STUDY ON CRACK DYNAMIC PROPAGATION PROCESS OF ROCK SAMPLES BASED ON ACOUSTIC EMISSION LOCATION
STUDY ON CRACK DYNAMIC PROPAGATION PROCESS OF ROCK SAMPLES BASED ON ACOUSTIC EMISSION LOCATION
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发表时间：
2007
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通讯作者：
Liu Jianpo
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作者：
Liu Jianpo
声发射（Acoustic emission，AE）是许多材料中普遍存在的与脆性断裂相关的现象，它是微裂纹发生或扩展过程中产生的一种声发射现象。声发射技术可以实时、连续地监测岩石中微裂纹的发展过程，具有其它方法无法比拟的优越性。将声发射定位技术应用于岩石破坏过程的研究中，采用不同预切裂纹的花岗岩试件，对岩石破坏过程进行了研究。采用盖革定位算法，由声发射传感器确定声发射事件的初至时刻位置，用于研究裂纹的萌生和扩展过程，结果表明，在整个加载过程中，裂纹的声发射活动随应力的变化表现出不同的特征，从初始加载到裂纹萌生，声发射事件数量很少，裂纹萌生后，声发射事件明显增加，裂纹萌生后到裂纹扩展前，声发射事件处于平静期;从裂纹稳定扩展阶段到裂纹失稳扩展阶段，声发射活动急剧增加，尤其是在裂纹失稳扩展阶段，声发射定位结果中存在声发射事件的“空洞”;声发射事件的“空隙空间”是宏观裂纹突破的位置，可以用来预测岩石样品的裂纹突破位置，同时，声发射定位结果也直接反映了岩样内部应力场的扩展过程，声发射定位结果也直接反映了岩样内部裂纹扩展的空间位置、方向和空间曲面，这对研究岩石破坏机理具有重要意义。
Acoustic emission(AE),which is produced by the micro-cracks occurrence or growth,is a ubiquitous phenomenon associated with brittle fracture in many materials.AE technique can be used to monitor the micro-cracks development in the rock sample continuously and in-real-time,which is better than other methods.AE location technique is employed to study rock failure process.It is investigated using granite samples with different precut cracks;and AE sensors are mounted on the surface of the sample.A Geiger location algorithm allows AE event location from first arrival times to be determined by AE sensors,which is applied to study the crack initiation and propagation process,also to analyze the crack spatial evolution mode with stress changing during the total loading process.The experimental results show that AE activity represents different characters with stress-strain changing during the total loading process;the quantity of the AE events is very little from the initial loading to crack initiation;when the initial crack generates,AE events apparently increase;AE events are in quiet period after crack initiation up to the time before crack propagation;AE activity sharply increases from crack stable propagation up to crack unstable propagatione,specially in crack unstable propagation step,AE events reach to the most quantity in the division strain.There is “void space” of AE events during the AE location results;the “void space” of AE events is the position of macroscopic crack breakthrough,which can be used to predict the crack breakthrough position of rock samples.Meanwhile,AE location results are also direct reflection of interior stress field propagation process.AE location results also reflect directly the spatial position,direction and spatial curved face of crack propagation in the rock sample,which is very significant to study the mechanism of rock failure.