基于ANSYS的混凝土坝优化设计

根据混凝土坝的几何特征和设计要求确定优化设计变量、约束条件和目标函数,提出基于ANSYS软件的参数化设计语言（APDL）来编制程序,以实现混凝土坝的有限元体形优化设计。不同坝体都有反映其几何形状的特征参数,把这些特征参数作为设计变量,在有限元程序中由这些设计变量和一些已知参数建立坝体和相应地基的有限元模型,并把坝体体积作为目标函数,然后调用ANSYS软件的优化模块,以有限元模型为基础,根据约束条件不断对设计变量进行调整计算,直到坝体体积最后收敛于某一极小值,此时这一目标函数所对应的设计变量即为最优解,从而实现混凝土坝的体形优化设计。在实例中按照这种设计思路,分别对重力坝和拱坝进行了优化设计,计算结果表明该优化设计方法直观、合理。     

水砂石破坏混凝土坝力学机理

从水砂石宏观力学和微观力学的作用效果出发,定性地探讨了水砂石破坏混凝土坝的力学机理,得出了混凝土力学性能变化的趋势,并在此基础上提供了一些展望与看法。     

电算法在引水式水电站闸坝取水枢纽泄洪消能设计中的研究与应用

通过对闸坝枢纽泄洪建筑物下游消能的各种影响因素的分析,综合考虑泄洪建筑物泄洪时对下游河床冲刷严重的问题,结合低水头闸坝枢纽一般采用的底流消能方式,提出了在传统设计方法的基础上编制电算程序的设计方案,用试算法确定了坝闸下游消能的最不利工况,并将其结果应用到程序中,对其实用性和有效性进行了验证.结果表明:该电算法能使低水头...     

黄土丘陵沟壑区人工农田土壤钾素特征研究

通过土样分析,利用统计分析法系统研究了黄土丘陵沟壑区人工农地——坝地和梯田的土壤钾素含量、相关性、垂直和时空分异特征。研究结果表明:坝地和梯田钾素分布严重失衡;表层速效钾平均含量坝地属"中等",梯田属"缺乏";表层全钾平均含量坝地属"较高",梯田为"中等";缓效钾平均是速效钾的7.58倍(坝地)和11.06倍(梯田),但转化率较低;矿物钾平均占全钾的95.71%(坝地)和95.16%(梯田),却难以被作物利用。土壤各形态钾素间都呈极显著正相关,并受土壤有机质、CEC、pH值和颗粒组成的影响。表层与下层间的速效钾、坝地和梯田间的缓效钾都有极显著差异,但黄土母质土壤钾素整体分布均一;坝地速效钾沿剖面向下含量增加,且整体高于梯田;坝地因高耗钾作物玉米而导致缓效钾含量低于梯田。土壤有效性钾、速效钾和缓效钾在时间动态上都表现为先增后降,分水岭年限坝地约在40 a,梯田约在30 a。     

王茂沟流域淤地坝系土壤颗粒与有机碳分布特征研究

为了研究黄土高原丘陵沟壑区坝系坝地土壤颗粒与有机碳的分布特征,以陕北绥德县王茂沟小流域为研究对象,选取了47个土壤剖面,采集土样940个,分析了分形维数、粗化度、有机碳与各粒径组成之间的关系。结果表明:（1）研究区坝地的土壤粒径分布中,粉粒含量占主导地位,依次为砂粒、黏粒;（2）王茂沟坝地土壤颗粒的分形维数在2.674~2.829之内变化,垂直剖面上变化很微小,坝前、坝中、坝后土壤颗粒分形维数分别为2.803 3,2.783 6,2.795 8;（3）王茂沟坝地土壤质地粗化度在0.27~0.58,平均值为0.44,坝前（0.40） < 坝后（0.45） < 坝中（0.46）;（4）坝地土壤颗粒在0.05~0.002 mm和 < 0.002 mm范围内与土壤颗粒的分形维数成极显著正相关,在2.0~0.05 mm范围内与土壤颗粒的分形维数成极显著负相关;坝地土壤有机碳与粉粒和黏粒呈正相关,与细砂粒和极细沙粒含量呈负相关。     

Influence of river discharge on recreational harvest of paddlefish

The Neosho River at Chetopa Dam, Kansas, USA, supports a tailwater paddlefish, Polyodon spathula (Walbaum), snag fishery that is open annually to harvest from 15 March to 15 May and managed to provide anglers with maximum catch. Paddlefish inhabiting this portion of the river are presumed upstream spawning migrants from Grand Lake of the Cherokees, Oklahoma. Angler success in a paddlefish snag fishery is dependent on fish density, a factor that is likely influenced by river hydrology. However, links between river flow regime and angler harvest remain largely unquantified. In this study, hydrological factors that significantly affected paddlefish harvest were identified by regressing paddlefish harvest data from 1992 to 2005 against discharge variables. Two variables describing number of days discharge exceeded a critical threshold that allowed fish to pass a migratory barrier and frequency of discharge increases following decreases combined to explain 53% of variation in harvest. These results can be applied to promote more effective management of this population through increased understanding of relationships between hydrology and harvest. Specifically, anglers can be informed of factors leading to increased harvest in an attempt to increase satisfaction, and cooperating agencies can use these results to develop future water management plans in an effort to increase harvest.     

