A series of well-designed full-scale destructive load tests were conducted on six bored piles to investigate the influence of loose debris at the pile tip on end resistance. The results show that soft debris below the...A series of well-designed full-scale destructive load tests were conducted on six bored piles to investigate the influence of loose debris at the pile tip on end resistance. The results show that soft debris below the pile tip will weaken the mobilization of end resistance. The ultimate tip resistance of post-grouted pile is 2.05 times that of the pile without post-grouting and the ultimate tip resistance in the second load cycle is 2.31 times that of pile in the first load cycle. The relationship between unit end resistance and displacement follows a linear model and a bilinear mode in the first load cycle and the second load cycle, respectively, whereas the unit end resistance-displacement response of post-grouted bored pile can be simulated using a bilinear mode. The critical end resistance ranges between 2 000 kN and 3 000 kN and the critical displacement ranges between 2.5 mm and 4.5 mm in the bilinear mode. As for piles rested on moderately-weathered peliticsiltstone, the socketed length has no effect on the end resistance because of the existence of loose debris.展开更多
Triaxial cyclic loading tests have been performed to assess the influence of plastic deformation on inelastic deformational properties of anisotropic argillite with bedding planes which is regarded as a kind of transv...Triaxial cyclic loading tests have been performed to assess the influence of plastic deformation on inelastic deformational properties of anisotropic argillite with bedding planes which is regarded as a kind of transversely isotropic media.Considering argillite's anisotropy and inelastic deformational properties,theoretical formulae for calculating oriented elastic parameters were deduced by the unloading curves,which can be better fitted for the description of its elasticity than loading curves.Test results indicate that with the growth of accumulated plastic,strain,the apparent elastic modulus of argillite decreases in a form of exponential decay function,whereas the apparent Poisson ratio increase in a form of power equation.A ratio of unloading recoverable strain to the total strain increment occurred during a loading cycle is defined to illustrate the characteristic relations between anisotropic coupled elasto-plastic deformation and plastic strain.It is significant to observe that high stress level and plastic history have an inhibiting effect on argillite anisotropy.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)fiber composite has been extensively used to construct lightweight protective structures against ballistic impacts,yet little is known about its performance when subject...Ultra-high molecular weight polyethylene(UHMWPE)fiber composite has been extensively used to construct lightweight protective structures against ballistic impacts,yet little is known about its performance when subjected to combined blast and fragment impacts.Built upon a recently developed laboratory-scale experimental technique to generate simulated combined loading through the impact of a fragment-foam composite projectile launched from a light gas gun,the dynamic responses of fullyclamped UHMWPE plates subjected to combined loading were characterized experimentally,with corresponding deformation and failure modes compared with those measured with simulated blast loading alone.Subsequently,to explore the underlying physical mechanisms,three-dimensional(3D)numerical simulations with the method of finite elements(FE)were systematically carried out.Numerical predictions compared favorably well with experimental measurements,thus validating the feasibility of the established FE model.Relative to the case of blast loading alone,combined blast and fragment loading led to larger maximum deflections of clamped UHMWPE plates.The position of the FSP in the foam sabot affected significantly the performance of a UHMWPE target,either enhancing or decreasing its ballistic resistance.When the blast loading and fragment impact arrived simultaneously at the target,its ballistic resistance was superior to that achieved when subjected to fragment impact alone,and benefited from the accelerated movement of the target due to simultaneous blast loading.展开更多
The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Base...The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Based on an exponent model, the testing coefficients of straw bale were estimated using Levenberg-Marquardt Method. The results of test showed that the relation between failure density and loading ability and compressing energy was linear in the phase of high density. The loading ability of straw bale could meet the building bill.展开更多
This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests ...This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.展开更多
基金Project(51078330) supported by the National Natural Science Foundation of ChinaProject(2012MS21339) supported by China Postdoctoral Science FoundationProject(2012GN012) supported by the Independent Innovation Foundation of Shandong University, China
文摘A series of well-designed full-scale destructive load tests were conducted on six bored piles to investigate the influence of loose debris at the pile tip on end resistance. The results show that soft debris below the pile tip will weaken the mobilization of end resistance. The ultimate tip resistance of post-grouted pile is 2.05 times that of the pile without post-grouting and the ultimate tip resistance in the second load cycle is 2.31 times that of pile in the first load cycle. The relationship between unit end resistance and displacement follows a linear model and a bilinear mode in the first load cycle and the second load cycle, respectively, whereas the unit end resistance-displacement response of post-grouted bored pile can be simulated using a bilinear mode. The critical end resistance ranges between 2 000 kN and 3 000 kN and the critical displacement ranges between 2.5 mm and 4.5 mm in the bilinear mode. As for piles rested on moderately-weathered peliticsiltstone, the socketed length has no effect on the end resistance because of the existence of loose debris.
