, compressive waves velocity and uniaxial compressive strength) allowed to establish correlations between the geomechanical parameters. 2 GEOLOGY AND GEOMORPHOLOGY Geomorphologically the area is known by Plateau of Torre (Figure 1), and it was subject to the recent glaciations (Vieira, 2004). The actual relief results of a commitment between the erosion and tectonics phenomena that are well marked in the entire area. Tectonical behaviour generates on the all massif several fracturing surfaces originating on hercinic age orogenic movments and granitic intrusion resulting in strong litostatic decompression in the framming lithologies. The fracture network observed in aerial photo at a scale of 1/26000 is dense and it presents an predominant orientation of NNE-SSW. A second family, almost perpendicular to the first, appears with an orientation that oscillates of E-W and WSW-ENE. In situ measurements of the existent fracture network allowed the analysis of the geometry of these planes as it is observed in the Figure 2. The spacing among discontinuites varies from family to family, being the more representative values, from 0.25 to 0.40 m, those correspond, according to the classification of ISRM (1976), to a degree F3 or medium spacing between faults. The discontinuity surfaces are quite narrow, 1 to 2mm of opening and in general showing traces of percolation with iron oxides or caulinite. 3 GEOTECHNICAL CHARACTERIZATION Geotechnical studies were conducted in two stages โ field and laboratory work. During the field work, a 1:5000 scale engineering geology map of the study area was made (Figure 3). Studies of the direction, persistence, spacing, opening, roughness and filling of discontinuites in the granite and the degree of weathering along the joints was included.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Igneous Rock > Granite (0.84)
ABSTRACT A newly developed fast geomechanical test system for coal roadway anchorage design is presented in this paper. It includes in-situ stress measurement, strength determination of roadway surrounding rock mass, and borehole observation. The applications of the system in Luan coal mining district are introduced. The practice proves that the system is of importance for improving the safety level of roadway supporting. 1 INTRODUCTION The roadway surrounding rock mass is an extremely complicated geological body. It has two characteristics. First, it has various discontinuous interfaces such as joints and fissures, but their existence apparently change the characteristics of strength and deformation, resulting in the extremely large strength differences between the rock mass and blocks consisting of the rock mass. Second, it has internal stresses and the magnitude and orientation of such stresses obviously affect its deformation and failure. Therefore, to understand thoroughly the geomechanical characteristics of the roadway surrounding rock is very imperative for works related to roadways such as their layout and support design, especially their anchor support design (Gale, 1993). Beijing Mining Institute, China Coal Research Institute has developed a fast geomechanical test system serving the coal roadway anchor support. The system can rapidly and correctly measure the geomechanical parameters of the surrounding roadway rock mass and has been applied successfully in Lu-an and Jincheng coal mining districts. 2 A GEOMECHANISC TEST SYSTEM FOR ROCK MASS SURROUNDING ROADWAYS The geomechanical test system mainly includes the following three parts: the borehole stress measurement, the rock strength determination, and the borehole observation. 2.1 Borehole stress measurement The method used by the system is the hydraulic fracturing method. Compared with the stress relief test, it has advantages as follows (Li, 1985; Su, 1985):capable of testing stresses at comparatively deep positions; directly testing without understanding and measuring the elastic modulus of rock. The test rig used is the SYY-56 Hydraulic Fracturing Test Rig developed by Beijing Mining Institute, China Coal Research Institute. It can rapidly and massively measure stresses within a small diameter borehole (ฯ 56 mm). The same borehole can also be used in the strength test of the roadway surrounding rock mass. The rig is composed of sealing tubes print tube, direction finders, hand pump, energy storage component, exploding-proof oil pump, and recorder (Fig. 1). Test is carried out in the selected borehole segments with complete rock cores. First, put the sealing tube in the selected borehole segment, then bring pressure to bear on the borehole segment by the exploding-proof oil pump until rock breaks up, and finally record hydraulic fracturing curves and take fracture prints by the print tube The measurement data recorded are processed by a special software for the hydraulic fracturing stress test (Cheung, 1989). 2.2 Rock strength determination The used instrument is the WQCZ-56 test rig (see Figure 2). It is composed of displacement reading device, probe, hand pump, and installing rod. The diameter of the probe is ฯ 54 mm.
