干燥、潮湿合成盐岩流变细观机制的对比研究

1.北京市地质工程勘察院 岩土工程公司,北京 100048; 2.中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京 100083

流变细观机制; 合成盐岩; 位错流变; 晶界水; 动态重结晶

Contrast study on micromechanisms of dry and wet synthetic rocksalt rheology
DING Jing-yang1,ZHOU Hong-wei2,ZHANG Jin-xiang1

(1.Geotechnical Engineering Company,Beijing Institute of Geological and Prospecting Engineering,Beijing 100048,China;2.State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Beijing 100083,China)

micromechanisms of rheology; synthetic rocksalt; dislocation creep; grain boundary water; dynamic recrystallization

DOI: 10.13800/j.cnki.xakjdxxb.2017.0401

备注

针对盐岩流变细观机制的研究,对于合理建立本构模型、实验室尺度数据外推均具有重要意义。采用盐岩合成技术进行恒定应变率条件下的干燥盐岩流变实验,并对其细观结构进行了显微镜观测,同时借助于潮湿盐岩的研究成果作为对比,结果表明在晶界水的促进作用下,盐岩流变细观机制将会发生转化:干燥盐岩应力—应变曲线较为平缓,晶内存在波状滑移线、亚晶粒等细观特征,表明位错交叉滑移或位错攀移为流变主导机制; 潮湿盐岩应力—应变曲线形状较为波动并存在晶界迁移等细观结构,动态重结晶机制将对流变产生重要作用; 对干燥、潮湿盐岩的实验数据拟合分析表明,流变机制由位错流变向纯压溶转化。因此在盐构造地质演化、盐岩地下储库稳定性等研究过程中,要注意温度、应变率、应力水平、含水量等因素对流变应变率控制机制的影响。

The research on micromechanisms of rocksalt rheology is important for the establishment of a reasonable constitutive model and the extrapolation of laboratory sale data.Therefore,the rheological experiments for the dry synthetic rocksalt under constant strain rates are carried out and the microstructures are observed with the help of microscope.For comparison,the findings for the wet synthetic rocksalt indicate that the micromechanisms of rocksalt rheology may be transformed by fluid assisted grain boundary migration:①the stress-strain curves of dry rocksalt are relatively gentle and wavy slip bands,subgrains mean that cross-slip or climb of dislocation is the strain-rate controlled mechanism; ②the stress-strain curves of wet rocksalt show fluctuant and the microstructures of grain boundary migration can be observed,which mean that the dynamic recrystallization plays an important role in rocksalt rheology; ③the curve fitting for the steady-state flow data of both dry and wet rocksalt indicate the micromechanisms transformation from pure dislocation creep to pure solution-precipitation creep.As a result,factors such as temperature,strain rate,stress level and water content should be paid more attention to the study of geological evolution of salt tectonic and stability of underground reservoir.