The idea of Green quasifunction method is clarified in detail by considering bending of simply-supported trapezoidal shallow spherical shells. A Green quasi-function is established by using the fundamental solution an...
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The idea of Green quasifunction method is clarified in detail by considering bending of simply-supported trapezoidal shallow spherical shells. A Green quasi-function is established by using the fundamental solution and boundary equation of the problem. This function satisfies the homogeneous boundary condition of the problem. The differential equation of the bending problem of simply-supported trapezoidal shallow spherical shells is reduced to two simultaneous Fredholm integral equations of the second kind by Green formula. There are multiple choices for the normalized boundary equation. Based on a chosen normalized boundary equation, a new normalized boundary equation can be established such that the singularity of the kernel of integral equations is overcome. Finally, the radial deflection of shell is obtained by the numerically discrete algebraic equations derived from the integral equations. Numerical results show high accuracy of the Green quasifunction method.
The idea of quasi-Green＇s function method is clarified by considering a free vibration problem of the simply-supported trapezoidal shallow spherical shell. A quasi- Green＇s function is established by using the funda...
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The idea of quasi-Green＇s function method is clarified by considering a free vibration problem of the simply-supported trapezoidal shallow spherical shell. A quasi- Green＇s function is established by using the fundamental solution and boundary equation of the problem. This function satisfies the homogeneous boundary condition of the prob- lem. The mode shape differential equations of the free vibration problem of a simply- supported trapezoidal shallow spherical shell are reduced to two simultaneous Fredholm integral equations of the second kind by the Green formula. There are multiple choices for the normalized boundary equation. Based on a chosen normalized boundary equa- tion, a new normalized boundary equation can be established such that the irregularity of the kernel of integral equations is overcome. Finally, natural frequency is obtained by the condition that there exists a nontrivial solution to the numerically discrete algebraic equations derived from the integral equations. Numerical results show high accuracy of the quasi-Green＇s function method.
The idea of Green quasifunction method is clarified in detail by considering a free vibration problem of simply-supported trapezoidal shallow spherical shell on Winkler foundation.A Green quasifunction is established ...
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The idea of Green quasifunction method is clarified in detail by considering a free vibration problem of simply-supported trapezoidal shallow spherical shell on Winkler foundation.A Green quasifunction is established by using the fundamental solution and boundary equation of the *** function satisfies the homogeneous boundary condition of the *** mode shape differential equation of the free vibration problem of simply-supported trapezoidal shallow spherical shell on Winkler foundation is reduced to two simultaneous Fredholm integral equations of the second kind by Green *** are multiple choices for the normalized boundary *** on a chosen normalized boundary equation, the irregularity of the kernel of integral equations is ***, natural frequency is obtained by the condition that there exists a nontrivial solution in the numerically discrete algebraic equations derived from the integral *** results show high accuracy of the Green quasifunction method.
The field test of comprehensive psychological measuration scale for safety behavior to 237 miners of different work types was carried out, so knowledge system about miner safety behavior indexes were constituted. By t...
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According to the demands of safety standardization in metallic and non-metallic opencast mines and the demands of safety production and management in mining enterprises, it analyses the elements of safety standardizat...
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According to the demands of safety standardization in metallic and non-metallic opencast mines and the demands of safety production and management in mining enterprises, it analyses the elements of safety standardization system in mine and their PDCA running mode and proposes the establishing process of the system. Based on the philosophy of mining safety standardization and modern safety management, it develops “modern safety management system” which is mainly used in opencast mines using B/S mode, deeply analyses the function and advantages of the system, and finally elaborates its application way and effect briefly.
Smoldering is an oxygen control reaction and its velocity is determined by oxygen supplying rate. Oxygen volume fraction gradient was used to characterize oxygen supplying rate in roadway according to situation that t...
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Smoldering is an oxygen control reaction and its velocity is determined by oxygen supplying rate. Oxygen volume fraction gradient was used to characterize oxygen supplying rate in roadway according to situation that the velocity of wind flowing is very low during smoldering in roadway. Relationship of smoldering velocity and oxygen volume fraction gradient in roadway during lignite smoldering was researched in experiment drawing support of seam smoldering simulating experiment device in roadway and one-variable linear regression technology was used to establish the relation equation of smoldering velocity and oxygen volume fraction gradient in roadway when lignite was smoldering. This relation equation showed that smoldering velocity and oxygen volume fraction gradient took on linear increasing relationship in roadway during lignite smoldering.
As one geological disaster in the area of the Three Gorges Reservoir of China, perilous rocks dominate stability of slopes in the area. Most cliffs or steep slopes are alternately composed of inflexib
As one geological disaster in the area of the Three Gorges Reservoir of China, perilous rocks dominate stability of slopes in the area. Most cliffs or steep slopes are alternately composed of inflexib
Taking the heading face of a coal mine as an example, the test of deep-hole pre-splitting blasting was processed. The amount of gas draining after pre-splitting was compared to the amount of direct drainage, and the e...
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Taking the heading face of a coal mine as an example, the test of deep-hole pre-splitting blasting was processed. The amount of gas draining after pre-splitting was compared to the amount of direct drainage, and the effective radius of drainage was surveyed. The test results showed that the drainage rate of K 1 coal seam reached 37.13%, which reduced the drainage time by 60%, 10 days after pre-splitting, and the gas desorption index exceed the standards until the fifth blasting. The drainage rate of K 4 needed 12 days to reach 34.28%, which reduced the drainage time by 60%, and the gas desorption index exceed the standards when the third blasting processed. Obviously, the effect of gas drainage was improved by pre-splitting blasting. The effective drainage radius of K 1 and K 4 were 4.5 m and 5.2 m respectively after pre-splitting blasting.
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.
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