西安建筑科技大学学报(自然科学版)

微波辐射下,岩石中矿物成分微波敏感性的差异会造成岩石内温度场的不均匀,诱发热应力,导致岩石的力学性能劣化,提高破岩效率并减少能源消耗.以常见的硬岩——花岗岩为研究对象,以矿物结构显微图像为基础,建立二维数值模型,探讨了微波辐射下,矿物间温度场和应力场演化规律.实验分析了微波辐射对岩石断裂韧性的影响规律.结果表明:微波辐射下,矿物非均匀温度场诱发的热应力可使岩石的断裂韧性下降28%.岩石内部应力分布状态受到矿物分布和矿物体积含量的影响,石英边界处的应力远大于长石—黑云母边界处的应力.随着加热时间的持续,热应力可引发裂纹萌生及扩展,造成岩石的断裂韧性随辐射时间持续下降.

Under microwave radiation, differences in microwave sensitivity of different minerals in rocks may cause inhomogeneous temperature field in rocks, induce thermal stress, and lead to the deterioration of rock mechanical properties, which can assist mechanical rock breaking, improve rock breaking efficiency and reduce energy consumption. In this paper, taking the common hard rock--granite as the research object, based on the microscopic image of mineral structure, established a two-dimensional model, and analyzed the evolution law of temperature field and stress field between minerals under microwave radiation. The influence of microwave on fracture toughness of rock was analyzed by experimental. The results show that the thermal stress induced by non-uniform temperature field can reduce the fracture toughness of rock by 28% under microwave radiation. The stress distribution in rock is affected by mineral distribution and mineral volume content. The stress at quartz boundary is much greater than that at feldspar-biotite boundary. With the duration of heating time, the thermal stress can cause crack initiation and expansion, resulting in the fracture toughness of the rock to continue to decline with the radiation time.

引言
1 微波加热模型
2 实验
3 结果分析与讨论
4 结论

图1 矿物结构模型(Pl:长石,Bt:黑云母,Qtz:石英)<br/>Fig.1 Mineral structure model

图1 矿物结构模型(Pl:长石,Bt:黑云母,Qtz:石英)
Fig.1 Mineral structure model

表1 数值模型的热力学参数[18]<br/>Table 1 Thermodynamic parameters of the numerical model[18]

表1 数值模型的热力学参数[18]
Table 1 Thermodynamic parameters of the numerical model[18]

图2 实验试件及设备<br/>Fig.2 Experimental sample and equipment

图2 实验试件及设备
Fig.2 Experimental sample and equipment

图3 微波辐射下矿物间的温度梯度<br/>Fig.3 Temperature gradients between minerals under microwave irradiation

图3 微波辐射下矿物间的温度梯度
Fig.3 Temperature gradients between minerals under microwave irradiation

图4 矿物及边界处温度梯度的阶跃变化<br/>Fig.4 Step change of temperature gradient at mineral interface

图4 矿物及边界处温度梯度的阶跃变化
Fig.4 Step change of temperature gradient at mineral interface

图5 微波辐射下矿物间的应力场<br/>Fig.5 Stress field between minerals under microwave irradiation

图5 微波辐射下矿物间的应力场
Fig.5 Stress field between minerals under microwave irradiation

图6 矿物交界面处von Mises应力的阶跃变化<br/>Fig.6 Step change of von Mises stress at mineral interface

图6 矿物交界面处von Mises应力的阶跃变化
Fig.6 Step change of von Mises stress at mineral interface

图7 矿物模型的损伤演变<br/>Fig.7 Damage evolution of mineral model

图7 矿物模型的损伤演变
Fig.7 Damage evolution of mineral model

$图8 试件断裂处的微观形貌(微波辐射时间(min))<br/>Fig.8 The microscopic morphology of the specimen fracture (time of microwave irradiation(min))$

图8 试件断裂处的微观形貌(微波辐射时间(min))
Fig.8 The microscopic morphology of the specimen fracture (time of microwave irradiation(min))

图9 微波辐射后试件断裂韧性的变化<br/>Fig.9 Fracture toughness of specimens after microwave irradiation

图9 微波辐射后试件断裂韧性的变化
Fig.9 Fracture toughness of specimens after microwave irradiation

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备注

引言

1 微波加热模型

2 实验

3 结果分析与讨论

4 结论

期刊信息