【求助】如何判断岩石结构的稳定性

wxbbb

我想将部分论文以附件形式放在贴子上，以便交流。
  
但不知道是否允许？（因为要占空间）
不知道有无必要？（因为一些期刊网上都有）
是不是显得张扬？（我只是想交流）
  
请大家指教？

wgao

大家找不到的贴出来可以的

azhong

我的论文是关于局部化、局部破坏、剪切带、FLAC、稳定性、应变软化、应变梯度等方面的，交个朋友吧，哥们！
168azhong@163.com
QQ　：185775986

azhong

发了这么多文章　太好了，终于找到老师了

WENDYLGL

给我发过来吧，谢谢！idalgl@163.com

wxbbb

[1] 梯度塑性理论及其在地质灾害预测研究中的应用  
  
岩石结构稳定性问题是岩土工程实践中迫切需要解决的重要课题之一.文章以地震为例,讨论了地质灾害的局部化特征,介绍了经典弹、塑性理论的某些缺陷及梯度塑性理论的几点优越性1)控制方程总是适定的;(2)病态网格依赖性消失;(3)局部化带宽度由材料的内部长度完全确定;(4)可对岩石结构的尺寸效应及失稳回跳进行合理解释和预测;(5)对预测宏观及微观问题均比较有效.介绍了基于梯度塑性理论的岩石变形、破坏及稳定性研究进展.梯度塑性理论可用于研究单轴压缩条件下,岩石试件发生剪切破坏时全程应力-应变曲线、尺寸效应、剪切带倾角尺寸效应及失稳回跳等问题,它们对土木工程及岩土工程均十分重要.若将单轴压缩岩样比拟为矿柱,则该失稳判据即为矿柱岩爆准则.梯度塑性理论可用于研究韧性断层带内部应变、应变率分布规律、断层带错动位移及带内孔隙度分布规律,为韧性断层带定量分析提供了新的手段.此外,该理论还可对直剪试验机--岩样系统不稳定性进行分析,系统失稳可比拟为断层岩爆.发展基于梯度塑性理论尺度律及失稳判据等解析解一方面可加深对岩石变形、破坏的理解;另一方面,还可用来检验数值结果的正确性.

wxbbb

[2] 基于梯度塑性本构理论的岩样侧向变形分析(Ⅰ):基本理论及本构参数对侧向变形的影响  
  
研究了岩样在单轴压缩条件下轴向应力-侧向或环向变形的全程曲线特征.基于考虑峰值剪切强度后微小结构之间相互影响和作用的梯度塑性理论,得到了由于剪切局部化而引起的侧向塑性变形.利用虎克定律描述了试件的弹性变形,得到了轴向应力-侧向变形全程曲线的解析解.在软化阶段,试件中部侧向变形及对靠近试件上端或下端部位的侧向变形并不相同.与轴向应力-应变曲线可能出现的回跳现象类似,试件中部轴向应力-侧向应变曲线也可能出现回跳现象.在应变软化阶段,与应力-侧向应变曲线相比,应力-环向应变曲线不容易发生回跳现象.若在试件内部出现多条剪切带,则应该以等效剪切带宽度替代本文中的剪切带宽度.随着剪切带倾角、内部长度参数的降低、剪切模量的增加及弹性模量的降低,轴向应力-侧向应变曲线越陡;甚至能出现弹性回跳.

wxbbb

[3] 考虑水致弱化及应变梯度的断层岩爆分析  
  
研究了岩石含水量对断层-围岩系统稳定性及岩爆(冲击地压)对韧性断层变形的影响.含水量不仅影响岩石强度,也对应力-应变曲线应变软化阶段斜率有影响.基于梯度塑性理论和水致弱化函数,得到了剪切带内部的塑性剪切应变、总剪切应变及塑性剪切位移的分布规律.此外,还得到了不同含水量时剪力-塑性剪切位移的关系.研究结果表明:随着岩石含水量的增加,塑性剪应变降低,塑性剪切位移降低;含水量越大,则弹性阶段越短,耗散势能越小,外力功越小,断层岩爆释放的弹性能量也越小;岩石的含水量增加,则断层-围岩系统不容易发生失稳.

