考虑颗粒分布的不确定性,在排列熵计算过程中引入蒙特卡罗(Monte-Carlo,简称M-C)方法,用以表征排列混乱程度.为探究粗粒土剪切过程中排列熵的演化规律,以粗颗粒含量P5为指标,设立4种不同类型的粗粒土结构为研究对象,结合常法向应力下的...考虑颗粒分布的不确定性,在排列熵计算过程中引入蒙特卡罗(Monte-Carlo,简称M-C)方法,用以表征排列混乱程度.为探究粗粒土剪切过程中排列熵的演化规律,以粗颗粒含量P5为指标,设立4种不同类型的粗粒土结构为研究对象,结合常法向应力下的剪切试验(CNL)试验结果,运用Image Pro Plus等图像处理软件,同时通过室内剪切试验和数值模拟双向验证所揭示规律的可靠性.在206 kPa的法向应力下对4种结构的粗粒土进行剪切试验,以一组骨架密实结构数据为算例,利用多项式拟合试验结果,对比分析数值模拟和室内剪切试验排列熵变化结果.研究结果表明:剪切初期,粗粒土的排列熵随剪应力的增加呈先增大后减小的趋势,在达到峰值后随着剪应力的缓慢减小表现为先增大后减小的趋势.随着粗颗粒含量的升高,粗粒土结构发生变化,排列熵值增大,同时其排列分布的有序性受剪切作用的影响越大.展开更多
Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behavior...Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behaviors.The Barton-Bandis(B-B) joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints.The B-B model accounts for asperity roughness and strength through the joint roughness coefficient(JRC) and joint wall compressive strength(JCS) parameters.Nevertheless,many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr-Coulomb(M-C) model,which is only appropriate for smooth and non-dilatant joints.This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior.To bridge the B-B and the M C models,this paper aims to provide a linearized implementation of the B-B model using a tangential technique to obtain the equivalent M-C parameters that can satisfy the nonlinear shear behavior of rock joints.These equivalent parameters,namely the equivalent peak cohesion,friction angle,and dilation angle,are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing.The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre-and post-peak regions of shear displacement,respectively.Likewise,the pre-and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established.Verifications of the linearized implementation of the B-B model show that the shear stress-shear displacement curves,the dilation behavior,and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.展开更多
In this paper, the existence, uniqueness, and asymptotic behavior of the solution of the density evolution equation for M/M/∞ model was studied by the semigroup theory of linear operators.
文摘考虑颗粒分布的不确定性,在排列熵计算过程中引入蒙特卡罗(Monte-Carlo,简称M-C)方法,用以表征排列混乱程度.为探究粗粒土剪切过程中排列熵的演化规律,以粗颗粒含量P5为指标,设立4种不同类型的粗粒土结构为研究对象,结合常法向应力下的剪切试验(CNL)试验结果,运用Image Pro Plus等图像处理软件,同时通过室内剪切试验和数值模拟双向验证所揭示规律的可靠性.在206 kPa的法向应力下对4种结构的粗粒土进行剪切试验,以一组骨架密实结构数据为算例,利用多项式拟合试验结果,对比分析数值模拟和室内剪切试验排列熵变化结果.研究结果表明:剪切初期,粗粒土的排列熵随剪应力的增加呈先增大后减小的趋势,在达到峰值后随着剪应力的缓慢减小表现为先增大后减小的趋势.随着粗颗粒含量的升高,粗粒土结构发生变化,排列熵值增大,同时其排列分布的有序性受剪切作用的影响越大.
基金support from the University Transportation Center for Underground Transportation Infrastructure at the Colorado School of Mines for partially funding this research under Grant No.69A3551747118 of the Fixing America's Surface Transportation Act(FAST Act) of U.S.DoT FY2016
文摘Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing,inducing dilation and resulting in nonlinear joint shear strength and shear stress vs.shear displacement behaviors.The Barton-Bandis(B-B) joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints.The B-B model accounts for asperity roughness and strength through the joint roughness coefficient(JRC) and joint wall compressive strength(JCS) parameters.Nevertheless,many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr-Coulomb(M-C) model,which is only appropriate for smooth and non-dilatant joints.This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior.To bridge the B-B and the M C models,this paper aims to provide a linearized implementation of the B-B model using a tangential technique to obtain the equivalent M-C parameters that can satisfy the nonlinear shear behavior of rock joints.These equivalent parameters,namely the equivalent peak cohesion,friction angle,and dilation angle,are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing.The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre-and post-peak regions of shear displacement,respectively.Likewise,the pre-and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established.Verifications of the linearized implementation of the B-B model show that the shear stress-shear displacement curves,the dilation behavior,and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.
文摘In this paper, the existence, uniqueness, and asymptotic behavior of the solution of the density evolution equation for M/M/∞ model was studied by the semigroup theory of linear operators.
