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FLAC3D model construction for slide slope analysis has been one of the challenges to engineers when intending to model the topography and geology in the region of interest at the required engineering accuracy. After referring to the examples in the FLAC3D manual, this paper introduces an approach to build up slope models by utilizing an interpolation technique to simplify the data processing with a built-in function. Geological units in the slope are geometrically modeled through data interpolation and an associated logical calculation to ensure the required accuracy. Three types of built-in elements in FLAC3D have been selected to represent the geological changes such as thickness variation and termination of the geological unit. Each type of element is identified and employed automatically through FISH functions, according to the geological condition in the slope. This approach has been employed to build the FLAC3D model for the Upper Gutianzheng slide slope at Kala Hydropower Station on Yalong River, China. The modeling results are in a great agreement with limit equilibrium calculations, which intends to indicate the reliability of the model construction approach introduced in the paper. [ABSTRACT FROM AUTHOR]

Dam stability under seismic loading has long been a critical concern in water conservancy and Hydropower Engineering practice. This is particularly true when the dam is constructed in the tectonically active area. In the study of dam dynamical stability, understanding of the rock or soil behavior to dynamic loading conditions is fundamental because the response of the dam foundation to seismic loading can significantly affect the stress and deformation distribution, as well as the stability of the dam. This paper presents the entire procedure of dynamical analysis considering dam-foundation interaction during seismic loading for the case of Spillway Dam at CCS Hydropower Station in Ecuador. The analysis is implemented with FLAC in a complete non-linear manner. The models have revealed the stress and the deformation response of both dam and foundation to the seismic loading at various levels. Such results have been used to assess the dam stability through further interpretation and to help understand the mechanism of potential failures. In addition, a few important matters to dynamic analysis have been presented in the paper, including art ificial spectrum generation, estimate of dynamic properties for rock and soil; as well as boundary condition setting. [ABSTRACT FROM AUTHOR]

The quantitative understanding of the current stress state, which refers to correlation among the three principal stresses, along a fault is one of the challenging and interesting aspects in the study of fault permeability. This study is commonly conducted to help identify the possible existence of oil and gas resources for the given geological conditions during reservoir exploration and development. Taking the North Zone of DongyingBasin as an example, this paper introduces the numerical exercises with FLAC to help understand the stress distributions at different depths along the faults that are present with various dips within this domain of interest. The modeling results indicate that the stress state along a fault can be quantitatively described, and it varies with depth along the fault. The variation of stress state is essentially governed by the combination of gravity and tectonic stresses. The findings presented in this paper have provided effective indications for the further investigation of fault permeability, particularly in establishing the criterion to identify oil and gas reservoirs in faulted ground. [ABSTRACT FROM AUTHOR]

The paper firstly presents a generic approach of model construction with FLAC3D for rock slope analysis, which directly uses AutoCAD drawings to build the model by using SLIP in CAD software and FISH language in FLAC3D. Secondly the paper describes the model construction process for the left bank slope at Kala Hydropower Station, as well as the stress and strain distributions generated by the model. Finally the factor-of-safety calculation results are presented, which indicate a relatively unstable condition of the slope. During the FOS calculation, a sensitivity study has been carried out to investigate the influence of rock mass properties on the slope stability. The results indicate that FOS values are sensitive to the change of both friction and cohesion, whereas less sensitive to Young's modulus. A comparison between the FLAC3D model and the 2D EMU calculation has been conducted that indicates a reasonably good agreement with each other. However, the FLAC3D model appears to be able to more explicitly and accurately reveal and present the stability of the slope. [ABSTRACT FROM AUTHOR]

Both spalling and block failure have been observed while driving the audits in the proposed locations of the cavern in the right bank at Baihetan Hydropower Project site. Severe spalling occurred primarily in the roof, and the block failures were governed by the Shear Zone C4. In addition, field investigation showed that the stress-induced spallings are spatially associated with the existence of Shear Zone C4. The occurrences observed in the audits present a strong indication that both a stress-induced problem and structure-control failure should be anticipated and may co-exist when constructing the cavern. When conducting numerical analysis of cavern stability, attention should be paid simultaneously to both the discontinuous and the non-linear behaviors of the rock mass. This paper presents the entire procedure of numerical analysis for the cavern crown. The first step in the paper is to briefly describe the site occurrences and accordingly present their indications for numerical modeling. The model inputs are then numerically examined and calibrated against the observations, which include in-situ stress regime in general, properties for both pre- and post-peak stages in the non-linear constitutive models to be employed. The numerical modeling for crown stability analysis is finally implemented. Extra attention is paid to the potential failure modes and severities, including the stress-induced failure resulting from the stress localization in the vicinity of Shear Zone C4, as well as potential ground falls governed by C4 and additional geological structures. The modeling results provide clear and solid indications for the ground support design, particularly in the required extra support element and applicable locations, in addition to the commonly-used pattern. [ABSTRACT FROM AUTHOR]

