Papers by Keyword: Shear Strength

Abstract: For gravity dam with weak intercalated layer in foundation,the shear strength of the weak intercalated layers is the main factor in the control of the dam stability. It is the key point of geological and experimental work to ensure the shear strength to satisfy safety and economy of dam. The material composition,mineralogical composition and structure,genetic type and characteristics of shear stress and strain of weak intercalated layer in dam foundation of Datengxiapower station are analyzed,the valuation rule of the shear strength of weak intercalated layer with plasticfailure mode is discussed,and finally the recommended geological value of shear strength of weak intercalated layer in this project is proposed.

Abstract: With the rise in the water level of the Three Gorges Project, accurately measuring the shear strength parameters of the Three Gorges Project shore landslide has important implications for the safety of the Three Gorges Project’s surrounding area. Due to the material of reservoir area slope is complex, are mostly loose accumulation, these loose accumulation are mainly composed by landslide deposits, eluvia material, alluvial matter, landslides, strong weathered, and material composition is soil with gravel or fragments stone, the conventional small specimens test has been impossible. Badong County has long rainy season, abundant rainfall, mudslides, landslides and other geological disasters are frequent, so measuring reservoir landslide shear strength of Badong County is particularly important. Therefore, this paper takes the gravel soil of piled crushed landslide of the third senior middle school in Badong County as the research object, through lab large-scale direct shear test to research the gravel soil strength parameters’ variation of the soil samples with different coarse soil content under different moisture conditions.

Abstract: The discontinuity’s surface topography is often assumed as smooth and straight. To overcome non-considering roughness of discontinuity, direct shear numerical experiment is proposed to research influences of discontinuous roughness on its strength. Firstly, based on researched mechanical properties of discontinuity, the laws how asperity inclination angles and asperity heights of discontinuity and the mechanical behavior of discontinuity are studied. The results show that the failure of discontinuity considering roughness is not instantaneous. It is a complex process which goes through energy accumulation. The cohesive force increases with asperity inclination angle and asperity height increasing. The inner friction angle also goes through the same changes. However, when the normal stress reaches 500kPa for asperity inclination angle and 700kPa for asperity height, the shear strength experiences a decreasing process.

Abstract: The failure criteria and calculating methods of static and seismic shear strength of masonry under combined shear-compression action have been researched in this paper. According to the least energy consumption principle and the failure criteria of orthogonal anisotropic materials, the correlated formulae of masonry under combined shear-compression action are established. The correlated formulae are in good agreement with experimental results. On this basis, the calculation formulae of the static and seismic shear strength are established. The calculation formulae uniformly use the axial compression ratio as main variable to express. By analyzing examples, it shows that calculations by formulae given in this paper are in accordance with values of "Code for design of masonry structures" (GB 50003-2011) and "Code for seismic design of buildings" (GB 50011-2010). The methods in this paper may provide important references to engineering design as well as code revision.

Abstract: The soil is a brittle material compared to other engineering materials such as steel, concrete and wood. The clayey nature of the soils of western Paraná causes them to be chemically reactive towards certain compounds, thereby improving their engineering properties, especially its mechanical strength. The study involved treating the typical soil of the region with two residues from industrial and human activities: rice husk ash (RHA) at doses 0; 2.5; 5; 7.5 and 10%; and burned sewage sludge (BSS) at doses 0; 5; 10; 15 to 20%; in the dry soil mass. The test samples were compacted in Mini-MCV equipment and broken in triaxial compression tests of consolidated undrained type, with confining pressures of 25; 50 and 100 kPa. The results showed that both the RHA change dramatically as the BSS which passes viscoelastic plastic-linear mechanical behavior of the composites. There was a significant increase in deviator tension and elasticity modulus, implying a gain in strength and stiffness of the composite compared to the natural soil. The most striking effect was observed in the RHA cohesion parameter; while the substantial effect of BSS was observed in the interparticles friction angle. These results suggest that RHA promoted the formation of new products filling the pore space of the composite, changing the clayey material in a nature of a continuum, while the BSS promoted a substantial aggregation of the particles, wherein the soil reinforcement transformed clay in a particulate material coarser grain size.

