Plastic pipes reinforced by cross helically wound steel wires (PSP), which have exhibited excellent mechanical performance, consist of inner polyethylene (PE) layer, winding layer and outer PE layer. The winding layer...Plastic pipes reinforced by cross helically wound steel wires (PSP), which have exhibited excellent mechanical performance, consist of inner polyethylene (PE) layer, winding layer and outer PE layer. The winding layer is composed of two monolayers where steel wires are cross helically wound. An analytical procedure is developed to predict the short-term burst pressure of PSP as the monolayer is assumed to be elastic and orthotropic. The 3D anisotropic elasticity and Maximum Stress Failure Criterion are employed in the formulation of the elasticity problem. Good agreement between the theoretical results and the experimental data shows that the proposed approach can well predict the short-term burst pressure of PSP.展开更多
Deep beam anchorage structures based on spatial distribution analysis of the cable prestressed field have been proposed for roadway roof support, Stability and other factors that influence deep beam structures are stu...Deep beam anchorage structures based on spatial distribution analysis of the cable prestressed field have been proposed for roadway roof support, Stability and other factors that influence deep beam structures are studied in this paper using mechanical calculations, numerical analysis and field measurements, A mechanical model of deep beam structure subjected to multiple loading is established, including analysis of roof support in the return airway of S1203 working face in the Yuwu coal mine, China, The expression of maximum shear stress in the deep beam structure is deduced according to the stress superposition criterion, It is found that the primary factors affecting deep beam structure stability are deep beam thickness, cable pre-tension and cable spacing, The variation of maximum shear stress distribution and prestressed field diffusion effects according to various factors are analyzed using Matlah and FLAC3DTM software, and practical support parameters of the S1203 return airway roof are determined, According to the observations of rock pressure, there is no evidence of roof separation, and the maximum values of roof subsidence and convergence of wall rock are 72 and 48 mm, respectively, The results show that the proposed roof support design with a deep beam structure is feasible and achieves effective control of the roadway roof,展开更多
为了探明木薯拔起时块根最大应力的影响规律和确定块根不被拔断的允许最大拔起力,论文采用FEM(finite element method)和SPH(smoothed particle hydrodynamics)的耦合方法及二次回归旋转设计方法,通过构建土壤-块根-茎秆系统的数值模拟...为了探明木薯拔起时块根最大应力的影响规律和确定块根不被拔断的允许最大拔起力,论文采用FEM(finite element method)和SPH(smoothed particle hydrodynamics)的耦合方法及二次回归旋转设计方法,通过构建土壤-块根-茎秆系统的数值模拟计算模型,进行木薯块根拔起数值模拟试验,测定各因素组合条件下的块根最大拔起力和块根最大应力,建立块根最大应力与拔起速度、块根的大小、长短和生长深度及土壤的软硬程度的多因素耦合数学模型,研究了各影响因素及交互作用对块根最大应力的影响规律,同时,通过块根最大拔起力和块根最大应力的散点图,研究了块根最大拔起力和块根最大应力的相关性,确定了块根不被拔断的允许最大拔起力,且2014年12月底在广西武鸣县某木薯种植地,采用随机抽样方法,进行了木薯块根最大拔起力和块根拔断率的田间试验和统计分析,对块根不被拔断的允许最大拔起力进行了验证,最大拔起力小于0.98 k N时,块根拔断率为2.5%。结果表明,块根最大应力与各影响因素的多因素耦合数学模型的F检验在0.000 1水平上显著,精度较高,可用于块根最大应力的影响分析;块根最大应力随拔起速度的增大呈先增大,后减小的变化,随生长深度、块根长度和土壤硬度的增大而增大,随块根直径的增大而减小;块根最大应力与最大拔起力相关性不强,块根允许最大拔起力约为0.98 k N。展开更多
基金the New Century Excellent Talents in University, MOE, China (No. NCET-04-0526)the Specialized Research Fund for the Doctoral Program of Higher Education, MOE, China (No. J20050398)the Key Project of Wenzhou (No. G2004034), China
文摘Plastic pipes reinforced by cross helically wound steel wires (PSP), which have exhibited excellent mechanical performance, consist of inner polyethylene (PE) layer, winding layer and outer PE layer. The winding layer is composed of two monolayers where steel wires are cross helically wound. An analytical procedure is developed to predict the short-term burst pressure of PSP as the monolayer is assumed to be elastic and orthotropic. The 3D anisotropic elasticity and Maximum Stress Failure Criterion are employed in the formulation of the elasticity problem. Good agreement between the theoretical results and the experimental data shows that the proposed approach can well predict the short-term burst pressure of PSP.
基金provided by the National Natural Science Foundation of China (Nos. 51504259 and 51234005)the Fundamental Research Funds for the Central Universities (No. 2010QZ06)
文摘Deep beam anchorage structures based on spatial distribution analysis of the cable prestressed field have been proposed for roadway roof support, Stability and other factors that influence deep beam structures are studied in this paper using mechanical calculations, numerical analysis and field measurements, A mechanical model of deep beam structure subjected to multiple loading is established, including analysis of roof support in the return airway of S1203 working face in the Yuwu coal mine, China, The expression of maximum shear stress in the deep beam structure is deduced according to the stress superposition criterion, It is found that the primary factors affecting deep beam structure stability are deep beam thickness, cable pre-tension and cable spacing, The variation of maximum shear stress distribution and prestressed field diffusion effects according to various factors are analyzed using Matlah and FLAC3DTM software, and practical support parameters of the S1203 return airway roof are determined, According to the observations of rock pressure, there is no evidence of roof separation, and the maximum values of roof subsidence and convergence of wall rock are 72 and 48 mm, respectively, The results show that the proposed roof support design with a deep beam structure is feasible and achieves effective control of the roadway roof,
文摘为了探明木薯拔起时块根最大应力的影响规律和确定块根不被拔断的允许最大拔起力,论文采用FEM(finite element method)和SPH(smoothed particle hydrodynamics)的耦合方法及二次回归旋转设计方法,通过构建土壤-块根-茎秆系统的数值模拟计算模型,进行木薯块根拔起数值模拟试验,测定各因素组合条件下的块根最大拔起力和块根最大应力,建立块根最大应力与拔起速度、块根的大小、长短和生长深度及土壤的软硬程度的多因素耦合数学模型,研究了各影响因素及交互作用对块根最大应力的影响规律,同时,通过块根最大拔起力和块根最大应力的散点图,研究了块根最大拔起力和块根最大应力的相关性,确定了块根不被拔断的允许最大拔起力,且2014年12月底在广西武鸣县某木薯种植地,采用随机抽样方法,进行了木薯块根最大拔起力和块根拔断率的田间试验和统计分析,对块根不被拔断的允许最大拔起力进行了验证,最大拔起力小于0.98 k N时,块根拔断率为2.5%。结果表明,块根最大应力与各影响因素的多因素耦合数学模型的F检验在0.000 1水平上显著,精度较高,可用于块根最大应力的影响分析;块根最大应力随拔起速度的增大呈先增大,后减小的变化,随生长深度、块根长度和土壤硬度的增大而增大,随块根直径的增大而减小;块根最大应力与最大拔起力相关性不强,块根允许最大拔起力约为0.98 k N。
