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15 April 2015, Volume 37 Issue 2
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    2015, 37(2):  243-244.  doi:10.6052/1000-0879-14-013
    Abstract ( 502 )   PDF (213KB) ( 604 )  
    2015, 37(2):  245-248,244.  doi:10.6052/1000-0879-13-531
    Abstract ( 557 )   PDF (1730KB) ( 846 )  
    HORST FAULT ROCKBURST ANALYSIS BASED ON SHEAR BEAM THEORY
    ZHU Xiaojing, PAN Yishan, TANG Zhi, WANG Shijuan
    2015, 37(2):  182-188,213.  doi:10.6052/1000-0879-14-182
    Abstract ( 359 )   PDF (977KB) ( 701 )  

    In order to simulate the rockburst induced by the horst combination fault instability and to obtain the analytical solution for the roof equilibrium structure in the horst combination fault influence areas, the roof is simplified into a shear beam model. Based on the elastic shear beam model, the position of the maximum equivalent shear in the roof is determined and the computational formula for the roof's first caving step is obtained. The roof equivalent shear increases with the increase of the span of the gob.The first weighting takes place when the equivalent shear reaches the top limit, and the roof fracture location appears in the interior of the coal seam. The first weighting and the periodical weighting of the roof in the stope are analyzed. In the stope, horst faults are found. And the elastic-plastic shear beam model is used in the analysis. which shows that horst faults may exist in the stope.The faults will slip, the energy will be released and the mine tremor will occur, when the maximum equivalent shear reaches the shear limit of the faults.

    2015, 37(2):  276-281.  doi:10.6052/1000-0879-14-394
    Abstract ( 773 )   PDF (3714KB) ( 929 )  
    2015, 37(2):  282-286.  doi:10.6052/1000-0879-14-395
    Abstract ( 408 )   PDF (2530KB) ( 865 )  
    2015, 37(2):  161-170,181.  doi:10.6052/1000-0879-14-106
    Abstract ( 913 )   PDF (1035KB) ( 1119 )  

    The development of damage detection methods and safety monitoring technology of bridge are analyzed and summarized, and the existing methods are classified. The five major challenges and problems of the current existing methods in the application and research are also analyzed. Some hot research issuesdeveloped recently are further discussed. Then, some suggestions and the direction of the next research work are put forward, and the idea that using big data method to deal with bridge safety monitoring is also put forward, hoping that these ideas can inspire the researchers in the future research work.

    2015, 37(2):  171-181.  doi:10.6052/1000-0879-14-110
    Abstract ( 600 )   PDF (466KB) ( 1288 )  
    The dynamic model reduction is an important technology in the structural dynamic analysis. In this paper, various features of the model reduction methods are discussed and compared, which are commonly used in dynamic analysis of complicated structures. Some suggestions are made for the future researches.
    2015, 37(2):  189-192.  doi:10.6052/1000-0879-14-170
    Abstract ( 394 )   PDF (955KB) ( 481 )  
    Based on the relationship between the support and the surrounding-rock in a fully-mechanized sublevel caving face, a model for calculating the support load during cyclic weighting is built, and the formula for calculating impact load on the support during cyclic weighting is obtained based on the principle of the three-hinged arch balance. The model and the formula are applied to the no.1306 working face, and it is shown that the impact load on the support during cyclic weighting is 7190 kN, and the support load during cyclic weighting is 13300 kN. According to the measured results, the support load during cyclic weighting is 13110 kN. The effectiveness of the model for calculating the support load during cyclic weighting in the fully-mechanized sublevel caving face is thus verified. The method can be used for the support selection and the support load calculation during cyclic weighting in the fully-mechanized sublevel caving face.