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
ABSTRACT In Portugal groynes are one of the most common shoreline protection structures. This study presents a methodological proposal for the mapping and assessment of the block materials from coastal protection structures, such as groynes. An applied cartography for the armour layer of the Paramos groyne case was first developed in a georeferenced GIS base. Geotechnical and geomechanical parameters, particularly, petrophysical features, weathering grade and uniaxial compressive strength, were then assessed. The results obtained allowed to define a geotechnical zonation for the Paramos armour layer, according to the type of lithology, weathering grade and strength of the rock materials. The methodology developed proved economical and easy of use, providing a geological-geotechnical characterisation valuable to improve the diagnosis of the groynes' status, as well as the monitoring and maintenance of the kind of structures. In addition, it contributes to clarify our understanding of the coastal management of Espinho area. 1 INTRODUCTION The shoreline protection against coastal erosion is a complex problem. According to the specific framework, different methods and coastal structures may be used to protect the shoreline. Among the most generalized constructions in use there are the so-called groynes. These are transverse coastal structures, whose function is to retain the littoral sediment transportation, in order to stabilize the beach. Normally they are built in groups and are designated as fields of groynes. These coastal defenceworks may be integrated with longitudinal and adherent constructions, and in some cases, theymay be artificially nourished (e. g., LCPC, 1989; CIRIA/CUR, 1991; USACE, 1995). Due to their characteristics, these structures are designed under the condition that maintenance and repair works will certainly be needed during the structure's life (e.g., USACE, 1990; Silva, 1996; Santos et al., 2003). This study provides a proposal for the geotechnical mapping evaluation of the armour layer block materials in groynes, according to the type of lithology, weathering grade and strength of the rock materials. This is a profitable approach, in the sense that it provides information crucial to extend the average life-time of these coastal protection structures. It also emphasizes the importance, and need, of geotechnical studies for a more efficient planning of this kind of constructions. The cost of the structure, its expected behaviour, aswell as, the consequences of its failure on the groyne's base, do justify the geotechnical site investigations, which will help in the process of decision making concerning the time of maintenance or repair or of works initiation. 2 OBJECTIVES AND STUDY AREA The purpose of this study is to demonstrate the importance of coastal geology and engineering concepts for the planning of maritime structures, such as groynes (e. g., Gomes, 1977; LCPC, 1989; CIRIA/CUR, 1991; Mota Oliveira & Martins, 1991; USACE, 2002). The main aim of both the mapping and the systematic inspection of these structures is to define and characterise the natural and artificial blocks constituting the groynes.
