深部巷道具有强烈的动力扰动特征。采用有限差分数值计算软件FLAC(Fast La-grangian Analysis of Continua)对动力扰动下巷道围岩力学响应进行了数值分析。结果表明:动力扰动增大巷道顶、底板的水平应力峰值,并使峰值位置后置;扰动后巷...深部巷道具有强烈的动力扰动特征。采用有限差分数值计算软件FLAC(Fast La-grangian Analysis of Continua)对动力扰动下巷道围岩力学响应进行了数值分析。结果表明:动力扰动增大巷道顶、底板的水平应力峰值,并使峰值位置后置;扰动后巷道顶板下沉量及巷道围岩塑性区范围显著增加。原岩应力越大,动力扰动对巷道围岩应力场、位移场及塑性区范围影响就越显著,对于深部高应力巷道,动力扰动可使巷道顶、底板的水平应力峰值达到极高应力状态,并存在大范围的塑性屈服区域,具有发生岩爆的危险。展开更多
从人类旅游干扰与生态系统响应互作的双重视角，选择保护区3个核心景区的不同植被类型。在初春植物萌芽敏感期（旅游“五一”黄金周期间），分别进行0～500次的践踏处理，并在2周、3个月后跟踪调查植被与土壤的响应情况。研究结果表明...从人类旅游干扰与生态系统响应互作的双重视角，选择保护区3个核心景区的不同植被类型。在初春植物萌芽敏感期（旅游“五一”黄金周期间），分别进行0～500次的践踏处理，并在2周、3个月后跟踪调查植被与土壤的响应情况。研究结果表明：①旅游践踏强度与植物生长负效应呈显著相关，各种类型植被都表现为高度降低，盖度下降，种群发生变异，土壤硬度增加等负面效应，即使经过2周和3个月恢复，践踏对植被生长负面影响并没有消失，仍在持续；②不同植被类型对人类旅游践踏干扰响应差别较大。小南川景区对旅游践踏响应最大，梁殿峡次之，野荷谷最小；③结合旅游者对景区土壤裸露度的可接受改变限度（Limits of Acceptable Change，LAC）测定，小南川景区在处理前后，均超过了LAC阈值；梁殿峡景区仅在500次践踏强度处理下，2周后LAC超过阈值，3个月后。恢复到LAC阈值以内；野河谷景区在75～500次践踏处理后，2周内都超过LAC阈值，3个月后250次和500次处理仍超过阈值水平。可见，瞬间饱和践踏很容易对植被带来重大破坏，这些后续变化已影响到旅游者游憩体验。3种地表植被类型中，除野荷谷景区外，小南川和梁殿峡景区植被长期管理问题十分突出。因此，在目前保护区缺乏系统规划建设前提下，采取相关措施已十分必要。展开更多
The failure characteristics under coupled static and dynamic loading were investigated by the improved split Hopkinson pressure bar （SHPB） with axial pre-pressure and confining pressure. The results show that the st...The failure characteristics under coupled static and dynamic loading were investigated by the improved split Hopkinson pressure bar （SHPB） with axial pre-pressure and confining pressure. The results show that the stress—strain curve of the rock under static-dynamic coupled loading is a typical class I curve when the dynamic load is comparatively high; With the decrease of the dynamic load, the stress—strain curve transforms to a typical class II curve. The dynamic failure process was recorded by high-speed photography. Analyses of fracture surface morphology show that the failure modes of specimens are tensile failure or combined shear failure when the impact load energy is low, but the failure modes of specimens become tensile failure when the impact load energy is high. The results of fractal dimension show that the elastic potential energy release leads to increase in the degree of crushing of samples when the energy of impact load is low under coupled static and dynamic loads with high stress.展开更多
文摘深部巷道具有强烈的动力扰动特征。采用有限差分数值计算软件FLAC(Fast La-grangian Analysis of Continua)对动力扰动下巷道围岩力学响应进行了数值分析。结果表明:动力扰动增大巷道顶、底板的水平应力峰值,并使峰值位置后置;扰动后巷道顶板下沉量及巷道围岩塑性区范围显著增加。原岩应力越大,动力扰动对巷道围岩应力场、位移场及塑性区范围影响就越显著,对于深部高应力巷道,动力扰动可使巷道顶、底板的水平应力峰值达到极高应力状态,并存在大范围的塑性屈服区域,具有发生岩爆的危险。
文摘从人类旅游干扰与生态系统响应互作的双重视角，选择保护区3个核心景区的不同植被类型。在初春植物萌芽敏感期（旅游“五一”黄金周期间），分别进行0～500次的践踏处理，并在2周、3个月后跟踪调查植被与土壤的响应情况。研究结果表明：①旅游践踏强度与植物生长负效应呈显著相关，各种类型植被都表现为高度降低，盖度下降，种群发生变异，土壤硬度增加等负面效应，即使经过2周和3个月恢复，践踏对植被生长负面影响并没有消失，仍在持续；②不同植被类型对人类旅游践踏干扰响应差别较大。小南川景区对旅游践踏响应最大，梁殿峡次之，野荷谷最小；③结合旅游者对景区土壤裸露度的可接受改变限度（Limits of Acceptable Change，LAC）测定，小南川景区在处理前后，均超过了LAC阈值；梁殿峡景区仅在500次践踏强度处理下，2周后LAC超过阈值，3个月后。恢复到LAC阈值以内；野河谷景区在75～500次践踏处理后，2周内都超过LAC阈值，3个月后250次和500次处理仍超过阈值水平。可见，瞬间饱和践踏很容易对植被带来重大破坏，这些后续变化已影响到旅游者游憩体验。3种地表植被类型中，除野荷谷景区外，小南川和梁殿峡景区植被长期管理问题十分突出。因此，在目前保护区缺乏系统规划建设前提下，采取相关措施已十分必要。
基金Projects (10872218, 50934006) supported by the National Natural Science Foundation of ChinaProject (2010CB732004) supported by National Basic Research Program of ChinaProject (2011ssxt276) supported by the Central South University Innovation Fund, China
文摘The failure characteristics under coupled static and dynamic loading were investigated by the improved split Hopkinson pressure bar （SHPB） with axial pre-pressure and confining pressure. The results show that the stress—strain curve of the rock under static-dynamic coupled loading is a typical class I curve when the dynamic load is comparatively high; With the decrease of the dynamic load, the stress—strain curve transforms to a typical class II curve. The dynamic failure process was recorded by high-speed photography. Analyses of fracture surface morphology show that the failure modes of specimens are tensile failure or combined shear failure when the impact load energy is low, but the failure modes of specimens become tensile failure when the impact load energy is high. The results of fractal dimension show that the elastic potential energy release leads to increase in the degree of crushing of samples when the energy of impact load is low under coupled static and dynamic loads with high stress.
