Abstract: The paper presents the experimental study on the effect of flow shallowness on the scouring at semi-integral bridge piers. The experimental work was conducted in the Hydraulic Laboratory of University of Malaya. Out of 1020 data collected in the flow shallowness and time evolution experiments, 60 data were chosen at maximum scour depth to be analyzed. 30 data for sediment size of d50 = 0.8 mm and 30 data for d50 = 0.26 mm were taken at each side of the piers. The results showed that similar trend was produced for both sediment sizes, the depth of scour increased with the flow depth. Almost all of the data plotted gave the best correlation coefficient. The scour depth at the left and right side of the pier were almost averaged.
Abstract: As a very popular dam style, more concrete- faced rockfill dams have been built in the world, but there is presently only a few high CFRDs with dam height more than 100m built on thick alluvium deposits. ChaHaWuSu CFRD with dam height 107.60m and the maximum thickness of alluvium deposits 46.70m, has been built in Xinjiang province, China recently. The excessive of displacement of foundation and dam body may lead to big deformation of peripheral joint and cause the failure of seal materials and produce water leakage. Therefore, 3D finite element analysis was carried out to estimate the deformation of dam. Firstly, 3D mesh including surrounding mountain and alluvium deposits was established by use of advanced grid discreteness technique. Secondly, Desai thin layer elements were adopted to model the interface between the face slab and cushion layer. Moreover, joint elements were adopted to model the joints between the face slab and plinth, plinth and connecting slab, connecting slab and connecting slab, connecting slab and diaphragm wall. Finally, large scales of equations solving method were adopted in the procedure thus the computer calculation time was greatly reduced. The calculation result was compared with the monitored deformation date of ChaHaWuSu CFRD. All in all, the above research will do much benefit to the CFRD design on thick alluvium deposits.
Abstract: The paper has obtained a unified final solution for the waterhammer equations. The proposed solution, covering all kinds of initial conditions and boundary conditions, has been proved to be written in the form of the d'Alembert's wave functions. The periodical influence of the initial conditions on the results is discussed. The proposed solution, with two kinds of algebraic equations containing only finite terms, is suitable for numerical calculation, convenient for programming and liable to dealing with complex pipe systems. An example has been given to show the use of the method. The skill to perform the inverse Laplace transform in obtaining the solution is different from the traditional ones and can be extended to use in many other problems including the FSI waterhammer problem.
Abstract: The calculation of thermal stress is important to high concrete arch dam. In the progress of construction simulation analysis, the distribution of thermal stresses should be paid attention for it has great influence to arch design and rapid construction. The impacts on thermal stress are water temperature and air temperature and so on. In this paper, the author also thought about of the influence of creep, and applied the formulations of predecessors to finite element program. A engineering example about some high arch dam proves correctness and feasibility of considering thermal-creep –stress.
Abstract: The Xiaowan Hydropower Project is located in the middle and lower reaches of the Lancang River in Yunnan Province, China. The arch dam of this project, with a height of 294.5m, is by far the highest dam of its type that has been completed in the world. The great water potential makes it necessary to assess the seepage behavior in the dam-foundation system. Due to the complexity of geological conditions and seepage control system, the research is full of challenges. In this paper, the ﬁnite element method (FEM) is adopted to simulate the three-dimensional seepage field. The initial flow method and the boundary pre-adjustment method are combined to obtain the seepage free surface and overflow surface under complicated boundary conditions. The hydraulic potential contours, seepage gradient, drainage discharges, and so on, are all analysed and the results show that the seepage control system is reasonable and effective. Furthermore, the results of the seepage field can provide suitable seepage load in the stress-strain and stability analysis for the dam-foundation system of Xianwan. At present, the project is in good operation.
Abstract: With the deformation reinforcement theory (DRT), numerical simulation of Baihetan arch dam and foundation is carried out. According to the unbalanced forces distribution, fault F18 and shear zone LS3318 are the key reinforcement regions and unbalanced force of each fault is the corresponding optimal reinforcement force which is to maintain a stable state. To verify the validity of the results of numerical simulation, geomechanical model test of Baihetan arch dam is carried out. By analyzing displacement of corresponding measuring point in the overloading process, and observing failure of transverse section at each elevation, the results show that the unbalanced force distribution of each fault is consistent with the damage law of faults in geomechanical model test.
Abstract: In view of particularity of the Tanglai channels aqueduct，which crosses Beita Lake, the conventional construction methods and technologies fail to work, so the new two-way pre-stressing technology is employed. After the sidewalls in large span structures of aqueduct were pre-fabricated and hoisted，the secondary floor was poured in design and construction plan. The results show that the comprehensive function of aqueduct is implemented in complicated conditions，such as short construction period，larger span of structures，navigation under aqueduct，pre-fabrication and hoisting of larger sidewalls. The stress and deformation of aqueduct meet the requirements of design code.
Abstract: This study investigated the characteristics of various water resources in Tianjin, explored the needs for the study of water resources allocation, and identified the current issues of water resources allocation in Tianjin. The water resources allocation framework was established by adopting the cultural algorithm approach. A case study was done for Tianjin by utilizing this framework to evaluate the water resources allocation in 2008. It shows that the integrated approach of water resources allocation can effectively relieve the water shortage pressure of Tianjin, maximize the benefits for the limited water resources. This study provides a theoretical guidance for the water resources allocation in this area.
Abstract: Considering the dynamic response of high earth-rockfilled dam, dynamic elasto-plastic analysis method for dam slope reinforcement with geogrids was set up. Based on this model, the paper analyzed the deformation and failure mechanism of dam slope, as well as the effect of connection, the length, the spacing and the stiffness of geogrid on dam with deformation. The results show that geogrids with high elastic modulus and proper extensibility will apparently reduce the deformation and imporve the stability of the dam slope. In the case of high dam slope, the reinforcement length of geogrids is supposed to be 2a (a is the slip surface length), and the spacing is 2m.
Abstract: The safety and reliability of hydrological tower play an important role in the security and accuracy of the hydrological measurement. In order to simulate the space mechanical characteristics of the composite structure of tower with guy lines accurately, the finite element program is used to establish a precise three dimensional space finite element model. The structural strength and stability was also analyzed. Meanwhile, the static performance and vibration characteristics of the tower with guy lines was compared with the ones of the tower with none guy lines. The results show that the mechanical characteristics of composite structure are similar to the ones of continuous beams with lateral bearing spring. The guy lines rationalize the force distribution on structures, enhance the structural bearing capacity, and increase the structural stiffness. In addition, the paper can be a reference for the analysis of hydrological towers in aspects of numerical analysis, design methods and data.