Applied Mechanics and Materials Vols. 501-504

Abstract: Based on the compression-shear tests of different specifications LRBs (diameter 700mm,1000mm,1100mm) and shear strain correlation formula, the modified differential restoring force model (modified Bouc-Wen model) is suggested to simulate LRB. An isolated model, nine-story superstructure, is used as the numerical example. Using the unmodified and the modified differential restoring force model of the LRB, the differences of the seismic response of isolated structure are studied by numerical analysis and comparison. Result shows that, unmodified differential restoring force model commonly used in isolation design, except for acceleration response, other earthquake response has not significant error.

Abstract: Considering that during the earthquake, the maximum peak of acceleration changing in the process is a random quantity, which cant be regarded as a sign of dynamic motion characteristics. Therefore, in this paper, the root mean square acceleration is employed to calculate the corresponding seismic forces. Then according to the sine curve, seismic forces are loaded on the different layers of slope of loess slope. Giving a comparative study on the safety of the loess slope under the force of the earthquake provides reference for the design of loess slope against earthquake.

Abstract: Through three dimensional finite element analyzes, overall cast-in-place prestressed concrete pier seismic crack characteristic is researched. The separation formula finite element model is established by means of bilinear reinforce model and Kent-R.Park concretes model, without considering slip between concretes and. reinforce. It compares and analyzes the seismic crack characteristic between prestressed concrete pier and reinforcement concretes pier. The results show that the prestressed reinforcement can reduce the tensile zone of concrete, put off the appearance of cracks, improved the stiffness of pier, and reduced the top displacement.

Abstract: By using finite element software ABAQUS, the nonlinear finite element analysis of earthquake resistance behavior of T-shaped concrete-filled rectangular composite steel tubular columns is carried out, furthermore, the analysis results and the corresponding experiment results are compared. The results indicate that the calculated value of ultimate bearing capacity is less than the experimental value, and the results of FEM analysis can match the experiment results better, and thus, it can better reflect the earthquake resistance behaviors of the specimens.

Abstract: In North-south earthquake belt, half of more than Ms 8.0 great earthquakes were centralized since the history records were existed in our country. In order to study the typical buildings in this seismic belt, the seismic damages of the typical buildings occurred during 22 earthquakes in North-south earthquake belt, whose earthquake magnitude were more than Ms 6.0, were organized and analyzed. The seismic damage and its matrix of kinds of buildings belonging to the North-south earthquake belt in different intensities were obtained. The statistic results were obtained by comparison and analysis. According to the results of analysis, the seismic capacity of kinds of typical buildings in this region was provided: reinforced concrete frame structure showed fine seismic capability in all previous earthquake whose seismic damage was the slightest in the real statistics results; secondly were those of masonry and mortised timber frame buildings; the seismic damage of buildings, which was combined with timber frame and soil, stone, brick walls was the most serious.

Abstract: By Changsha Xiangjiang River Camp Road tunnel geological conditions and the overall analysis, the paper proposed the overall and the inner contour design of the underwater tunnel interchange segment .Establishing calculation model of the north-south main line and C, D segments interchange ramp, and using ANSYS finite element software to calculate and determine the design parameters of the tunnel cross-section . For the upper and lower layers tunnel use excavation construction, and applying the Center-Cross-Diaphragm (CRD) method to tunneling.

Abstract: The minimum rock cover thickness is the most important design parameters affecting cost and safety of the tunnel. Designing underwater tunnel need think project cost and risk and other factors to determine a reasonable minimum tunnel cover thickness. Under the actual conditions of Xiangjiang River Camp Road Tunnel, according to the current domestic and foreign common method for determining the minimum depth of underwater tunnel will not be able to meet the conditions surrounding the wiring, and it is difficult to play tunnels traffic relief function, while based on the Perform thorough research and theoretical analysis, putting forward the underwater tunnel determination method which is based on the engineering control measures.

Abstract: Based on many inquiries, analyses and researches, alternate measures of science and social science are taken in this paper, considering series of geo-environmental effect, and the harmfulness of geological effects in Chongqing main city are analysed. The basic counter measures and managing measures are suggested to treat geo-environmental problems in Chongqing main city so that a long-term plan of city-developing and the objective of a struggle based on real situation are set up. The analytic results are helpful to solve the serious geo-environmental effects, and push forward the study of urban geo-environmental problems of underground engineering in Chongqing.

Abstract: Underground highway is an effective measure to ease the traffic pressure. However, fire in underground highway is of great danger. This work investigated the instantaneous velocity field, gas field and temperature field distribution of the underground highway in case of fire theoretically. The smoke field and temperature field distribution was determined at the safe altitude. The expression of the critical flow velocity in the previous work was verified. The optimal escape time in the fire upstream and downstream is 30s and 90s, respectively. The optimal escape distance in the fire upstream and downstream is 35m and 200m, respectively. The best is to read these instructions and follow the outline of this text.

Abstract: This paper analyzes the stress of the pick-shaped cutter of rotary cutting machine in process of tunnel excavation in soft and hard interbedded formation, results show that the resistance of pick is obviously jumping fluctuations comparing to that of homogeneous formation. When pick transits from cutting hard rock to soft rock, cutting resistance and driving resistance of pick decrease instantaneously, which leads to momentary decreasing of rotation torque. And mud ball is compacted by high impact force of rotary cutting machine when cutting hard rock strata, as a consequence, resistance torque increases. When the sum of resistance torque and starting torque is greater than rotation torque, pick can`t rotate, leading to eccentric wear of pick. At last, this paper puts forward several improvement suggestions.