Applied Mechanics and Materials Vols. 212-213

Abstract: In arch dam design, every country has it own technical design standard. In Vietnam, the standard is far lessconprehensive compared with those of the United States and China. This research focus on analysis of the differences between three above standard systems, in order to give some suggestions to improve the Vietnamese standard for arch dam. Differnces in stability and strength analysis under static and seismic conditions is discussed in depth. A case study of Namchien arch dam in Vietnam, which has being constructed in Vietnam, is presented. The results show that if arch dam design based on the Vietnamese standard, stability and strength analysis should be paid more attention on the discussed differences. The research aims atcontributing constructive suggestions concerning to existing Vietnamese standard and providing some technical specifications for designer in arch dam design.

Abstract: The design “non-rope opening vertical interlock block” is used in the main dam of Linhuaigang Project for the first time in China. The opening of the block can effectively reduce the uplift pressure induced by waves. The vertical interlock can make block interlock three- dimensionally so as to enhance the integrity of the block and improve the anti-wave performance. The design can not only improve the protection of the main dam slope under long blowing distance and high wind and waves, but also save the use of stone and construction investment as well as protect the environment. Openings vertical interlock concrete block between the rigid in-situ concrete slope and the flexible dry stone slope, not only avoid the shortcomings of in-situ concrete slope suited to soft ground deformation, but also resist the larger storms owing to the better integrity than dry stone pitching ,from the interlocked effect between the blocks. Compared with the entity block, opening vertical interlock block thickness is reduced greatly. The earth dam project of Lin Huai Gang flood control project applied openings vertical interlock block successfully in water conservancy projects .The project has the pioneering position in the use in the wave elements of reservoirs, lakes and the other large water conservancy revetment constructions.

Abstract: 3-D dynamical response analysis of concrete-faced rockfill dam is presented. Using equivalent-linear model, based on different dam heights and different shapes of river valley, the responses of dam subjected to different seismic intensity inputs have been studied. Especially the systematic analysis about the influence of the valley width on the distribution of the acceleration at the central points the bank slope is conducted. The results show that, the distribution of the horizontal acceleration along the dam heights at the central points on the central section of concrete-faced rockfill dam performs that the acceleration magnification which increases remarkably over 0.8H is a little smaller during 0~0.8H. For high concrete-faced rockfill dam, with the base acceleration excitations unchanged and the bank slope becoming steep (a gradient of 0.4), the valley width has a great impact on the magnification of the horizontal acceleration. The narrower the river valley is, the bigger the acceleration magnification is. With the slowing of the valley slope, the distribution of the acceleration magnification remains unchanged but the maximum reduces a little.

Abstract: Independent component analysis (ICA) is a recent and well-known technique used to separate mixtures of signals. It can separate independent components from mixed signals and has many advantages in blind signal separation, redundancy removal and processing of frequency aliasing problems. Deformation monitoring data can be regarded as the digital signals series which is composed of different frequency. After making test on ICA in processing dam observation data we can draw a conclusion that it is practical and applicative for ICA to evaluate the stability of the dam and reflect the working condition of dam.

Abstract: The left bank slope in JinpingⅠhydropower station is one of the highest slope with the maximum excavation and the worst stability conditions in the current hydro power stations in the world. Based on the combination of the elasto-viscoplastic finite element method and artificial neural networks, a model of back analysis of the mechanical parameters of slope is established. In this paper, the left bank slope (II1-II1) in JinpingⅠhydropower station is taken as an example．Construction procedure and anchor measures are simulated carefully; the key mechanical parameter of rock is back analyzed according to the monitored displacement; the real time forecast of deformation and stability of the rock slope are realized by this model based on the monitored displacement. Most of research results are taken as the references for the optimization of design and information construction in the practical engineering．

Abstract: In this paper, the influence of the combination and fineness coordination of different cementitious materials on volume stability of hydraulic concrete were studied. With method of concrete drying shrinkage test, mortar flat test and steel ring test(ASTM C1581), the effects of cement with different fineness, different kind of mineral admixture and their combination with each different fineness levels on the concrete deformation were discussed. And the relations between the various influencing factor and concrete cracking were carried out.

Abstract: Reinforcement corrosion is one important factor affecting the durability and safety of reinforced concrete structures. Concrete carbonation and chloride ion penetration is the main cause leading to steel corrosion, also important indicators affecting the service life of concrete structures. An accelerated carbonation experiment and Chloride penetration experiment was carried out on ordinary Portland cement (OPC) concrete and admixture concrete in various conditions. Eight concrete specimens of different mixture properties were tested in experiment. Resistance of OPC concrete system with and without mineral admixture (fly ash, slag) and air-entraining agent against carbonation was investigated. Besides, the influence of mineral admixture on the chloride penetration was also studied. The carbonation process and the factors affecting concrete carbonation are discussed according to test results. The test results were presented and they were in good agreement with the results of previous research.

Abstract: Aqueduct is a overhead canal building spanning river, road, hill, and valley, and it is also one of the most widely used crossing building. Usually by simplifying the actual structure ( supporting simplified, pole simplified, load simplified), the mechanical model of beam truss aqueduct can be attained and be calculated. It is an important step to understand its stress characteristics and structural features, so aqueduct model is hand-made with white cardboard and glue materials. By simulating the water flowing with standard sand, aqueduct model is loaded and the test is finished. At the same time , the numerical calculation is performed with the structural mechanics solver and ANSYS finite element software, the results are compared with test data. The results show the upper and lower beam of Aqueduct model support mostly the bending deformation, truss rods mostly stand the uniaxial tensile or compression deformation. The reasonable selection shape can helps to make mechanical properties of the rods better. The appropriate arrangement of upper, lower chords and ventral pole position can makes the bending moment, shear and axial force value of the bar distribute reasonable, so the application range of beam aqueduct is improved greatly.

Abstract: Taking all the effects into account of thermal and mechanical properties, construction process, environment temperature, arch-closure and reservoir impounding orders, three dimension (3D) finite element methods(FEM) was adopted to simulate the whole construction process for temperature changing and thermal stress distribution of the dam. Typically, the results of the highest 22nd monolith were analyzed, from which the general law for both temperature field and thermal stress was acquired. And the results are valuable for temperature control of Xiaowan high arch dam.

Abstract: It is wildly attentive but controversial, in the area of structure engineering, how to assess and analyze the mechanical behavior of independent load-bearing or the joint load-bearing for double composite linings structure. The present paper is aim to discuss its working mechanism. The mechanical behavior of novel prestressed double composite linings is analyzed by using 3-D non-linear finite element method, comparing with the 1:1 simulation test. The numerical values are close to the test values including the deformation, the stress, and the opening of the gap between the inner and outer linings. The results show that the steel bars are most important component for joint load-bearing of the double linings and the cushion between the inner linings and outer linings can satisfy the independent load-bearing requirement. The numerical values are quite agreement with those of the test, which verify the mechanical behavior and working mechanism of the prestressed double composite linings. This research can help to the design of similar engineering projects.