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Stability analysis of underground mining openings with complex geometry

Abstract

Stability of mining openings requires consideration of a number of factors, such as: geological structure, the geometry of the underground mining workings, mechanical properties of the rock mass, changes in stress caused by the influence of neighbouring workings. Long-term prediction and estimation of workings state can be analysed with the use of numerical methods. Application of 3D numerical modelling in stability estimation of workings with complex geometry was described with the example of Crystal Caves in Wieliczka Salt Mine. Preservation of the Crystal Caves reserve is particularly important in view of their unique character and the protection of adjacent galleries which are a part of tourist attraction included in UNESCO list. A detailed 3D model of Crystal Caves and neighbouring workings was built. Application of FLAC3D modelling techniques enabled indication of the areas which are in danger of stability loss. Moreover, the area in which protective actions should be taken as well as recommendations concerning the convergence monitoring were proposed.

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3D Numerical Model of the Spherical Particle Saltation in a Channel with a Rough Fixed Bed

3D Numerical Model of the Spherical Particle Saltation in a Channel with a Rough Fixed Bed

The paper describes a 3D numerical model of the spherical particle saltation. Two stages of particle saltation were distinguished — the particle free motion in water and the particle-bed collision. The particle motion consists of the translational and rotational particle motion. A stochastic method of calculation of the particle-bed collision was developed. The collision height and the contact point were defined as random variables. Impulse equations were used and the translational and angular velocity components of the moving particle immediately after the collision were expressed as functions of the velocity components just before the collision. The dimensionless coefficients of the drag force and drag torque were determined as functions of both translational and rotational Reynolds numbers. The model is in good agreement with known experimental data. Examples of calculation of the particles' lateral dispersion and the mean absolute values of the deviation angle of the particle trajectory are presented.

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Comparison of Experimentally Measured Deformation of the Plate on the Subsoil and the Results of 3D Numerical Model

References [1] CAJKA, R. & LABUDKOVA, J. Influence of parameters of a 3D numerical model on deformation arising in interaction of a foundation structure and subsoil. In: Proceedings of 1st International Conference on High-Performance Concrete Structures and Materials (COSTMA '13). Budapest, Hungary, December 10-12, 2013, ISSN 2227-4359, ISBN 978-960-474-352-0. [2] CAJKA, R. & LABUDKOVA, J. Dependence of deformation of a plate on the subsoil in relation to the parameters of the 3D model. International Journal of Mechanics, 2014

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3D Numerical Modeling of Large Piled-Raft Foundation on Clayey Soils for Different Loadings and Pile-Raft Configurations

.1061/(ASCE)1090-0241(2006)132:12(1600) Sanctis L, D. Mandolini A. 2006 “Bearing capacity of the piled rafts on soft clays.” Journal of Geotechnical and Geoenvironmental Engineering 132 1600 1610 [22] Sinha, A., and Hanna A., M. (2016). “3D Numerical model for piled raft foundation.” International Journal of Geomechanics org/10.1061/(ASCE)GM.19435622.0000674 Sinha A. Hanna A. M. 2016 “3D Numerical model for piled raft foundation.” International Journal of Geomechanics org/10.1061/(ASCE)GM.194356220000674 [23] Viggiani, C. (2001

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Numerical and physical modeling of water flow over the ogee weir of the new Niedów barrage

Abstract

In this paper, two- and three-dimensional numerical modeling is applied in order to simulate water flow behavior over the new Niedów barrage in South Poland. The draining capacity of one of the flood alleviation structures (ogee weir) for exploitation and catastrophic conditions was estimated. In addition, the output of the numerical models is compared with experimental data. The experiments demonstrated that the draining capacity of the barrage alleviation scheme is sufficiently designed for catastrophic scenarios if water is flowing under steady flow conditions. Nevertheless, the new cofferdam, which is part of the temporal reconstruction works, is affecting the draining capacity of the whole low-head barrage project.

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Investigation of seasonal thermal flow in a real dam reservoir using 3-D numerical modeling

Abstract

Investigations indicate that correct estimation of seasonal thermal stratification in a dam reservoir is very important for the dam reservoir water quality modeling and water management problems. The main aim of this study is to develop a hydrodynamics model of an actual dam reservoir in three dimensions for simulating a real dam reservoir flows for different seasons. The model is developed using nonlinear and unsteady continuity, momentum, energy and k-ε turbulence model equations. In order to include the Coriolis force effect on the flow in a dam reservoir, Coriolis force parameter is also added the model equations. Those equations are constructed using actual dimensions, shape, boundary and initial conditions of the dam and reservoir. Temperature profiles and flow visualizations are used to evaluate flow conditions in the reservoir. Reservoir flow’s process and parameters are determined all over the reservoir. The mathematical model developed is capable of simulating the flow and thermal characteristics of the reservoir system for seasonal heat exchanges. Model simulations results obtained are compared with field measurements obtained from gauging stations for flows in different seasons. The results show a good agreement with the field measurements.