    THE MECHANISM OF THE NEW-TYPE YIELDING BOLT
    GUO Yongjian, JIANG Fei, ZHOU Hao, XIANG Xiaozhen
    2015, 37(2):  193-196,237.  doi:10.6052/1000-0879-14-210
    Abstract ( 394 )   PDF (1767KB) ( 791 )  
    The soft rock project with large deformation is characteristic of large stress released in the excavation and of large deformation in the construction process. Using the traditional rock bolt support, the large deformation of the rock mass may lead to a large tension, and make the rock bolt fracture. A new-type yielding bolt for soft rock projects with large deformation is proposed in this paper. This yielding bolt is a pressure dispersion-type yielding bolt, and contains a yield supporting device at the bottom of the bolt. The supporting mechanism of the yielding bolt includes three stages, and the yield force value is determined by experiments. The yielding bolt not only disperses the stress in the anchoring body, but also generates a yield deformation, so it could be applied to soft rock projects with large deformation.
    2015, 37(2):  197-204.  doi:10.6052/1000-0879-14-164
    Abstract ( 444 )   PDF (1147KB) ( 657 )  
    A 1/n part of the n-fold axisymmetrical Levy dome is equivalent to a statically indeterminate truss with one redundant degree. The methods to obtain the forces and the displacements of the struts in different radial directions are put forward, as well as the equations to calculate the constraint force. The displacement transfer matrix and the equation are derived. An example is given and the results are compared with those obtained by the FEM.
    ANALYSIS AND MANUFACTURE OF HANGING ECCENTRIC QIQI
    XU Jian, WANG Min, QI Xiaoli, WU Zongpengy
    2015, 37(2):  205-209.  doi:10.6052/1000-0879-14-077
    Abstract ( 972 )   PDF (3813KB) ( 1017 )  
    To make a qiqi of a simple structure that can be easily processed, an eccentric design is proposed, and MATLAB and Pro/E are used to establish the mathematical model and the 3D solid model. The position of the center of gravity of the qiqi is simulated on this basis, and the feasible hanging region concept is proposed. The impact of several important structure parameters on the size of the feasible hanging region is analyzed, the qiqi can thus be designed with related parameters optimized. The real qiqi is manufactured, and the experiment confirms the desired effect.
    2015, 37(2):  210-213.  doi:10.6052/1000-0879-14-102
    Abstract ( 725 )   PDF (16070KB) ( 452 )  
    High-place operation basket is used to support the operations of decorating outer walls of high-rise buildings. Hanging suspension machine of the basket is a steel structure set up on the top of high building to support overhanging platform and to bear designed load through the steel wire rope. Based on the mechanical analysis of the hanging suspension machine of the basket, the issues on lever balance, rational design of the strength of member bar and safety assessment are studied for a simple model, a compound rods. This kind of popular issues in reality could be good examples for basic education of mechanics and used as project for students' design course to improve their academic abilities like deeper observation, independent thoughtcreation, comprehensive knowledge utilization to ana-lyze and solve practical problems.
    THE EXTENDED FINITE ELEMENT METHOD BASED ON THE STATE VECTOR
    XU Jianxin1, CAO Xuan, QING Guanghui
    2015, 37(2):  214-217,226.  doi:10.6052/1000-0879-14-203
    Abstract ( 421 )   PDF (806KB) ( 547 )  
    The displacement field and the stress field are computed by a semi-analytical method based on the Hamilton canonical equation, and the results are found very satisfactory. But when the tip field is considered, the tip field must be more finely meshed. Both the stiffness matrix and the stress field must be calculated anew when the crack propagates, which makes very low resolution efficiency. Based on the extended finite element method, the discontinuity of the crack could be taken care of, to avoid the re-meshing. In order to take a full advantage of the Hamilton system and the extended finite element method, this paper combines them to analyze the fracture problem, such as the calculation of the stress intensity factor and the simulation of the crack propagation. The results from the case analysis demonstrate that the method is feasible.
    2015, 37(2):  218-222,231.  doi:10.6052/1000-0879-14-146
    Abstract ( 371 )   PDF (1659KB) ( 709 )  
    This paper studies the relation between the non-parallel flow and the gradually varying flow in gradually contraction plates by numerical simulations. The influence of the incline angle of the plates on the flow is analyzed. According to the data obtained by means of the EXP(CES) mode, a one per cent relative deviation is seen between the non-parallel flow at the incline angle of 5.455° and the parallel flow, while one sees a ten per cent deviation at 13.26°. The angle of 5.455° corresponding to a one per cent deviation is regarded as the critical value of the gradually varying flow. The reasonability and reliability of the numerical simulation of the flow between gradually contraction plates are discussed at the end of the paper.
