Applied Mechanics and Materials Vols. 580-583

Abstract: Large landslides usually dam lakes that may easily fail and then result in catastrophic flood threatening the population downstream. The grain size composition within landslide dams is considered as a vital factor that impacts the timing of failure and the resulting magnitude of flood. Therefore, experiments were conducted to investigate the features of size distribution in accumulation bodies. The results indicate that the grain size distribution varies in different parts of the deposits. The inverse grading phenomenon can be observed. Grains in the front of the deposit are coarser, while grains in the rear are finer. For the front of the deposit, the grains in the middle are finer than the other two sides. The grain size segregation is believed to be the governing mechanism that contributes to this special distribution. The speculations of the grain size distribution inside the landslide dam are presented.

Abstract: The arch dam of Jinping I hydropower station is on obvious high ground area, and the foundation rock masses may relaxed while excavating. Limit tensile strain is put forward to be relaxation criterion. By three-dimensional elastic-plastic finite element method analyzing, and imitating the dam excavating steps, the maximum principle strain of the dam foundation rocks is obtained. The research indicates that the maximum principal strain of upstream side is greater than that of downstream side commonly, and some area would relaxed, with 41m maximal relaxed depth. By engineer analogical research with Xiaowan arch dam foundation rock mass, which have relaxed while excavating, the calculate method and criterion of this paper are reliable, and they can provide reference for engineer design.

Abstract: In the process of comprehensive treatment for the Tangdao Bay in Qingdao,the dikes need to be constructed firstly and then the construction for treatment can be started,in this paper,the author uses the two-dimensional mathematical model to analyze the change of the flow field in the water area of Tangdao Bay before,during and after the diking construction in simulation and analyze the influence on the marine environment after diking.By use of the diking method of throwing sand in jute bags,the new secondary pollution caused in the diking construction process can be prevented effectively and nice economic and social benefits can be obtained.

Abstract: The phenomenon of the actual situation leave the design index is very common during the civil project construction especially in the coastal levee construction. As the way to reduce the probability of diseases occurrence, from the aspect of quality accident analysis, construction quality monitoring moisture, quality inspection and accident early warning system, the paper studied the levee construction quality control monitoring system deeply and advanced some useful conclusion.

Abstract: At present, many oil tank wharfs of 300,000DWT which taken the maximum of 450,000DWT supertanker into account had been built in our country. In this paper, through the physical model test on 450,000DWT supertanker, the mooring line tension with different mooring arrangements, cable diameters and cable materials were studied and the wave condition for the supertanker safety operation was given. The results showed that: on the same wave condition, to increase the steel cable’s diameter could reduce the ship’s movements, which could enhance the ability to operation. In addition, using the combination cable on the same diameter instead of the steel cable could reduce the tension of mooring line and increase the working ability effectively. The research results can provide reference and guidance for the future of supertankers mooring operation.

Abstract: The traditional method of the offshore caisson positioning and installing is using the barge or floating crane, but for the large caisson with 26,000 tons, the method is unable to achieve apparently. In this paper, the offshore location and installation of the large caisson with mooring line system and anchor cable system are studied. The research gets the wave and flow conditions results as well as the related and advertent items, which provide the reference for large caisson positioning and installation as well as the similar engineering construction technology.

Abstract: Two-Dimensional finite element analysis was used to investigate the performance of seawall construction over weak subgrade soil using artificial base layer material consisted of cemented sand cushion comprising geosynthetics materials. Two types of base layer materials pure sand and cemented sand comprising husk rich ash and two types of geosynthetics materials geogrid and geotextile were used. Constitutive models were used to represent different materials in numerical analysis. The competence of two-dimensional numerical analysis was compared with experimental results. Numerical results showed a superior harmony with the experimental results. Finite element analysis model proved to be a great tool to determine the parameters that are difficult to measure in laboratory experiments. In addition, finite element analysis has the benefit of cost and time saving when compared to experimental investigation work. Numerical results showed strain induced in geosynthetics eliminated beyond a distance approximately equal six times of footing width.

Abstract: Ocean tide models with satellite altimetry can simulate global ocean tides conveniently and accurately. However, it was not sure for them to have a same good performance in estuaties and coastal zones. To assess their accuracy in the Pearl River estuaries, tidal elevations were computed respectively by three models NAO.99b, OTPS and WWT, and compared with the hourly observed data. RMS misfits were calculated and the results suggest that the models are competent to demonstrate the basic time features of tides and the accuracy is not lower than that of traditional methods in some certain periods and areas. The models behave better in the mouth zones, especially in the open area outside, but in the upstreams have differences between dry season and flood season. At the entrances, compared with the river-dominated estuary, the models indicate more accurate estimations for the tide-dominated estuaries. WWT is recommended among these three models.

Abstract: In this paper, a 2D model for the simulation of shallow water flow by convection and diffusion over variable bottom is presented, which is based on the FVM (finite volume method) over triangular unstructured grids. The format of Reo’s approximate Riemann is adopted to solve the flux terms. And the bed slope source term is treated by split in the form of the flux eigenvector. For the diffusion terms, the divergence theorem is employed to obtain the derivatives of a scalar variable on each triangular cell. The numerical model is adopted to simulate the hydrodynamic impact from HZM (Hongkong-Zhuhai-Macao) bridge on Pearl River estuary. The simulated results show that the HZM bridge has little influence on the distribution of hydrodynamic environment in the Pearl River estuary.

Abstract: The tube tugging and mooring is the key step in the process of the immersed tunnel, and the most important theoretical is the calculation of water flow force. According to the numerical simulation and physical model of the tube in the Pearl River, the difference value of the flow resistance coefficient can be calculated. The fluent software is used to simulate the process of the tube tugging and mooring. On the basis of the empirical data of the tube experiment in the Pearl River, the flow resistance coefficient is obtained in the process of the tube tugging.