With the growing development of underground resources in the mining industry in China, stope stability has gradually become a research focus for extracting ores from large-scale mines in hard rock. Taking a given mine in China as an example, this paper introduces a procedure that helps optimize stope design by using a numerical approach in conjunction with an orthogonal regression method. As presented in the paper, this procedure starts with estimation of in-situ stress regimes and rock mass properties obtained through geological investigation. These data are used as inputted constants for numerical modeling with FLAC3D to analyze stope stabilities. The numerical modeling runs are set up based on the various assumptions of mining scenarios. Each scenario represents a combination of the four stope parameters including stope width, stope length, pillar width, and panel size. The setting of all these scenarios follows the orthogonal regression theory. Four indexes of maximum tensile stress, maximum compressive stress, sum of yielding area, and sum of area in tension are selected and employed as criteria to comprehensively evaluate the stope stability corresponding to each mining scenario. As a result, a statistic relation between stope parameters and stop stability has been established according to the modeling results. Such a relation is further used to calculate an optimized stope design, involving a set of stope parameters that can minimize the impact on stope stability among all assumptions. [ABSTRACT FROM AUTHOR]

Referring to the principal of the PSC Model developed by Potyondy in PFC, a constitutive model named SC Model was previously developed by the authors for FLAC3D to describe the cracking propagation behavior of brittle rock at engineering scale. This model had been validated against the monitoring data collected at the early stage (by 2009) of construction period of time at the Jinping II Deep Tunneling Project site. The model had been applied to the study of occurrence of a ground damage zone increasing over time as well as the ground support requirement and effectiveness to control such response. This paper presents the further validation of the SC model using the updated monitoring data at the time by the year of 2012. The further-verified SC Model is then used to examine the safety of the proposed ground support system including rock bolts, and particularly the concrete lining, over the operation life time. The model indicates the long-term stability can be ensured after taking into account the extra load applied to the support, resulted from crack propagation of the surrounding rock. [ABSTRACT FROM AUTHOR]

The reasonable estimate of rock mass properties is fundamental to the stability analysis and safety assessment in engineering practice. One of the challenges in property estimation is derived from scale-effect of rock mass behaviours. This paper presents a case study of the scale-effect of rock mass properties considering stochastic joints. During this study, joints samples are firstly collected on the Baiyunbo Eastern Iron Open-pit in Inner Mongolia, China, by means of a scanline method. Laboratory tests have been carried out to obtain properties of both intact rock and joints. The joint samples are then further processed using Monte-Carlo theory to generate a computerized 3D joint network. The three dimensional discrete element code, 3DEC, is finally employed to construct a number of rock mass specimens with various sizes for the attempt to conduct numerical tests at different confinements. During the numerical triaxial tests, the Coulomb-slide model is assigned to joints and the intact block is assumed to follow the strain-softening law. A number of completed stress-strain curves are obtained and each of the curves corresponds to one particular numerical test on a given size of specimen and at a given confinement. As a result, the diversity among the curves corresponding to different specimen sizes represents the influence of specimen sizes on rock mass behaviours. The numerical tests show that, for the dolomite at this particular mine site, the properties obtained from the specimen with the volume of 15 m × 15 m × 15 m are considered most representative and are thus suggested for future use in stability analysis. [ABSTRACT FROM AUTHOR]

Pile loading capacity can be affected by the reduction of effective stress due to the mobilization of excess pore pressure while driving and penetrating a pile into soil that squeezes the surrounding soil. Based on the cylindrical cavity theory and the excess pore pressure theory, this paper firstly introduces four optional approaches that can generate excess pore pressures with FLAC. Each approach is then examined through the assessment of the distribution of numerically generated excess pore pressures, as well as the comparison against the corresponding analytical calculation results. The most suitable approach can thus be identified. The studies show that, for the cylindrical cavity expansion mode in plane-strain, the elastic-plastic model considering cavity expansion and fluid-flow presents a reasonably good agreement with analytical solutions and thus seems the most applicable. The radial expansion approach appears to be the most suitable for the axisymmetric expansion mode, although the radial deformation boundary approach and the pile penetration approach may also apply. [ABSTRACT FROM AUTHOR]