不同水损伤程度下泥岩断裂力学特性试验研究

发布时间：2018-11-03 14:02

【摘要】：为研究不同程度水损伤作用对泥岩断裂力学特性的影响,对水中浸泡不同时间条件下的泥岩半圆盘试件进行三点弯曲试验,同时利用PCI 2型声发射系统对泥岩试件的断裂全过程进行实时监测。结果表明:天然泥岩的断裂力学行为受水岩作用影响显著,随着浸泡时间的增加,其峰值载荷不断下降,浸泡200 min后,该泥岩纯I型至纯II型断裂韧度分别降低至未损伤条件下的53%,56.5%,61%,64%,64.7%和67.6%,且泥岩的断裂破坏形式由脆性逐渐转变为延性。通过声发射定位确定了不同损伤程度下泥岩半圆盘试件中断裂过程区长度,随着损伤程度加深,断裂过程区长度逐渐减小,声发射事件累计总数不断增加;同时,将试验得到的等效断裂韧度与纯I型断裂韧度的比值与引入T应力后改进的最大周向应力理论比值进行比较,表明在未浸泡及短时间浸泡条件下试验结果符合该理论结果;但随着损伤程度的加深该试验结果拟合曲线逐渐偏离理论曲线,浸泡时间达到200 min时,该偏离情况较为明显。
[Abstract]:In order to study the effect of different degrees of water damage on the fracture mechanical properties of mudstone, the three-point bending test of mudstone semi-disc specimen immersed in water for different time was carried out. At the same time, the whole fracture process of mudstone specimen is monitored in real time by using PCI type 2 acoustic emission system. The results show that the fracture mechanical behavior of natural mudstone is significantly affected by the action of water and rock. With the increase of soaking time, the peak load of natural mudstone decreases continuously, and the peak load decreases continuously after immersion for 200 min. The fracture toughness of pure type I to pure II of the mudstone is reduced to 56.565% 64.7% and 67.6% respectively under the condition of no damage, and the fracture failure form of mudstone is gradually changed from brittleness to ductility. The length of fracture process zone in mudstone semi-disc specimen with different damage degree was determined by acoustic emission location. With the deepening of damage degree, the length of fracture process zone gradually decreased, and the accumulative total number of acoustic emission events increased. At the same time, the ratio of equivalent fracture toughness to pure mode I fracture toughness obtained by experiment is compared with the ratio of the improved maximum circumferential stress theory after introducing T stress. The results show that the experimental results agree with the theoretical results under the condition of unsoaking and soaking for a short time. However, the fitting curve deviated from the theoretical curve gradually with the deepening of the damage degree. When the immersion time reached 200 min, the deviation was obvious.
【作者单位】：太原理工大学矿业工程学院;太原理工大学原位改性采矿教育部重点实验室;
【基金】：国家杰出青年科学基金资助项目(51225404) 山西自然科学基金项目(2014011044)~~
【分类号】：TU45

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