基金Program(2011CB710601) supported by National Basic Research Program of ChinaProject(50925933) supported by National Natural Science Foundation of China+1 种基金Project(2008BAB29B03) supported by National Key Technology Research and Development Program of ChinaProject(2010-122-011) supported by Guizhou Provincial Department of Transportation,China
文摘Triaxial cyclic loading tests have been performed to assess the influence of plastic deformation on inelastic deformational properties of anisotropic argillite with bedding planes which is regarded as a kind of transversely isotropic media.Considering argillite's anisotropy and inelastic deformational properties,theoretical formulae for calculating oriented elastic parameters were deduced by the unloading curves,which can be better fitted for the description of its elasticity than loading curves.Test results indicate that with the growth of accumulated plastic,strain,the apparent elastic modulus of argillite decreases in a form of exponential decay function,whereas the apparent Poisson ratio increase in a form of power equation.A ratio of unloading recoverable strain to the total strain increment occurred during a loading cycle is defined to illustrate the characteristic relations between anisotropic coupled elasto-plastic deformation and plastic strain.It is significant to observe that high stress level and plastic history have an inhibiting effect on argillite anisotropy.
基金supported by the National Natural Science Foundation of China(Grant No.12032010,11902155 and 12072250)by the Natural Science Foundation of Jiangsu Province(Grant No.BK20190382)+2 种基金by the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(Grant No.MCMS-I-0222K01)by the Fund of Prospective Layout of Scientific Research for NUAAby the Foundation for the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Ultra-high molecular weight polyethylene(UHMWPE)fiber composite has been extensively used to construct lightweight protective structures against ballistic impacts,yet little is known about its performance when subjected to combined blast and fragment impacts.Built upon a recently developed laboratory-scale experimental technique to generate simulated combined loading through the impact of a fragment-foam composite projectile launched from a light gas gun,the dynamic responses of fullyclamped UHMWPE plates subjected to combined loading were characterized experimentally,with corresponding deformation and failure modes compared with those measured with simulated blast loading alone.Subsequently,to explore the underlying physical mechanisms,three-dimensional(3D)numerical simulations with the method of finite elements(FE)were systematically carried out.Numerical predictions compared favorably well with experimental measurements,thus validating the feasibility of the established FE model.Relative to the case of blast loading alone,combined blast and fragment loading led to larger maximum deflections of clamped UHMWPE plates.The position of the FSP in the foam sabot affected significantly the performance of a UHMWPE target,either enhancing or decreasing its ballistic resistance.When the blast loading and fragment impact arrived simultaneously at the target,its ballistic resistance was superior to that achieved when subjected to fragment impact alone,and benefited from the accelerated movement of the target due to simultaneous blast loading.
基金Supported by the Returnee Foundation of Ministry of Education and Project (1054hz023)Supported by the Key Research Foundation of Ministry of Science in Heilongjiang Province
文摘The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Based on an exponent model, the testing coefficients of straw bale were estimated using Levenberg-Marquardt Method. The results of test showed that the relation between failure density and loading ability and compressing energy was linear in the phase of high density. The loading ability of straw bale could meet the building bill.
文摘This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.
