Mechanical properties of bedded rock salt and creep failure model
Mechanical properties of bedded rock salt and creep failure model
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发表时间：
2010
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通讯作者：
Wan Wen
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作者：
Wan Wen
以湖北省云营盐矿600～700 m级含泥岩夹层氯化钠岩盐试件为研究对象，进行了试件的常规力学试验和多批次应力水平下的单轴压缩蠕变试验。常规力学试验结果表明，层状岩盐是一种特殊的组合软岩，其弹性模量较小，但在单轴压应力状态下，岩盐的侧向变形较大。通过蠕变实验，得到如下结果：（1）如果蠕变持续时间足够长，层状岩盐蠕变过程中会出现衰减蠕变阶段、稳定蠕变阶段和加速蠕变阶段，其中加速蠕变阶段与其他岩石相比持续时间较长。 (2)稳定蠕变阶段出现岩盐夹层内陷和隆起现象。不协调的蠕变变形可能导致互层中的剪切错位。建立了层状岩盐的蠕变破坏模型，其中损伤变量为试件环拉应变与极限拉应变之比。从理论上揭示了夹层蠕变特性与岩盐蠕变特性差异引起的岩盐地层蠕变破坏机理。合理解释了互层岩盐层间先劈裂破坏，然后层间驱动拉裂裂纹扩展破坏的实验现象。
Taking the Sodium Chloride rock salt specimens containing mudstone interbed, located at 600～700 m level of Yunying salt-mine in Hubei Province as the research objects, the conventional mechanical tests on the specimens and uniaxial compression creep tests on the specimens under multi batch stress levels were performed. The conventional mechanical tests obtained the result that the bedded rock salt is a kind of special combined soft rock, its elastic modulus is comparative little, but lateral deformation of the rock salt is great under uniaxial compression stress state. Through creep experiments, the results were obtained as follows: (1)If the duration of creep is enough long, the attenuation creep stage, the steady creep stage and the accelerative creep stage are appeared during the bedded rock salt creep, with the accelerative creep stage last longer compared with other rocks. (2)The phenomenon of invagination of interlayer and bulge of rock salt is found at the steady creep stage. Uncoordinated creep deformation may lead to shear dislocation in the interbed. Creep failure model of bedded rock salt is also established in which the damage variable is viewed as the ratio of the ring tensile strain of specimens and ultimate tensile strain. Mechanism of creep failure in the rock salt strata induced by the differences in creep characteristics of the interlayer and that of rock salt theoretically is revealed. The experimental phenomena that the interlayer splits failure firstly, then the failure of interlayer driving tension cracks propagating in interbedded rock salt is reasonably explained.