wxbbb

[4] Localized shear deformation during shear band propagation in titanium considering interactions among microstructures  
  
Closed-form analytical solutions of plastic shear strain and relative plastic shear displacement during shear band propagation are proposed under dynamic loadings based on gradient-dependent plasticity considering the effect of microstructures due to heterogeneous texture of Ti. According to the differences in shear stress levels, Ti specimen is divided into three regions. residual region, strain-softening region and elastic region. Well-developed shear band is formed in the residual region and the relative plastic shear displacement no longer increases. In the normal and tangential directions, the plastic strain and the displacement are nonuniform in the strain-softening region.At the tip of shear band, the shear stress acting on the band is increased to shear strength from the elastic state and the shear localization just occurs. Prior to the tip, Ti remains elastic. At higher strain rates, the extent of plastic strain concentration is greater than that under static loading. Higher strain rate increases the relative plastic shear displacement. The present analytical solution for evolution or propagation of shear localization under nonuniform shear stress can better reproduce the observed localized characteristics for many kinds of ductile metals.

wxbbb

[5] 基于应变梯度塑性理论的直接剪切试验尺寸效应、剪切变形及扩容分析
  
The paper concerns the issue of size law, localized deformation and dilation or compaction due to shear localization. It is assumed that the shear localization initiates at the peak shear stress in the form of single shear band, and based on gradient-dependent plasticity, an analytical solution on size effect or snap-back is obtained. The results show that the post peak response becomes steeper and even exhibits snap-back with increasing of length. For small specimen, the relative shear displacement when specimen failure occurs is lower than that of larger specimen and the shear stress-relative displacement curve becomes steeper. The theoretical solution on non-uniformity of strains in shear band is obtained and evolution of the relative shear displacement is represented. By resorting to the linear relation between local plastic shear strain and local plastic volumetric strain, the dilation and compaction within shear band are analyzed.Relation between apparent shear strain and apparent normal strain and relation between shear displacement and vertical displacement are established.

wxbbb

[6] 岩样单轴拉伸损伤不均匀性分析--第一部分:基本理论  
  
研究了损伤变量(率)的局部化特征.基于非局部理论,将损伤变量作为非局部变量,它与局部损伤变量及其二阶梯度有关.岩石的本构关系取为双线性应变软化.利用弹性区与损伤局部化区域交界处的交界条件(局部损伤变量为零)及损伤局部化区域的宽度为局部损伤变量达到最大值时所对应的宽度的假设,得到了应变软化阶段局部损伤变量、局部损伤变量率及损伤局部化区域的宽度的解析解.此外,在应变软化阶段,拉应力、拉应变及非局部损伤变量的关系与经典损伤模型在应变软化阶段的定义方式不相同,其差别在于非局部损伤变量前的系数是2而不是1.这样定义的优越性是可以保证局部损伤变量的最大值为1,意味着在损伤局部化区域的中部试样完全被拉断,与人们的常识相符.局部损伤变量在损伤局部化区域的平均值就是非局部损伤变量,而且,最大局部损伤变量是平均损伤变量的2倍.

