Advanced Materials Research Vols. 718-720

Abstract: ndoor steel stairs, which are usually designed by professional construction companies, are controlled by the stiffness and strength. However the vibration problem is not considered and may lead to the problem of comfortability and even safety. This paper focuses on vibration of steel stairs by a case study. Both the vertical and the lateral vibration are concerned in the study by site test and numerical analysis. Based on the test and analytical results, the vibration evaluation is done for it. Finally some suggestions for indoor steel stair are given to reduce the problem of vibration.

Abstract: The detecting precision is an important aspect of error control. The Standard scheduled the bituminous mixture type and water absorption level to improve detecting precision.The date statistical analyses of water absorbing capacity water absorption and air voids of practical project are made. The conclusion is that the dispersion of water absorbing capacity and water absorption is obvious because of the existence of discrete values. According the variability analysis of air voids distribution in different level and range of water absorption and different range of air voids, the detecting precision of air voids impacted by the water absorption and how to control the detecting precision of air voids in different water absorption of and air voids range were analyzed. The air voids at different water absorption level or in different water absorption range was preliminary predicted, and calculated the necessary sample numbers in different water absorption range or air voids range for different degree of detecting precision.

Abstract: In recent years, nondestructive testing is applied more and more widely on the road detection, PQI as a kind of advanced testing equipment in asphalt pavement detection, it has been paid great attention by the road testing personnel. Based on the analysis of the densities which measured by PQI of different types of asphalt pavement, it sums up that the surface texture depth of asphalt pavement significantly affects the measuring accuracy of the density of PQI. In this paper, it suggests to use sand to fill the surface texture depth of asphalt pavement combining with PQI for pavement density measurement. Field testing shows that, compared with the bulk density of core sampling method, the density measured by PQI has obviously been affected by the surface texture depth of asphalt pavement. As the surface texture depth of the asphalt pavement is deeper, the error between the two methods is larger. Considering the influence of texture depth, the author improved the PQI detection method. The improved method shows that, compared with the bulk density of the core sampling, the coefficient of variation of the original testing method is 10.2%, and the new method is 3.8%. In the original testing method , it use the average value of the core sample densities as the compensation value of PQI measurement in the degree of compaction testing, and the maximum measurement error reached up to 2.2%. While, the improved testing method use the average value of the core sample densities as the compensation value of PQI measurement, the maximum measurement error reduces to 0.7%, the accuracy of the testing result is significantly improved.

Abstract: It takes the typical coal of mining in S₂S₉ face of Daping mine, using the 3-D numerical simulation to reveal on its face with the vertical characteristics of the stress field and displacement field .The study showed that the overburden strata migration features during the mining process in in thick seam mining of Daping mine.This research can be a reference for safety and high efficient coal mining of other parts of the soft overburden in extra- thick seam mining technology.

Abstract: Based on the experiment of eight reinforced concrete T-shaped columns under low cyclic load, the factors which affect bearing capacity and seismic behavior, such as limb length, axial load ratio, stirrup ratio and the arrangement of longitudinal bars, etc., are analyzed. Tests results show that the bearing capacity of the columns increases, but the ductility is decreased with an increase of axial load ratio. The bearing capacity of T-shaped column increases when the web gets longer, while its deformability and ductility decrease. Besides, increase of stirrup ratio and longitudinal bars in the end of the web also have effect on the ductility of the columns.

Abstract: According to the dynamic compaction project of Beijing Garden EXPO Park, an experiment is designed to monitor the deformation and vibration range impact by dynamic compaction.The vibration velocity, vibration acceleration, settlement and deep horizontal displacement of the foundationare obtained through the continuous real-time monitoring during the experiment.In this paper, the expression of vibration velocity and acceleration decreased by distance is established according to the experimental data, besides, the relation ofsingle settlement and total settlementof tamp pit changed with hit numbers is also achieved.The study shows that,under the 3000kJ compact energy,the settlement range is about a circle with radius12.7m; the deep horizontal displacement changes only in range of radius 7.7m; the safety distance of vibration is 47.7m, and to fulfilling the requirement of consolidation 7 hits is appropriate. The study provides a reference to dynamic compacting processof this project.

Abstract: In order to delve better what research methodology of height of water conducted fissure zone are, especially in mining of thick coal seam with soft, 3-D numerical simulationin was used to S₂S₉ face of Da Ping mine, it reveals the damage movement rule of overlying strata in mining roof-coal in "Three Soft" coal seam in the end . Thus it confirms the height of the water flowing fractured zone and tests the simulation result by the theoretical analysis and simple hydrology observation result. it provides a new idea for the application soft overburden in extra- thick seam mining technology.

Abstract: t is easy to cause the Yangtze River embankment soil of slip even collapse to have a deep foundation pit construction adjacent to the Yangtze River outsideembankment,there are a lot of risk. In this paper, a new combining technique of construction for large caisson is presented. Based on the construction environment, theconstructiontechnology,the smaller earthwork excavation of deep high pressure rotary jet grouting pile with undrained caisson combined construction technology combined with monitoring data for the open caisson excavation control is adopted. It has achieved relatively good results and summarized the advantages of deep high pressure rotary jet grouting pile with undrained caisson combined construction technology in engineering application owing the reference value for engineering applications.

Abstract: The arch slab roof has been widely used in engineering because of its beautiful appearance, good heat preservation and insulation behavior. In this paper, the arch slab crack on its lower chord was analyzed and calculated by project instance, for the causes on the problems of concrete strength below design standard. We can come to the conclusion form studies that the prestressed arch slab roof with strength of C30 or lower should not be used, while C35 may continue to use according to strength calculation and test. Studies dealing with the same type of problems are of profound practical significance.

Abstract: This paper investigates an effective strategy for dynamically adjusting the threshold of Internet information rating. The threshold of Internet information rating is different from generation to generation, people in different period have different standards to the things around. How to adjust the threshold is the focus of this paper. In this paper, we propose an clustering based algorithm to divide the age span and use the cluster centers to represent the standards of this age stage, some improved strategy are also proposed.