Applied Mechanics and Materials Vols. 204-208

Abstract: This paper applies RS and GIS technology to study zonation of the landslide hazards in the study area from Badong county to Zigui county in TGP reservoir region. The causative factors involves lithology, distance to faults, slope angle, slope aspect, elevation, drainage network, distance to river and distribution of plant, which are derived from geological map, Spot imagery data and Digital Elevation Model (DEM) based on RS and GIS technology. We analyze the zonation of the landslide hazards with artificial neural network. The research result is very coincident with the occurrence of the known landslides in the study area.

Abstract: Experiments of five fire extinguishing agents on the fires of wood stack and oil were conducted in ISO9705 room. It focused on comparing the extinguishing abilities of the five fire extinguishing agents on Class A fire represented by wood stack fire. It is can be concluded that FM200 had the best extinguishing performance for wood stack fire, and it could prevent wood stack reburning; while IG541 and hot aerosol extinguisher do worst on preventing the wood stack fire reburning. In addition, the effects of extinguishers on heat release rate were compared.

Abstract: China is one of the countries suffered the most serious typhoon disasters in the world. Typhoons have occurred frequently, which resulted in the loss and impact, and caused widespread concern and attention of the international community. Therefore, it is urgent to analyze the main features of typhoon and the evolution of typhoon disaster of China. By analyzing the typhoon landed frequency changes of China since the 20th century, theoretical support would be provided and more targeted defense work of typhoon would be done which could put forward countermeasures and suggestions of typhoon defense work in China.

Abstract: The axial compressive mechanical behavior of steel fiber reinforced ceramsite concrete filled steel tubes (noted as SFR-CCST) after exposure to fire are experimentally studied. Effect of furnace temperature, dosage of steel fiber in specimens on the post-fire mechanical performance of the specimens after exposure to fire was especially discussed. The results show that all the specimens of SFR-CCST have higher post-fire bearing capacity and better plastic deformation, and there was no obvious descending segment in the load-strain curves of the most specimens after exposure to fire. It was concluded that the furnace temperature applied to the specimens and dosage of steel fiber in the specimens of SFR-CCST has some effect on the post-fire mechanical performance of the ceramsite concrete-filled steel tubes after exposure to fire, and the dosage of steel fiber of 0.5% has the most effect on the post-fire performance of lightweight aggregate concrete filled steel tubes after exposure to fire.

Abstract: Debris-flow risk assessment plays an important role in territorial planning and hazard prevention and alleviation, especially after 5.12 Wenchuan Earthquake, it can provide guidance for post-disaster restoration and reconstruction. Based on plenty of references, such as monograph, journal, thesis and other document, this paper summarized the present research situation of Chinese debris-flow risk assessment, put forward that the current debris-flow risk assessment model is not suitable for earthquake-stricken areas and urgently need to establish a new risk assessment model to guide post - disaster planning and reconstruction.

Abstract: The paper chooses new Fengjie county with the area of 66.90 km² as research region to interpret landslide that picked with the proportion of 1/1000 by remote sense technique. Interpretation results of landslide are basically consistent with the results of field survey. It proves that the remote sensing technology in the landslide investigation is feasible and effective,which have strong practicability and guidanciality to engineering construction of the three Gorges Reservoir.

Abstract: Simulation of nonstationary processes has become an indispensable tool in study and prevention of natural disasters. A new method of simulation of nonstationary random processes is presented based on the orthogonal HHT spectra of sample observations and random phase. It takes advantage of orthogonal EMD, the instantaneous frequency, amplitude of the Hilbert transform and independent random phase angle, thus overcoming difficulties in the estimation of the frequency modulation and interdependence of frequency and amplitude modulation functions faced by most currently available methods. The new method extracts and preserves the true physical features of the process. The examples of earthquake ground motion and subway vibration, as low frequency and high frequency nonstationary process respectively, were simulated in the paper. The time history of sample, Fourier amplitude spectrum of sample, arithmetic average of sample, variance of sample, Wavelet time-frequency distribution of sample amd autocorrelation coefficient of sample compare well with those of the records. Scattering extent of the peaks of the sample processes is also analyzed in the paper. We can conclude that the method has great potential for engineering applications when dealing with nonstationary, nonlinear random peocesses exist in natural disasters, such as earthquake wave, vibration wave , wind wave and ocean wave.

Abstract: In order to analyze the mechanical properties under three conditions of fire-damage, rehabilitation and strengthening of spatial concrete frame structures after fire, two novel numerical models are developed in this paper by dividing the cross-sections of beams and columns into a lot of concrete fibers and steel fibers and dividing slabs into several layers along the direction of the slab thickness based on the concept of the fiber element model and the layered shell element model. These two models can consider the distribution of non-uniform temperature in the cross-sections of structural members and the changing of mechanical properties of fire-damaged, rehabilitated and strengthened materials. Besides, the Analytical System of Fire-damaged Concrete Frame (ASFCF) is established through the secondary development of ABAQUS Software that is completed by the programming language of Python. This system is used to analyze and compare the mechanical responses under three conditions of fire-damage, rehabilitation and strengthening of a multi-story, multi-span spatial concrete frame after fire. The results indicate that ASFCF can properly analyze the mechanical properties under three conditions of fire-damage, rehabilitation and strengthening of spatial concrete frames after fire, and it provides valuable references for assessing the residual mechanical properties and the mechanical properties after rehabilitation and strengthening of global concrete frame structures after fire.

Abstract: Four full-scale SRC columns with special-shaped cross section were experimentally investigated in fire following ISO834 standard heating process and were implemented in the compression test after fire .The section temperature field after two hours of fire, deformation laws under fire and the mechanical behaviors after fire were got. Find: (1) Bond slips between concrete and steel were small which indicates that concrete and steel can work together. (2) Reasonable way with steel cross-section had a significant effect on the mechanical properties of columns. (3) The two sides of SRC special-shaped column were under fire conditions, sections were damaged. When the load was at the centre of the cross section, columns were in the state of axial compression before fire and the state of eccentric compression after fire.

Abstract: Gully erosion depth is one of the most important parameters for the assessment and prevention of debris flows. So far, there is no good method for calculating the gully bed erosion depth of viscous debris flow. This paper discussed the calculation method of erosion depth of viscous debris flow based on theoretical deduction. The formula for calculating the erosion depth was constructed based on deduction from the viewpoint of theoretical mechanics. Then, the affecting factors of gully erosion were discussed. This method can be used to calculate the erosion depth for viscous debris flow under different frequencies and provide a better evaluation and prevention tool for mitigating debris flow disaster.