Based on fractal super fibers and binary fractal fibers, the following objectives are approached in this paper： First, the concept of multiple-cell elements is induced and abstracted. Second, through multiple-cell el...Based on fractal super fibers and binary fractal fibers, the following objectives are approached in this paper： First, the concept of multiple-cell elements is induced and abstracted. Second, through multiple-cell elements, the constructability of regular multifractals with strict self-similarities is confirmed, and the universality of the con- struction mode for regular multifractals is proved. Third, through the construction mode and multiple-cell elements, regular multifractals are demonstrated to be equivalent to generalized regular single fractals with multilayer fine structures. On the basis of such equivalence, the dimension formula of the regular single fractal is extended to that of the regular multifractal, and the geometry of regular single fractals is extended to that of regular multifractals. Fourth, through regular multifractals, a few golden fractals are constructed.展开更多
This is a quantitative method for studying the fractal character of magnetic anornaly fields and delineating tectonic elements using fractal theory . For an area with different geological and geophysical features , th...This is a quantitative method for studying the fractal character of magnetic anornaly fields and delineating tectonic elements using fractal theory . For an area with different geological and geophysical features , the definition of Hausdorff dimension is used to calculate the fractal dimension of the area’s magnetic field , then delineate geological tectonic elements by comparing this value . Use of 1978- 1986 geophysical survey data in this method applied to the South China Sea yielded three first grade tectonic elements and nine second grade ones , in six of which subsecond grade elernents were found.展开更多
Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the h...Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument.And according to the geology of this working face,a discrete element model was calculated by UDEC.Combining in situ experimental data with numerical results,the relationship between the fractal dimension of boreholes'wall and the distribution of advanced abutment pressure was studied under the condition of mining advance.The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value.The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face.When the working face is set as the original point,the trend of fractal dimension from the far place to the origin can be divided into three phases:constant,steady increasing and constant.And the turning points of these phases are the max-influencing distance(50 m)and peak value(15 m)of abutment pressure.展开更多
为定量表征混凝土破坏过程中裂纹扩展及损伤演化规律,借助激光扫描技术与骨料投放算法构建混凝土细观结构模型,结合室内试验,基于连续-非连续单元方法(continuous-discontinuous element method,CDEM)对数值混凝土切面细观模型进行单轴...为定量表征混凝土破坏过程中裂纹扩展及损伤演化规律,借助激光扫描技术与骨料投放算法构建混凝土细观结构模型,结合室内试验,基于连续-非连续单元方法(continuous-discontinuous element method,CDEM)对数值混凝土切面细观模型进行单轴压缩数值模拟。结果表明:模拟所得应力-应变曲线及破坏模式与室内试验吻合较好;混凝土细观损伤演化过程表现为裂纹萌生、扩展、贯通、最终破坏的典型阶段特征,细观破裂度可揭示混凝土在破坏过程中的细观损伤演化规律;分形维数能够定量表征混凝土受压破裂过程中裂纹发展的复杂随机性,sigmoid型演化模型适用于描述混凝土单轴压缩裂纹分形维数的非线性演变过程。展开更多
岩石颗粒破碎是影响粒状材料剪切强度和变形的最主要因素,岩石颗粒破碎并不是想象的那么难,像花岗岩颗粒有时在很小的压应力作用下就可以破碎。岩石单颗粒破碎的物理试验结果常常很离散,完成大量单颗粒破碎的物理试验费时费力不现实,采...岩石颗粒破碎是影响粒状材料剪切强度和变形的最主要因素,岩石颗粒破碎并不是想象的那么难,像花岗岩颗粒有时在很小的压应力作用下就可以破碎。岩石单颗粒破碎的物理试验结果常常很离散,完成大量单颗粒破碎的物理试验费时费力不现实,采用离散单元法(Discrete element method,DEM)PFC软件模拟单颗粒压缩破碎试验,既能克服单颗粒破碎物理试验的缺陷,又能解决单颗粒破碎物理试验工作量大的难题,是研究单颗粒破碎的理想选择。基于DEM的软件PFC2D,将粒径为0.075~0.1245mm的基本粒子捆绑成不同粒径的单颗粒,模拟岩石单颗粒压缩破碎试验,观察颗粒破碎演化过程,统计单颗粒破碎强度。计算单颗粒压缩破碎后颗粒分布的分维,验证单颗粒破碎强度的分形模型和单颗粒破碎强度的尺寸效应。文中引用玄武岩单颗粒破碎试验结果,与单颗粒破碎的离散单元模拟结果进行比较,验证单颗粒破碎强度的尺寸效应和修正的Weibull理论的离散单元模拟结果。展开更多
基金supported by the National Natural Science Foundation of China (No. 10872114)the Natural Science Foundation of Jiangsu Province (No. BK2008370)
文摘Based on fractal super fibers and binary fractal fibers, the following objectives are approached in this paper： First, the concept of multiple-cell elements is induced and abstracted. Second, through multiple-cell elements, the constructability of regular multifractals with strict self-similarities is confirmed, and the universality of the con- struction mode for regular multifractals is proved. Third, through the construction mode and multiple-cell elements, regular multifractals are demonstrated to be equivalent to generalized regular single fractals with multilayer fine structures. On the basis of such equivalence, the dimension formula of the regular single fractal is extended to that of the regular multifractal, and the geometry of regular single fractals is extended to that of regular multifractals. Fourth, through regular multifractals, a few golden fractals are constructed.
