Applied Mechanics and Materials Vols. 405-408

Abstract: Unsaturated cracked slopes are easily to be affected by rainfall in the soil. Actually, some of the rainfall becomes the surface runoff and the rest permeates the crack under the ground in water cycle system. The infiltration makes the groundwater level rise. It also increases the pore water pressure and slide stress of the soil and decreases the anti-shear strength of soil. That makes the slope fracture or deform. However, most of the slope stability analyses set the physical properties of the soil as constant values but neglect the influence of the crack and infiltration. Those analyses underestimate the influence of the crack and the change of water content to the anti-shear strength of the soil. Therefore, it was unable to predict the possible damage time point by these evaluation results. The knowledge and methodology of the rainfall combine infiltration and slope stability analysis in this research. Simulations of the moisture content of the soil and the groundwater level are performed by FEMWATER numerical model. The simulating conditions are based on the different cracked positions and rainfall durations. The data of moisture content changes of the soil will be transformed into the parameters of safety factors fitted by STEDWIN numerical model. The influence of the slope stability with different cracked positions was gained from the simulations.

Abstract: Preliminary design is core content of establishing emergency evacuation plan. A Link-Node space network structure model is founded for simulating public places in this paper. Based on the model, the basic model of crowd evacuation plan is analyzed and validated with an example. Then, a method of logical shortest path calculation is put forward, and satisfied preferably request of emergency evacuation plan design.

Abstract: One of the main geological disasters in Wuhan City is karst surface collapse. Analytically the main elements affecting karst collapse contain Karst development, covering layer condition and hydrogeological condition. This paper aims to set up the risk zoning evaluation model about this disaster upon BP neural network theory. And then evaluate the risk zoning of karst collapse. The assessment result shows karst surface collapse of high risk in Wuhan City mainly distributes in Ruanjia Lane, Lujia Street, Justice School, Fenghuo Village,Zhongnan Steel Mill and Maotan Harbor.

Abstract: This paper describes the results of a fire test conducted on two-way simply supported concrete slab. The details of support condition, arrangement of reinforcement, position of displacement transducers and thermocouple trees are described. The experimental results such as the temperature distributions within the slab, vertical deflections and horizontal displacements are presented. The experimental results show that the temperature distribution along the slab depth was nonlinear and the temperature gradients in the slab were large. Three main cracks parallel to the short span direction occurred on the top surface of the slab. It is shown that two-way simply supported concrete slab has good fire resistance.

Abstract: As the relationship between geotechnical slope stability and influencing factors is complex and nonlinear, the least squares support vector machines (LS-SVM) is used to establish the nonlinear relation between slope stability and influencing factors. And in consideration of that parameters selection of LS-SVM exerts a major influence on modeling results, the parameters of LS-SVM are optimized by chaos genetic algorithm (CGA). Thus the CGA LSSVM is proposed for forecasting slope stability. Through the comparison between the method and the simple genetic algorithm (SGA) parameters optimization. The result shows that parameters optimization of the CGA has better faster convergence speed, higher prediction precision. And the model is applied to predict the safety factor of the actual slope engineering and the results are well consistent with the actual situation. It is shown that the model is reasonable and feasible.

Abstract: As mining progresses to deeper reserves, the accompanying high stress and rockburst hazards increase and cannot be prevented. Therefore, the position of rockburst, hazard level, as well as how much energy released need to have quantitative analysis, which can provide a safe and effective guideline for mining operation. In this paper, take the Linglong Gold Mine as background, the relationship of surrounding rockmass and rock impact energy index could be derived from simulating the ground stress environment in lab. Based on above equation, FLAC 3D is used for simulating the mining operation of Linglong Gold Mine in regard of the size of rock impact energy in current excavation stress condition, which breakdown the limitation of previous method of getting the indicator of rock burst tendency evaluation from uniaxial compressive full stress-strain curve, and provide the reference for safe mining operation.

Abstract: A numerical model of three-dimensional motion of plate-type wind-borne debris in uniform wind field based on quaternions is proposed in this paper. This model can simulate the complex 3D spinning flight robustly and efficiently with rotational quaternions, which are also free from the gimbal lock that is associated with Euler rotational matrix. The predictions from the model were then compared with the results of another quasi-steady model, and good agreement is found. For the unsteady flow involved in autorotational flight mode, the present model was improved by revising the damping moment in order to simulate the two-dimensional motion of plates with higher accuracy. Calibration of the damping moment coefficient was performed through a direct comparison of the predicted non-dimensional angular velocity with the results of CFD-RBD model. The predictions of the improved model agree reasonably well with the CFD-RBD results, which verifies the accuracy of the improved model in predicting the two-dimensional trajectories of plates.

Abstract: Marine oil spill does cause huge economic losses and brings serious damages to the marine ecological environment. Therefore, how to claim compensation for oil spill damages has become very crucial for the environmental restoration. In recent years, many researchers have designed various kinds of assessment models for evaluating oil spill damages. This paper analyzes these assessment models, discusses the legal claim and technology claim, finally the suggestions for further research of oil spill damage assessment is proposed, and then the application of fuzzy neural network in technology assessment is also recommended.

Abstract: City is the centre of politics, economy and culture. With the development of modernization., the population and wealth largely gathers to the city. And the civil engineering is the focus of city modernization. When unexpected events occur, it will cause huge casualties and economic losses, affecting the sustainable and healthy development of a city. This paper introduces the development and countermeasures of disaster prevention and reduction domestic and overseas. And through the introduction of the emergency rescue system of the city pubic security, the intelligence city, the digital city, present the advises to improve disaster prevention and reduction.

Abstract: Subway is one of the most important public transportations in cities, and its operation security is a very prominent problem. Subway fire is an outstanding issue. The paper begins with the characteristics and reasons of subway, and sets forth the emergency countermeasure and rescue plan of subway fire.