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在较高的应变水准(强度为90～95％)下对稻田花岗岩、多胡砂岩、水泥砂浆和秋芳大理岩进行了单轴压缩蠕变实验。获得如下结果: 1) 所有样品的一次蠕变符合对数蠕变规则。 2) 应变速率几乎是恒定的二次蠕变仅对水泥砂浆是明显的。对其它样品来说最初应变率不断减小,当达到最小值后则增加。 3) 对多胡砂岩和秋芳大理岩,在最小应变率点上的蠕变应变值几乎等于相同蠕变应力的横剖面上全应力—应变曲线幅度的一半。在花岗岩中最小应变速率点的蠕变应变是相当小的,而在胶结碎斑(cement—mortar)几乎是幅度的二倍。 4) 三次蠕变在某一指定时间的应变速率与到最终破坏点的残余寿命(residual time)成反比。如果将这一规律应用于岩盘,就可以预测地下建筑物的破坏。 5) 除水泥砂浆外,刚好在最终破坏前(在破坏前1s)的蠕变几乎等于全应力—应变曲线横刻面的宽度。对胶结碎斑(cement—mortar)来说,刚好破坏前的蠕变应变较这个宽度要大得多。
Uniaxial compression creep experiments were carried out on granite, granite, sandstone, cement mortar and Qiufang marble at high strain levels (intensity of 90-95%). The following results are obtained: 1) One creep of all samples meets the logarithmic creep rule. 2) Secondary creep with almost constant strain rate is only evident for cement mortar. For other samples, the initial strain rate continuously decreases and increases when the minimum value is reached. 3) For Dohu sandstone and Qiufang marble, the creep strain at the point of minimum strain rate is almost equal to half the amplitude of the full stress-strain curve on the transverse section of the same creep stress. The creep strain at the point of minimum strain rate in granite is quite small, and is almost twice that of cement-mortar. 4) The creep rate of a three-time creep at a given time is inversely proportional to the residual time to the final failure point. If this rule is applied to rock disks, the destruction of underground buildings can be predicted. 5) In addition to cement mortar, the creep just before final failure (1s before failure) is almost equal to the width of the full facet of the stress-strain curve. For cement-mortars, creep strain just before failure is much greater than this width.