Advanced Materials Research Vols. 243-249

Abstract: The large-scale high-speed landslide has a strong destructive power which seriously threatens human lives and belongings. In order to study the dynamic process of large-scale high-speed landslide disasters and find the causes, the back analysis is made to study the Frank slide, a typical large-scale high-speed landslide disaster which happened in Canada, by combining dynamic model equation and method of finite volume discretization. At the same time, the simulation realizes the reappearance of the dynamic process of large-scale high-speed landslide disasters. It is can be seen from the calculation results which are identical to the actual situation that the established theoretical model and the numerical solution are effective. Besides, the low bottom friction parameter obtained from the back analysis shows that the decrease of the friction resistance is one of the most important causes of large-scale high-speed landslide. The further analysis reveals that several factors such as high-speed motion, fluid pressure on the sliding surface and high normal stress can reduce the friction resistance on the sliding surface.

Abstract: It is well-known that seismic disaster will cause serious damage, so the prediction and evaluation of seismic loss before earthquake event happened can provide foundation of disaster reduction program. And after seismic event happened, it is very important to fast evaluate the seismic disaster loss. Traditional seismic loss prediction method is vulnerability list method which need detailed information about all kinds of structures and facilities of the evaluated areas, and for most areas, it is very difficult to get such detailed information. This paper brings forward a new simple fast prediction method for seismic economic loss. Firstly, a macroscopic vulnerability model was discussed. secondly, a three-layer BP network model for seismic economic loss prediction is built up, BP network model is one of the most widely used artificial neural network (ANN) model, but due to its deficiencies such as easy to get into local extreme minimum value, genetic algorithm (GA) is introduced to overcome the deficiencies. In this model, seismic intensity, average GDP per capita and per area, population density are selected to be the input layer index, and GDP loss ratio as the output layer, 80 earthquake events which happened recent years are regarded as training and check up samples. Finally, the economic loss caused by Wenchuan earthquake is evaluated by the proposed model, and the feasibility and practicability are validated by the numerical example.

Abstract: Based on the technology such as remote sensing(RS), geographic information system(GIS), 3D simulation, and damage prediction, the simulation technology of earthquake disaster scene (STEDS) is the important content of digital disaster reduction and has important research value, which can be used to decision support, virtual training, and popular science education and so on. The general idea of STEDS is introduced in this paper and the key technologies to simulate an earthquake disaster scene livingly are analyzed. Taking a real city for example, the disaster scene of building blocks is completed, which take different colors as the signs of different damage levels under earthquake effect. The 3D building model bases are established by 3D modeling technology, which include 3D intact building models and the damage ones with different damage levels. Based on the replacement rules of models, the preliminary disaster scene of 3D damage building models is realized.

Abstract: The stability conditions after the instability of sliding is a concern issue; it is the significant foundation to conduct objective assessment for selecting engineering management measures. According to the geological background and geological exploration data, some representative sections as well as their stability conditions were studied and analyzed based on limit equilibrium method for rigid block and three-dimensional nonlinear FEM in this paper. The impacts on the slop stability by different depths of the transient saturated zone caused by groundwater as well as rainfall infiltration were taken into consideration during the calculation analysis. It is indicated by the results that the impacts on the landslide mass displacement by rainfall have distinguish spatial properties; the impacts on vertical displacement is bigger than that of the horizontal direction; the obvious impacting zone is located in the little backer anterior border area of the landslide mass. The calculation results can provide important references for the control and reinforcement of the landslide mass as well as the prevention of landslide hazard during the later engineering construction activities.

Abstract: This paper provided three test data pertaining to the mechanical properties of reinforced concrete columns after exposure to ISO834 standard fire and three comparative test data pertaining to the mechanical properties of reinforced concrete columns at room temperature, mainly concerning the influence of fire on failure mode, distortion performance and ultimate load bearing capacity of reinforced concrete columns under axial and eccentric compression. Test results show that the failure mode of reinforced concrete columns after exposure to fire is basically same with that at room temperature. With the same concrete strength and heating condition, the bearing capacity of specimens reduces as the eccentricity increases. Strain along the section height of eccentric columns after fire basically agree with the plane section supposition while the flexural rigidity and ultimate load bearing capacity decreases obviously. The residual load bearing capacity of reinforced concrete columns after exposure to fire is only about 25% to 37% of that at room temperature.

Abstract: Significance of full-scale experiments, analyzing wind and pressure fields in the proximity or on tall buildings, is evident from the attention that has been dedicated by researchers to these programs in the recent past. In the south and southeastern regions of China this problem is of particular relevance due to the presence of Typhoons. This paper presents some recent results measured from a super tall building located near the coast of Xiamen, Fujian province, China. In the first part of this study, attention is devoted to the characterization of the wind field atop a super-tall building; a comprehensive investigation on wind velocity and turbulence characteristics during the passage of Typhoon Fanapi is summarized. In the second part, results associated with the mean pressure and mean pressure coefficient were concentrated on the identification of direction-dependent pressure characteristics is analyzed.

Abstract: At 14:28, May 12th 2008, a strong earthquake measured Ms8.0 hits Longmenshan mountain area, west Sichuan province, China. The quake is induced by the thrust of Longmenshan central fault, results in around 50000 rock avalanches and landslides, destroys numerous villages and towns, and causes nearly 90000 fatalities or missing. Based on field reconnaissance, the geology and fault patterns in Longmenshan mountain area are firstly introduced, then the damage or failure phenomena of slope protecting and retaining structures in quake-hit area is described and discussed, including slide-resistant piles, gravity retaining walls, shotcrete, anchored concrete frame, cable bolts and protecting nets. Special discussion is given to the behaviour of cable bolts based on measured data. And finally design issues is discussed in quake-prone areas.

Abstract: In current seismic design code of each country in the world, the mainstream of earthquake input for calculating the building is to use X and Y directions conveniently. The X and Y directions are the main axis of the building, and the strong-column weak-beam damage mechanism has been considered only followed to these main axis. However the building response in the oblique direction is higher than in the main axis, and the frequency in the oblique direction of the building is higher than the X or Y direction as well. Moreover the column usually connects with two beams in the orthogonal directions and the strength ratio of the column to beams in the oblique direction is less than in X or Y direction. Therefore it could be the major reason to cause the column-plastic-hinge damage mechanism during the earthquake. In this paper, it is discussed how the seismic input in the oblique direction influence on the strong-column weak-beam damage mechanism for RC frame through the perspectives of the dimensional mechanical analysis, cyclic loading experiment and the finite element analysis for the dimensional column-beam joint, and then proposed that considering the seismic input in the oblique direction is necessary in the future structural design in order to reach the actual strong-column weak-beam mechanism.

Abstract: According to the code and technical regulation, a regular RC frame with specially shaped columns have been designed, which situated at the area of fortification intensity 7(0.15g). Subsequently, the nonlinear dynamic analysis has been carried out for the structure by inputting ground motions in one direction. After summing up the calculation results, this paper have examined seismic performance of the structure under the rare seismic actions and given a primary evaluation on the structure to see if it achieves the predetermined seismic aims. It indicates that the structure designed the codes can achieve the predetermined seismic aims under the rare earthquake.

Abstract: Selected the typical loess landslide to analyze and calculate, adoption of elastic-plastic dynamic FEM and Drucker-Prager yield criterion, using Earthquake motion time-histories as the seismic input will be based on the fitting of , class standard response spectrum curve in the current seismic resistance design code. From the analysis of loess slope deformation and breach at different peak acceleration, spectral and duration, it shows the dynamic response and change rule of soil under earthquake effect.