大水桥水库浮游植物群落结构特征研究

于2011年2月(枯水期)、5月(丰水初期)、8月(丰水末期)和11月(平水期)对大水桥水库的浮游植物群落结构进行研究。结果表明,浮游植物有6门、42种,丰度在6.6×106～3.7×108个/L,丰水期丰度最高,枯水期丰度最低,枯水期、丰水期和平水期第一优势种分别为蓝藻门的拟柱孢藻(Cylindrospermopsis rackiborskii)、湖泊假鱼腥藻(Pseudanabaena limnetica)和湖丝藻(Limnthriox redekei)。浮游植物群落结构显示,水库处于中-富营养状态;丰水期水质较差,枯水期和平水期相对较好。浮游植物丰度与硝氮(r=-0.898,P<0.01,n=12)、总氮(r=-0.894,P<0.01,n=12)及透明度(r=-0.594,P<0.05,n=12)表现出显著性负相关,与pH(r=0.676,P<0.05,n=12)、总磷(r=0.703,P<0.05,n=12)、水温(r=0.754,P<0.01,n=12)表现出显著性正相关。

乌兰县小考

沿青藏公路西行,翻过橡皮山,越过大水桥,首先映入人们眼帘的是晶光闪烁的茶卡盐湖,这就明白无误地告诉人们:你的双足早已踏上了“乌兰”这片古老而又神奇的土地。

Distribution and characterizing sources of polycyclic aromatic hydrocarbons of surface water from Jialing River

Sixteen priority polycyclic aromatic hydrocarbons(PAHs) in surface water samples were analyzed by gas chromatograph-mass spectrometer(GC-MS) to study their distribution and characterizing sources.The water samples were collected from five sites(J1-J5) in the Jialing River of Chongqing downtown area from September 2009 to August 2010.The results demonstrate that the concentration of total PAHs in three samples upstream are relatively higher than those in other two sites downstream,with average concentration of total PAHs for each site ranging from 811.5 ng/L to 1585.8 ng/L.The 2,3 and 4-ring PAHs for sampling stations account for 13.0%,56.6% and 28.6%,respectively,in total PAHs.There are obvious tendencies of seasonal change for PAHs concentration in surface water.The PAHs concentration in April of wet season is 1 301.6 ng/L,which is 1.3 times the lowest amount of total PAHs in August of flood season.Ratios of specific PAH compounds were used to characterize the possible pollution sources.Experimental results indicate that the PAHs in surface water samples are primarily from pyrolytic PAHs because of factories along these sites,while the direct leakage of petroleum products may be significant for two sites,Jiahua Bridge(J4) and Huanghuayuan Bridge(J5),because of the wharf boat nearby.

Design and construction of Sutong Bridge deep-water main-pylon foundations

This paper,from three aspects including construction conditions,foundation design and construction,introduces some considerations in the designing of main-pylon foundations and some practical measures to deal with certain unfavorable construction conditions,such as deep water,tidal effect,soft stratum and heavy traffic,during the construction of main-pylon foundations.

Bridge Pressure Flow Scour at Clear Water Threshold Condition

Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally.The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional;all the measured scour profiles can be described by two similarity equations,where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth;the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge;the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge;and the maximum scour depth decreases with increas-ing sediment size,but increases with deck inundation.The theoretical analysis shows that:bridge scour can be divided into three cases,i.e.downstream unsubmerged,partially submerged,and totally submerged.For downstream unsubmerged flows,the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied;for partially and totally submerged flows,the equilibrium maximum scour depth can be described by a scour and an inundation similarity number,which has been confirmed by experiments with two decks and two sediment sizes.For application,a design and field evaluation procedure with examples is presented,including the maximum scour depth and scour profile.

Research on subsidence method aided by water injection and its engineering application for the north anchor of Taizhou Bridge

The north anchorage caisson of Taizhou Bridge encountered some difficulties during the sinking process for the large sidewall frictional resistances. To solve this problem, a new concept and method called subsidence method aided by water injection is proposed. Numeral analysis is adopted to simulate the effects of this method for the north anchor of Taizhou Bridge, which confirmed the feasibility and validity. Finally, the method is applied to the north anchor caisson during the caisson sinking procedure and helps the caisson sink and embed to the designed position smoothly.

