Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
ABSTRACT Rock masses are usually in wet or saturated condition in the nature. Interaction of rocks with water leads to a reduction in rock mechanical properties, and quantifying this effect has been always a problem in rock engineering projects. Despite the fact that a considerable number of research has been carried out on this topic, they are not thorough and general. In this paper, a new rock classification system is presented in order to evaluate wet rock properties.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.47)
ABSTRACT Because of the inherent high nonlinearity of rock material, associated with the extreme complicity of mechanical and geological conditions, it is usually very difficult to model the response of rocks to engineering activities mathematically and physically. Recently, with integrated applications of artificial intelligence, system science, rock mechanics and engineering geology, an interesting alternative methodology, intelligent analysis methods, for recognition of rock mechanics models was proposed. This paper reviews the new developments of this kind of method and gives some prospects for further works.
A Rock Mass Classification to Estimate Excavation Rate, Support and Rock Properties in a Borehole Survey
Sawada, M. (Central Research Institute of Electric Power Industry) | Shin, K. (Central Research Institute of Electric Power Industry) | Inohara, Y. (Central Research Institute of Electric Power Industry) | Shidahara, T. (Newjec Inc.) | Hatano, T. (Electric Power Development Co. Ltd) | Miwa, T. (Tohoku Electric Power Co. Inc.)
ABSTRACT A method of evaluating engineering rock mass characteristics has been proposed for the purpose to help the adequate selection of the detailed investigation areas, which is an important decision making for the selection of the final disposal site of high level radioactive waste in Japan. The method requires classification of qu: uniaxial strength of rock core, RQD and Jc: joint condition. Relation between the 3 parameters and advance rate of excavation and support has been analyzed based on published records of tunnel excavation. Also Relation between the 3 parameter-rock mass description and rock mass properties of strength and Young's modulus has been analyzed based on published in situ rock shear tests and plate jack tests in Japan. Based on the findings, graphs of estimating the engineering rock mass characteristics of excavation rate, support, strength and Young's modulus have been made. The features of this method are that it uses the 3 dimensional information of qu, RQD and Jc without converting the information to one dimensional value as in RMR, and that the 3 parameters are able to be obtained in a borehole survey.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type (0.94)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.62)
- Geophysics > Borehole Geophysics (0.62)
- Water & Waste Management > Solid Waste Management (0.89)
- Energy > Power Industry > Utilities > Nuclear (0.50)
- Well Drilling (0.88)
- Health, Safety, Environment & Sustainability > Environment > Waste management (0.70)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Borehole imaging and wellbore seismic (0.62)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.51)
ABSTRACT The prior knowledge of the rock mass behavior along a projected roadway is fundamental for planning activities and safety measures at a construction site. However, pre-investigations are often costly and time-consuming. To generate high resolution images of geotechnically important structures and changes in the rock mass, the Integrated Seismic Imaging System (ISIS) was developed at the GFZ. Seismic measurements offer detailed information on the rock mass, especially if the data acquisition takes place on-site during tunneling. However, to be of importance for the decision making on-site, the data needs to be processed and interpreted within a small timeframe. To meet this requirement the interpretation process needed to be automated. In the ONSITE project, a first step towards automating this process has been done by developing adapted routines with self-learning algorithms for rock mass classification based on seismic measurements. For the classification, the widely known RMR and RQD have been used so that a general idea about the rock mass behavior and not only single parameters can be gained from the results Based on the RMR, two rock mass classes were determined along seven seismic profiles from the Faido adit that belongs to the Gotthard base tunnel. The boundary between those classes was at 60 RMR which separates "fair" from "good" rock in the classification scheme. The RQD was separated into 3 classes, based on the number of occurrences, with either values in the range "excellent" (RQD>90), "good" (RQD 75 to 90) or "lower" (RQD<75). Both classification approaches using SVMs showed good training and testing accuracies, though the RQD was not as sensitive to the seismic velocities as had been expected.
- Geology > Rock Type (0.73)
- Geology > Geological Subdiscipline > Geomechanics (0.49)
- Geophysics > Seismic Surveying > Seismic Modeling (0.38)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.36)
- Geophysics > Seismic Surveying > Seismic Processing (0.35)
ABSTRACT Deformation modulus of a rock mass is one of the most important geomechanical parameters for a design and successful execution of rock engineering projects such as tunnels, dams, powerhouses. Field tests including plate loading, plate jacking, radial jacking, flat jack, etc, are the most commonly used methods to measure the deformation modulus of rock masses directly. However, these methods usually require extensive and difficult procedures and hence they are time consuming and costly. Thus, developing empirical equations to properly estimate the modulus of rock mass deformation on the basis of rock mass properties are of practical and economical advantageous. In this paper, at first, it is aimed at establishing an empirical predictive model for determination of the modulus of deformation based on GSI system using simple regression model. Then, the in situ plate loading test data and the rock mass properties are used to apply bivariate correlation analysis to determine the independent variables that affect on the modulus of deformation. Next, the results are used to develop a new empirical predictive model for determination of the rock mass deformation modulus with the aid of multiple regression analysis. This study includes a comprehensive credibility assessment of the prediction performances of some existing empirical equations as well. Subsequently, the results of the existing empirical equations were compared with that obtained by the equations proposed in this paper. Finally, it is concluded that the new empirical equation proposed in this paper provides more accurate results compared with the existing empirical equations.