    2015, 37(2):  223-226.  doi:10.6052/1000-0879-14-155
    Abstract ( 544 )   PDF (449KB) ( 765 )  
    The bone has the ability to adapt to an altered mechanical environment. Through the analysis of the bone remodelling and based on the engineering strength design criteria, a mechanism of the bone remodelling with consideration of the load characteristics is proposed. The effect of the load characteristics on the mechanical stimulus is discussed and the bone formation of the alveolar bone in the area under a tensile stress and the bone resorption in the area under a pressure are analyzed and simulated. It is shown that the mechanism of bone remodelling with consideration of the load characteristics is reasonable and it can improve the mechanism of bone remodelling.
    2015, 37(2):  227-231.  doi:10.6052/1000-0879-14-191
    Abstract ( 421 )   PDF (1181KB) ( 721 )  
    The traditional four-pole stress sensors suffer some major drawbacks. The structural symmetry varies in different sensors, and their zero value at the zero point is difficult to be guaranteed. In this paper, a selfcompensation structure and a zeroing circuit are designed to solve these problems. With the self-compensation structure, the environmental variables are automatically compensated. By adopting in-phase series and using the voltage output between the middle contact point of the coils and the potentiometer sliding key, the value of the zero point is easily adjustable. The experimental results indicate that the zeroing circuit makes the adjustment of the zero point value easy. Moreover, the output of the sensor is linearly consistent with the theoretical simulation. Therefore, the uniaxial stress in the ferromagnetic materials can be determined accurately by the self-compensation structure sensor with the zero-value adjusting circuit.
    EXPERIMENTAL STUDY OF THE EFFECT OF PH VALUE ON MELTING RATE OF ICE
    WANG Yongyan, DU Xipeng, MENG Xiangrui
    2015, 37(2):  232-237.  doi:10.6052/1000-0879-14-162
    Abstract ( 419 )   PDF (3333KB) ( 1115 )  
    The winter snow, the deep soft rock rheological deformation on the roadway and the frost boiling of the plateau permafrost all bring about great inconvenience to our life and the construction. These phenomena are related to the transformation between solid and fluid. Therefore, the theoretical study of materials transformation between solid and fluid have important theoretical significance and application value. In this paper, the pH value is taken as the independent variable, and its effect on the ice melting rate is studied through the ice cube melting experiment. It is shown that with the increase of the pH value, the melting rate of the ice will slow down firstly and then increase. An empirical formula is obtained, which can describe the relationship between the pH value and the ice melting rate. Finally, a simulation analysis is carried out by using Fluent.
    2015, 37(2):  238-242.  doi:10.6052/1000-0879-15-032
    Abstract ( 825 )   PDF (371KB) ( 1110 )  
    2015, 37(2):  249-252.  doi:10.6052/1000-0879-14-207
    Abstract ( 664 )   PDF (278KB) ( 1200 )  
    2015, 37(2):  252-254.  doi:10.6052/1000-0879-14-045
    Abstract ( 885 )   PDF (408KB) ( 999 )  
    The virtual reality experiments in structural mechanics
    Ren Weijie, Li Chunlin, Song Weiyuan
    2015, 37(2):  257-262.  doi:10.6052/1000-0879-13-511
    Abstract ( 565 )   PDF (6635KB) ( 1175 )  
    2015, 37(2):  265-269.  doi:10.6052/1000-0879-15-050
    Abstract ( 753 )   PDF (505KB) ( 609 )  
    Seashell I: Science and art treasures
    Jiang Chiping, Chai Hui
    2015, 37(2):  270-272.  doi:10.6052/1000-0879-15-071
    Abstract ( 450 )   PDF (5697KB) ( 1188 )  
    Solitary waves and solitons
    Tang Shaoqiang
    2015, 37(2):  272-276.  doi:10.6052/1000-0879-15-066
    Abstract ( 413 )   PDF (10935KB) ( 2065 )