There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and ...There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and foundations, and tunnel walls, undergo both static and cyclic loading caused by drilling and blasting, and vehicle-induced vibrations. This type of loading often causes rock to fail at a lower than its static strength due to the effect of rock fatigue. A series of laboratory diametrical compression tests was performed on Brisbane tuff disc specimens to investigate their mode-I fracture toughness response to static and cyclic loading, as a function of the applied load. Both the static and cyclic loading tests were carried out on CCNBD （cracked chevron notched Brazilian disc） rock specimens. In the tests described herein, the reduction in fracture toughness under dynamic cyclic loading was found to be up to 48% of the static fracture toughness. Contrary to the static tests, the cyclic tests produced much more crushed material in front of the tip of the chevron notched crack.展开更多
Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks u...Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks under cyclic loading fail at much lower strength as compared to those subjected to the monotonic loading conditions. A few selected cored granodiorite and sandstone specimens have been subjected to uniaxial cyclic compression tests to obtain the unconfined fatigue strength and life. This study seeks to examine the effects of cyclic loading conditions, loading amplitude and applied stress level on the fatigue life of sandstone, as a soft rock, and granodiorite, as a hard rock, under uniaxial compression test. One aim of this study is to determine which of the loading conditions has a stronger effect on rock fatigue response. The fatigue response of hard rocks and soft rocks is also compared. It is shown that the loading amplitude is the most important factor affecting the cyclic response of the tested rocks. The more the loading amplitude, the shorter the fatigue life, and the greater the strength degradation. The granodiorite specimens showed more strength degradation compared to the sandstone specimens when subjected to cyclic loading. It is shown that failure modes of specimens under cyclic loadings are different from those under static loadings. More local cracks were observed under cyclic loadings especially for granodiorite rock specimens.展开更多
文摘There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and foundations, and tunnel walls, undergo both static and cyclic loading caused by drilling and blasting, and vehicle-induced vibrations. This type of loading often causes rock to fail at a lower than its static strength due to the effect of rock fatigue. A series of laboratory diametrical compression tests was performed on Brisbane tuff disc specimens to investigate their mode-I fracture toughness response to static and cyclic loading, as a function of the applied load. Both the static and cyclic loading tests were carried out on CCNBD （cracked chevron notched Brazilian disc） rock specimens. In the tests described herein, the reduction in fracture toughness under dynamic cyclic loading was found to be up to 48% of the static fracture toughness. Contrary to the static tests, the cyclic tests produced much more crushed material in front of the tip of the chevron notched crack.
基金Mining Research Institute of Western Australia (MRIWA) for the financial support
文摘Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks under cyclic loading fail at much lower strength as compared to those subjected to the monotonic loading conditions. A few selected cored granodiorite and sandstone specimens have been subjected to uniaxial cyclic compression tests to obtain the unconfined fatigue strength and life. This study seeks to examine the effects of cyclic loading conditions, loading amplitude and applied stress level on the fatigue life of sandstone, as a soft rock, and granodiorite, as a hard rock, under uniaxial compression test. One aim of this study is to determine which of the loading conditions has a stronger effect on rock fatigue response. The fatigue response of hard rocks and soft rocks is also compared. It is shown that the loading amplitude is the most important factor affecting the cyclic response of the tested rocks. The more the loading amplitude, the shorter the fatigue life, and the greater the strength degradation. The granodiorite specimens showed more strength degradation compared to the sandstone specimens when subjected to cyclic loading. It is shown that failure modes of specimens under cyclic loadings are different from those under static loadings. More local cracks were observed under cyclic loadings especially for granodiorite rock specimens.
