Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground wa...Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground water is of great significance. Compression and creep experiments on sandstone with varying water contents were conducted using a deep soft rock five-linked rheological experiment system. The experimental conditions, including water content (0%, 0.8%, 1.6%, 2.4% and 3.3%) and confining pressure (0, 6, 9 and 12 MPa), were determined based on pressure-free water absorption tests and in-situ stress measurements. The experimental results show that the compressive strength, creep failure stress, and dilatancy stress of sandstone decrease exponentially with increasing water content, while they increase exponentially with confining pressure. The ratio of lateral to axial instantaneous strain increases nearly linearly with the increase of stress, and the lateral creep strain characteristics of the sample are more significant than the axial ones. The duration of the attenuation creep stage of sandstone decreases with increasing water content and increases with increasing confining pressure. The lateral strain enters the steady-state creep stage before the axial strain, and the onset time of the accelerated creep stage of lateral strain under the failure stress is earlier than that of axial strain. The long-term strength of sandstone was determined based on the lateral steady-state creep rate curve, showing a negative exponential relationship with water content and a positive exponential relationship with confining pressure. A method for determining the long-term strength of rocks based on the ratio of lateral strain to axial strain (μc) is proposed, which is independent of water content. The research results provide a reliable theoretical basis for the analysis of the long-term stability of roadways under the influence of groundwater and the early prediction of creep failure.展开更多
基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法...基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法.首先,基于L波段极化干涉数据,用三阶段反演方法获取植被覆盖地表下地形有效散射中心的相位;接着,基于C波段极化干涉数据,用ESPRIT算法估计植被冠层有效散射中心的相位;最后,对二者的相位差进行相位到高度的转换得到植被的高度.根据研究区域的实测林相数据,对该算法估计的植被高度结果进行了比较和验证,结果表明:该方法具有足够高的植被高度估计精度,如果能得到P和X波段的双频极化干涉雷达数据,该方法估计植被高度的精度将会得到进一步的提高.展开更多
在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人...在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人机典型作战想定,设计了仿真流程,并进行仿真推演。结果表明此战法打击效果较好,具有一定实用意义,为无人机作战研究提供了一种新的可行研究思路。展开更多
反舰导弹装备应用研究是水面舰艇装备形成战斗力的关键环节。给出了一种基于STAGE和D e lph i的反舰导弹装备应用研究仿真平台,介绍了单项仿真与综合仿真相结合的仿真方法和基于STAGE的建模仿真研究框架。以“飞鱼”反舰导弹为例进行了...反舰导弹装备应用研究是水面舰艇装备形成战斗力的关键环节。给出了一种基于STAGE和D e lph i的反舰导弹装备应用研究仿真平台,介绍了单项仿真与综合仿真相结合的仿真方法和基于STAGE的建模仿真研究框架。以“飞鱼”反舰导弹为例进行了搜捕特性建模和仿真研究,找出了其搜捕方案存在的技术问题,并提出了优化和改进方案。指出基于仿真的装备应用研究方法具有明显的实用价值。展开更多
基金Projects(52174096, 52304110) supported by the National Natural Science Foundation of China。
文摘Water is a critical factor affecting the mechanical properties of rocks, leading to their degradation. Understanding the creep mechanical behavior of deep roadway surrounding rock under the influence of underground water is of great significance. Compression and creep experiments on sandstone with varying water contents were conducted using a deep soft rock five-linked rheological experiment system. The experimental conditions, including water content (0%, 0.8%, 1.6%, 2.4% and 3.3%) and confining pressure (0, 6, 9 and 12 MPa), were determined based on pressure-free water absorption tests and in-situ stress measurements. The experimental results show that the compressive strength, creep failure stress, and dilatancy stress of sandstone decrease exponentially with increasing water content, while they increase exponentially with confining pressure. The ratio of lateral to axial instantaneous strain increases nearly linearly with the increase of stress, and the lateral creep strain characteristics of the sample are more significant than the axial ones. The duration of the attenuation creep stage of sandstone decreases with increasing water content and increases with increasing confining pressure. The lateral strain enters the steady-state creep stage before the axial strain, and the onset time of the accelerated creep stage of lateral strain under the failure stress is earlier than that of axial strain. The long-term strength of sandstone was determined based on the lateral steady-state creep rate curve, showing a negative exponential relationship with water content and a positive exponential relationship with confining pressure. A method for determining the long-term strength of rocks based on the ratio of lateral strain to axial strain (μc) is proposed, which is independent of water content. The research results provide a reliable theoretical basis for the analysis of the long-term stability of roadways under the influence of groundwater and the early prediction of creep failure.
文摘基于重复轨道航天飞机SIR-C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three-Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法.首先,基于L波段极化干涉数据,用三阶段反演方法获取植被覆盖地表下地形有效散射中心的相位;接着,基于C波段极化干涉数据,用ESPRIT算法估计植被冠层有效散射中心的相位;最后,对二者的相位差进行相位到高度的转换得到植被的高度.根据研究区域的实测林相数据,对该算法估计的植被高度结果进行了比较和验证,结果表明:该方法具有足够高的植被高度估计精度,如果能得到P和X波段的双频极化干涉雷达数据,该方法估计植被高度的精度将会得到进一步的提高.
文摘在对无人机作战特点及使用样式深入研究的基础上,综合运用STAGE(scenario toolkit and generation environment)仿真软件,给出以HLA为核心的无人机作战仿真系统框架,构建无人机和导弹等关键实体扩展模型,开发了战场仿真环境。结合无人机典型作战想定,设计了仿真流程,并进行仿真推演。结果表明此战法打击效果较好,具有一定实用意义,为无人机作战研究提供了一种新的可行研究思路。
文摘反舰导弹装备应用研究是水面舰艇装备形成战斗力的关键环节。给出了一种基于STAGE和D e lph i的反舰导弹装备应用研究仿真平台,介绍了单项仿真与综合仿真相结合的仿真方法和基于STAGE的建模仿真研究框架。以“飞鱼”反舰导弹为例进行了搜捕特性建模和仿真研究,找出了其搜捕方案存在的技术问题,并提出了优化和改进方案。指出基于仿真的装备应用研究方法具有明显的实用价值。