- North America (0.46)
- Europe (0.46)
ABSTRACT In geological investigations, drill hole information can come from core and chip samples, the monitoring of drill performance and various forms of down-hole testing such as geophysical logging. Fusion of some of these forms of measurements is possible and can improve the geological understanding. In this paper we conduct fusion of drill monitoring data and geochemical assays of drill hole samples using Multiple Task Gaussian Processes (MTGPs). MTGPs are a popular statistical supervised learning and fusion technique in the machine learning community. The proposed algorithm autonomously learns the intrinsic interconnections between rock strength parameters and geochemistry and uses these interconnections to improve the quality of the geological model. We demonstrate the principles of our approach by fusing drill monitoring data from closely spaced blast hole drilling at an open pit iron ore mine and assay results from more widely spaced exploration drill holes. The drill monitoring data are represented by a parameter we call the Adjusted Penetration Rate (APR) and we observe a strong correlation between APR and iron grade from the assays. Fusion allows a more detailed geological model to be obtained.
- Geology > Geological Subdiscipline > Geochemistry (0.55)
- Geology > Geological Subdiscipline > Geomechanics (0.51)
ABSTRACT It is well known that there are many joints, cracks and faults in rock mass. The dimensions of these discontinuous vary from meters to millimeters. In the engineering practices, the failure of surrounding rock mass mostly related to the interaction of discontinuous interface with varied dimensions. However, it is lack of effective numerical simulation method for crack-weakened rock mass which can take the multiple scale mechanical behavior of rock mass into account. In order to solve this problem, some breakthroughs should be made in the fundamental theory of numerical simulating method for crack-weakened rock mass. On the basis of extended finite element method, a multiple scale model for simulating the damage evolution in crack-weakened rock mass is proposed. The coordination between the internal boundary (such as cracks and holes) and mesh is not needed in this new model. By combining the displacement projecting method and displacement loading method, the connection between different sizes of mesh behaves smoothly. This multiple scale model, which saves the storage space, indeed overcomes difficulties in mesh. The contact constraint on crack surface is embedded within the total stiffness matrix by adopting the penalty method. In addition, the path of crack growth and stress field are determined through iterative computations. Because additional discontinuous functions and enriched tip elements are added in the displacement field, the geometry of cracks is independent of the finite element mesh. As a result, remeshing is not necessary to model crack propagation by using this new model. As the frictional contact of crack surface is taken into account, the present method is suitable for modeling the growth of multiple cracks in geomaterials under compressive loads. Finally, the method is employed to simulate multiple crack growth when frictional contact exists on the crack surfaces, and the results show good agreement with the experimental ones.
- Research Report (0.69)
- Overview > Innovation (0.54)
ABSTRACT Rock and Rock mass are typical discontinuous materials. A proper contact mechanism is the prerequisite to perform discontinuous numerical simulations. At present, analytical models, physical models and parameterized models are broad used. Physical models are suitable for explicit methods while parameterized models are suitable for implicit methods. The penalty model has the advantage of not increasing the unknown variables but the choice of the penalty number is difficult. In this paper, a spherical contact model is presented using penalty method and open-close iteration algorithm. The model is validated by the collision test which describes the contact properties of materials. The results show that penalty numbers can be filtered with given maximum interpenetration rate and the coefficient of restitution.
- Europe (0.47)
- Oceania > Australia (0.28)
- North America > United States (0.28)
ABSTRACT In the field of practical rock engineering, there are two independent computations: continuous computation and limit equilibrium computation. Limit equilibrium is still the fundamental method for global stability analysis. For any numerical method, reaching limit equilibrium requires large displacements, discontinuous contacts, precise friction law, multistep computation and stabilized time-step dynamic computation. Therefore three convergences are unavoidable: convergence of equilibrium equations, convergence of open-close iterations for contacts and convergence of the contact forces of dynamic computations. This paper focuses mainly on applications of two-dimensional discontinuous deformation analysis (DDA). The applications show DDA has the ability to reach limit equilibrium of block systems. This paper presents dam foundation damage computation and slope reinforcement computation, where the block sliding is a main issue. This paper also presents underground chamber rock stability and bolting computations.
ABSTRACT The processes of the stochastic generation of a discontinuous rock mass model are presented in this paper, using the orientation data measured directly in the abandoned underground gallery of Saint-Béat castle, in the southwest of France. This gallery is particularly interesting because, even without reinforcement, all the walls and the roof are perfectly stable. The fracture measurements are carried out in order to investigate the stability and design of a 1 km long tunnel, which will be part of the new ring road of the city of Saint-Béat. The statistical parameters extracted from the fracture measurements are then used in the code developed using the AutoCAD software in order to generate seven 3D stochastic models of jointed rock mass media. The stability analysis of the models is carried out using the LMGC90 code, based on the Non-Smooth Contact Dynamics (NSCD) method. In this paper, this method is used to simulate rock mass media, as large collections of rigid blocks under unilateral constraints and frictional Coulomb's law.