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岩石类材料变形破坏的时间空间特性

ISSN号：1000-3835
期刊名称：《振动与冲击》
时间：0
分类：TU435[建筑科学—岩土工程;建筑科学—土工工程] TU42[建筑科学—岩土工程;建筑科学—土工工程]
作者机构：北京建筑大学土木与交通工程学院北京市未来城市设计高精尖创新中心,北京100044
相关基金：国家自然科学基金项目（51478027,51174012）;“973”重大科学研究计划项目（2015CB0578005）;国家自然科学基金创新群体（51021001）

关键词：构造层次, 尺寸效应, 应变率效应, 临界尺寸, 临界应变率, structural hierarchy, size effect, strain rate effect, characteristic size , characteristic strain rate

中文摘要：

基于岩石类材料的内部构造层次模型和裂纹扩展速度的有限性,研究了岩石类材料变形破坏的时间和空间特性.研究表明,内部构造和和裂纹扩展速度的有限性对于岩石类材料的力学行为具有决定性的影响.岩石类材料强度的尺寸效应是不同尺度上单元界面强度的体现.岩石类材料强度的应变率效应是由于裂纹扩展速度的有限性所致超载所激活的小尺度单元界面的强度.基于Maxwell型应力松弛模型,建立了应变率与所激活的内部单元尺度之间的关系.基于这一关系,阐明了岩石类材料尺寸效应与应变率效应之间的内在联系.揭示了岩石类材料动力尺寸效应的物理机理,确定了应变率一定时,静力尺寸效应和动力尺寸效应之间转换的临界试件尺寸,以及试件尺寸一定时静力尺寸效应和动力尺寸效应之间转换的临界转换应变率,结果与实验数据吻合,说明了模型的正确性.

英文摘要：

This paper studied the temporal-spatial properties of deformation and fracture of rock-like materials based on the internal structural hierarchy model and finiteness of crack propagation speed. It is shown that internal structural hierarchy and finiteness of crack propagation speed have decisive effect on mechanical behaviours of rock-like materials. Size effect of strength of rock-like materials is the demonstration of strength of boundary layer of elements at different scale levels. Strain rate effect of dynamic strength of rock-like materials is the overload induced by the finiteness of crack propagation speed, and is the strength of boundary layer of smaller elements activated by the overload. Based on Maxwell relaxation model, the relation between strain rates and dimension of activated internal elements is established, and further the intrinsic relation between size effect and strain rate effect of rock-like materials strength is revealed. The physical mechanism underlying dynamic size effect is clarified, and the critical sample size of static-to-dynamic size effect transition under fixed strain rate and the critical strain rate of static-to-dynamic size effect transition under fixed sample size are determined which agree well with the experimental data, demonstrating the validity of the proposed model.

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