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91.
92.
The interaction between waves and porous breakwater has an important theoretical significance and great application value of engineering. In this paper, the tests of the core material’s influence in rubble mound breakwater on wave propagation are carried out. The relations among the transmitted wave height, incident wave element, and breakwater width are discussed. The calculation formula is obtained. The test results show that different core materials have obvious influence on wave propagation. 相似文献
93.
公路工程建设呈现的岩土工程问题主要有地基稳定问题、边坡稳定问题、围岩稳定问题和渗透稳定问题。这些问题对工程的影响体现在变形和强度两个方面,根据工程的功能和性质,应考虑按变形控制或强度控制来确定工程安全标准和评价工程稳定性。基于岩土工程问题的产生条件,提出了在工程实践中应注重的内容及研究方向,如:路基岩土的强度与变形特性研究、地基处理技术及工程特性研究、深基础与地基相互作用研究、边坡稳定性评价方法研究、边坡治理技术及可靠性研究、围岩与结构应力变形研究、地下水对各种岩土体的作用研究等等。 相似文献
94.
A numerical model is presented in this study to investigate the wave transformation over a submerged permeable breakwater on a porous slope seabed. For this purpose, the time-dependent mild-slope equation is newly derived for waves propagating over two layers of porous medium. This new mild-slope equation involves the parameters of the porous medium, and it is a type of hyperbolic differential equation, therefore numerically efficient. The validity of the present model is verified based on the comparisons with the previous experiments. The effects of the permeable properties of both the porous seabed and the submerged permeable breakwater are discussed in detail. The geometry of the submerged permeable breakwater to the wave transformation is also investigated based on the numerical solutions. 相似文献
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The activities of extracellular enzymes that initiate the microbial remineralization of high molecular weight organic matter were investigated in the water column and sandy surface sediments at two sites in the northeastern Gulf of Mexico. Six fluorescently labeled polysaccharides were hydrolyzed rapidly in the water column as well as in permeable sediments. This result contrasts with previous studies carried out in environments dominated by fine-grained muds, in which the spectrum of enzymes active in the water column is quite limited compared to that of the underlying sediments. Extracts of Spirulina, Isochrysis, and Thalassiosira were also used to measure hydrolysis rates in water from one of the sites. Rates of hydrolysis of the three plankton extracts were comparable to those of the purified polysaccharides. The broad spectrum and rapid rates of hydrolysis observed in the water column at both sites in the northeastern Gulf of Mexico may be due to the permeable nature of the sediments. Fluid flux through the sediments is sufficiently high that the entire 1.5 m deep water column could filter though the sediments on timescales of a few days to two weeks. Movement of water through sediments may also transport dissolved enzymes from the sediment into the water column, enhancing the spectrum as well as the rate of water column enzymatic activities. Such interaction between the sediments and water column would permit water column microbial communities to access high molecular weight substrates that might otherwise remain unavailable as substrates. 相似文献
99.
针对气藏的生产特征,基于稳定渗流理论,以气体高速非达西渗流为基础,考虑真实气体PVT参数动态变化,结合气藏物质平衡方程,推导建立同时考虑滑脱效应、启动压力梯度、应力敏感等因素共同影响的低渗气藏动态预测模型,分析各因素对气井产量变化的影响.结果表明:在考虑高速非达西流的基础上,考虑滑脱效应将导致渗流阻力降低而引起气井稳产年限增加和地层压力下降变快,考虑启动压力梯度和应力敏感效应时将导致渗流阻力增加而引起气井稳产年限降低和地层压力下降变慢;启动压力梯度和渗透率变形系数越大,气井稳产年限下降幅度越大,地层压力下降越慢,而滑脱因子越大,气井稳产年限增加幅度越大,地层压力下降越快. 相似文献
100.
The Havriliak-Negami model for dynamic viscoelastic material behavior and Biot's theory of poroelasticity are employed to develop an exact solution for three-dimensional scattering effect of harmonic plane P-SV waves from a circular cavity lined with a multilayered fluid-filled shell of infinite length containing viscoelastic damping materials and embedded within a fluid-saturated permeable surrounding soil medium. The analytical results are illustrated with numerical examples where the effects of liner/coating structural arrangement, viscoelastic material properties, liner-soil interface bonding condition, seismic excitation frequency, and angle of incidence on the induced dynamic stress concentrations are evaluated and discussed to obtain representative values of the parameters that characterize the system. It is demonstrated that incorporating viscoelastic damping materials with a low shear modulus in the constrained layer configuration is an efficient means of enhancing the overall seismic isolation performance, especially for near-normally incident seismic shear waves where the amplitudes of induced dynamic stresses may be reduced by up to one-third of those without isolation in a relatively wide frequency range. Some additional cases are considered and good agreements with solutions available in the literature are obtained. 相似文献