As one geological disaster in the area of the Three Gorges Reservoir of China, perilous rocks dominate stability of slopes in the areaMost cliffs or steep slopes are alternately composed of inflexible rock such as san...
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As one geological disaster in the area of the Three Gorges Reservoir of China, perilous rocks dominate stability of slopes in the areaMost cliffs or steep slopes are alternately composed of inflexible rock such as sandstone and soft rock such as mudstone in the area, and due to different weathering velocities rock cells in soft rock below inflexible rock are usually developedAny perilous rock belongs to a part of inflexible rockTo appraise the safety of perilous rock, it is essential to approach duration for perilous to form is of interestIn the present paper, authors analyze weathering velocity of rock cell and establish method to calculate length of critical rock cellDuration for perilous rock to form can be divided into three parts,(1) duration to form critical rock cell,(2) damage duration of control fissure, and(3) fracture duration of control fissureFurther, methods to calculate these durations are established in details based on damage mechanics and fracture mechanics.
In this paper, the peeling behavior and the spalling resistance effect of carbon fiber reinforced polymer （CFRP） sheets externally bonded to bent concrete surfaces are firstly investigated experimentally. Twenty one...
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In this paper, the peeling behavior and the spalling resistance effect of carbon fiber reinforced polymer （CFRP） sheets externally bonded to bent concrete surfaces are firstly investigated experimentally. Twenty one curved specimens and seven plane specimens are studied in the paper, in which curved specimens with bonded CFRP sheets can simulate the concrete spalling in tunnel, culvert, arch bridge etc., whereas plane specimens with bonded CFRP sheets can simulate the concrete spalling in beam bridge, slab bridge and pedestrian bridge. Three kinds of curved specimens with different radii of curvature are chosen by referring to practical tunnel structures, and plane specimens are used for comparison with curved ones. A peeling load is applied on the FRP sheet by loading a circular steel tube placed into the central notch of beam to debond CFRP sheets from the bent concrete surface, meanwhile full-range load-deflection curves are recorded by a MTS 831.10 Elastomer Test System. Based on the experimental results, a theoretical analysis is also conducted for the specimens. Both theoretical and experimental results show that only two material parameters, the interfacial fracture energy of CFRP-concrete interface and the tensile stiffness of CFRP sheets, are needed for describing the interfacial spalling behavior. It is found that the radius of curvature has remarkable influence on peeling load-deflection curves. The test methods and test results given in the paper are helpful and available for reference to the designer of tunnel strengthening.
Gas Station safety is non-linear systems that refer to many factors and multilayer. There are much flammable and explosive compressed natural gas in gas station, and it is considered as a kind of major hazard source. ...
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Gas Station safety is non-linear systems that refer to many factors and multilayer. There are much flammable and explosive compressed natural gas in gas station, and it is considered as a kind of major hazard source. Therefore, the safety assessment of gas station has their special important and realistic significance. Based on the types of accident and risk factors, a new index system of safety assessment was set up. The weight of the evaluation index would be analyzed by analytic hierarchy process, and then the matrix of evaluating results could be calculated through fuzzy comprehensive evaluation. At last, the grade of safety for gas station could be obtained. This Safety Assessment Model can be applied for every gas station.
Gas Station safety is non-linear systems that refer to many factors and multilayer. There are much flammable and explosive compressed natural gas in gas station, and it is considered as a kind of major hazard source. ...
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Gas Station safety is non-linear systems that refer to many factors and multilayer. There are much flammable and explosive compressed natural gas in gas station, and it is considered as a kind of major hazard source. Therefore, the safety assessment of gas station has their special important and realistic significance. Based on the types of accident and risk factors, a new index system of safety assessment was set up. The weight of the evaluation index would be analyzed by analytic hierarchy process, and then the matrix of evaluating results could be calculated through fuzzy comprehensive evaluation. At last, the grade of safety for gas station could be obtained. This Safety Assessment Model can be applied for every gas station.
