Papers by Keyword: Shear Strength

Abstract: The shear strength of expansive soils is now a key geotechnical problem. The water content and dry density of expansive soils have deep effect on its shear strength. For analyzing the detail relationship of the water content, dry density and shear strength of this special soil, direct shear test was carried out with the samples from Xinxiang in middle line of South to North water diversion project. The results indicate that both of the cohesion and friction angle grow with dry density and decrease with initial water content. Applying the linear regression calculation, we obtained mathematical expressions which reveal the variation of shear strength with the dry density and initial water content of Xinxiang expansive soils.

Abstract: Apparent particle size grading is the important characteristic of super-high bench dumping site, and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of granular. With the copper mine dumping site which had the feature of apparent particle size grading, the thesis carried out the study of on-site particle size investigation and indoor laboratory. The particle-size distribution law with the changing of dumping-site height was analyzed and quantitative relationship between the fragmentation distribution and shear strength parameters of granular was discussed. The research results indicated that coarse-grain contents and maximum grain size were increased significantly according to the decreasing of dumping-site height, which showed that the dumping-site had the feature of apparent particle size grading. The coarse particle content in the grain size composition and internal friction angle φ of shear strength parameters increased with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ could be expressed by exponential function curve.

Abstract: The hypothesis on effective stress of unsaturated soils is validated by consolidation strength results of triaxial tests for the compacted residual soil. The effective stress can describe the unsaturated soil behavior, which was defined from shear strength or from soil water characteristic curves. Since the effective stress from consolidation agrees with that from the shear strength, the effective stress from soil water retention curve could describe the unsaturated behavior consistently on both consolidation path and stress at failure. The effective stress can describe the entire unsaturated behavior from consolidation to failure.

Abstract: The shear strength properties of bulky rock material were studied by the fractal geometry theory. The results show that: (1)The research indicates that the fractal dimension D can be a quantitative parameter of the particle composition of bulky rock material.and there was a clear linear correlation between the D and particle size distribution when bulky rock material was at good gradation.(2) Curve of stress-strain relationship had no obvious peak strength and it was strain-hardening. Gfailur and fractal dimension D have a obvious negative exponent relation while bulky rock material at the good gradation.(3) There was a negative exponent relation between φ and D at good gradation,but relationship of c and D was relatively disperse.

Abstract: Three different plasticity index subgrade soils are selected from seasonal frozen soil area. Triaxial compression test under different confining pressures are executed on the samples exposed to 0 to 7 times closed-system freeze-thaw cycles. The conclusion gotten is that to the same kind of soil under the same freeze-thaw cycles, the shear strength increases with confining pressure; Shear strength with the same confining pressure decreases with the number of freeze-thaw cycles; With the same confining pressure and the same freeze-thaw cycles, shear strength increases with the plasticity index. Exponential function is adopted for multiple nonlinear fitting on the test results. The relationship between shear strength and confining pressure, plasticity index, freeze-thaw cycles is obtained and shows a good correlation.

Abstract: This paper presents the results of reinforced concrete (RC) beams strengthened in shear by external reinforcement with RC or epoxy resin mortar. The test specimen was 2000mm long with a cross section of 150mm×200mm and after section enlargement the cross section was increased to 250mm×300mm, in addition, shear span to beam depth ratio of a/h0 was 2.35. All specimens had the same geometry and were distinguished by the configurations of stirrup which was the primary test variable. No shear reinforcement was provided in the first phase of test, while in the second phase external RC or epoxy resin mortar was provided to enable failure due to shear. Experiments are undertaken to investigate the influence of preexisting damage, configurations of stirrup and different methods on the strengthened behavior and mode of failure. A group unstrengthened control beams were tested and failed in shear. In contrast to the control beam, all of the strengthened beams showed a significant improvement in their ultimate load capacity when they were failing in shear. The enlarged section with reinforced concrete can significantly increase the ductility and ultimate shear strength of a concrete beam. The method of section enlargement with RC is a high effective technique to enhance shear ability. An analysis for shear strengthening of beams using external reinforcement with RC has also been carried out as well.

Abstract: It is well known that alloy 718 shows excellent mechanical strength and corrosion resistance and this alloy is now successfully utilized for aerospace and oil industry application. In order to design and manufacture components to satisfy the design requirements of the applied system, it is necessary to consider formability and weldability of the material. This paper provides experimental results of lap shear strength of welded specimens of alloy 718 with EBW(Electron Beam Welding) and LBW(Laser Beam Welding) and Brazing. The purpose is to determine the optimum welding method for overlap welding of alloy 718 for blow forming.

Abstract: The significant particle size grading and the particle breakage of deep soils are two major characteristics of super-high dumping-site. Based on the refitted large-scale direct shear experiments, this paper studied the particle breakage and shear strength of different coarse-grained soil. The experimental results indicates a conclusion: particle breakage index is very small when upright stress is less than 400kPa .The breakage rate increases obviously with the increase of upright stress. The particle breakage index is very little when coarse-grained contents are less than 46.0% .It increases significantly when coarse-grained contents are larger than 46.0%. Hyperbolic curves can express the relationship between particle breakage index and upright stress. The experiments studied on shear strength shows that the shear stress-strain curves are micro-softening model or micro-hardening model under low upright stress. The curves are slight-softening model at higher upright stress when the coarse-grained contents are equal to 24.0%. At coarse-grained contents equal 78.0%, the shear stress-strain curves are softening model under low upright stress. The shear strength envelope expressed nonlinear under higher upright stress.

Abstract: To find the effects of pedoturbation on soil erosion of lands for agriculture and forestry in Menglianggu watershed of Linyi city from soil mechanics, shear strengths of 3 typical land uses (6 different soils) which are undisturbed and remolded respectively were measured by direct shear apparatus. Effects of particle size and binding materials on shear strength were analyzed by comparing shear properties of undisturbed and remolded soils with the same dry density, water content and vertical loads. The results show that all the angle of internal friction ( ) and most of soil cohesion ( ) of undisturbed soils are bigger than that of remolded soils; The final shearing stress also comply with the law above; The main factors affecting shear strength are soil particle size and binding materials.

Abstract: The expansive soil behaviour of expansive deformation and shear strength is deeply influenced by humidity condition. Different soil drying rate was set with constant temperature and different relative humidity. When saturated soil samples was dried to the different predetermined water content, the expansion ratio test with the upper load was made. It is shown that in the condition of high relative humidity, the expansion ratio is high. The smaller initial water content and upper load may lead to a larger swelling deformation. When soil samples with different initial water content was fully expanded, the consolidated direct shear tests were made. It is shown that the smaller drying rate leads to the greater shear strength after full expansion. What’s more, the upper load may improve the soil shear strength.