- North America > United States (1.00)
- Europe > Portugal (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type (0.90)
- Government > Regional Government > North America Government > United States Government (0.31)
- Government > Military > Army (0.31)
ABSTRACT 3D terrestrial laser scanning is nowadays the technique for 3D mapping and documentation of rock faces and tunnels that shows most potential. In this paper two state-of-the-art methods are described to map rock mass fractures on the basis of 3D laser scan data: a semi-automatic method and a fully automated approach. Both methods give good results and have both their advantages and disadvantages in terms of practical implementation. Both methods make use of the very high level of detail and precision that the 3D laser scan data provide. This, together with the rapid method and simple way of data acquisition makes 3D lasers scanning the most promising fracture mapping tool in the future. 1 INTRODUCTION In a rock engineering project, fracture mapping is one of the important steps, which provides the input data for further rock mechanics analysis, rock engineering design and numerical modeling. Currently, fracture mapping at rock faces is well-known performed by using compass and inclinometer, and documentation by recording information on a notebook and photographing with a camera. Although these so-called traditional methods are now still used in most of the rock engineering projects, the quality and quantity of the data are sometimes unable to meet the requirement in rock engineering projects. The most well-known drawback for traditional methods is that too much personal work are involving in the in-situ data acquisition procedure, which is time-consuming, not accurate enough, sometimes difficult and dangerous to reach the rock faces physically. In addition, the way of data recording and storing can not make the full use of modern IT and computer technology to speed up the data processing, and then provide the input data in a required format for further analysis and designing. Therefore, it has been recently realized that applying a new method for in-situ data acquisition is the key point to solve the bottleneck problem for improving the rock face mapping data with both quality and quantity. In recent years, the efforts of developing new techniques for in-situ data collection at rock faces are in progress. Techniques, such as photogrammetry (e.g. Harrison, 1993; Coe, 1995), image processing (e.g. Post and Kemeny, 2001), total station (Bulut and Tudes, 1996; Feng, 1999) and laser scanning (Feng 2001, Slob et al., 2002, 2004), have been tested for measuring of different joint parameters and documentation of rock faces. The presented method has applied a newly-developed 3D visual laser scanning technique to characterization and documentation of joint and jointed rock masses at rock faces. A 3D terrestrial laser scanner can quickly record a great amount of digital 3D information of an object. Each scan takes just few minutes with a high-speed sampling rate up to hundreds of thousands of points per second, and covers up to hundreds of square meters with the optimal scanning resolution in the order of mm's. Each scanning point can be recorded by 4 parameters, i.e. the3Dco-ordinates (X, Y, Z) and the reflected intensity (I).
- Europe (1.00)
- North America > United States (0.48)
ABSTRACT In this paper an extension of the known Hoek-Brown failure criterion to three dimensions is presented. First of all, a recompilation of compression, extension and true triaxial tests made with rocks, present in the technical literature, is made. The main conclusion drawn from those tests is the importance of the intermediate principal stress in the failure strength of rocks. Taking this idea into account, the Hoek-Brown failure criterion is modified. The laboratory test results are modelled with this new criterion with great success, which proves the goodness of the modification done. 1 INTRODUCTION In many rock engineering problems it is necessary to have a failure criterion able to reproduce correctly the real stress condition at failure under three-dimensional configuration. Particularly, the spread in the use of Finite Element Method programs that let calculate three-dimensional models requires compulsoryly the definition of three-dimensional failure criterion to be able to make adequate calculations. By other hand, among other criteria present in the technical literature, probably the most used model in Rock Mechanics is the one developed by Hoek โ Brown established in 1980. where ฯ 1 is the major principal stress at failure, ฯ 3 is the minor principal stress at failure, ฯ c is the uniaxial compression strength of the rock matrix and mb and s are constants that depend on the characteristics of the rock and its degree of fracturing. The values of m0 are given for different rocks in Hoek and Marinos (2000). GSI is the Geological Strength Index (Hoek et al, 1992) of the mass rock and D is a factor which depends upon the degree of disturbance to which the rock mass has been subjected by blast damage and stress relaxation. If the study is based on laboratory specimens, GSI can be considered equal to 100 and D equal to 0, which means, from a practical point of view, a minimal disturbance. Having into account these previous ideas, in this paper an extension of the Hoek โ Brown failure criterion is made to reproduce the failure in three-dimensional stress states. 2 RECOPILATION OF LABORATORY TEST RESULTS 2.1 Compression and extension triaxial tests The first results that proved the influence of the intermediate stress (ฯ 2) in the failure strength were those obtained in the so-called triaxial compression tests in which the intermediate stress is fixed equal either to the minimum principal stress (as in the compression test under confining pressure) or to the maximum principal stress (as in the extension test under confining pressure). Examples of these kinds of tests can be found in Mogi (1967) who made 26 extension and 21 compression triaxial tests, in which Westerly granite, Dunham dolomite and Solenhofen limestone were used. The results obtained in that research can be seen in Figure 1. The fact that the extension curve lies above the compression curve indicates the marked influence of the intermediate principal stress on the failure strength. This idea is one of the main conclusions that can be drawn from those particular results.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.56)
