非稳定井流模型的半解析解

为了提高非稳定渗流计算的计算精度 ,通过数学分析得到了水位传导系数随时间变化时 ,一类非稳定渗流井流模型的半解析解 ,并进行了计算比较     

WAVE INTERACTION WITH PERFORATED CAISSON BREAKWATERS

The reflection coefficient of perforated caissons and the total horizontal forces acting on them were experimentally and numerically analyzed and discussed when wave propagates normally. To consider the viscosity effect of fluid and nonlinear action of waves on structures, the VOF (Volume Of Fluid) method combined with the k-ε turbulence model was used to simulate the interaction between waves and structures. Governing equations were solved with the finite difference method. Through 2D experimental study in the wave flume, the empirical relationship between the reflection coefficient of perforated caissons and the main affecting factors were obtained from the experimental data using the least square method. Also the correlation between the ratio of the total horizontal force acting on perforated caisson and the force acting on solid caisson and the main affecting factors were regressed from the experimental data.     

复合形法优化内河航道重力式护岸

采用复合形优化法,结合《港口及航道护岸工程设计与施工规范》中推荐的抗滑、抗倾稳定的分项系数计算方法,并考虑了内河航道船形波等作用的影响效应,对重力式护岸断面进行了优化。     

浅论我国农产品流通企业扩张的基本规律与政策规制

通过对农产品流通企业扩张形式全面的理论梳理, 研究总结了二种类型的农产品流通企业扩张基本规律,即纵向扩张和横向扩张,并对中国农产品企业扩张问题进行了实证研究,最后对我国农产品流通企业扩张提出建议.     

掺气减蚀设施水力计算的改进

结合小湾工程泄洪洞模型试验进行了11种挑跌坎型和6级流量的试验观测，据此提出了特别适用于大单流量条件的射流出射角修正式，提出了射流近底流速的选取原则.与实验资料对比证明本文计算方法有足够精度。     

热分层流动计算中若干差分格式的比较

本文应用常规的守恒方程及湍流模型，对二维池内热分层流动建立了数学模型，并在Ｐａｔａｎｋａｒ的压力校正法基础上对该数学模型进行了数值计算，计算中的差分格式为乘方格式、一阶迎风、二阶迎风和ＱＵＩＣＫ。通过与实验的比较分析，建议计算应采用ＱＵＩＣＫ格式，并在进行风格独立性试验的基础上使用加密网络。     

Variations in Spectral Slope in Lake Taihu,a Large Subtropical Shallow Lake in China

Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm⁻¹ for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm⁻¹ and 13.62 ± 2.11 μm⁻¹ for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight.     

山西引黄工程南干线7# 隧洞衬砌外水压力研究

本文采用综合修正系数取代规范建议的单一折减系数,用渗流场分析方法确定作用在引黄入晋南干线7#隧洞衬砌上的外水压力。由己知钻孔水位及泉水位反演出各地层的渗透张量及地表入渗强度求得初始渗流场。衬砌外水压力分析中考虑了衬砌混凝土的渗透性以及排水、灌浆等工程措施的影响。根据分析结果,提出了系统排水孔布置的建议,得出了在相应的排水减压措施下衬砌厚度由原设计35cm减至25cm,这一建议已被采用,取得了巨大经济效益。     

EXPERIMENTAL INVESTIGATIONS ON LONGITUDINAL DISPERSION CHARACTERISTICS OF TIDAL RIVERS

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横泉水库旧坝体及黄土台地强夯处理实践

山西省横泉水库在原有遗留工程基础上进行重新建设，以往的4次施工，填兢了长400m、高17m左右的左岸坝体，填土约120万m^3，但坝体填筑质量极差，干客重和渗透系数根本无法满足设计要求。此次重新建设，决定对这部分干客重不迭设计要求且具有湿陷性的左岸旧坝体以及左岸黄土台地进行强夯处理，对坝体进行强夯处理在省内还是首次进行，在国内也比较少见，通过处理，坝体质量达到了设计要求，并且节约了投资，效果明显。