ABRASION OF THE BOTTOM OUTLETS AND ITS REPAIR IN SANMENXIA PROJECT

The Sanmenxia Project completed in 1960 is a multi-purpose hydro project with emphasis on flood control. After the expounding, serious deposition occurs in the upstream part of the reservoir and the Weihe River. The project has to be rebuilt twice in the period from 1964 to 1978. Thus the discharge capacity is greatly enlarged by excavating two side tunnels on the left bank, converting three penstocks into sluice conduits and reopening & bottom outlets formerly used for di- version. By changing the operational mode from storing water year round to stor- ing clear water during the dry season and sluicing sediment during the flood season, the sediment problem of the reservoir is largely solved and multi-purpose benefits of the project are partially retained. But the heavy sediment load still caused serious abrasion on bottom outlets and turbines, particularly on the inlet gate slot, the service gate slot and the floor. Much effort has been made to clarify the mechanism of the damage and to choose abrasion-resistant material for repair. The repair of the bottom outlets has been going on since 1980. This paper describes the abrasion on the bottom outlets in details and the subsequent repair effected.     

Full scale wake and boundary layer instrumentation feasibility study

Fluid-flow measuring devices intended for full scale use were designed and tested. One device consisted of a rake supporting different types of pitot tubes. This will be used to obtain a velocity profile of the boundary layer of a test ship. The other device was a five-hole pitot tube that was used in a wake survey. The pressure transport medium (i.e. the medium that carried the pressure signal from the pitot tube to the pressure transducer) was air instead of water. This proved to be successful, as the results indicate.     

Elastic properties of seafloor sediments from the modelling of amplitudes of multiple water waves recorded on the seafloor off Bear Island,North Atlantic

Wide‐angle seismic data acquired by use of air‐guns and ocean bottom seismometers (OBS) contain strong direct water arrivals and multiples, generally considered as noise and thus not included in the modelling. However, a recent study showed that standard ray‐tracing modelling of the water multiples recorded off the Bear Island, North Atlantic, provided a reliable estimate of the velocity distribution in the water layer. Here, we demonstrate that including the amplitudes in the modelling provide valuable information about the V_P contrast at the seafloor, as well as the V_P/V_S ratio and attenuation (Q_P) of the uppermost sediments. The V_P contrast at the seafloor is estimated at about 250 m/s, within a precision of approximately ±30 m/s. The V_P/V_S ratio in the uppermost sedimentary layer is modelled in the range 2.25–2.50 and the Q_P factor is estimated at 1000 for the water, 30–50 for the uppermost layer and 40–50 for the second sedimentary layer. The values obtained for the sediments suggest a lithology dominated by silty clays, with porosity below average.     

康山“古油藏”讨论之三——康山“沥青脉”的成因

通过对康山固体可燃脉体产状、脉石矿物性质、构造发展史的综合分析,认为其成因很可能是下寒武统荷塘组中的软沥青和有机质,在加里东运动期间,由于区域应力体系的变化而爆炸运移形成的。康山脉石矿物是沥青和有机质,不是煤和无机物。沥青的源岩为下寒武统荷塘组富有机质的黑色泥岩、硅质泥岩、硅质岩。康山脉中的固体沥青和有机质,当初挤入时应呈塑性流动状态,康山沥青系由石油经热演化而成。     

中国地震局<大陆强震机理与预测>项目学术交流代表团赴美考察

２０００年５月,以《大陆强震机理与预测》项目首席科学家张国民研究员为团长的中国地震局《在陆强震机理与预测》项目学术交流代表团一行８人赴美进行学术交流和访问。代表团在美国期间,先后参观访问了门洛帕克美国地质调查局、加州大学洛杉矶分校、加州理工学院、华盛顿卡内基研究所、美国国家科学基金会和麻省理工学院等单位,并与美方有关专家学者和项目管理人员就有关学术问题科研项目的评审和管理等问题进行了交流和讨论。     

雅鲁藏布江缝合带的双陆内俯冲构造与部分熔融层特征──INDEPTH项目结果的初步综合

根据中、美两国合作开展的西藏深反射地震结果,提出雅鲁藏布江缝合带（YZS）的"双陆内俯冲"构造模式和缝合带南、北分别存在着不同特征的、规模不一的部分熔融层;提出YZS处断裂向深部延深有限,认为YZS处地壳增厚有4种机制：①地壳规模的大的俯冲增厚;②上部地壳内的俯冲和背冲增厚;③下地壳内的底部垫托增厚和挤压增厚;④深部熔融体的向上挤入而引起的地壳增厚.提出可能存在两条大的伸展性断裂,造成江孜南、北地块间出现了大升降.     

国家973项目“我国南方致洪暴雨监测与预测的理论和方法研究”获准立项并启动

2004年中国气象科学研究院国家973项目“我国南方致洪暴雨监测与预测的理论和方法研究”获准立项实施,院长张人禾研究员受聘为该项目的首席科学家。项目研究期限为2004年10月至2009年 10月。参加单位中除了中国科学院和高校的有关单位外,还包括中国气象局所属的国家气象中心、国家气候中心、国家卫星气象中心、中国气象局培训中心、武汉暴雨研究所、上海台风研究所、广州热带海洋气象研究所等单位。项目意义:正确的暴雨预报是各级政府指挥抗洪救灾的主要科学依据之一,要深入了解暴雨的机理、提高暴雨预报能力,必须深入研究空间尺度为几十公里至上百公里(中β尺度)的强对流系统(即暴雨     

SEDIMENTATION PROBLEMS IN THE ACCESS CHANNELS OF THE GEZHOUBA NAVIGATION LOCKS

Sedimentation problems in the access channels of the Gezhouba Navigation Locks at the Third Channel, which is of great importance for the navigation are discussed in this paper:1) the cause of deposition in the access channel, 2) effects of the deposit--reducing embankment and sediment sluices and 3) the relation between the sediment deposition at the Third Channel and the sediment discharge of the Yangtze River. Analyzing a four years' field data of sounding records with respect to the lock operation, it can be seen that the flood release through the navigation channel resulted in severe deposition, especially the sediment deposits induced by eddy current are difficult to be cleared off by flushing and jeopardize the working conditions of the lock operation. It is obvious that the flood release through the navigation channel should be minimized. In order to reduce the sediment deposits caused by eddy current attempts should be made to adjust the alignment of the boundaries and layout of the entrance of access channels.     

洛阳市水资源可持续开发利用对策研究

洛阳市是一个水资源总量偏少的地区。按可供水资源量、现状尚可维持．预计2005年和2010年全区将缺水0．75亿m^3／a和2．43亿m^3／a。为了保证洛阳市经济快速、持续的发展，水资源的可持续开发利用已成为关键性因素之一。对于本市来讲，依法治水、科学用水、节约用水、污水资源化是实现市域水资源开发利用和保护良性循环的重要举措，核心是抓好农业节水和城镇用水。本文对域内水资源可持续开发利用，进行了可行性研究。