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Non–Destructive Testing of Conductive Material by Eddy Current Air Probe Based on Swept Frequency

Abstract

This article deals with non-destructive testing of conductive materials by eddy current method based on swept frequency. A 2D numerical model of eddy current air-core probe was created in the LTspice software at first. The probe consists of two coils: exciting coil and receiving. The probe is positioned in air in this case. Experimental and calculated frequency responses of the probe are obtained within a wide frequency range using swept frequency in order to validate the model. Frther a 3D model used for non-destructive testing of austenitic steel plate with three electro-discharge machined notches is then developed accordingly. Results of measurement are compared with 3D numerical model using COMSOL Multiphysics software.

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Application of HDMR method to reliability assessment of a single pile subjected to lateral load

Abstract

The paper presents an application of High Dimensional Model Representation (HDMR) to reliability assessment of a single pile subjected to lateral load. The purpose is to compare HDMR with some classical method based on response surface technique.

First 3D numerical model of the problem for finite elements computations in the ABAQUS STANDARD program has been presented. The soil model is assumed to be linear elastic. However, contacts between the sidewall and the foundation of the pile and the soil are modelled as Coulomb one with friction and cohesion.

Next the Response Surface Method is briefly reviewed in conjunction with reliability approach.

Then the High Dimensional Model Representation approach is presented. In our approach the HDMR algorithm is based on polynomial of the second degree. Finally the numerical studies have been carried out. The first series of computations demonstrate the efficiency of HDMR in comparison to neural network approach. The second series allows comparison of reliability indices resulting from three different approaches, namely neural network response surface, first-order HDMR and second-order HDMR. It has been observed that for increasing values of the length of the pile reliability indices reach similar values regardless of the method response surface applied.

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Monitoring and Numerical Modeling of a Road in Landslide Terrain

Abstract

Due to the significant role and noticeable development of transportation routes running from the north to the south of central Europe, several problems related to the construction and functioning of roads in the Carpathian foothills have been revealed. Recent climate change causes areas, where transport routes are particularly exposed to hazards, to succumb to technical exploitation and degradation. The elimination of the threats related to the activation of landslide phenomena becomes particularly expensive. Old roads, which were once designed for significantly lower axle loads and less heavy traffic conditions, are predominantly exposed. At the present, these roads are heavily exploited and have become overloaded. As a result, both the roadway and the subgrade undergo damage, which causes an increase in dynamic loads, and in potentially endangered areas, the activation of landslides. Landslides in the Carpathian flysch have a peculiar susceptibility to activation due to its geological structure. This paper addresses the problem of monitoring and analysing the effects of a landslide associated with the operation of a transportation route running through the slope of the Carpathian flysch. The studies include both field work and laboratory testing of basic geotechnical parameters. The parameters obtained during the geotechnical investigations, conducted for the purpose of building a numerical model, have been completed. The field work includes surveys made by a terrestrial laser scanner. The study also includes a number of 2D and 3D numerical models. These models, along with the substrate parameters, have been introduced into the FEA package and then calibrated. Subsequently, an analysis of the effects of landslide susceptibility and the behaviour of the road and terrain surface, due to the different variants of the loads, is shown along with the results of surveys.

Open access
Numerical model of spherical particle saltation in a channel with a transversely tilted rough bed

rough bed. Proc. Engineering Mechanics 2003, Svratka (Czech Republic), 12-15 May 2003, (CD ROM, 7 pages). LUKERCHENKO N., CHARA Z., VLASAK P., 2004: 3D Numerical model of particle-bed collision in particle-laden flow in channel with rough bed. Proc. 12 th Int. Conf. on Transport & Sedimentation of Solid Particles, Prague (Czech Republic), 20-24 September 2004, pp. 493-499. LUKERCHENKO N., CHARA Z., VLASAK P., 2006: 2D Numerical model of particle-bed collision in fluid-particle flows over bed. J. Hydraul. Res. , 44

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