Applied Mechanics and Materials Vols. 395-396

Abstract: In order to study the force capacity of the cross steel reinforced concrete special-shaped column in horizontal load, the finite element analysis software ABAQUS has been used. We adopt a horizontal direction displacement loading method to apply horizontal load, and its displacement is 20mm. We simulate the stress distribution of the six rates of steel bone and the six different cross section sizes of steel reinforced concrete special-shaped columns. According to the result, the load - displacement curve has been dropped, and we analyze the mechanical properties of cross steel reinforced concrete special-shaped column by the curve. The results show that the bearing capacity of cross steel reinforced concrete special-shaped column has improved with the increasing of rate of steel bone and the cross section size.

Abstract: The generation of Damintun Depression base-rock reservoirs are mainly controlled by fracture development. Currently, for the fracture-system space distribution characters, we haven’t understood clearly. Therefore, we must find fracture developing zones and learn their development state in order to study the planar distribution law of factures. The principal stress was calculated and fractures were identified using sonic and electrical image logging data. Combined with the relationship in borehole breakout method that borehole collapse direction was substantially perpendicular to principal stress direction, the modern horizontal principal stress was determined. Then the base-rock fractures were extracted manually in imaging interactive interpretation graphic. Thus the relation is obtained that the maximum horizontal Earth stress direction is vertical to fracture distribution, and the structural-zone faults are consistent with the fracture distribution law.

Abstract: This article deals with the microstructure and mechanism of action of ultra-high-early strength concrete patching material through the three modern testing means: XRD, DTA and SEM .The results show that a large quantity of Aft and AFM are generated in the initial stage of the reaction in the patching material and hinge with each other to form an initial skeleton, so there is a high early strength in the macro performance. Meanwhile, there exists a significant reduction in the number of Ca (OH) ₂ crystals which is detrimental to the structure, and a growing number of CSH gel are generated and uniformly filled in the initial skeleton, resulting in the formation of a dense structure. Furthermore, the addition of mineral admixtures improves the interface structure of the concrete, thus making the late strength of the concrete stable.

Abstract: The cementation technology to deal with the mine tailings is adding cementation material and then dehydrating tailings and piling on suitable spot. In order to find the law of the mixing ratio of the cementitious material of the mine tailings of Xishimen Iron Mine, Portland cement and cementitious material A are selected to be compared in the experiment of strength test of cementation of the mine tailings of Xishimen Iron Mine. The result shows that both kinds of cementitious materials can meet the needs when the mixing ratio is 2-3%, but the cementation performance of material A is better than Portland cement. The experiment of adding admixture to improve the cementation performance of material A is carried and the result shows that Na₂CO₃ and KAl(SO₄)₂•12H₂O can improve the strength of cemented whole tailings while Na₂SO₄ , CaSO₄ and Na₂SiO₃is helpless to improve the strength.

Abstract: This article describes the research progress and the development situation of soil dynamics. The soil dynamic constitutive model, dynamic test methods and research status of dynamic parameters are mainly discussed. Finally, some existing problems on the study of soil dynamic characteristics are proposed.

Abstract: Drought monitoring is one of important researching areas. The soil moisture data retrieved from AMSR-E and SPI both can be employed as the indexes for drought monitoring. In this paper, they are compared in temporal and spatial variation in the hilly area of central Sichuan basin for 2006-2008. The results show that in general they agree well in temporal and spatial distribution. They both indicate that the hilly area of central Sichuan basin was wetter in the spring and summer and drier in winter. Besides, they become greater from the northwest to southeast of the study area.

Abstract: Acoustic emission (AE) is capable of real time continuous monitoring and it's not sensitive to the geometry of components,so it's widely used in nondestructive testing of concrete. The AE b-value occupies an important position in the study of concrete damage evaluation as a parameter of AE technology. The basic theory of AE b-value and the related technical problems of AE b-value calculation was discussed. Then the research of AE b-value on concrete was reviewed. At last, the AE b-value in the damage process of cement mortar (CM) and polypropylene diber reinforced mortar (PFRM) under compression was studied and concluded that the trend of AE b-value of CM and PFRM was obviously different.The AE b-value is closely related to the formation and propagation of cracks in the damage process of concrete and it declines rapidly before final fracture occurs.

Abstract: The chloride migration coefficients of concrete specimens with different shapes and different sizes were tested with modified rapid chloride migration test. The results indicate that the shape and thickness of concrete specimens slightly affect the test results of chloride migration coefficient of concrete specimens; When the size of the diffusion face of the specimen is larger than the electrode plates of the cell, the measured chloride migration coefficient will be a little smaller. The thickness, thus the electrode space also has effect on the test results, the thicker the specimen, the smaller the chloride migration coefficient measured. The effect is larger for that the specimen with the migration face larger than the electrode plates of the cell than those about the same size with the electrode plates

Abstract: A process to evaluate the paving block design is proposed. A numerical tire model is developed appropriately for the analysis. The contact pressure between the tire and paving block is calculated. Its distribution pattern is compared with the result of the field tests and is found to be in a good agreement. The present study shows that the magnitude and the distribution pattern are sensitive to the roughness of the road surface. The contact pressure induced by the dynamic impact due to a bumpy surface could be several times higher than that contributed from a smooth run-over. The hot spots in paving blocks are identified as a preliminary study of a research project regarding paving block durability. The tire model is composed of half a deformable tire skin, a rigid rim, a suspension, tire mass, and vehicle mass. The tire-block contact, the tire inner pressure, and the dynamic forces due to inertia are considered as the major loads. It is CPU efficient for less than 1200 CPU seconds required on a personal computer in one drive-through simulation. The proposed study shall be the initial investigation using direct pressure measurement on paving blocks. The lab test results will be fed into numerical model to analyze the failure mechanism which may lead to possible design improvements. Wide application can be expected in the future.

Abstract: This paper is devoted to so-called direct discrete-continual boundary element method of structural analysis. Operational formulation of the problem is given. Using fundamental operational relations of direct approach after construction of corresponding fundamental matrix-function in a special form convenient for problems of structural mechanics and its application resolving set of differential equations with operational coefficients is obtained. The discrete-continual design model for structures with constant physical and geometrical parameters in one direction is offered on the basis of discrete-continual boundary elements. Basic pseudodifferential operators are approximated discretely by Fourier series. Fourier transformations and Wavelet analysis can be applied as well.