摘要
本文通过分析地壳半脆性域岩石蠕变破坏-失稳的复杂性,提出应该建立能够判别地壳岩石半脆性蠕变破坏-失稳基本规律的准则,以便尽可能准确地预测地壳半脆性域岩石蠕变破坏-失稳的类型及其与温度压力等环境条件的关系。
The experimental researches on creep-failure of quartzite and granite, taking place at the middle-lower crustal conditions, show that semi-brittle creep-failure of crustal rocks, resulted either from fracture or from flow, could be of sudden or gradual instability modes. The transition of failure-instability modes of crustal rocks is strongly temperature, pressure and plastic component-dependent, which makes the semi-brittle failure of rocks much more complex.To identify such a complex deformation-failure process, it is the first thing to distinguish fracture, friction from flow, which are considered to be the basic failure modes of crustal rocks, and then the instability modes, sudden (caused by shear fracture or stick-slip) or gradual (caused by creep flow). It is obvious that the traditional strength criterion will not be able to predict these deformation events.On the basis of experimental results, the following conclusions have been drawn:1. The limited strength of middle-lower crustal rocks varies in some range, the upper limit is given from shear fracture strength of intact rocks, and the lower limitfrom frictional strength of rocks with saw-cut. In relatively deep part of the crust, the lower limit will be given from the limited flow stress, which can also be expressed as limited strain. Generally, fracture failure, which mainly occurs in upper-middle part of the crust, is limited-stress-dependent, and flow failure, which is more often observed in lower part of the crust, is limited-strain-dependent.2. Traditional strength criterion can only be used to identify the failure conditions and failure modes (fracture or flow), but can not reflect the instability modes. A new multicri-terion has been set up to identify the instability modes of rocks. An empirical criterion for this purpose has been given in form of critical stress or the plastic component.3. The semi-brittle failure mechanisms and the corresponding instability modes of crustal rocks can be classified by cal culating the critical stress and strength of rocks using the suggested multicriterion, and then a deformation-failure mechanism diagram can be drawn out, which directly reflects the relationship between environment (such as temperature and pressure) and rock failure-instability modes at relatively high stress, as well as the possible distribution of creep failure by different mechanisms.
出处
《地质科学》
CAS
CSCD
北大核心
1991年第1期60-68,共9页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
岩石
地壳
半脆性
蠕变
失稳
semi-brittle creep, crustal rocks, instability modes
