摘要
不同深度温压条件下的三轴压缩实验结果表明 ,花岗岩强度随深度持续增加直至30 km左右 .在地壳浅表部位 ,岩石破坏表现为低压突发或准突发失稳 ,破坏前后有分布大体均匀的声发射 ( acoustic emission,以下简称 AE)事件发生 ;向下进入以渐进式破坏为特征的深度范围时 ,破坏前基本没有或仅有很少的、随时间逐渐稀疏的 AE分布 ,破坏后也仅有极少的 AE被记录到 ;在更深的以高压准突发失稳为特征的深度范围 ,破坏前依然 AE极少 ,但破坏后伴随不等周期粘滑应力降的产生而有较多的 AE被记录到 ;在更高的温压条件下 (约2 6km) ,破坏形式为高压突发失稳 ,破坏前即有逐渐密集、累积频次呈指数增加的 AE活动 ;在 35km深度附近 ,岩石强度急剧降低 ,样品表现为半延性、延性渐进式破坏 ,无 AE记录 .声发射 b值随深度增加似有减小的趋势 ,并且 b值在岩石破坏前略小于破坏后 .声发射时间序列奇异性强度因子 α的数值分布范围在 1 8km左右深度的温压条件下最宽 ,表明其标度类型最多 ,结构最为复杂、无序 ;在浅部及更深部位的温压条件下均变窄 .因而 ,当温压条件模拟真实的地壳深度向下改变时 ,微破裂时间序列奇异性强度因子α的分布范围可能会经历“由窄变宽、再由宽变窄”的变化过程 .
Results of triaxial compression experimentresults show thatgranite rock strength increases with the depth until 3 0 km.In shallow crust,rock failure exhibits abrupt or quasi- abrupt instability under lower pressure.Acoustic Emission(AE for short) distributed almost uniformly before and after failure.Go through downwards into the depth range with progressive failure feature,there are no or only a few number of AE before and after failure. In deeper range,rock failure shows some feature of quasi-abrupt instability under high pressure.There are still few AE before failure,but with the stick-slip,much more AE events were detected afterfailure.Underthe temperature and pressure condition of more deep crust (about2 6km) ,rock failure takes abruptinstability underhigh pressure asmain feature, there are dense AE activities before failure and cumulated frequency of AE increases exponentially before the failure.In about3 5km depth range,rock strength decreases quickly with the depth and sample exhibits semi-ductile or ductile progressive fails,there are no AE being detected before and afterfailure.The b value of AE sequence before failure seems a little smaller than thatafterfailure,and b valueroughly decreased with depth.The numerical range of index a is the widest in about1 8km depth and becomes narrow in the condition of more shallow or more deep crust.So,when the temperature and pressure condition simulating the real environment of focal depth changes from shallow to deep in the crust,the range of a of microfracture sequence would undergo such an evolvementprocess thata changes from narrow to wide and then to narrow again.
出处
《地震学报》
CSCD
北大核心
2000年第4期395-403,共9页
Acta Seismologica Sinica
基金
中国地震局"九五"重点攻关项目 95-04-02-01
山东省自然基金项目 Y97E02079的部分成果
中国地震局构造物理开放实验室共同资助
中国地震局地质研究所论著2000B012
关键词
高温高压
花岗岩
变形破坏
声发射
标度指数谱
high temperature and high pressure
granite
deformation and failure
acoustic emission
local scale index spectra