wxbbb

[7] 考虑塑性应变率梯度的单轴压缩岩样轴向响应  
  
基于剪切应变率梯度格式,采用解析方式研究了岩石材料在单轴压缩条件下的应变软化的结构响应.根据非局部连续介质模型,提出了一维二阶剪切应变率梯度格式.非局部剪切应变率与局部剪切应变率及其二阶梯度有关.将经典塑性理论中的局部剪切应变率替换为非局部剪切应变率,可以直接得到局部剪切应变率的封闭解析解,而不必通过将局部剪切应变对时间求导获得.通过对局部剪切应变率积分,得到了沿剪切带方向的相对剪切速度.试件峰值强度后的端部速度由弹性及塑性两部分构成.前一部分由虎克定律描述;后一部分与相对剪切速度有关.对弹性及塑性两部分速度求和,得到了单轴压缩岩样剪切破坏问题轴向响应的解析式.研究表明:试样高度越大、内部长度越小、剪切软化模量越大及泊松比越小,则岩样的轴向响应倾向于脆性.根据岩样与矿柱的相似性,岩样响应倾向于脆性,意味着矿柱将失去稳定性,发生矿柱岩爆.目前的基于剪切应变率梯度格式的主要优点是简洁.

wxbbb

[8] Analysis of localized shear deformation of ductile metal based on gradient-dependent plasticity  
  
Shear localization in linear strain softening heterogeneous material under simple shear was investigated analytically.The closed-form solutions obtained based on gradient plasticity theory considering interactions and interplaying among microstructures due to heterogeneity of metal material show that in the normal direction of shear band,elastic shear displacement is linear; while plastic and total shear displacement are non-linear.Elastic shear strain in the band is uniform and the non-uniformity of total shear displacement stems from localized plastic shear displacement.In the center of the band,plastic and total shear displacement all reach their maximum values.In strain-softening process,elastic displacement decreases as flow shear stress decreases.Contrarily,plastic and total shear displacement increase and manifest shear localization occurs progressively.Under the same shear stress level,plastic and total shear displacement increase as strain softening modulus and elastic shear modulus decrease.The present analytical solutions were compared with many experimental results and the agreement is good.

wxbbb

[9] Effect of Relative Stress on Post-Peak Uniaxial Compression Fracture Energy of Concrete  
  
Fracture energy in strain softening regime was investigated analytically by considering microstructures interaction and interplay. Based on gradient-dependent plasticity, the thickness cf localized band was determined completely and strictly by characteristic length in relation to average grain diameter. After obtaining the plastic shear displacement of the band, the formula on axial response of concrete was proposed and the analytical post-peak fracture energy was deduced. A comparison between present theoretical results and earlier experimental results was carried out and the analyticol result is reasonable and has a plausible foundation as considering the localized failure theoretically. Decreasing the relative stress leads to increasing the fracture energy non-linearly. The larger the shear elastic modulus and shear softening modulus, the lower the post-peak fracture energy. A larger fracture energy is caused by a larger thickness of shear band or a larger characteristic length of concrete material.If the inclination angle of the shear band and the compressive strength are not concerned with structural size of specimen, the post-peak fracture energy is size independent.

wxbbb

[10] 考虑应变率及应变梯度效应的断层岩爆分析  
  
从理论上研究了考虑应变率效应及微小结构相互影响的断层带-弹性岩石系统的剪切不稳定性.在经典弹-塑性理论的屈服函数中引入应变梯度及考虑应变率效应的函数.将断层岩爆简化为一维动态剪切问题,利用:局部塑性剪应变的对称性;在断层带的边界上,其应变值为零;断层带的宽度由塑性剪切应变取极值来确定等条件,得到了断层带内部的局部塑性剪切应变及局部塑性剪切位移,二者都随应变率的增加而趋于明显增加.同时,还得到了应变软化阶段系统结构响应的理论表达式.令峰后刚度为无穷大,则可得到岩爆发生的临界加载应变率,该参数不仅与岩石材料的本构参数有关,而且还与岩石结构的几何尺寸(即弹性区域的尺寸)有关.应变率增加使断层-弹性岩石系统容易发生失稳回跳.此外,若不考虑应变率效应,则本文的理论结果可以退化为对断层岩爆的静力分析结果.

