Deformational behavior and change of micro-fabric of rocks in creep

近年来，利用地下建设核废料处置库、地下厂房、储油、储水、储气、储粮设施等已受到广泛关注。在这些结构的施工、维护和管理中，对岩体的长期稳定性进行评价已成为一个重要的问题。为弄清岩石蠕变破坏现象和机理，开展了一系列单轴压缩试验、单轴蠕变试验和细观观察。对KIMACHI砂岩、AKIYOSHI大理石、OGINO凝灰岩和KURIHASHI花岗闪长岩进行了蠕变试验。从蠕变试验结果来看，根据轴向应变率的变化规律，将蠕变曲线中分为3个区域的二次区域再细分为2个区域。细分后的区域表现为轴向应变率减小，细分后的区域表现为轴向应变率增大。更多的试样被加载到一定的压应力水平，并在显微镜下观察。从微观观察中发现，检测岩石裂缝和孔隙的药剂必须选择，以使其适合于每种岩石的结构和质地。然后，通过对栗桥花岗闪长岩薄片蠕变加载的微观观察发现，随着蠕变的进行，晶内微裂纹扩展为主，晶间微裂纹数量增加。此外，为了研究单轴压缩破坏过程与单轴压缩蠕变之间的关系，在施加蠕变载荷后的一段时间内或在给定的蠕变区域内对岩石试样进行了单轴压缩试验。从试验结果可以看出，岩石试件的残余单轴抗压强度直到前一个次级蠕变区域才发生变化，随着时间的推移，后一个次级蠕变区域的残余单轴抗压强度逐渐降低。少

Recently, much attention has been paid to the utilization of underground to build the repository for nuclear waste, the underground power house, the facilities for storage of oil, water, air and food, and so on. In the construction, maintenance and management of these structures, it has become important to evaluate the long-term stability of rockmass.In this study, to clarify the failure phenomenon and machanism of creep in rocks, a series of uniaxial compression tests, uniaxial creep tests and the microscopic observations was carried out.Creep tests were done for KIMACHI sandstone, AKIYOSHI marble, OGINO tuff and KURIHASHI granodiorite. Judging from the results of creep tests, secondary region in creep curve, which is divided into 3 regions, is subdivided into 2 regions according to the behavior of axial strain rate. The subdivided former region is characterized by the decrease of axial strain rate, and the latter one is by the increase of it.The thin sections were made from the rock … More specimens loaded until some compressive stress level and observed by the microscope. From the microscopic observations, it was found that the agent for detecting the cracks and pores in rocks has to be selected so that it may be suitable for the fabric and texture of each rock. Then, from the microscopic observations of the thin sections of KURIHASHI granodiorite loaded under creep tests, it was recognized that the intracrystalline microcracks extend mainly, and the number of intercrystalline microcracks increases as creep proceeds.Also, to investigate the relationship between the failure processes of uniaxial compression and uniaxial compressive creep, the uniaxial compression tests were done for the rock specimens after creep load is applied to them during some elapsed time or until a given creep region. From the results of these tests, it was found that the residual uniaxial compressive strengths of rock specimens don't change until the former secondary creep region, and are lower from the latter one with the passage of time. Less