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岩石具有流变性质,这一特性在实际工程中得到越来越广泛的重视。岩石的典型蠕变过程分为瞬时弹性应变、瞬态蠕变、稳态蠕变和加速蠕变4个阶段。由现有的流变元件(虎克体、牛顿体和圣维南体)组合成的模型,可以描述前3个蠕变阶段。本文补充一个描述加速蠕变的流变元件,并提出一个反映岩石蠕变全过程的模型系统。 对于某种岩石,当施加的应力较小时,应变趋于一稳定值(图1曲线1);当施加较大应力时,应变将以稳定的速率发展(图1曲线2)。因此存在一临界应力δ_f,当施加的应力小于该临界应力时,岩石不会发生蠕变破坏,当施加的应力大于临界应力时,岩石就会持续变形,并发展到破坏(曲线2虚线)。这个临界应力称为岩石的长期强度。
Rocks have rheological properties, and this feature has gained more and more attention in practical engineering. The typical creep process of rock is divided into four stages: instantaneous elastic strain, transient creep, steady-state creep and accelerated creep. The combination of existing rheological elements (Hook, Newton, and Saint-Vinant) can describe the first three creep stages. This paper adds a rheological element describing accelerated creep, and proposes a model system that reflects the entire process of rock creep. For a rock, when the applied stress is small, the strain tends to a stable value (curve 1 in Fig. 1); when a large stress is applied, the strain develops at a steady rate (curve 2 in Fig. 1). Therefore, there is a critical stress δ_f. When the applied stress is less than the critical stress, the rock will not undergo creep failure. When the applied stress is greater than the critical stress, the rock will continue to deform and develop to failure (curve 2 dashed line). This critical stress is called the long-term strength of the rock.