wxbbb

[11] 基于梯度塑性理论的岩样单轴压缩扩容分析  
  
采用梯度塑性理论,对岩样剪应变局部化引起的扩容进行了理论分析.假设岩石的剪切本构关系为弹性-应变软化双线性,局部化启动于应力峰值强度,利用局部塑性剪应变与局部塑性体积应变的线性关系,得到了局部塑性体积应变、局部塑性体积增量及剪胀引起的剪切带总塑性体积增量的解析式,这体现了该理论在研究剪胀问题时的优越性.另外,还得到了弹性阶段及应变软化阶段的轴向应力-体积应变曲线的理论关系.塑性体积应变是专指由剪切带剪胀而引起的,因而,轴向应力-体积应变不具有尺寸效应,与局部化带的尺寸无关,但扩容角、剪切降模量及泊松比却对该曲线有重要影响.在弹性阶段及应变软化阶段轴向应力-体积应变均呈线性.在相同的应力水平下,扩容角越大则剪胀程度越大;剪切降模量越大,剪胀程度越小.在应变软化阶段,泊松比不影响塑性体积应变.

wxbbb

[12] 围压对剪切带倾角影响的梯度塑性理论分析  
  
The inclination angle of shear band is analyzed considering heterogeneity of rock material when a single shear band is formed in the center of specimen under triaxial compression. The analytical solution of post-peak axial stress-axial strain curve is deduced using the assumption that the total post-peak deformation is composed of entire uniform elastic deformation and localized shear plastic deformation dependent on the thickness of shear band. The obtained solution shows that the post-peak stiffness is related to the inclination angle of shear band,confining pressure,thickness of shear band and elastic modulus,etc. Using the solution,the expression for the inclination angle of shear band can be presented easily and it is dependent on constitutive parameters of rock material and geometry parameters of rock specimen. Larger dilation angle or loading rate leads to increment of the inclination angle. In addition,the inclination angle increases with the thickness of the shear band,which cannot be explained or forecasted by other existing solutions,such as Coulomb inclination,Roscoe inclination and Arthur inclination,etc.

wxbbb

[13] 基于剪切应变梯度塑性理论的断层岩爆失稳判据  
  
应用应变梯度塑性理论及能量准则,提出了断层岩爆的失稳判据的解析解.断层带被视为一维剪切问题,断层带尺寸由岩石内部长度确定.断层带的一半及带外一侧的弹性岩石被视为一个系统.得到了依赖于断层带尺寸的断层带的耗散势能及峰后刚度表达式.应用能量准则,得到了断层带-围岩系统的失稳判据,它不仅与岩石材料的本构参数有关,也与岩石结构的几何尺寸有关,说明系统的稳定性具有尺寸效应.断层岩爆失稳判据与矿柱岩爆失稳判据具有类似性.目前的断层岩爆失稳判据的优越性在于:断层带的宽度、断层带的耗散势能、峰后刚度及失稳判据等都可以解析表示;而且,断层带内部具有不均匀的(塑性)剪切应变,这一点与有关的实际观测结果相符合.

wxbbb

[14] 岩样失稳回跳与直剪试验机-岩样系统失稳回跳关系研究  
  
研究了岩样及直剪试验机-岩样系统的弹性回跳不稳定性.将试验机简化为具有一定高度和剪切模量的钢块,利用梯度塑性理论得到了直剪试验机-岩样系统的剪应力-剪应变的理论关系.当不考虑钢块的高度时,这一关系便蜕化为岩样的剪应力-平均剪应变的理论关系.如果试验机-岩样系统回跳,那么岩样可能失稳回跳,也可能不失稳回跳;当钢块高度及剪切模量比值越大,试验机-岩样系统越容易发生失稳回跳.当这一比值较大时,纵然岩样不回跳,系统也会回跳;当这一比值较小时,只有当岩样回跳,系统才会回跳;当系统不回跳时,试样必不回跳.试样回跳,必然导致系统回跳;如果试样不回跳,则系统可能回跳,也可能不回跳.理论结果可解释若干常见的实验现象.