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开展不同剪切角度的压剪实验和疲劳实验,研究压剪作用下盐岩的力学特性和晶体位错特性,基于损伤力学观点,建立以位错为度量指标的损伤关系模型。得到的主要结论有:(1)大于45°角剪切时,盐岩晶体位错的滑滞阻力较小,盐岩抗变形能力、峰值应力和最大变形量均随着剪切角度的增大而减小。裂纹以剪切面附近扇形裂纹发育为主。(2)疲劳寿命与循环荷载的上限应力水平相关。剪切角度不同时,若应力水平相同,则其疲劳寿命(循环数)基本相同;若应力大小相同,则剪切角度越大,疲劳寿命越短。(3)变向剪切对盐岩的疲劳寿命影响巨大,使疲劳寿命下降90%以上。(4)盐岩疲劳裂纹的成核和位错的不断挤入、挤出有关,裂纹扩展是多滑移系交替滑移的结果。建立基于位错理论的盐岩损伤模型,使损伤能从本质上表达盐岩的破坏过程。疲劳损伤越大盐岩的承载能力下降越明显。
The shear experiments and fatigue tests with different shearing angles were carried out to study the mechanical properties and the crystal dislocation characteristics of salt rock under the action of pressure and shear. Based on the damage mechanics, the damage relation model with dislocation as the metric was established. The main conclusions obtained are as follows: (1) When the shear stress is larger than 45 °, the sliding resistance of salt rock dislocations is small, and the deformation resistance, the peak stress and the maximum deformation of rock salt increase with the increase of shear angle And reduce. Cracks in the shear plane near the fan-shaped crack development. (2) Fatigue life is related to the upper stress level of cyclic load. If the shear angle is different, if the stress level is the same, the fatigue life (cycle number) is basically the same; if the stress is the same, the larger the shear angle, the shorter the fatigue life. (3) The change of shearing has a great impact on the fatigue life of salt rock, so that the fatigue life drops by more than 90%. (4) The nucleation of fatigue cracks in salt rock is related to the continuous extrusion and dislocation of dislocations, and the crack propagation is the result of the alternate slip of multi-slip system. The salt rock damage model based on dislocation theory is established so that the damage can express the destructive process of salt rock in essence. The more the fatigue damage is, the more obvious the bearing capacity of rock salt decreases.