Abstract: As examples of the most typical methods to determine the shear strength of SiC/SiC composite joints, the asymmetrical four point bending test of a butt-joined composite, the tensile test of a lap-joined composite, and the compression test of a double-notched composite joint were analyzed by using a finite element method with the interface element. From the results, it was found that the shear strength in the asymmetrical bending test was controlled by both the surface energy and the shear strength at the interface regardless of their combination while the strength in the tensile test or the compression test was governed by the surface energy when both the surface energy and the shear strength were large. In addition, the interface element was employed in order to examine the influence of the specimen geometry on the microstructural fracture morphology in nanoSiC/SiC composite during a miniaturized Double Notch Shear (DNS) test. From the serial computations, it is revealed that a relationship between the inter-laminar shear strength and the yield stress seems to be very important for selecting appropriate specimen geometry of the miniaturized DNS test.

Abstract: This research presents an experimental study related to the shear behavior of simply supported reinforced concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Four concrete beams reinforced with GFRP bars and four control concrete beams reinforced with steel bars were tested until failure. In order to realize the occurrence of shear failure, all tested beams were designed with longitudinal reinforcement only and without shear reinforcement. The test variables used in this study were the concrete strength, f'c, and longitudinal reinforcement ratio, ρ. The crack patterns, location of the diagonal crack and angle of the diagonal crack were also observed during the test. The shear design equations obtained from the codes and references were used to evaluate the data obtained from the test. Finally, based on the data obtained from experimental and theoretical analysis, comments and recommendation on the shear strength equations were suggested.

Abstract: This in-plane behavior of two one-half scale reinforced concrete (RC)-brick masonry walls with opening before and after retrofitting with basalt fiber reinforced polymer (BFRP) is investigated. One specimen was served as the reference without any strengthening scheme; another one was first tested to the severely damaged level, and then retrofitted with BFRP in a mixed strengthening configuration on two sides. Both of these specimens were tested under in-plane constant vertical load and cyclic lateral load. Test results are analyzed in terms of failure mode, maximum shear strength, ultimate drift, energy dissipation and equivalent viscous damping coefficient, which indicated that the use of BFRP composite material can effectively improve both the strength and deformation capacity of the damaged masonry wall as well as changing failure mode and maintaining the wall’s integrity.

Abstract: Subway stations or shield wells are often built using steel reinforced concrete supporting structure materials. These concrete retaining structure materials must be destroyed before launching and receiving of shield, so, some security risks may arise during destroying, and time limit for project may be longer, and the structure strength may be weakened; there are the same problems in crossing the existing subsidiary structure. In the supporting structure, concrete supporting structure materials have been partially substituted by GFRP bars in shield engineering in the world. In order to study the mechanical properties of GFRP bars deeply, experimental research on strength of GFRP bars have been made, and some relation shapes between stress and shear strength have been discussed; all of these are expected to make some basis for the design of GFRP concrete in shield engineering.

Abstract: In view of the limitation that happens when the adhesion between SBS modified asphalt and aggregated rock is evaluated by water-boiling method, on the basis of adhesion mechanism analysis of asphalt and aggregated rock, we design the evaluation method of the adhesion between asphalt and aggregated rock based on shear test, advance the quantitative index to evaluate the adhesion——shear strength, and validate the feasibility of shear strength index, analyze how the type and dosage of SBS modifier and the temperature of test influence the adhesive effect of SBS modified asphalt and aggregated rock. Result shows that The incorporation of SBS significantly improve the adhesion of asphalt and stone , especially the effect of star-modified asphalt and with the increase of dosage of SBS ,the adhension of asphalt and stone significantly increased, the shear strength of SBS modified asphalt and stone is increased about 100% than matrix asphalt when the dosage is 4%. It also describes that the shear strength index can quantitatively evaluate the effect of asphalt binder and aggregates to provide a reference for performance evaluation and quality control of modified asphalt .