Applied Mechanics and Materials Vols. 353-356

Abstract: According the analysis of the test in Baiping coal mine, obtain the characteristics of deformation and failure in three-soft seam roadway; get the exact data of roadways main deformation parameters and make sure the main deformation region division. By using the theory of equilibrium arch, analyze and finally determine bolt (cable) support attached with U shaped tents parameters. On-site tests show that this kind of support scheme can effectively control the deformation in three-soft seam roadway.

Abstract: when high-speed train passing through tunnel, the micro-pressure wave noise will be created at tunnel exit, which worsening the living environmental condition along the railway line. Building hood at tunnel entrance is an effective method for solving this problem. In this paper, using numeral simulation method, the efficiency of single opening tunnel hood relieving micro-pressure wave noise was researched, the sensitive of hood opening parameter, such as opening ratio, ratio of length and width, was analyzed. In the end, the tunnel hood optimizing parameters was drawn out, which will play an important guiding role for high-speed railway tunnel hood design.

Abstract: More and more scholars have attached importance to the piston effect, which seriously impact the metro environment. In this paper, after referring the present researches on the piston effect domestically and oversea, the author studied their methods and results and then summed up the disadvantages, for the further exploration.

Abstract: Based on the 3D incompressibleequations and the standardturbulent model, taking numerical calculation as the main research method, the relative motion model of station-train was established, the air flow field environment that when a train (CRH2) ran in the intercity railway tunnel at a speed of 200km per hour was simulated. The changing process of the train wind on the platform when the train passed through the platform was analyzed, the distribution characteristics of the train wind on the platform were discussed, according to the train wind reference standards, the safety avoidance distance of people on the platform had been worked out. The results show that: the gradient of the boundary layer wind speed close to the train wall is very large; the train wind near the tail of the train is the most unfavorable position; in order to keep the personal safe, protective measures should be taken when necessary.

Abstract: Using the pseudo-excitation method, a simple model was built to study the seismic response of buried pipeline laid through three-soil site for vertical incidence of seismic waves. Seismic ground motions are considered as stationary stochastic processes, and the cross-PSD function was established based on auto-PSD model, coherence model, and site response model. The results show that the peak bending stress depends on the properties of adjacent soils and the width of middle-soil, and appears in the pipeline near the soil interfaces.

Abstract: The seismic damage and even collapse of the infilled walls in RC frame infilled wall structure is the issue that needs thorough study, In this paper, firstly introduces the improved infilled wall model which can consider the interaction of in-plane and out-of-plane, and can judge the damage state of infilled walls, as well as the interaction between RC frame and infilled walls. Then, based on the finite element software OpenSees, under rare earthquake, performed the nonlinear numerical simulation of two finite element models-RC frame without infilled walls and RC frame with infilled walls, comparative analysis differences of both plastic hinge zone’s steel strain, drift and acceleration response, and in-depth study of the infilled walls effect in RC frame infilled wall structure and reason analysis.

Abstract: In order to study the seismic performance of fiber reinforced concrete pier, four scaled piers whose material is reinforced concrete (RC), carbon fiber reinforced concrete (CFRC), polypropylene fiber reinforced concrete (PPFRC) and hybrid fiber reinforced concrete (HFRC) respectively have been tested under dynamic and static hydraulic servo testing system. The hysteretic curves, dissipating capability, residual deformation and ductility of each specimen are compared and studied. Experimental results indicate that the residual deformation of specimen PPFRC is not as good as CFRC, but it has well ductility. The specimen HFRC possesses the characteristic of small residual deformation and well performance of material dissipation and restoration ability. The dissipating ability of HFRC, CFRC and PPFRC are increase by 12%, 8% and 6% respectively as compared with RC. The HFRC has the best seismic performance due to small residual deformation, good restoration ability and ductility.

Abstract: The dynamic compressive tests of microconcrete were carried out under the strain rate of seismic action. Based on test results, the rate-dependent compressive constitutive model of microconcrete was proposed. In order to verify the accuracy and efficiency of the proposed constitutive model, the dynamic compressive tests of microconcrete were simulated by finite element software ABAQUS. Results show that the dynamic compressive strength and elastic modulus of microconcrete increase with the increasing strain rate. There was no obvious change on strain at peak stress. The compressive stress-strain curves of microconcrete were similar to concrete. The results of numerical simulation approximately agree with test results. The proposed constitutive model can simulate the dynamic compressive property of microconcrete very well.

Abstract: Active control and passive base isolation strategies are exerted on one continuous isolated prestressed concrete bridge. The goal of this study is to check the applicability of the LQR control law on the isolated continuous or rigid-connection type bridge, to find a more effective control strategy when nonlinearity is introduced. A spaced frame finite-element model is developed by a MATLAB program coded by the author, its validity is checked through comparisons with a sap2000 model. In this program, the nonlinearities of 3 different columns and 5 isolators are considered with their bilinear force-deformation relationship. the factors such as the control devices, sensors, and the corresponding noises and time delay are all considered in the model. Model reduction technique was applied to set up the controllers. The seismic response measurements and regulated outputs are adjusted to optimize control effects.

Abstract: A three dimensional numerical model for a typical earth dam and its valley site was established and the nonlinear seismic response of this model was performed. Experimental data of cyclic triaxial tests were adopted to determine the curves of modulus ratio and damping ratio that vary with dynamic strain amplitude. Free-field artificial boundary and viscous artificial boundary were employed and the input waves were the revised ground motions obtained from the station near the dam. Distributions of the PGA, displacement, residual deformation, shear strain increment and element failure state were presented. Results demonstrate that the 3D local valley site effect has a significant influence on the seismic response of earth dam.