The effects of strain rate and saturation on a micro-cracked marble
The effects of strain rate and saturation on a micro-cracked marble
复制标题
DOI：
10.1016/j.enggeo.2005.09.001
复制
发表时间：
2006-01
影响因子：
7.4
通讯作者：
Y. Mahmutoğlu
中科院分区：
文献类型：
--
作者：
Y. Mahmutoğlu
众所周知，岩体中含有从微裂隙到断层大小不等的多种类型的软弱面。裂缝频率、饱和度和时间是影响其特性的基本岩石参数。然而，在大多数情况下，在实验室环境中测试严重破裂的岩石实际上是困难的。本文通过小型物理试验，探讨了微裂纹、应变率和含水饱和度对强度的影响。它是试图分离的晶粒边界的粗粒岩石标本的Mujuela大理石的热处理，将作为一个小规模的物理模拟岩体中的裂缝，并使时间依赖的力学行为的变化进行讨论。对大理石试件在不同频率下的热致微裂纹进行了实验研究。除A类和G类外，每个试样在惰性气氛条件下的热处理时间为24小时。在最后一次F类热循环后，有效孔隙率增加到2.4%。然后，在伺服控制试验机上对干试件和饱和试件进行了不同应变率的常规压缩试验。结果表明，与热致微裂纹相关的应变速率降低和孔隙率增加对强度和失效路径有重要影响，渐进失效完全沿循环热处理开裂的晶界沿着进行，晶间变形取决于热影响程度。小规模的实验室模型能够证明，参数，如联合频率，时间和饱和度有显着的影响，岩体的力学行为。
It is well known rock masses contain several types of weakness planes varying from micro-fissure to fault in size. The fracture frequency, degree of saturation and time are the basic rock parameters affecting its behaviour. However, in most cases, it is practically difficult to test heavily fractured rock in laboratory environment. In this study, the effects of micro cracks, strain rate and water saturation on strength are discussed using a small-scale physical experiments. It is attempted to detach the grain boundaries of coarse-grained rock specimens of the Muğla marble by thermal treatment that would serve as a small-scale physical simulation of fractures in rock masses and enable a discussion of the variations in time dependent mechanical behaviour. An experimental study was conducted on marble specimens induced thermally by micro-cracks in different frequencies. The thermal treatment periods being 24 h in inert atmospheric condition were varied for each test specimen except categories A and G. Effective porosity increased up to 2.4% after the last thermal cycle of category F. Then conventional compression tests with different strain rates were carried out using a servo-controlled testing machine on both dry and saturated specimens. It is concluded that both lowering strain rates and increasing porosity related with thermally induced micro cracks have important effects on strength and failure path. The progressive failure entirely occurs along the grain boundaries fissured by cyclical treatment and inter-granular deformation depends upon degree of thermal influence. The small-scaled laboratory model enabled to demonstrate that parameters such as joint frequency, time and saturation have a significant effect on mechanical behaviour of rock masses.