One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solut...
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One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solution of the transient temperature field in the coke drum is obtained, which is different from the known FEM results. The length of the coke drum is considered finite. The dynamic boundary conditions caused by fluid uninterrupted rising in oiling and watering stages are simulated with the iteration method. Numerical results show that the present theoretical model can accurately describe basic features of the transient temperature field in the coke drum. Effects of the geometry of the coke drum and the rising velocity of quench water on the axial temperature gradient are also discussed.
To address the problem of subdividing inflexible rectangular grid models and their poor definition of velocity interfaces, we propose a complex structure triangular net for a minimum traveltime ray tracing global algo...
To address the problem of subdividing inflexible rectangular grid models and their poor definition of velocity interfaces, we propose a complex structure triangular net for a minimum traveltime ray tracing global algorithm. Our procedure is: (1) Subdivide a triangle grid based on the Delaunay triangular subdivision criterion and the relationships of the points, lines, and the surfaces in the subdividing area. (2) Define the topology relationships and related concepts of triangular unit ray tracing. (3) The source point and wave arrival points at any time compose the propagating plane wave and the minimum traveltime and secondary source positions are calculated during the plane wave propagation. We adopt the hyperbolic approximation global algorithm for secondary source retrieving. (4) By minimum traveltime ray tracing, collect the path from receiver to source points with the neighborhood point’s traveltime and the direction of the secondary source. Numerical simulation examples are given to test the algorithm. The results show that the triangular net ray tracing method demonstrates model subdivision flexibility, precise velocity discontinuity interfaces, and accurate computations.
The energy changes in the processes of coal and gas outbursts were studied using the principle of energy conservation. The stress conditions, potential energy of elastic deformation were analyzed when digging distance...
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The energy changes in the processes of coal and gas outbursts were studied using the principle of energy conservation. The stress conditions, potential energy of elastic deformation were analyzed when digging distance was L. The released work from the accumulated internal energy of coal gas was specially studied. Also the energy used to throw the fragments of the coal, fracturing energy and kinetic energy of the gas were investigated, and the energy condition for coal and gas outburst was obtained. Took the 2nd mining area in Huachu Coal Mine of Guizhou Province as an example, studied the energy conditions of outburst. The results show that gas internal energy which is the main energy source for the outburst is bigger than potential energy of elastic deformation. An outburst with less critical gas content is more likely to happen in the following conditions: The higher stress in coal seam is, The smaller Protodyakonov coefficient is. Under the stress level in certain circumstances, outburst will happen with little critical gas content after the long digging distance. The influence of coal seam thickness for the critical gas content in outburst is not obvious.
Geological conditions in front of the tunnel is complex and changeable, in the kasrst zone, the geological disaster, such as water inrush, cave and collapse often occur in the tunnel construction, which make a serious...
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Geological conditions in front of the tunnel is complex and changeable, in the kasrst zone, the geological disaster, such as water inrush, cave and collapse often occur in the tunnel construction, which make a serious impact on the safety of the tunnel construction, progress, economic benefits. In order to guarantee the safety, geological prediction must be carried out in tunnel Construction. This paper mainly introduces principle, data processing of TGP206 tunnel geological prediction system and its several application in prediction for Zhongxing tunnel. Through analyzing the reflected signals in the karst area, it can accurately predict the rock parameters as well as the location of the cave in front of the tunnel. It is a guiding significance for tunnel geological prediction in similar geological conditions to prove the correctness and feasibility of theory and techniques of the system.
Introduce the principles of Support Vector Machines, and indicate the broken zone thickness can be forecasted by four factors: rock strength, joint coefficient, buried depth and span length. The results show that Supp...
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Introduce the principles of Support Vector Machines, and indicate the broken zone thickness can be forecasted by four factors: rock strength, joint coefficient, buried depth and span length. The results show that Support Vector Machine (SVM) is a reliable method to predict broken zone thickness, and the predictive values agree well with the verify data.
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