2 edition of Analysis of pervious high pressure tunnels using boundary and finite elements found in the catalog.
Analysis of pervious high pressure tunnels using boundary and finite elements
Zhao kang Lu
Thesis (M.Phil.) - University of Portsmouth, 1995.
individual element. A in thick slab could still be modeled using plate elements providing that the plan dimensions of the slab were greater than ft. Two of the potential problem areas in the use of thin plate elements in the analysis of pressure vessels are the assumption of a linear stress distribution and the lack of shear deformation. In this paper, using the finite difference method by the FLAC software, the analysis of Sardasht dam water tunnel which has been filled with mineral pumice in falling zones has been carried out. Results indicate that by increasing the falling zone thickness while the lining is porous or non-porous, the inner forces are decreased.
Keywords: Rock tunnel, Weak rock layer, Explicit finite element analysis, Stability 1. Introduction The empirical method and the numerical analysis method are two main methods to analyze the stability of the tunnel surrounding rock mass at present. The empirical method is to mainly qualitatively analyze the stability of tunnel. the tunnel axis and the pile axis, W, is one tunnel diameter W=D, i.e., the minimum possible distance between the vertical pile axis and the tunnel wall is m D. Finite-Element Analysis of Soil Movements The ﬁrst step in this analysis of tunnel-pile interaction is to pre-dict the elastic free-ﬁeld soil displacements induced by a tunnel-.
Tunnel face Figure 3: Phase2 finite element model of an advancing tunnel face represented by a vertical section along the tunnel axis. No support is installed within 3 m of the face and tractions are applied to the tunnel boundary to represent increasing support pressures behind the face. Surface subsidence Deformed boundary. approach. The aim of this paper is to describe the modelling of a tunnel construction in a 2D approach using different methods. Previously a brief introduction in the finite element method principle and the most common used finite elements in a tunneling construction simulation will be discussed. Rezumat.
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New design criteria for pervious pressure tunnels are recommended. the tunnel was modeled, using acoustic elements that are capable of simulating the hydrodynamic forces.
in Abaqus Finite. The areas have been determined using tunnel pressure calculations made using the AEROTUN/4 one-dimensional characteristics program, an earlier version of THERMOTUN (ThermoTun Online, ).
Tunnel areas are provided for a range of tunnel and train parameters for single- and double-bore tunnels. The hydraulic tunnel with high internal water pressure is investigated using the coupled finite element method.
The reinforced concrete lining would crack under the effect of internal pressure and afterward, the inner water flows out along the cracks. The seepage forces give a load on the lining and surrounding by: 9.
Design of Pressure Tunnels Using a Finite Element Model Article (PDF Available) in International Journal on Hydropower and Dams 19(5) October with Reads How we measure 'reads'.
Ahmadi et al. () presented a model using Schleiss technique () within the FEM framework for the stability analysis and the optimum design of pressure tunnels.
The researchers explained that to enhance the safety, an increase in the reinforcing percentages is more effective than the increase in the lining by: 2.
UNDRAINED TUNNEL HEADING USING FINITE ELEMENT LIMIT ANALYSIS A dissertation submitted by scenarios with either a surcharge or internal tunnel pressure applied. The results obtained Mesh view of a model with boundary conditions and a fixed distributed pressure.
Using finite element method (FEM) and the Schleiss technique, a detailed study on the design of a pressure tunnel lining in a real construction situation with different conditions is performed. The behavior of a tunnel face reinforced with longitudinal pipes was investigated using a 3D finite-element model.
A series of 3D finite-element analyses were performed on a wide range of boundary conditions by varying the tunnel cover depth (C / D), the ground condition, and the reinforcement layout such as the density (number), length, and.
This journal is specifically dedicated to the dissemination of the latest developments of new engineering analysis techniques using boundary elements and other mesh reduction methods. Boundary element (BEM) and mesh reduction methods (MRM) are very active areas of research with the techniques being applied to solve increasingly complex problems.
The FE model, shown schematically in Fig. with boundary conditions, consists of both finite and infinite elements and the infinite elements are assumed to be elastic elements used as non-reflecting boundaries.
Eight-node finite elements can undergo non-linearity with large deformation to cope with high-pressure impact.
A pressure tunnel with an inner diameter of m was modeled in Abaqus Finite Element Analysis (FEA), using the finite element method (FEM).
analysis of cracked elements of the surrounding. High-head schemes can now incorporate pressure tunnels with an internal pressure up to m and shafts up to m and this poses extreme stresses on the linings.
Dynamic response of concrete lining structure in high pressure diversion tunnel under seismic load is of great importance for engineering design and safety assessment. In light of the basic idea of static damage constitutive in strain space, a dynamic damage and cracking model of concrete suitable for programming is established.
Based on the explicit finite element method for analyzing the. boundary in case of d while the modeling becomes complex to solve in case of 4d. Therefore the optimum dimension is considered as 3 times the diameter on all sides. During the model generation, the bottom end of the tunnel is fixed, while the sides and faces are provided with roller support.
Fig. Tunnel grid with finite element mesh. using a three-dimensional finite element simulation model for shield-driven tunnel excavation. A Cam-Clay plasticity model is used to describe the material behaviour of cohesive soils. Shalabi () investigated ground movement and contact pressure on the lining of Stillwater Tunnel (Utah, USA) using axisymmetirc finite element analysis.
The upper-bound solutions with critical load parameters for a practical range of tunnel depth-to-height values, as well as the soil properties, are obtained by using the Upper-bound Finite Element Method with Rigid Translatory Moving Elements (UBFEM-RTME).
For practical use, the results are presented in the form of dimensionless stability charts. Finite element analysis is carried out using the mesh presented in Fig. 2(a). The finite element mesh is adopted in the analysis.
The finite element mesh was 60 m long, 60 m high, and m wide. It consisted of elements and nodes. Eight-noded brick elements and four-noded shell elements were used to.
A pressure tunnel with an inner diameter of m was modeled in Abaqus Finite Element Analysis (FEA), using the finite element method (FEM). It was assumed that transient pressures occur inside the tunnel due to control gate closure in a hydroelectric power plant, downstream of the tunnel, in three different closure modes: fast (14 s), normal.
Groundwater can cause many hazardous problems when a tunnel is excavating. Seepage force acting on the support structure and the tunnel surface cannot be negligible. Under high groundwater table condition, the seepage situation becomes more complex and it is more difficult to control the leakage of groundwater to flow into a tunnel.
In the paper, a multiple times grouting method is proposed. The paper high lights the elastic and elasto-plastic analysis of the twin tunnel system subjected to gravity, hydrostatic pressure conditions combined with blast induced pressures. The intention is to study the blast effects of a terror-attack on the tunnel system, by simulating a pressure wave and study the effects on neighboring tunnels for.
The procedure of analysis and design of pervious high pressure tunnel is as follows: 1) The analysis of the instrumentation data from water filling of the 1st stage of GP-SPS(MW), and definition of the boundary condition of seepage field in rockmass; 2) In accordance with geological condition, the determination of anisotropic perme-ability.using the 2-D finite element analysis.
Ground movement and construction influence are obtained by the nmerical u model. Several tunnels have been constructed around the world and in Egypt to solve the transportation problems such as the Greater Cairo metro and the El-Azhar road tunnels are considered as major projects in Cairo city.In numerical simulations, attention is usually restricted to a finite region.
Then an artificial boundary condition is needed to make the computational domain finite. In addition, for computational efficiency, it is desirable to minimize the number of elements in a finite-element analysis, by minimizing the size of the discretized region.