A Study of the system control model of caisson dewatering of the north anchorage of Taizhou Bridge

A caisson foundation is applied to the north anchorage of Taizhou Yangtze River Highway Bridge of which the initial caisson sinking requires dewatering. Since the caisson foundation is quite close to nearby buildings, a system control model is established with source (sink) distribution and intensity being the object function, minimum requirements of settlement and deformation of surroundings caused by dewatering and dynamic water levels during different working procedures being constraints, and the design parameter of pumping wells being the variable,so as to lower the jeopardizing of surrounding buildings, which provides a new method for active control over settlement during dewatering. Such a method of dewatering based on system control model should be of significance for similar projects involving dewatering.

A Method to Improve First Order Approximation of Smoothed Particle Hydrodynamics

Smoothed particle hydrodynamics (SPH) is a useful meshless method.The first and second orders are the most popular derivatives of the field function in the mechanical governing equations.New methods were proposed to improve accuracy of SPH approximation by the lemma proved.The lemma describes the relationship of functions and their SPH approximation.Finally,the error comparison of SPH method with or without our improvement was carried out.

Design and construction of scour protection for deep-water group pile foundation structures of two pylons in the Sutong Bridge project

Sutong Bridge,as a world-record cable-stayed bridge with its main span exceeding 1 000 m constructed in Yangtze River estuary region in China,is located at a site with complicated hydrologic conditions and poor geotechnical conditions and therefore,scour protection will be a decisive factor for ensuring smooth and successful construction of this bridge.This paper,starting from structural description of deep-water group pile foundation,analyzes impact to the bridge safety introduced by scour and its protection and further presents different solutions of scour protection for foundation structures of this bridge.

On-site tests to estimate aquifer permeability of drainage area of south caisson anchorage construction of Taizhou Bridge

During the construction of the south caisson anchorage of Taizhou Bridge, the drainage area is located in the lower reaches of the Yangtze River and the permeability of stratums there is considerable. In order to maintain progress and guarantee safety during the sinking of the caisson, water should be drained in the initial period. Subsequently, detailed information about the aquifer permeability is required to make sure that the drainage will proceed successfully, which consequently necessitates the on-site estimation of the aquifer permeability in the drainage area. Therefore, the traditional pumping test and slug test are implemented respectively on site. The comparison of computational results of these two tests indicates that they are consistent overall. Notwithstanding, as slug test can be conducted with portable facilities in a short time and the manipulation is easy and few people need to be involved, the advantages of slug test is conspicuous compared with the traditional pumping test. It could be speculated that slug test will gain a prevalent application in the measurement of aquifer permeability in the future.

“群众的笑脸是装不出来的”——卢钟鹤主任率检查组赴湛江督查实施“十项民心工程”、《广东省社会救济条例》情况侧记

6月24日至25日,风和日丽,省人大常委会主任卢钟鹤率省人大常委会检查组到湛江,对该市实施"十项民心工程"、贯彻落实《广东省社会救济条例》城乡低保制度情况进行督办检查。湛江市领导邓维龙、张志、吴智华、陈亚德等陪同检查。徐闻县位于祖国大陆的最南端,昔日是湛江市一个苦旱的贫困县。

安居乐业移民笑——湛江市人大常委会督办解决水库移民遗留问题议案回眸

2009年1月15日,省十一届人大常委会第八次会议听取和审议了省人民政府《关于解决水库移民遗留问题议案办理情况的报告》。会议认为议案经过15年的实施,取得了明显成效,基本上达到了立案目的,决定不再延长议案办理时间并如期结案。《关于解决水库移民遗留问题的议案》顺利结案,标志着我省水库移民扶持工作取得了阶段性的胜利。

播撒“迷彩绿”,收获“迷彩梦”

迷彩绿,生命的颜色,大自然的颜色,老百姓的幸福色。我对绿军装充满热爱,尤其对迷彩服情有独钟。17岁从军,我穿着它从雷州半岛军营起步,走过骄阳,走过风雨,23载军旅征程,一路走来,我痴心不改地播撒着"迷彩绿",同时也收获了军旅人生沉甸甸的"迷彩梦"。1996年,我在湛江某部服役。雷州半岛适逢百年不遇的台风灾害和干旱天气。