限制性剪切蠕变的渐进式破坏发育模式与本构方程分析

以标准红砂岩方形试样为研究对象,运用自行研制开发的软弱煤岩剪切蠕变试验设备和煤岩细观力学特性测控软件、超声波检测设备,对红砂岩限制性剪切、限制性剪切蠕变过程的破坏过程、破坏模式、渐变特性进行了分析。结果表明:红砂岩试样在限制性剪切、限制性剪切蠕变条件下表现出明显的渐变破坏特性;大部分试验过程中试样内部的超声波速减小幅度较小,仅在临近破坏处有明显减小;红砂岩限制性剪切蠕变破坏发育过程表现为先形成主控破裂面,又在其附近区域形成丰富微裂隙,并发育、相互贯通,最后克服剪切面摩擦力并发生突发式破坏,且伴有较大断裂声;其破坏模式发育过程呈渐进式,破坏模式呈突发式;建立了一种可以表征红砂岩剪切蠕变渐进式破坏发育过程的本构模型。

Study on progressive destruction model and constitutive model of red sandstone under limiting shear creep

Taking square rock block of red sandstone as research object, we studied all of progressive properties, process and model of destruction of red sandstone under restrictive shear and restrictive shear creep with a self-designed shear creep experimental device of coal or weak rock, a monitor software of coal or rock micromechanics properties and ultrasonic test equipment. The results show that apparent progressive property of red sandstone samples is shown under condition of restrictive shear and restrictive shear creep. The decrease extent of ultrasonic wave velocity in red sandstone samples is samller than those in most of the testing process, and the significantly decrease extent is only shown near the destruction of the sample. The destruction process contains four stages:key fracture plane forms firstly, then abundant secondary micro-fractures forms, and these secondary micro-fractures develope and interconnect, and finally the friction on shear plane is overcome and burst destruction occurs and the main large crack appears in beneath of samples. The development process of destruction is progressive, and the destruction model is burst. A constitutive model that can be used to express the properties of progressive destruction of red sandstone is proposed.