A method to estimate aquifer artificial recharge from a hill dam in Tunisia

In arid and semi-arid areas, artificial recharge is a key technology in groundwater resources management, and a reliable estimate of artificial recharge is necessary to its sustainable development. Several methods are available to estimate the artificial recharge; however, most of them require field data or model parameters, thus limiting their applications. To overcome this limitation, we presented an analytical method to estimate the artificial recharge through monitoring the water release by piezometer and analysing the controlling factors of the artificial recharge from a hill dam in Tunisia. A total of 97 measurements of water flow in the streambed recorded from 4 gauging stations were analysed. Results indicated that the average infiltration velocity ranged from 0.043 to 0.127 m/d and the infiltration index varied from 7.6 to 11.8 L/(s·km). Pearson's correlation coefficient analysis shows that the infiltration index, the stream gradient, the thickness of unsaturated zone, the number of infiltration pond, the stream geometry, and the water flow rate were found to be the main factors in determining the infiltration. The high correlation coefficients(0.908 for the number of infiltration pond and 0.999 for the stream geometry) mean that the number of infiltration pond and the stream geometry are the most influential factors. Time variations of groundwater level were used to analyze the recharge effects on the piezometry of aquifer. The analysis showed that during the artificial recharge, the water table increased at a rate of 5 mm/d and that the increase was limited to the area surrounding the recharge site. Based on the results of the study, building infiltration ponds along streambed and improving the potential of rainwater harvesting over the study area are recommended.     

淤地坝赋存信息在流域侵蚀产沙研究中的应用

黄土高原淤地坝在拦蓄大量泥沙的同时,也赋存了大量环境变化信息。该文从淤地坝赋存信息在小流域侵蚀产沙速率、泥沙来源和泥沙输移比研究方面的作用进行了归纳和总结,分析了目前研究中存在的问题,提出了今后研究的发展方向,以期能为更好地利用这些赋存信息,发挥其在黄土高原土壤侵蚀和环境演变过程研究中的作用提供参考。     

Impact of Land Use Change and Dam Construction on Soil Erosion and Sediment Yield in the Black Soil Region,Northeastern China

Since the 1960s, the implemented soil conservation measures on steep slopes and the densely planted shelterbelts as well as the constructed reservoirs and ponds in Baiquan County, northeastern China have dramatically altered the landscape and would greatly influence soil erosion and sediment yield (SY ). However, how these land use changes and the constructed dams affected soil erosion and SY still remained unclear. A physically distributed soil erosion model WaTEM/SEDEM that has been calibrated and validated using 25 reservoir SY s in the study area was applied using nine land use scenarios (land uses in 1954, 1975 and 2010, each with 8, 32 and without dams) to assess their impacts on sediment delivery at the Shuangyang catchment (915 km²). The results show that land use changes as well as the increased dam numbers progressively decreased catchment sediment delivery and the impact of dams on sediment delivery was more efficient under the intensified land use condition (1954 land use without reservoirs). With respect to 1954 land use without dams, current land use condition (2010 land use with 32 dams) was simulated to decrease SY by 61·8%. Soil conservation measures (terrace and contour tillage as well as shelterbelts) on the slopes greatly influenced SY and over 80% of the reduced SY were caused by land use changes. This study indicates that soil conservation measures are sustainable sediment control measures for the black soil region because the accumulation of sediment in dams causes shortening of the useful life in reservoirs and ponds and implies increasing financial costs. Copyright © 2016 John Wiley & Sons, Ltd.     

辽河干流坝间耕地土壤重金属污染特征研究

通过对辽河干流坝间10个断面耕地土壤0~5 cm、5~15 cm、15~30 cm沉积层重金属铜、镉、锌、铅含量测定,评价了该区土壤重金属污染程度,并采用地质累积指数法评价单一重金属污染状况与潜在生态危害指数,综合评价重金属生态危害程度。研究结果表明,该区土壤铜、铅、锌与镉含量均值分别为32.42 mg?kg~(-1)、38.23 mg?kg~(-1)、47.35 mg?kg~(-1)和1.625 mg?kg~(-1);铅、锌含量均值在达牛渡口最大,分别为55.54 mg?kg~(-1)和80.51 mg?kg~(-1);铜、镉含量均值在通江口处最大,分别为50.24 mg?kg~(-1)和3.103 mg?kg~(-1)。除镉外,铅、铜、锌含量各断面不同深度浓度均低于全国土壤环境质量Ⅱ级标准,镉含量均值是全国土壤环境质量Ⅱ级标准的1.70倍,最大值为3.402 mg?kg~(-1);辽河大桥上游干流镉含量是下游镉含量的6.47倍。镉的地质累积指数值在坝间均显污染,其中,辽河大桥以上各断面显强污染。通江口至毓宝台特大桥重金属潜在生态风险指数值最强。各断面镉对多种金属潜在生态风险指数值的贡献达78.77%~98.23%,贡献率与潜在生态危害指数(RI)呈正相关。多种重金属潜在生态风险指数值变化趋势与镉地质积累指数分布趋势相同,最大值出现于通江口断面。