Applied Mechanics and Materials Vols. 105-107

Abstract: A large-scale indoor model test with water pressure is conducted in order to investigate the stress and deformation properties of reinforced concrete lining structures with circular cross-sections. After lining structure cracks, the stress and deformation of reinforcement in lining structures tend to decrease. Although the interaction force between lining structure and surrounding rock increases with the increase of water pressure, but the ratio of interaction force and water pressure decreases, which reveals that the load-bearing capacity of lining structures decreases, and surrounding rock gradually performs as the primary load-bearing body. The internal water pressure carried by lining structure is about 20%~40% of water pressure before cracking and less than 30% after cracking. Test results illustrate that surrounding rock and inner water seepage significantly influence the stress and deformation properties of lining structure, and inner water seepage is the main reason for the reduction of load-bearing capacity of lining structures.

Abstract: A finite element method of space vibration analysis of the time-dependent system of long span suspension bridge and train under wind load is put forward in this paper. The correlation coefficient of wind along long span bridge is taken into account to simulate the wind speed curve in every point along the bridge. The matrix of space vibration equations of the time-dependent system of train and bridge are assembled by the principle of “Sit in the right place”. We calculate and analyze the critical wind speed of the train both from aspects of safety and riding comfort. Taking into account the effect of rail irregularity, wind action and various kind of nonlinear factor etc, we made a detailed vibration analysis for the system of bridge and train, and obtained the warning wind speed and bridge-closed wind speed when trains running on the bride.

Abstract: This paper studies on deducing the analytic formulae on Gauss coordinates displacement before or after the increase of major radius of ellipsoid expanded modals, which is based on the partial derivatives of geodetic coordinates in Gauss coordinates deducing from direct solution formulae of the Gauss projection coordinates in conjunction with differential coefficient formulae and variable of geodetic coordinates. On this theoretical foundation, analyzing the relationships between Gauss coordinates displacement and other mathematical parameter . The relationship of graphics between point displacement components of latitudinal coordinate dy and longitudes is similar to the straight lines. The relationship of graphics between point displacement components of longitudinal coordinate dx and latitudinal coordinate dy, and the geodetic height is similar to the straight lines.

Abstract: With the lesson from the overturning accident of single-pier bridge and based on the analysis on the size and distribution mode of the load on the bridge surface when the ramp bridge of Tianjin segment in the Jin-Jin Expressway collapsed, this Article drafts the load size and distribution mode are (possibly undertaking up to 4x165t load) studied out for analysis and design of single pier bridge of pier-girder consolidation for the analysis on the calculation of the overturning resistance for single-column girder, and analyzes the overturning resistance capacity of single-column girder with pier-girder consolidation according the planned load size and distribution mode. In addition, this Article proposes the reinforcement measures by adding the column supports at the horizontal direction of the single-column pier, thus effectively improving the overturning resistance capacity of main girder. This Article may be used as the reference for the study of overturning resistance and the reinforcement of single-column pier bridge.

Abstract: The stress histories of monitored members are used to get stress spectrums for a steel truss bridge through rain-flow algorithm, then the distribution functions and their characteristic parameters of stress spectrums are obtained to simulate the stress spectrums numerically through Monte Carlo methold, which used to evaluate the structural fatiguelife based on stress-probabilistic model and accumulated damage theory, and the fatiguelife and its hot spots of whole bridge are acquired , which is important for the strategy of bridge management.

Abstract: The dissipation of porous perpendicular pipe breakwaters are studied experientially in this study, the investigations on wave transmission of the porous pipe breakwaters are carried out in the laboratory with different wave conditions and various combinations of pipe diameter and length. The wave energy is mainly dissipated due to the drag and interception of the resultant motion by the pipe breakwaters, the reflectivity of such effect are thus discussed by the evaluation of partly reflected and transmitted ratio, and consequently the performance of the pipe breakwater for predicting wave transmission coefficient is investigated. Experimental results revealed that the attenuation is much effective with the decreasing of pipe diameter than increasing of the length.

Abstract: The shield tunnel for water conveyance is usually composed of two-layer liner tube. The outer layer is fabricated reinforced concrete structure consisting of the sectors of liner tube which are connected by binder bolt, and the inner layer is liner tube of depositing reinforced concrete. Under the action of inner and outer water pressure, there will be some discontinuous deformation on the crack sections and the interface between liner and soil, which bring great difficulty to the establishment of the model. Based on the interface stress element theory of discontinuous mechanics, this paper has proposed a computing model of shield tunnel for water conveyance in accordance with the project of transporting water through Yellow River for diverting water from the South to the North. This model can reflect the discontinuous deformation characteristics of various cracks. The effects of binder bolt and reinforced bar can also be well simulated. The theoretical analysis and practical computation results show that the model suggested in this paper is effective in simulating and computing, thus being regarded as an ideal model of shield tunnel for water conveyance.

Abstract: This paper studies the basic principles of finite element method, then researches on the core algorithm of finite element method, according to Saint-Venant principle, introduce the concept of composite element, proves that if the element is composite element, the original integration is still able to calculate. Based on the feature that numerical integration solution is in fact the Gaussian integration points are calculated, we endow element internal with different material property values according to the different location artificially. This is the efficient and local accuracy decrease algorithm. The algorithm is able to simplify the work of mesh generation, improve the overall computing efficiency, is especially suitable for underground engineering, and we can quickly get the overall characteristics of the structure that we are most concerned about. Finally, builds the actual examples of underground engineering, uses the finite element software Ansys and the efficient and local accuracy decrease algorithm program to calculate the actual examples respectively, compares the results between them, expounds and set the analysis theory and relevant principles, makes conclusion: the efficient and local accuracy decrease algorithm can simplify mesh generation, improve the overall computing efficiency; and it can be used in underground engineering very well.

Abstract: In order to carry on control and countermeasure of mining damage effectively, by analyzing the conditions of geology, mining and entironment in west of china, the text discusses the possibly arisen problems of structural establishment, traffic establishment and environment and so on when western regions enter a large-scale mining phase. It analyses all these problems which will restrict and affect continuable development of mining area’s economy, and advances some thoughts about harmonious development of mining industry and environment protection by controlling mining technology and approach of synthetical treatment.

Abstract: The saturated and unsaturated soil were widely studied by many researchers nowadays. With the development of calculation mechanics and computer, the discrete element method (DEM), as a powerful technique, has been implemented in saturated soil mechanics. This paper review the development of DEM and its application in saturated soil research. Meanwhile, it also prospect the application of DEM in unsaturated soil research. Besides, it also raised some problems that might be met in the real practice and it also tried to put forward some reasonable methods to solve these problems. In the end, this paper put forward a new DEM contact model based on the surface energy to analysis unsaturated soil.