Applied Mechanics and Materials Vols. 580-583

Abstract: The project of substituting small hydropower for fuel (SHPF project in short) in China has been implemented for ten years and has achieved significant economic, social and ecological benefits. The construction, completion situations, results and major experience of the SHPF project are summarized. The existing problems are analyzed. Some suggestions are given for the construction and management of similar projects in future.

Abstract: The phenomenon of spalling at Baihetan Hydropower Station is influenced by such factors as the stress redistribution in surrounding rock, the local stress concentration and also poor properties of disturbed belt. In this paper, a series of numerical simulation were carried out and some beneficial conclusions were gained as follows: 1) the ratio of maximum shear stress and uniaxial compressive strength is more rational in the prediction of spalling and can give confident explanation for “V” shape pits; 2) the in-situ geo-stress direction is in accordance with NNE and NE.

Abstract: It was convenient to go through the river after the building of bridge, but the flow water around the bridge can be influenced seriously. The level of water will become high and the velocity will reduce because of the influencing of resistance water by the bridge pier, and the level and the velocity of downstream water decreased. Between the bridge piers the velocity will increase where the water was extruded. All of these will have an effect to the safety of bridge and river flood controlling. In this paper, a 2D numerical model is established to simulate the variation of the level and velocity after the bridge was built, and to learn the effecting of the bridge on the flood controlling.

Abstract: Rainfall information is critical in understanding the hydrologic balance on a global scale and the complex interactions among the small-and large-scale components within the hydrologic cycle [1]. In this study, the monthly rainfall data from 1976 to 2006 at the stations of Rongchang, Dazu, Tongliang and Yongchuan were used to analyze the statistical characteristics and trends of rainfall changes in the west of Chongqing. The average monthly rainfall at Rongchang, Dazu, Tongliang and Yongchuan were 89.4mm, 83.5mm, 88.3mm and 84.8mm in thirty years. The probability distribution of rainfall is a normal distribution. Moreover, the histogram of frequencies showed a clear tendency toward a obvious seasonality of the rainfall distribution [2].

Abstract: The seepage field regulation is important for the stability canal liner plate and slope for along the Middle Route of the South-to-North Water Transfer Project, especially for stretches excavated in expensive soil area with groundwater level. In order to analyzing the rationality and efficiency of seepage regulation measures comprehensively, a typical section was modeled, and the seepage field was simulated with the 3D finite element technology. The distribution of seepage field was analyzed and the seepage control measures were compared. The results show that water pressure on the underside of canal pavement would be reduced significantly by the measures, such as the measure of drainage cushion with drainage holes which open just when ground water level is higher than the canal water level, the measure with drainage cushion replaced by the drainage board. The differences among the two kinds of measure were compared. Their application conditions were discussed and proposed.

Abstract: Monthly precipitation data from Huangtai Bridge Station were used to study seasonal and annual precipitation characteristics and trend. The covered time-period is from 1956 to 2007. Different methods including linear regression, 5-year moving average, anomalies in decadal scale and the Mann-Kendall test were applied in the study. Nearly two-thirds of the total rainfall amount is concentrated in summer, with autumn and spring months to follow, and only about 3% in winter. An increasing trend in spring months is found. It starts in 1978, becomes significant after 2002, and probably continues into the future. A decreasing trend is recorded in winter and begins in 1980. No significant trend is found in summer, autumn and yearly precipitation. The same fluctuations are observed between summer and annual precipitation indicating the dominant influence of the summer season.

Abstract: New U (moment) implements the optimum water section of rectangular slot structure, besides all advantages of the traditional U and T-shaped slot in the canal seepage, also has advantages of reducing covers area of higher performance and price ratio. The kind of canal seepage control structure is upgrading products of the traditional U and T-shaped slot. In this paper, through design research on new U (moment) slot structure, giving U (moment) slot structure size, it can provide technical support for the product development of new type U (moment).

Abstract: Siltation in the rivers downstream of floodgates is serious in China, making the discharge capacity of rivers decrease obviously and threatening the flood control in upper rivers. Tidal wave deformation is one conclusive dynamic factor leading to siltation downstream of floodgates in estuaries. A 2-D numerical model of tide and sediment transport is established to simulate the distribution of sediment siltation downstream of the floodgate, and several conclusions are obtained in this paper which can provide some theoretical basis for the prediction and analysis of the siltation characteristics in lower reach caused by floodgates in estuaries.

Abstract: In dam seepage line monitoring process, dam saturation line "inverted siphon" phenomenon appeared. In order to study the time effect, indoor model test were done. The dam seepage line rules and conditions were determined. The results show that when the reservoir water level dips, the dam seepage line with the decreasing of the water level will drop. But the changing has lagged far behind. Hysteresis and permeability dam, seepage path length, the upstream water level and other factors related to the rate of decline.

Abstract: For a temperature rebound in the irrigated high arch dam during the construction period, using finite element method to research the influence of environment temperature to temperature rebound of the irrigated high concrete arch dam. Assuming that the initial temperature of the dam concrete is the joint grouting temperature. This paper presents a simulation of the temperature rebound of the high arch dam which is caused by the monthly average environment temperature, and performs sensitivity analysis to research the influence of thermal conductivity and surface heat preservation on the temperature rebound. According to the analysis,when the high arch dam sealing temperature is lower than the dam site annual average temperature, the dam site temperature inevitably would flow backward,slowly,to the irrigation area.The larger the thermal conductivity is,the quicker the temperature rebound speed will be. And benzene board insulation can reduce concrete temperature rebound rate, if the heat preservation benzene board is thicker,the temperature rebound rate is smaller.