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ABSTRACT: A tool that has proliferated within engineering in recent years is geographic information systems (GIS). Based on elastic theory and GIS technology, the model of GIS raster digitized model with face element related GIS-based modeling is established to predict mining subsidence by means of system integration. In this paper, the explicit expressions of the displacement are derived, and stress and strain can be given corresponding to displacement components. The system is developed into software package that can calculate displacement, stress and strain for any point in any overburden layer. Finally, a full case study in Seita reservoir area, Japan, is demonstrated with the application of the integrated system. The model is proven to be highly effective and particularly aims at predicting subsidence at any point with any shape of excavation covering a wide range of mining geometry, providing automation, intellection and visualization in subsidence prediction. I. INTRODUCTION With the development of economy, we need more and more underground resources. As a result, mining subsidence is becoming into one of the most important factors affecting the environment. Many scholars have studied it for many years and put forward many methods to predict mining subsidence. In general, subsidence prediction methods can be divided into two categories: Empirical Modeling: With this grouping falls a number of formulae that have been established from observed surface behavior. The empirical data method, the profile function method and the influence function method have been used successfully for subsidence prediction in many countries. The best know of these methods is the UK NCB empirical model (SEH. 1996), which has an accuracy of generally better than 10% of the scam extraction for prediction of the amount of resulting subsidence. Also, the methods of profile function and influence function are included in this group. The characteristics of this group is that parameters used in the model have no mechanical meaning and they generally apply specifically to the ground and mining conditions which prevail where the observation were made. Theoretical Modeling: These models are analytical or mechanistic in nature, and can be categorized according to several criteria. Models that have been used for subsidence studies include various types of linear elasticity, elasto-plastic material formulations to simulate failure zones, viscoelastic equations to account for time-dependent subsidence. Computer based techniques, such as the finite Element (FEM), Boundary Element (BEM) and Distinct Element (OEM) methods of modeling of overburden rock mass and simulation of mine geometry have been used recently for the prediction of subsidence over mine panels (Jones, 1985). In this paper, based on the above two models, a combined method, called GIS raster digitized method with face element, is put forward to predict mining subsidence with the help of GIS and computer techniques. 2. SYSTEM INTEGRATION USING GIS The present subsidence systems usually use CAD-like and Data Base Management System (DBMS) environments for the handling of numerical, textural and graphical data, because mining geometry, mining method, geology of overburden, surface configuration, and surface infrastructure.
- Asia > Japan (0.36)
- Europe > United Kingdom (0.24)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.47)
- Information Technology > Geographic Information Systems (0.55)
- Information Technology > Databases (0.54)
- Information Technology > Information Management (0.35)
- Information Technology > Software (0.34)
ABSTRACT: The assessment of the shear strength of rock joints is essential for many rock engineering projects. The shear behavior of rock joints is usually investigated in the laboratory by using a direct shear apparatus, where the normal load is kept constant (CNL) during the shear process. However, they may be quite inappropriate for the situations where the normal stress on the joints surfaces changes considerably during the shear process. In this study, a high-performance direct shear apparatus and computer control system have been developed to accommodate the change in normal stress with dilation under constant normal stiffness (CNS) condition. The shear test results of the artificially prepared joint specimens show that the normal stiffness has a significant influence on the shear strength of joints. 1 INTRODUCTION A rock mass of a site is not continuum and its mechanical behavior is significantly affected by the existing discontinuities, such as bedding, joints, faults and fractures. Therefore, the correct evaluation of the shear strength of rock joints plays an important role in the cases of design of deep underground openings and stability analysis of rock slopes. The shear behavior of joints is usually investigated in the laboratory by using a direct shear apparatus, but mainly under constant normal load (CNL) conditions (Huang, X. et al., 1993). They may be quite inappropriate for the situations where the normal stress on the plane of shear is far from being constant during shearing process, for example, in deep underground openings or in grouted rock anchors. In such cases, a more representative behavior of joints would be achieved if the shear tests were carried out under conditions of constant normal stiffness(CNS). There are several references concerned with the shear test of joints under CNS conditions. However, the normal stiffness is very difficult to be changed according the deformability of the joint surfaces and rock mass because of using the springs or the equivalent beam to apply the amount of stiffness (Brahim,B. & Gerard,B., 1989; Indraratna,B., et al., 1999; Ohnishi, et aI., 1990), and the joint surfaces are easily damaged when the spring is too strong. This study is to develop a new direct shear test apparatus of a joint interface under the conditions of CNL and CNS, and to describe a rational procedure for the determination of the shear behavior of rock joints. The value of the normal stiffness can be set automatically by a computer with the A/D and D/A boards. Shear test of the artificial joint specimens is carried out with the developed apparatus in order to clarify the influence effects of the normal stiffness on the shear strength of joints. 2 DEVELOPMENT OF HIGH-PERFORMANCE DIRECT SHEAR APPARATUS A servo-controlled direct shear apparatus was designed and fabricated for the purpose of testing both natural and artificial rock joints under conditions of CNL and CNS. The loading capacity of machine is 400kN in both normal and shear directions (Fig. 1 and Fig. 2).