大理岩压溶蠕变与微裂隙愈合实验研究

An experimental study on pressure solution creep and micro-crack healing of Carrara marble

压溶蠕变可能是间震期断层带的主导变形机制之一,开展压溶蠕变及其对微裂隙愈合的实验研究对理解强震孕育和发生具有重要意义。以Carrara大理岩为样品,开展相同围压(800 MPa)和应变速率(1×10-7s-1)、不同温度(300、400、500℃)下大理岩压溶蠕变实验。利用扫描电镜研究实验变形样品的微观结构与变形机制,利用傅里叶变换红外吸收光谱测试实验样品的含水量。实验结果表明:在300℃条件下,碎裂和压溶是样品主要变形机制,400℃时样品同时出现碎裂、压溶和局部动态重结晶,500℃时样品主要变形机制为压溶和动态重结晶。压溶主要出现在样品强变形区域,粒度减小与含水量增加促进了压溶发生,而压溶引起孔隙和微裂隙愈合。

Pressure solution creep is one of the main deformation mechanisms which control crack healing kinetics around active faults.The experimental study of pressure solution creep and micro crack healing is one of the methods to understand the mechanism of earthquake nucleation and occurance of strong earthquakes.We conducted pressure solution creep experiments using samples of Carrara marble at different temperatures(300,400,500℃),constant confining pressure(800MPa)and strain rate(1×10-7s-1).Scanning electron microscopy(SEM)was used to study the microstructure and deformation mechanisms of the initial and deformed samples.Fourier transform infrared absorption spectrum were used to measure the water content of the samples.The experimental results show that cataclasis and pressure solution are the main deformation mechanism at300℃;cataclasis,pressure solution and local dynamic recrystallization appear at400℃;and pressure solution and dynamic recrystallization are main deformation mechanism at500℃.The experiments suggest that the high water content,the large strain and fine grains are favorable for pressure solution to occur;which further leads to the healing of micro cracks and pores.