This paper presents an Artificial Neural Network approach for a quick displacement prediction using the results of field measurement for NATM tunnels. The data obtained for NATM tunnels constructed in unconsolidated ground were analyzed with respect to key tunneling parameters, such as tunnel geometry, support condition and displacement observed during construction. Prediction of tunnel displacement at final stage was made at different timings of prediction. The results obtained suggest that the artificial neural network approach proposed here can predict tunnel deformations at the final stage with fairly high level of accuracy even for less information before construction.

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One of the stopes which is being mined by Pongkor Underground Gold Mine using cut-and-fill mining method is located in South Ciurug Mine. The rock mass in this location is weak due to the extensive joint occurrence. In order to understand the effect of rock joints to the stability of stope, an investigation was carried out by means of specific drilling from two crosscuts to acquire rock samples from this location, and observing the joints orientation in the drilled holes wall using a borehole camera.The stability of stope due to the extensive joints occurrence in this location was then analyzed by empirical and numerical methods.Rock mass classification in this location was evaluated by RMR and Q-System method. Numerical analysis was carried out by simulating models which represent the rock mass conditions, using 3DEC Program. The analysis was focused on the back of the stope, due to the effects of joints existence in this location.

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In this study, an attempt has been made to investigate the deformation and moisture transfer behaviour of Shirahama sandstone using small cylindrical samples. A series of comprehensive laboratory experiments were performed in one-dimensional moisture transfer condition under zero confining pressure. Saturated cylindrical samples were dried in a climatic chamber and thereafter rewetted by high air humidity while deformation and evaporative water loss were being monitored. The quasi-continuous strain measurements gave three-dimensional deformability of the samples with respect to water content variation. The results obtained from the experiments were further used to evaluate matric suction evolution following the linear poroelastic relation. Following this the observed strains and estimated matric suctions were examined in conjunction with their pore structures obtained from mercury intrusion porosimetry. Moreover, mercury intrusion porosimetry also helped to understand the nature of pore available in the samples and their relative abundance in the selection of the mathematical model to represent the estimated matric suction behaviour. This study revealed that Shirahama sandstone can withstand the volume reduction until saturation decreased to 60% and will not show significant hardening until saturation lower than 50%. Although, further testing and confirmation by numerical modeling is required to understand this behaviour more completely, the present experimental test results shed light on essential elements in the studies of ground movement, fluid flow and isolation properties around underground facilities and large structure foundation.

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Geochemical characteristics and the increase of total reactive surface area of the sulphide-bearing waste rock due to weathering processes at dumping area are expected to enhance the oxidation of sulphide minerals, commonly present as pyrite (FeS₂), leading to acid mine drainage (AMD) generation. Having investigated the geochemical characteristics of the waste rock at the surface layer (0 - 200 cm depth) of Pit J (2 years-old) and Sangatta North (10 years-old) dumping areas, the study indicated that the oxidation of sulphide-bearing waste rock uniformly occurred and it was influenced by the physical weathering as the forerunners of chemical weathering. The formation of clay minerals was then considered to have a potency of being oxygen and water barrier which consequently would reduce the AMD generation. In addition to that, an investigation of in situ waste rocks from Melawan area was also conducted. The results of investigation indicated that the rocks were physically easy to break down hence increasing the total reactive surface area for chemical reaction upon exposed to the climatic condition, and should be considered as an important factor in determining the processes of AMD generation afterward at dumping area.

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A conceptual model is presented to follow the evolution of permeability in siliceous rocks mediated by pressure solution comprising the serial processes of interfacial dissolution, diffusion, and free-face precipitation. In this work the main minerals of siliceous rocks that are quartz, cristobalite, and amorphous silica, are notably focused to examine differences of the permeability evolutions attributed to the composed minerals, at the effective pressures of 1, 5, 10 MPa, and temperatures of 20 and 90 °C. The rates and magnitudes of the permeability degradation increase with increments of pressures and temperatures prescribed. Ultimate permeabilities reduce by the order of 90% at the completion of dissolution-mediated compaction at 10 MPa and 90 °C.

