Applied Mechanics and Materials Vols. 170-173

Abstract: Concrete cut-off wall has been widely used in the reinforcement project of earth-rock dam. Its design method and construction technology are comparatively mature, but comprehensive study of interaction of cut-off wall and dam is few, especially for the case that new cut-off wall built in earth-rock dam. In order to discuss the principal and law of interaction of cut-off wall and earth-rock dam in the reinforcement project, seepage field and stress field coupled numerical model was established by using ABAQUS. The contact between the wall and the dam together with the coupling of the stress and the seepage were taken into account in the model. Through coupling calculation of typical earth-rock dam project, the results show that, the model is feasible to simulate the interaction of cut-off wall and earth-rock dam, and the method can provide reference for design calculations of cut-off wall in reinforcement project of earth-rock dam.

Abstract: The dynamic response mechanism of the high arch dam structure is very complicated under the strong earthquake, based on the theory of stochastic dynamics analysis, starting from the basic dynamics equations of structure, the mathematical model of natural frequency of the structure is established by considering random variable of dynamic role of water pressure, earthquake ground acceleration and elastic modulus of the structure. The model numerical results show that the natural frequency of average value and coefficient of variation have a certain correlation and the common characteristics of random is affected by random input variable, and the different vibration mode has average value and coefficient of variation, and the average value of variation has a certain change rule, but coefficient of variation changes small.

Abstract: The selection of the settlement correction coefficient is difficult in the design of seawall engineering. Two cases were enumerated, the settlement correction coefficients were back calculated using in situ monitoring data. The settlement correction coefficients derived from site monitoring fitted total settlement ranged between 1.94 and 2.78. They are much larger than 1.3 applied in design in two cases, and they exceed the recommended range of 1.2 to 1.8. The results indicate that the settlement correction coefficient given in design is lack of a scientific and systematic selection basis and it can hardly reach the real settlement of seawall engineering. The job of in situ monitoring is a good guidance to the selection of the settlement correction coefficient for similar projects in this area.

Abstract: Besides wave attenuation, hollow-block mound breakwater acts as artificial reef which could protect the marine biology and repair the marine ecological environment. Transmission coefficient is the main index of breakwater’s wave attenuation effect evaluation. In this paper through the sectional model experiment on the special assembled hollow-block mound breakwater under regular wave, affecting factors (opening size, water depth, wave period, incident wave height) of the transmission coefficient of breakwater were studied. The main factors that influence the wave attenuation of the hollow-block mound breakwater are the opening size of the hollow-block and the depth of the water while the wave period and the wave height of the incident wave have less influence for the wave attenuation of the breakwater. The research results can provide the reference for the following theoretical research and engineering practice.

Abstract: Hydrological observations at 13-19 stations were conducted synchronically in Lianyungang nearshore area during the spring and half tide in winter and summer respectively. Data of suspended sediment concentrations (SSC), currents and water levels at observation stations were used to study the suspended sediment transport by the method of mechanism decomposition. The advection transport plays an important role during the whole observations, with the direction generally same to the flood current. The tidal pumping transport plays a significant role in the nearshore area, which is the main factor for the periodical variation of SSC. The direction of the tidal pumping transport is mainly toward the land, which indicates that the periodic component of SSC is transport to the land with the form of peaks in the bottom layer. The results may help to improve understanding of the coastal engineering and environmental applications related to sediment transport.

Abstract: The influence of performance is difference along with the change content of chloride ion through the experimental study, so it is necessary to carry on the analysis of the reaction mechanism in blend. At the base of dissemination mechanism and solidification mechanism, the thorough research can be conducted about chloride ion is cured by cement-fly-ash-flushed-by-seawater. The contrast analysis about the dissemination and solidification of chloride ion in base-materials will be researched through microscopic experimental and the analysis of solidification rate. The best chloride ion content can be discovered from the research that it can obtain the best dissemination-solidification and make the influence of performance to be smallest. The dissemination-process of chloride ion in fly-ash-flushed-by-seawater is from the surface of fly-ash-flushed-by-seawater to the interior of cement-gelatin, it is different from internal addition method, and it is proposed for the first time in this what simulate the fly-ash-flushed-by-seawater by soaking fly-ash by the solution of NaCl.

Abstract: The marine riser has transfer dynamic cyclic load to the top of casing string when deepwater drilling operating. Considering with the nonlinear characteristics of seabed soil, the variable string cross section, and the axial load on the top of string, a dynamic differential equation of casing string below mud line and its numerical solution were established. Results illustrate that, the lateral displacement, the bending moment, and the shear of the casing string are not equal when lateral dynamic cyclic loading achieves amplitude due to the soil hysteresis effect. The diameter and wall thickness of conductor have less affect to string vibration frequency, cannot adjust the string natural frequency by adjusting these parameters. The natural frequency of casing string in sand is bigger than it in clay. The undrained shear strength of soil has great effect on the natural frequency of casing string in clay. The lateral displacement amplitude is highest when the vibration frequency of casing string at its natural frequency.

Abstract: In order to give full play to the advantages of FPSOs in the development of offshore oilfields, a new non-ship-shaped FPSO concept named IQFP is put forward through intensive study on various factors affecting the performance of FPSOs. Then, the optimized IQFP general design of a project case is presented based on the IQFP concept. The intact stability and damage stability of the IQFP are calculated and checked according to IMO rules. The hydrodynamic performance in frequency domain is simulated using the three-dimensional potential flow theory and compared with that of a ship-shaped FPSO with similar tonnage. The results indicate that the IQFP has a large stability margin and more excellent hydrodynamic performance than the ship-shaped FPSO. Through the research of this paper, the excellent characteristic of the new FPSO concept IQFP is verified and the basis and foundation are provided for the further studies.

Abstract: Marine environment especially coastal ecosystem has unique hydrological and biological characteristics. However, increased human activities have caused intertidal area destroyed at alarming rates. Environment protection and restoration engineering have become world’s focus. The coastal ecosystems in Bohai Bay have been recognized for providing various ecological functions. The increasing stress caused by human activities induced changes in this area recently. The governors and researchers have conducted restoration engineering. To find out whether the ecosystem health status of marine environment in this area has been changed correspondingly, multiple ecological indicators of different levels including diversity, species biomass and abundance, and thermodynamic indicators were applied. The indicators include Shannon-Wiener index, Margalef index, W-statistic and exergy. The results showed that the marine environment become to moderate disturbed from severely disturbed after coastal restoration engineering according to all the indicators.

Abstract: With the fast development of technology, offshore wind power generation is playing a major role for developing renewable sources in the whole world nowadays. According to the proposed Hangzhou Bay wind farm in China, using general-purpose finite element software, bearing capacity behaviors of the multi-piles foundation for offshore wind turbine are simulated in this paper by the 3D finite element method. The Mohr - Coulomb model is adopted as the elastic - plastic constitutive model of the soil and also the Coulomb Friction model as the pile - soil contact model. The bearing capacity behavior of multi-piles foundation for offshore wind turbines under monotonic and combined loading are discussed, also the bearing capacity behaviors by changing diameters, spaces of piles and loading directions as well.