ABSTRACT To determine the response of a rock mass to an applied stress field, one must first adequately characterise that rock mass. Numerical modelling is increasingly put forward as a method of improving understanding of the behaviour of rock masses. To achieve maximum potential from numerical modelling, series of models that test the natural variability and uncertainty in fracture geometries and consequent rock mass behaviour must be run. The proposed approach uses the Discrete Fracture Network (DFN) software FracMan to produce 3D stochastic models of rock masses from mapped fracture data that contain the geometrical characteristics of the fractures. Geomechanical modelling is carried out using the program Elfen, which assesses the influence of the initial fracture geometries on the rock mass behaviour. This study focuses on the size of sample required to adequately characterise a fractured rock mass, taking in to account the natural complexity and variability of fractures within rock masses. 1 INTRODUCTION The 3D characterisation of the structural features of rock mass is a challenging problem facing engineering geologists. There are two main issues: firstly, what constitutes an adequate characterisation of the rock mass. This will clearly depend on the purpose of the survey, and will be scale dependent. The second issue is the extrapolation of the collected data into 3D descriptions of the features within the rock mass. Sampling carried out in two dimensions (2D), via mapped windows on exposures, or in 1D, via boreholes, must be extrapolated to provide a 3D description of the rock mass. To some extent, the second issue depends on the first: how accurate a rock mass characterisation is needed. At a more fundamental level, it addresses the question of the statistical description of rock masses and their scaling properties. Typically, rock mass characterisation has been based on geotechnical mapping data. Traditionally, the collection of geotechnical field data from exposures has been a manually intensive, slow, laborious process. The increased accessibility of digital imaging technology such as photogrammetry and 3D laser scanning (for example Coggan et al., 2006) has made it possible to acquire large volumes of high quality spatial data associated with a given rock mass outcrop. This allows for a much better quality of rock mass characterisation based on the statistics of the gathered data, and allows the possibility of characterisation on multiple scales. The proposed approach in this paper combines a stochastic description of the fractured rock mass with geomechanical modelling. This approach allows the natural variability of the fractured rock mass to be explored and characterised using the DFN program FracMan (Dershowitz et al., 1998, ). A Monte Carlo approach to the geomechanical modelling, using the program Elfen (Owen et al. 2004, ), can incorporate the range of initial fracture geometries within the rock mass, and assess their importance to the overall behaviour of the rock mass. The FracMan modelling suite has been used on numerous civil engineering, mining and oil and gas projectswhere a good understanding of the effects of fracture networks is required.
- North America (0.68)
- Europe > United Kingdom (0.46)
ABSTRACT The destruction of rock mass may be caused by improper excavation in rock engineering, and the main external factors affect the rock slope's stability may be groundwater and seepage. To analyze the relationship between unloading and permeability coefficient of the rock, the method and steps of experiment for the rock mass under unloading condition are put forward. The relationship curves of the seepage-unloading at different phases are found by experiments. According to the experimental results, the seepage-stress relation of rock mass under unloading has been established, and the variation rule of the unloading value with the permeability coefficient is discussed. Two points can be concluded, i.e. the permeability coefficient is almost unchanged in the elastic phase of unloading process; and the permeability coefficient is changed very much in the plastic phase of unloading process; especially, as the unloading value reaches over 80% of ultimate one, the permeability coefficient increases rapidly. 1 INTRODUCTION The mechanical essence of rock excavation usually belongs to the category of unloading mechanics. In practical rock project there is often complicated geological condition accompanied, it mainly includes high stress, groundwater, coal bed gas and so on. In these problems, the study of the coupling mechanism of the seepage field and damage field for fractured rock masses is very important; bywhich the co-operation mechanism of geological condition such as groundwater etc with the surrounding rock and support structure can be known, which has important significance for prevention and cure of groundwater. Academician Wang Sijin, the president of Chinese Society for Rock Mechanics and Engineering had pointed out: "Rock Mechanics is developing from the study on unitary solid discontinuous material to multiple fields with coupling and multiphase movement". The experts of rock mechanics had noticed the important effect of water on the mechanical behavior of rock mass. But, with the development of mechanical behavior of rock mass and the simultaneous existence of the multi-fields of heat, flow, solid and chemistry etc, a further study on their interaction and coupling mechanism should be carried out in the future." [1] Moreover, now the study on characteristic of seepage from rock mass is mainly in respect of loading process, while the study of unloading process is still less. 2 ANALYSIS ON ROCK UNLOADING PROCESS The practice of many projects at home and overseas indicated that almost all the destruction of rock mass does not commence at the start, but due to the variation of excavation unloading, after the rock excavation, there is stress redistribution occurred in the rock mass, leading to deformation of the rock mass at the interface with the weak structure; there is a great change in fissures and the mechanical properties of rock mass are deteriorated.
