Applied Mechanics and Materials Vols. 193-194

Abstract: The existing roads, railways can no longer meet the growing expansion of the traffic needs, some newly built roads, railways must be crossed with the old lines, the difficulty of construction is considerable, especially Pro tight both line and rock blasting operations, it is necessary to consider boththe safety of the line, but also to ensure that the construction schedule. Based on an example of the rebuilding of the railway grade crossing to interchange from Loudi Prefecture in Zhuliu highway to dragon section of the sand Huaihua, Hunan Province, the article describes the safety and protection measures construction blasting in conditions close to the complexity of the existing lines, the construction of similar projects the organization, management provide some reference.

Abstract: In this paper, a 20-storey Benchmark model is used to compare the effects of various control systems, including Damper control system, TMD control system and Hybrid control system. In the course of the optimization, the displacement reducing coefficient (DRF) and the storey drift reducing coefficient (SDRF) are used as the objective functions to optimize the control parameters based on Genetic Algorithm (GA). Numerical results prove the advisability of the Hybrid control system of dampers and TMD, which can not only decrease the floor displacement, but also improve the mutation of the storey drift.

Abstract: In this paper, a comprehensive advanced geological prediction method in highway double-arch tunnel construction was put forward, which could take the advantages of geological radar technology and the horizontal of advanced drilling in karst area. The method would give relatively accurate judgments in the construction of the highway double-arch tunnel by using different geological radar survey line layout, combining with advanced horizontal hole, which ensure the construction safety of the tunnel. The practical application of comprehensive advanced geological prediction in double-arch highway tunnel in karst area had received a good effect, and it showed the method had a certain guiding function.

Abstract: In order to solve the long span problem of mega-beam, arranging additional columns in MSCSS(Mega-Sub Controlled Structure System).Calculating vertical displacement and acceleration response of the mega-beam,which under vertical seismic, in order to discuss the mega-beam dynamic response that changing location, quantity and contact type of the additional columns. The results shows that: additional columns arranged in the middle of mega-beam , controlling the mega-beam vertical dynamic response is better; compared to the number of additional columns,the location of additional columns has a greater effect on controlling the mega-beam vertical dynamic response; contact type of additional columns has a little effect on controlling the mega-beam vertical dynamic response.

Abstract: The main structure of passenger dedicated railway serves in complex physical environment, so its high durability is expected. In contrast to normal HPC applications, higher requirements are addressed for the application in passenger dedicated railway, which include control of raw material quality, selection of HPC design strength, and mix proportion design procedures. In this paper, the choice of HPC constituents, the principles of mix proportion design, and the design of HPC mix proportion for passenger dedicated railway based on overall calculation method are presented. Its application case in Quzhou Section of the Hangzhou-Changsha Passenger Dedicated Railway has shown that t the design of HPC mix proportion for passenger dedicated railway based on overall calculation method is effective and deserves popularization.

Abstract: How to determinate the pre-stressing losses is a key issue for the pre-stressed concrete structure design and construction. Especially for the major engineering projects, the actual value of pre-stressing loss should be detected in site to check or revise the original design parameters and keep the engineering in safety. Compared with the straight strand, the frictional lose between strand with multi-curves and ducts would occupy the most part of all losses. It is a crucial ingredient to determinate the pre-stressing losses. This paper introduces the detection and evaluation results about frictional loss of a typical pre-stressed concrete invert siphon with multi-curve strands according to Chinese specification. The testing procedure is given and a formula is derived to calculate the frictional lose for the multi-curve strands. Then a simplified method is advised to evaluate the friction coefficient and wobble factor. The results show that the theoretical values recommended in the code fit with the testing deductive values and prove that the given values of friction lose for the design are reasonable as well. The conclusions would serve as a reference for similar engineering structures.

Abstract: Due to the complexity of underground engineering, study on creep characteristics of surrounding rock mainly adopts laboratory simulation experiment. Recently, the similar materials are used to do the experiment both at home and abroad, yet it can't reflect the original nature and others of rock fissure in original rock mass. Through the field collection of undisturbed sample of Tertiary mudstone, the conclusions are made by laboratory model test on surrounding rock of underground tunnel and creep process regularity and failure mechanism in the surrounding rock in this paper as follows: there are three obvious stages of creep under certain stress levels, which is measured on the surface of surrounding rock mass in argillaceous soft rock tunnel--decay creep ,steady creep and accelerated creep. The surrounding rock will produce the accelerated creep damage when the stress level is over a threshold value. Creep damage of surrounding rock mainly includes the forms of roof sinking, floor working up, and forming a macro- fracture surfaces etc. Test results showed that the undisturbed surrounding rock fracture would be dissimilar to the homogeneous surrounding rock without fracture in damage model, and original fissure have a larger effect on creep damage of surrounding rock.

Abstract: The stochastic model of chloride diffusion is the foundation of evaluating concrete structures’ reliability in marine environment. In this paper, the random field of chloride diffusion coefficient was described as a group of random variables by local average theory. The chloride distribution matrix, diffusion matrix and nodal concentration vector were expanded by using the Taylor series. The stochastic finite element method was developed, and the mean and standard deviation of the chloride distribution concentration were yielded by the presented method. A numerical example demonstrated the high precision of the stochastic finite element method presented, and the service life of concrete structures could be predicted by the method.

Abstract: Based on phenomenological method, the paper carried out experimental study for a kind of typical bolted joint structure, three kinds of testing specimens was designed, from the test result, the phenomenological model was obtained and the nonlinear mechanics behavior was comprehended, at last, the phenomenological model was verified experimental and numerical

Abstract: Cement concrete pavements were used in most airports built early in China. Nowadays the main task of airports is how to cover and reinforce damaged pavements. To ensure the life-span of pavement after covering, on the basis of analyzing the treatment methods of original cement concrete pavement, cement and asphalt concrete were used to realize the covering and reinforcement of old cement concrete pavement, and key technologies of Preventing reflective cracks of concrete pavement were put forward, which had a good result in practice