Applied Mechanics and Materials Vols. 90-93

Abstract: Dazhuangshang Bridge is made a flood impact assessment from the hydrologic analysis, flood analysis, river potential analysis etc.. With the evaluation, it can be proved that the bridge construction has little effects on flood control of the channel and some rationalization proposals are proposed to resolve the potential problems.

Abstract: Caves have great influences on the upper structure of shiplocks and this paper established a three-dimension numerical model cave foundation –lock head–backfill soil using finite element software ANSYS on the condition of cave at Jietan ship lock in LianJiang River Guangdong Province. The relationship between the different development paths of the cave and the stress on the floor is analyzed, and the results are of referential value for other ship lock construction in the LianJiang River and other similar projects.

Abstract: A digital image processing method based on partial differential equation(PDE) for rock’s heterogeneity is introduced. The actual microstructures of the rock sample was obtained by multiphase level set method. The main components of granite, quartz, feldspar and biotite, can be easily identified. The numerical results show that the method has advantage of self-adaptation and is benefit for grid generation in the following mechanical properties analyzing with Abaqus.

Abstract: Since 1990s, a large number of in-service structures of water transport engineering in China have been close to their lifespan. Therefore, reinforcing and renovating constructions will be a long-term colossal task. Taking appropriate methods and effective means to evaluate the effect of the construction is a technical engineering problem which needs to be urgently solved. Based on the consolidation grouting construction of in-service shiplocks on the Karst Foundation, this paper makes a proper appraisal on reinforced effect by using a method combining field monitoring and numerical simulation. The results show that the measure of consolidation grouting has made a positive effect on improving the structural strain of shiplocks, which is in the safe state after construction. This comprehensive analysis method of field monitoring and numerical simulation is an effective means to validate the reinforced effect of waterway engineering structure.

Abstract: According to a series scour resistance experiment of basalt fiber and carbon fiber hydraulic concrete, in which different length and different volume ratio of basalt fiber and carbon fiber to compare to cement volume are mixed in the concrete, the scour resistance characteristics of hydraulic fiber concrete are analyzed in this paper. Experimental results show that basalt fiber and carbon fiber may enhance scour resistance of hydraulic concrete, and the volume ratio of fiber to compare to cement volume in concrete is the main reinforcement factor, but the influence of fiber length in concrete on the scour resistance of concrete is not obvious.

Abstract: Conceptual model is considered as one of the crucial and essential methods for scientific research on cold region hydrology. However, graphical conceptual model that integrates with a variety of influencing factors and specializes in describing soil moisture dynamic in seasonal frozen unsaturated zone has never occurred in any related researches, due to which the study on mechanism of frozen soil moisture movement has been delayed in a certain degree. Firstly, three stages of freezing and thawing process are divided in this article to serve for the further study in seasonal frozen unsaturated zone, which respectively are: the Stage of Freezing (Instable Freezing Stage and Stable Freezing Stage), the Stage of Thawing (Instable Thawing Stage and Stable Thawing Stage) and the Stage of Freeze-free. Secondly, based on different stages above, three characteristics and the relationships are analyzed, which include freeze-thaw-action and groundwater table, freeze-thaw-action and groundwater storage, freeze-thaw-action and soil surface evaporation. Thirdly, referred to related theories (Frozen Soil Hydrology and Snow & Ice Hydrology) and the construction of watershed model in warm regions, a whole set of graphical conceptual model and corresponding symbolic model have been built with freezing and thawing process as x-axis (time coordinate) and both soil frozen depth and different parameters as double y-axis. The different parameters include groundwater depth, soil water moisture rate and soil surface evaporation intensity. The graphical and symbolic conceptual models comprehensively describe the entire process and the factors relationships of soil moisture movement in seasonal frozen unsaturated zone. These models are expected to provide scientific basis for practical work in cold areas, such as hydrologic and hydraulic calculation in cold seasons, assessment and utilization of frozen area water resources and agricultural irrigation in cold regions, and also to provide references to the development of mathematical or experimental models in related researching fields.

Abstract: Meiliang Lake is located at north of Tai lake, it is one of the most important part of Tai Lake. Water quality of Meiliang Lake is being worse because the TP, TN and COD is released from the bottom sediment. So th goverment is decided to dredg the bottom sediment to improve the water quality. This paper used WASP5 numerical model to simulate the water quality of Meiliang Lake before and after the sediment dredging. The results show that sediment dredging is useful for improving the water quality of Meiliang Lake.

Abstract: A new method that 3D numerical simulation combined with anti-cut stability analysis is employed to analyze the stability of Majiabian gravity dam, and the results of the analysis conform to the measured value. And this method can be used in analysis of congener gravity dam. When the results of 2D sliding stability analysis satisfy Code’s requirements, elastic material can be used in 3D numerical simulation. The results of water level sensitivity analysis and deformation modulus of its foundation sensitivity analysis indicates that this gravity dam is insensitive to water level; grouting method can be adopted to enhance its foundation. The results of abutment under tension stress analysis indicate that tension stress of abutment must be considered in high gravity dam design, and arch can be used for reducing the tension stress.

Abstract: This paper examined the engineering characteristics of the near-fault ground motion. The four-story reinforced concrete frame was designed under Code for seismic design of building (GB50011-2010).The SAP2000 software was applied to model it, and the nonlinear time history analyses of structure were implemented. Near-fault ground motions with forward directivity and fling-step and far field ground motions were selected as seismic inputs．The results show that in terms of some structural dynamic response parameters, such as the vertex displacement, between the corner of the layer displacement, and the base shear et al., the structural responses to the ground motion with near-fault are increased by considerable magnitudes when the seismic responses of structures step into the elastic-plastic stage, compared with far-field ground motion, and the influence of damaging the mid-lower structure is significantly greater.

Abstract: Stability of dam foundation with Karst caves is analyzed in the presented work.Conceptual model is established according to load analysis such as dam gravity and water press. The curve of point safety coefficient on the structure plane is draw out by using stress checking method.With the comparison of curves under different work conditions, it shows that the most dangerous position of Karst cave is at the dam toe area,with the increasing of dip angle of the structure plane,the safety coefficient declines.Then the possible damage zones,mechanism and failure mode of the dam foundation with Karst caves are analyzed. The result can be used in evaluating the stability of dam foundation with Karst cave.