不同加載路徑對巖石Kaiser效應影響的試驗研究
發(fā)布時間：2019-03-14 11:45
【摘要】：使用巖石Kaiser效應方法來測量原巖地應力,具有便捷、經濟的優(yōu)點,近年來被廣泛研究和使用。但是,目前該方法還存在一些尚未解決的技術問題,其中之一就是:在鉆取巖芯以便通過室內Kaiser效應試驗來測量地應力時,在所鉆取的巖芯的軸線方向與現場主應力的主方向不一致(即,初次加載方向與后續(xù)加載方向不一致)的條件下,Kaiser效應是否存在,能否獲得正確的結果。本文采用花崗巖試樣進行室內試驗,研究了單軸加載條件下初始加載方向與后續(xù)加載方向之間存在一定夾角時,夾角大小對Kaiser效應的存在與否以及夾角對Kaiser點判斷的影響的研究。同時,還進行了三軸加載條件下不同預加載路徑對Kaiser效應影響的研究。所獲主要結論如下:1.在初次加載應力處于遠低于試樣強度的30%低應力水平的條件下,當聲發(fā)射信號很少時,會出現Kaiser效應不顯著情況。在這樣的情況下,以能量計數和振鈴計數第一次開始持續(xù)增加時對應的應力水平平均值作為Kaiser點,比較準確。2.在初次加載應力達到較高應力水平(大體接近試樣強度的65%)的條件下,當第二次加載應力還未達到先前最大應力時,聲發(fā)射信號就變得活躍,以累計能量計數和累計振鈴計數曲線的拐點后出現的第一個曲率增大點對應的應力水平平均值作為Kaiser點,誤差較小。3.三軸加載試驗得到:①.在先加圍壓后加軸壓條件下,第二次單軸加載出現的Kaiser點對應的應力對之前所預加載的軸壓有很好的記憶性。即,此時圍壓對Kaiser效應沒有影響。②.先加軸壓后加圍壓條件下,Kaiser效應不顯現。③.在三向等壓加載下條件,Kaiser效應不顯現。4.單軸加載后,后續(xù)加載方向分別改變15°和20°試驗得到:在進行第二次加載時,都能夠觀察到顯著的Kaiser效應;但對之前受到最大應力的記憶是提前的;且對后續(xù)加載方向改變15°和20°的情形,FR值分別為0.76和0.71。
[Abstract]:It is convenient and economical to use the method of rock Kaiser effect to measure the in-situ stress of the original rock, which has been widely studied and used in recent years. However, there are still some unsolved technical problems in this method. One of them is that when drilling the core to measure the in-situ stress through indoor Kaiser effect test, Under the condition that the axis direction of the core drilled is not consistent with the principal direction of the field principal stress (that is, the direction of initial loading and the direction of subsequent loading), whether the Kaiser effect exists or not and whether the correct results can be obtained. In this paper, the granite samples are tested in laboratory, and the angle between the initial loading direction and the subsequent loading direction under uniaxial loading is studied. The influence of angle size on the existence of Kaiser effect and the influence of angle on Kaiser point judgment are studied. At the same time, the influence of different preloading paths on Kaiser effect under triaxial loading is also studied. The main conclusions obtained are as follows: 1. Under the condition that the initial loading stress is much lower than the 30% low stress level of the specimen strength, when the acoustic emission signal is very little, the Kaiser effect will not be significant. In this case, the average stress level corresponding to the first continuous increase of the energy count and ring count is used as the Kaiser point, which is more accurate. Under the condition that the initial loading stress reaches a higher stress level (approximately 65% of the specimen strength), the acoustic emission signal becomes active when the second loading stress does not reach the previous maximum stress. Taking the average stress level corresponding to the first curvature increase point after the inflection point of cumulative energy count and cumulative ring counting curve as the Kaiser point, the error is small. 3. The results of triaxial loading test are as follows: 1. Under the condition of first confining pressure followed by axial compression, the stress corresponding to the Kaiser point in the second uniaxial loading has a good memory for the pre-loaded axial compression. That is, at this time the confining pressure has no effect on the Kaiser effect. Under the condition of axial compression first and confining pressure, the Kaiser effect does not show up. 3. Under the condition of three-way isobaric loading, the Kaiser effect does not appear. 4. After uniaxial loading, the direction of subsequent loading was changed by 15 擄and 20 擄, respectively. The results showed that the significant Kaiser effect could be observed during the second loading, but the memory of the maximum stress before loading was earlier. When the direction of subsequent loading is changed by 15 擄and 20 擄, the FR values are 0.76 and 0.71 respectively.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD315
本文編號：2439951
[Abstract]:It is convenient and economical to use the method of rock Kaiser effect to measure the in-situ stress of the original rock, which has been widely studied and used in recent years. However, there are still some unsolved technical problems in this method. One of them is that when drilling the core to measure the in-situ stress through indoor Kaiser effect test, Under the condition that the axis direction of the core drilled is not consistent with the principal direction of the field principal stress (that is, the direction of initial loading and the direction of subsequent loading), whether the Kaiser effect exists or not and whether the correct results can be obtained. In this paper, the granite samples are tested in laboratory, and the angle between the initial loading direction and the subsequent loading direction under uniaxial loading is studied. The influence of angle size on the existence of Kaiser effect and the influence of angle on Kaiser point judgment are studied. At the same time, the influence of different preloading paths on Kaiser effect under triaxial loading is also studied. The main conclusions obtained are as follows: 1. Under the condition that the initial loading stress is much lower than the 30% low stress level of the specimen strength, when the acoustic emission signal is very little, the Kaiser effect will not be significant. In this case, the average stress level corresponding to the first continuous increase of the energy count and ring count is used as the Kaiser point, which is more accurate. Under the condition that the initial loading stress reaches a higher stress level (approximately 65% of the specimen strength), the acoustic emission signal becomes active when the second loading stress does not reach the previous maximum stress. Taking the average stress level corresponding to the first curvature increase point after the inflection point of cumulative energy count and cumulative ring counting curve as the Kaiser point, the error is small. 3. The results of triaxial loading test are as follows: 1. Under the condition of first confining pressure followed by axial compression, the stress corresponding to the Kaiser point in the second uniaxial loading has a good memory for the pre-loaded axial compression. That is, at this time the confining pressure has no effect on the Kaiser effect. Under the condition of axial compression first and confining pressure, the Kaiser effect does not show up. 3. Under the condition of three-way isobaric loading, the Kaiser effect does not appear. 4. After uniaxial loading, the direction of subsequent loading was changed by 15 擄and 20 擄, respectively. The results showed that the significant Kaiser effect could be observed during the second loading, but the memory of the maximum stress before loading was earlier. When the direction of subsequent loading is changed by 15 擄and 20 擄, the FR values are 0.76 and 0.71 respectively.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD315
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