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The occurrence of ground subsidence and its development are important issues focusing on a study above the Gunung Bijih Timur (GBT), Intermediate Ore Zone (IOZ) and Depth Ore Zone (DOZ) block caving at PT Freeport Copper & Gold mining, Papua, Indonesia. Geologically, the hosted rock is the lower Waripi Formation of the Tertiary New Guinea Limestone Group which trending to N30^oE/50-55 degrees northeast. Furthermore, the Waripi Formation also consists of sandy dolomite, silty to sandy limestone and highly fragmented rock that controlled by faults and joints. These geological factors will make any influences with the development of subsidence. The main structural trend in this area is west-northwest (WNW), this trend can be found in the steeply dipping Ertsberg 1 Fault, Ertsberg 2 Fault, Ertsberg 3 Fault and the Ertsberg 4 Fault that distribute from north to south.This paper describes the relationship between geological condition and subsidence development above three levels of block caving mining. The surface topographic change in vicinity of mining has been detected using Geographic Information System (GIS) and aerial photogrammetry. The analytical aerial triangulation method is performed to develop a multi temporal Digital Elevation Model (DEM) by calculating the tie points ground coordinates. The geological conditions such as effect of faults, steep topography and type of lithology are analyzed using GIS to study the occurrence of topographic change such as progressing surface subsidence and sedimentation area. The GIS analysis emphasizes the subsidence occurrence and the governing role of the geological structure in defining the development of asymmetry distribution of subsidence.

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Technologies of an underground natural gas storage system, a Lined Rock Cavern (LRC) gas storage system called ANGAS (Advanced Natural GAs Storage), have been studied. The purpose of the project is to develop a suitable LRC system for Japan, and to contribute to expanding use of natural gas. It is necessary to study measures to shave off the daily peak load of natural gas through pipelines and it is expected that the ANGAS is one of key countermeasures for peak shaving. In the project, our goal is to ensure the design method of the LRC system under the Japanese geological conditions. One of the key technologies of the developed design method is based on plastic deformation of the steel liner considering the rock deformation appropriately. Using the developed design method and procedures, a small test cavern which is located at the Kamioka mine, the midland of Japan, was designed and constructed. The test cavern is surrounded by a sedimentary rock mass which consists of mainly sandstone and mudstone. The inner design pressure of the test cavern is 20MPa. In this paper, some results of the verification tests are presented and the validity of the LRC system for Japan is confirmed. Specifically, the steel liner was deformed up to its plastic zone, in order to be unified with the buffer material and the backfilled concrete as a hybrid structure. The displacements in the surrounding rock mass were stable under the inner design pressure 20MPa. Furthermore, the real crack intervals of the backfilled concrete are recognized to be less than the designed maximum interval and the real maximum crack width is inferred to be close to the designed one under 20 MPa pressure. Therefore, the design considering the crack properties of the back filled concrete has been verified.

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To examine the fatigue process of granite, fine-grained Westerly granite specimens were subjected to the cyclic loading test at room temperature under uniaxial compression with maximum stress 160MPa, almost 80% of the estimated peak stress, and a series of specimens stressed to six characteristic stages classified by the number of loading cycles were retrieved. The development of microcracks in the tested specimens was observed microscopically and their growth patterns were investigated using the image analysis technique. The results were as follows. With increasing loading cycles, the number and the population of microcracks within the specimen increased. Intragranular cracks generated at the first stage of loading, most of them occurring around the biotite or muscovite grains especially in quartz grains. Many cracks preferentially elongated parallel to the loading direction and grew into transgranular cracks. It was confirmed that during the quasi-stable middle stage microcracks generated and elongated but did not grow into intergranular cracks across the grain boundaries. With further cycles, the newly generated cracks gradually widened, and some of them grew into intergranular cracks. It was estimated that the generation and growth of these intergranular cracks induced rock failure. The decrease in strength was caused by the increase in crack population and preferentially orientated microcracks, and a different mechanism for the failure process of fatigue was indicated compared to monotonic compression.

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