Applied Mechanics and Materials Vols. 638-640

Abstract: The deformation and contact behavior between concrete face and rockfill are important to the safety of concrete face rockfill dams. Based on the monitoring data of Shanxi concrete face rockfill dam, the stress of concrete face, deformation of rockfill and facing joints were studied. It is shown that the rockfill deforms under the water pressure and weight, and the concrete face is compressed in central and otherwise around abutment during the reservoir filling. As the upstream concrete face deforms as the result of the rockfill deformation, the peripheral joints appear tensile, shear and settlement deformation. In addition, the main deformation of peripheral joints is settlement, which has a significant relationship with water level, especially for the upper ones.

Abstract: In order to speed up the progress of the concrete dam construction, the concrete thick layers and short time intervals fast pouring method is proposed. The temperature cracking and stress safety of the dam under concrete fast pouring method is a big trouble. From the concrete cracking safety point of view, a concrete gravity dam is introduced as a case study, the influence of different thickness of layers, different time intervals and different pouring temperature on the temperature and thermal stress characteristics of the concrete dam at the early age as well as the cracking risk of the concrete are deeply studied. According to the analysis, the corresponding cracking prevention technology is put forward. The research provides a technical support for establishing the concrete temperature control criteria and the relevant temperature control measures for the concrete fast pouring method.

Abstract: Concrete plate is mainly anti-seepage structure for rockfill dam and essential to avoid dam destruction. Cooling shrinkage will be effectively compensated by mix MgO, as a result, it have been widely used in hydraulic structure. However, with large radiating surface, uniform heat exchange and small bottom restriction, stress characteristic of concrete plates is much different from conventional massive concrete structure. Therefore, impact of MgO on stress characteristic of concrete plates is unclear. In view of this, construction process using MgO concrete and ordinary concrete are simulated based on practical project data. Conclusions indicate that tensile stress of concrete plates in cooling stage can be reduced by adding MgO.

Abstract: The earth-rock allocation is the core problem affecting the overall situation of the rock fill dam construction, how to reasonable and effective for earth-rock allocation implementation is directly related to the project schedule, quality and economic goals. Through systematic analysis of rock-fill dam’s earth-rock allocation determine the features of excavation project, reclamation projects, excavation yard, debris field, transit field, and define the relationship between the various sectors of excavation, filling, transit, debris, mining and other aspects of rock-fill dam’s earth-rock allocation. Use the minimum value of the allocation sum cost as the objective function, combined with the qualitative and quantitative constraints in allocation process to build earth-rock allocation models. According to the established model, combining the actual project, based on the VS2008, develop a rock-fill dam’s earth-rock allocation system. Detailed simulate the process of rock-fill dam’s earth-rock allocation, and take charts to show intuitively.

Abstract: The seepage control is one of the most important aspects of dam security measures, which is usually related to the depth, thickness, permeability of concrete curtain. Based on finite element method, this paper calculated the sensitivity of dam foundation seepage discharge with the permeability, depth, and thickness of concrete curtain. The results show that seepage discharge mainly relies on the depth of curtain in case of shallow overburden. The total seepage discharge will sharply decrease when the curtain trend to be closed. The thickness is a key factor of seepage control for a thinner concrete curtain. The effect of increasing the curtain thickness on seepage control becomes more and more unapparent as it thickening. The sensitivity of curtain permeability to the seepage discharge increases first and then decreases with the strengthening of curtain impermeability.

Abstract: The dam foundation seepage control is usually a main work of dam design. This paper presented the effects of different concrete curtain boundary conditions on the dam foundation seepage control through numerical calculation with the finite element method. The results show that the depth of concrete curtain strongly depends on the permeability of dam foundation. The middle of curtain should be deeper than its sides if the permeability of central riverbed is higher. Therefore the design of curtain should be based on the numerical analysis of the dam foundation seepage with different curtain boundary conditions in order to make sure the safety and economy.

Abstract: A series of studies, including structure layout, detail design, material test, construction technology and prototype monitoring, etc are performed for the cofferdam on the left downstream bank of Shatuo hydropower station, which is situated on Wujiang River, Guizhou, China. Based on the research, the hardfill cofferdam with super-sized aggregates and ultralow cement in practical construction is firstly investigated. In which, the maximum aggregate size reaches 70cm and the minimum usage of cementing materials is 50 kg/m³ (25 kg/m³ for cement). According to the results of field detection and prototype monitoring, the implementation effect of the project is objectively evaluated. The research achievements and engineering practice can provide references for the design and construction of temporary cofferdam and low-medium permanent dam.

Abstract: Calculation of seepage stability is important method in selection and justification of reinforcing dike seepage control measures. In the reinforcement design of the Qinhe river dike downstream, the finite element method of AutoBank is used to calculate the seepage stability of the dike reinforced before and after, and an economic and reasonable reinforcement scheme is selected then.

Abstract: The Three Gorges Project is the biggest hydraulic engineering and it brings great comprehensive benefits such as flood control, power generation, navigation, and water supply. According to the sedimentation prototype observation on the early stage of the Three Gorges Project operation, the sedimentation pattern of dam area and the upper part of power plant, as well as the channel sedimentation are analyzed after the systematic arrangement of the prototype observation, at the same time, the formation mechanism and development of siltation are studied based on river dynamics theory. The analysis shows that: the early siltation does not have important influence on the operation of the Three Gorges Project, the sedimentation of dam area occurs mainly in the wide section while little siltation in the narrow section and the siltation intensity is greater while the location is close to the dam from the view of the siltation distribution.

Abstract: In order to effectively predict the opening of crack, the variation law of the crack is studied, and the indicator variable principal component neural network model is established by combining indicator variable model and principal component analysis with neural network theory. This new model can solve the problems of nonlinearity between the effect variable and the affecting factors and the colinearity between the affecting factors effectively and improved the prediction accuracy. By a case study, it showed that the prediction results are close to the actual values.