Papers by Keyword: Interface

Abstract: The ground-liner interaction research has important engineering value for the underground engineering design optimization and evaluation of construction safety. The interface between ground and liner is considered. In this paper, the effect of different ground-liner stiffness ratio, lateral pressure coefficient, thickness and different interface stiffness ratio and other factors on the support structure for internal forces and interface stress is analyzed. The analysis results show that liner internal force and interface stress increase with the increase of stiffness ratio between liner and ground, and the impact is very significant. Effect of lateral pressure coefficient on liner internal force and interface stress mainly reflects on laws around the cavern, where 1 is the limitation of lateral pressure coefficient. It presents symmetrical distribution. With the increase of liner thickness, the liner internal force and interface normal stress increase, but it make no difference to the contact interface tangential stress.

Abstract: To reveal the mechanical property on the interface between the surrounding rock and the supporting structure, inducting the definition of the interface, based on ABAQUS software, two finite element models were established to compare and analysis the interaction through the aspects of stress, deformation and plastic region of surrounding rocks and the resistance of supporting structure. At last, compare the simulative and the metrical results. The result shows that the ideal full-constraint between the surrounding rock and the supporting structure isn’t possibility. It becomes more reasonable to define an interface during the numerical analysis and design calculations, the selection of the constitutive relation of the interface is directly related to the accuracy of the numerical calculation results.

Abstract: Ethylene - vinyl acetate copolymer (EVA)-modified mortar is widely used in China because of better adhesion strength and flexibility as compared to traditional one. This paper, based on a laboratory program, evaluated the effects of EVA-cement and different fillers on interface properties of EVA-modified cement mortar such as adhesive strength and dynamic cracking resistance, and the mechanism was also analyzed by scanning electron microscopy (SEM). The results showed that under laboratory condition, adhesion strength and dynamic cracking resistance of EVA-modified cement mortar increased with EVA-cement rising. Interface performance of the EVA-modified mortar improved greatly as EVA-cement increased from 0% to 12% and amplification slowed down when it increased further. EVA-cement around 12% was the optimal proportion considering all factors in this study. Fillers of different particle grade contributed to interface properties of EVA-modified cement mortar, A/fillers around 1/6~2/3 is the optimal proportion in this study.

Abstract: This paper dealt with the influence of the steel-concrete interface quality and environmental conditions on reinforcement corrosion. High size concrete members were cast to get different interface quality decreased with the height of rebar due to the top-bar effect. Five groups of specimen with two concrete covers have subjected to different exposed programs. The experimental results showed that the concrete cover significantly influenced corrosion initiation and corrosion rate by blocking the penetration of aggressive agents. The height of rebar affected the corrosion initiation because of the variation of concrete porosity, interface defects and chloride threshold. The existence of defects at the interface was more important than the size of defect for corrosion initiation.

Abstract: In the pile driving process, the soil dynamic performance and the dynamic contact on the interface are very complex. In order to analyze the interactions between the pile and soil, the simulation model of the pile-soil system is created by the finite element software. The numerical solution and the displacement curves of the pile are obtained based on suitable parameters of the pile-soil system and the D-P criterion. Then the amplitude and the frequency of the exciting force as well as the stiffness and the damping of the soil are changed to obtain the displacement curves of the pile. Through the comparisons between the curves, the influences on the pile driving process coming from the exciting force and other parameters are found out.

Abstract: The direct shear mechanical characteristics of soil-structure interface under different experimental condition were studied systematically using the DRS-1 high normal stress direct and residual shear apparatus. The results show that the normal stress is an important factor which determines the mechanical characteristics of soil-structure interface. The curve of shear stress-shear displacement presents strain softening when the normal stress<3MPa, linear hardening when =3~5MPa and strain hardening when12MPa, separately. At the same time, the volume of the soil expands when <3MPa and contracts when >3MPa. But the volume of the soil expands and contracts simultaneously during the process of direct shear when =3MPa.The roughness of the interface influences not only the shape of the shear stress-shear displacement curve but also the shear strength of the interface. Under same normal stress condition，the shear strength of interface increases with the roughness but the influence degree of interface roughness reduces gradually with the increase of normal stress. The grain breakage degree is different under different normal stress. It increases evidently with the increase of normal stress.

Abstract: Based on the model of effective friction coefficient, the change tendency of effective friction coefficient under different harmonic forces and the method of improving its decrease rate have been studied. The model of vibratory piling machine has been taken as a research object for friction reduction, and the stress of soil particles and the situation of friction resistance on pile surface have been analyzed while sinking the pile. The effect on interface friction of pile-soil system under vibration, caused by the depth of pile sinking, pile structure parameters and vibration acceleration, has also been studied, so that an effective method of decreasing interface friction can be found. Thus, the sinking efficiency would be improved by being analyzed, evaluated and parameter optimized.

Abstract: In this work, the spatial theoretical solutions of concentrated normal forces acting in the substrate and at the interface of semi-infinite coating materials have been deduced based on the image point method. The explicit solution is given in the series of the displacement functions corresponding to each image point. It is found that all displacement functions can be deduced by the order of the image point. Numerical analysis has been carried out to verify the theoretical deductions. It is found that the accurate enough theoretical solution can be obtained by only taking the displacement functions corresponding to the first several image points into account. The fundamental solutions for a concentrated force acting at interface of two bonded semi-infinite bodies is also deduced, which is necessary in the analysis of coating materials by using these theoretical solution as the fundamental solution.

Abstract: The problem of a normal force acting in the thin layer of semi-infinite coating materials has been studied by adopting the image point technology in this paper. The explicit fundamental solution is given in the series of the displacement functions corresponding to each image point. The displacement functions corresponding to the higher order image points can be determined from those to the lower ones by the recurrence formula presented in this paper. Numerical analysis by means of the finite element method has been carried out to verify the theoretical results. It is found that the accurate enough theoretical solution can be obtained by only taking the displacement functions corresponding to the first several image points into account.

Abstract: In order to obtain a robust dissimilar joint between titanium and aluminum alloy, a method of resistance spot welding with a cover plate were used to weld two kinds of material. The interfacial microstructure was observed using transmission electron microscopy. The effects of welding parameters on the mechanical properties of the joint were investigated. An approximately 160 nm thick layer of Al solid solution supersaturated with Ti was observed at the welding interface, in which contain the precipitates TiAl3. Mechanical property analysis suggests that the reaction layer has no effect on the tensile shear load of the joint.