文摘This is a quantitative method for studying the fractal character of magnetic anornaly fields and delineating tectonic elements using fractal theory . For an area with different geological and geophysical features , the definition of Hausdorff dimension is used to calculate the fractal dimension of the area’s magnetic field , then delineate geological tectonic elements by comparing this value . Use of 1978- 1986 geophysical survey data in this method applied to the South China Sea yielded three first grade tectonic elements and nine second grade ones , in six of which subsecond grade elernents were found.
基金financial support from the State Key Basic Research Program of China(Nos.2011CB201201and 2010CB226802)the National Natural Science Foundation of China(No.51204112)
文摘Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument.And according to the geology of this working face,a discrete element model was calculated by UDEC.Combining in situ experimental data with numerical results,the relationship between the fractal dimension of boreholes'wall and the distribution of advanced abutment pressure was studied under the condition of mining advance.The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value.The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face.When the working face is set as the original point,the trend of fractal dimension from the far place to the origin can be divided into three phases:constant,steady increasing and constant.And the turning points of these phases are the max-influencing distance(50 m)and peak value(15 m)of abutment pressure.
文摘为定量表征混凝土破坏过程中裂纹扩展及损伤演化规律,借助激光扫描技术与骨料投放算法构建混凝土细观结构模型,结合室内试验,基于连续-非连续单元方法(continuous-discontinuous element method,CDEM)对数值混凝土切面细观模型进行单轴压缩数值模拟。结果表明:模拟所得应力-应变曲线及破坏模式与室内试验吻合较好;混凝土细观损伤演化过程表现为裂纹萌生、扩展、贯通、最终破坏的典型阶段特征,细观破裂度可揭示混凝土在破坏过程中的细观损伤演化规律;分形维数能够定量表征混凝土受压破裂过程中裂纹发展的复杂随机性,sigmoid型演化模型适用于描述混凝土单轴压缩裂纹分形维数的非线性演变过程。
文摘岩石颗粒破碎是影响粒状材料剪切强度和变形的最主要因素,岩石颗粒破碎并不是想象的那么难,像花岗岩颗粒有时在很小的压应力作用下就可以破碎。岩石单颗粒破碎的物理试验结果常常很离散,完成大量单颗粒破碎的物理试验费时费力不现实,采用离散单元法(Discrete element method,DEM)PFC软件模拟单颗粒压缩破碎试验,既能克服单颗粒破碎物理试验的缺陷,又能解决单颗粒破碎物理试验工作量大的难题,是研究单颗粒破碎的理想选择。基于DEM的软件PFC2D,将粒径为0.075~0.1245mm的基本粒子捆绑成不同粒径的单颗粒,模拟岩石单颗粒压缩破碎试验,观察颗粒破碎演化过程,统计单颗粒破碎强度。计算单颗粒压缩破碎后颗粒分布的分维,验证单颗粒破碎强度的分形模型和单颗粒破碎强度的尺寸效应。文中引用玄武岩单颗粒破碎试验结果,与单颗粒破碎的离散单元模拟结果进行比较,验证单颗粒破碎强度的尺寸效应和修正的Weibull理论的离散单元模拟结果。
