Applied Mechanics and Materials Vols. 212-213

Abstract: In combination with the practice of a hydropower station steel-liner reinforced concrete penstock, the finite element model is established to analyze bearing characteristics of the penstock. In the paper, cracking behaviors of the surrounding concrete as well as stresses of the steel liner and reinforcement under normal water pressure are intensively studied based on the model test. The results can provide the basis for the safety operation of the steel-liner reinforced concrete penstock.

Abstract: In order to reduce erosion impact around pier footings, the SMS-2D applied in this study to analysis stepped apron set in critical scour downstream and discuss its scour protection due to bow wave around the bridge pier on the main deep trough of new Taitung Bridge in 100 years return flood peak flow, on the downstream BeiNan River in East-Taiwan as case study. Further, the topic of this study is to compare the different dimensions of aprons for apron deflecting characteristics, making the beach effect and take preventive measures, and in case of excessive cost, suitable sizes and sets for stepped apron are provided for reliable information and references for bridge engineers.

Abstract: By using 3-D finite element software ABAQUS, the load-sharing ratio of piles and soil about the squared piles composite foundation was studied. The magnitude of the load-sharing ratio of piles and soil is accurately evaluated and the calculations are identical with related tests. On the basis of studies and analysis on the different parameters, the variety of the load-sharing ratio of piles and soil about the squared piles composite foundation was known which would provide some references for the design of the actual engineering.

Abstract: When temperature difference between day and night is considered, there are worse effects on thin-walled concrete structure than its on mass concrete structure during construction. In the view of this problem, the 3-D FEM is adopted to simulate the thermal field and stresses field of thin-walled concrete launder during construction when temperature difference between day and night is considered. The simulation results show that the fluctuation of stress will appear not only in the surface but also in the inner of thin-walled concrete structure, so it brings a lot of difficulties for temperature control and crack prevention. In order to reduce the impact degree of temperature difference between day and night, some effective measures should be taken, including enhancing the level of external heat preservation and prolonging the form removal time and so on. If the variation of daily temperature is used to the simulation computation of thin-walled concrete structure during construction, the results should be very reasonable and effective. This research is of practical reference value for the construction of the concrete structure which is built in the area where large temperature difference between day and night easily occurs.

Abstract: In the analysis of dam displacement data, mostly, a single point is used for calculation. Based on the concept named Time-displacement, this paper proposes a new calculation method with multi-point, which can make up the scarcity of analysis on the data of the dam deformation for a long time. Based on the concept of Time-displacement, the method of building the multi-point model is as follows: firstly, according to the deformation monitoring period, displacement data of all monitoring points on the deformation body, can be converted into the displacement rate. And based on displacement rate value, an appropriate rate threshold can be chosen; the rate threshold based on the experience can be used many also. Then the number of every monitoring point exceeding the rate threshold throughout the monitoring period can be recorded, and according to the number, the monitoring points’ Time-displacement could be divided into different levels. If the number of monitoring points on the deformation body is less, the interpolation points would be laid along the direction of the original monitoring sites. By the method of decision tree classification, the interpolation points’ Time-displacement could be figured out. Finally, with the original monitoring points and the interpolation points, the figure about deformation body’s Time-displacement could be drawn, which can reflect the displacement situation about the deformation body more dynamically.

Abstract: Landslide stability is very important to the hydropower station construction. The volume of landslide accumulation mass in a hydropower station was more than 47, 500, 000 m³, it was a large landslide accumulation body rarely in the history of hydropower engineering. As a research object, the landslide accumulation mass in this hydropower station was divided into three parts by geologic ingredient, which included bedrock, slip soil and accumulation mass. According to mechanical parameters such as internal friction angle, cohesion, natural unit weight and saturated unit weight obtained by some research, limit equilibrium method was adopted to analyze the slope stability. Accumulation mass safety factors in different parts were calculated, the destruction style was illustrated and landslide accumulation mass stability was also analyzed. The results show under normal condition, rainstorm and earthquake condition, the safety factor cannot meet the specification requirement. The research provides meaningful reference to design and construction in similar hydropower station.

Abstract: Gate pier may cause damaged by construction joints under inappropriate pouring in Pengshui Hydropower Station. Based on nonlinear FEM, a contact algorithm is adopted to simulate interaction of construction joints between the overflow dam surface and gate pier. With different contact type and loading, the deformation and stress are analyzed comparatively in detail in order to evaluate the strength and safety of the gate pier. The results show that existence of construction joints reduces the stiffness of the structure, but satisfies the requirements of original reinforcement project, which have a little effect on safety of the gate pier.

Abstract: The dynamic risk of underground cavities after gas outburst in coal uncovering construction of hydropower station was emphatically analyzed. The tunnel construction conditions in Xiangjiaba hydropower station were taken as an example. Based on the computational fluid dynamics theory and gas outburst theory, this paper used the ANSYS CFX CFD code to model the gas diffusion after gas outburst. The space-time characteristics of underground cavities dynamic risk were analyzed. The results show that the danger area ranges of gas explosion and asphyxia reach respectively the maximum value at about 140s and 50s. The influence range and duration of the former are significantly higher than the latter. The direction of hazardous area movement is mainly consistent with the air flow direction. ANSYS CFX simulation can visually display dynamic risk of underground cavities, and has a good prospect in gas hazard prevention in hydraulic and hydroelectric engineering.

Abstract: The proposed Jinping-I hydropower station is located on the middle reach of the Yalongjiang River, Sichuan Province, P.R. China. It consists of a double-curvature arch dam with a maximum height of 305 m, which will be the highest in the world. Excavation disturbed zone (EDZ) in the left bank slope is one of the most important aspects in slope stability and deformation evaluation. This paper is focused on estimation of EDZ in the left bank slope of Jinping-I hydropower station based on numerical simulation. Geological conditions of the left bank slope are firstly analyzed. Then, displacement field of the slope during excavation is calculated by finite element method (FEM). It can be indicated that the model and parameters in this paper is reasonable by comparing observed results with calculated ones. EDZ in the left bank slope can be estimated based on the calculated displacement field. It can be inferred that the range of EDZ is related to the controlling discontinuities such as fault f42-9 and Lamprophyre X etc. which are adjacent to the excavation line.

Abstract: The competence model is commonly used for study of an enterprise’s capabilities related to performance in the specific background. However, there is no analysis on capability index system and project performance indicator system of owners as large hydropower development enterprises in the former studies on the competence-based organizational capacity. In this paper, the owner’s capability index system related to the performance is put forth by studying the capability factors of a large hydropower development enterprise, and verified in our analyses on them. So, the constituent elements of the owner’s capability can be revealed.