- Research Report > New Finding (0.40)
- Research Report > Experimental Study (0.40)
Evaluation of Fracturing Process of Soft Rocks At Great Depth By AE Measurement And DEM Simulation
Mito, Y. (Kyoto University) | Chang, C.S. (Kyoto University) | Aoki, K. (Kyoto University) | Matsui, H. (Japan Atomic Energy Agency) | Niunoya, S. (Japan Atomic Energy Agency) | Minami, M. (Tokyo Electric Power Company)
ABSTRACT The monitoring of EDZ (Excavation Disturbed Zone) is one of the most important required technologies for the design of rock caverns such as the high-level radioactive waste repository. The authors developed the stress-based evaluation system of EDZbyAE monitoring andDEM(Distinct Element Method) simulation, and verified the applicability of this system to the hard rock site. In order to apply this system to the soft sedimentary rock site, the authors examine the relationship betweenAE, stress change and rock failure in the soft sedimentary rock by conducting the high stiffness triaxial compression tests including AE measurements, and its simulations by DEM using the bonded particle model. As the result of the triaxial compression tests, it is clarified that predominant AE frequency is a significant AE parameters to monitor the stress change in fracturing process of soft sedimentary rocks. After that, the DEM simulation of the triaxial compression test using the bonded particles model is conducted to visualize the fracturing process in the rock specimen. As the results of the above examinations, the relationship between AE, stress change and rock failure in the soft sedimentary rock is clarified. Furthermore the three-dimensional DEM simulation under the in-situ stress condition provides a successful result to examine the borehole breakout observed in the actual deep borehole in the soft sedimentary rock, and the applicability of the simulation to the actual field is verified. 1 INTRODUCTION Underground excavation causes Excavation Disturbed Zone (EDZ) around the opening. It is very important to evaluate the EDZ accurately for the safety assessment and the development of the basis for engineering technologies of the high-level nuclear waste repository. Especially in highly stressed rocks at great depth, the formation of EDZ is strongly influenced by stress change in the rock mass. Therefore, it is essential to evaluate EDZ with stress change. For this purpose, AE measurementwould be a suitable in both of scientific and practical point of views, and this will enable to evaluateEDZaccurately. In order to establish stress based evaluation system of EDZ, the authors have already examined the relationship between AE, stress change, and fracturing in highly stressed hard rock masses by theAEmeasurement and theDEMsimulation using the bonded particles model. Based on this relationship the authors developed the EDZ evaluation system (Aoki et al., 2004), and the applicability of this system is verified by the field applications (Aoki et al., 2005). However, there is a few case history that theAE monitoring was carried out in the soft sedimentary rocks because of the lowerAE counts, smallerAE energy, and higher attenuation feature than those in the hard rocks, This study examine the EDZ evaluation system for the soft sedimentary rock site at great depth. In order to apply this system to the soft sedimentary rocks, it is necessary to clarify the relationship between AE, stress change and rock failure in the soft sedimentary rocks.