不同水压与初始卸荷水平下砂岩的力学特性及卸荷本构模型

发布时间：2018-08-09 20:53

【摘要】：为研究深埋高水压条件下岩石卸荷力学特性,以砂岩为研究对象,开展了不同水压及初始卸荷水平条件下的三轴加、卸荷试验,研究了卸荷下砂岩的应力-应变特征、强度变形特征等,并推导了卸荷本构模型。研究表明:对于卸荷试验,当初始卸荷水平n降低或者水压p增大时,砂岩的卸荷极限强度和轴向应变ε1降低,表现出更明显的脆性特征,侧向应变ε3增大,扩容特征越明显。相对于常规加载试验,卸荷试验的峰值黏聚力c最大降低59.78%,峰值摩擦角最大增加54.72%,初始卸荷水平n每降低0.1,峰值c(φ)约多减少10%(10%~15%)。将卸荷应力-应变曲线划分为4段,选取Mohr-Coulomb屈服准则,对参数a_f,a_r,b_f,b_r进行了一元、二元函数拟合,获得了各参数的变化规律,最后得到了卸荷条件下的本构关系。结果表明,理论模型与试验结果吻合较好。
[Abstract]:In order to study the unloading mechanical characteristics of rock under the condition of deep buried and high water pressure, the triaxial loading and unloading tests under different water pressure and initial unloading level were carried out, and the stress-strain characteristics of sandstone under unloading were studied. The strength and deformation characteristics are also derived, and the unloading constitutive model is derived. The results show that when the initial unloading level n decreases or the water pressure p increases, the unloading ultimate strength and axial strain 蔚 1 of sandstone decrease, showing more obvious brittleness, while the lateral strain 蔚 3 increases and the expansion capacity becomes more obvious. Compared with the conventional loading test, the maximum cohesive force c of unloading test decreases 59.78%, the maximum friction angle increases 54.72%, the initial unloading level n decreases 0.1, the peak c (蠁) decreases about 10% (1015%). The stress-strain curve of unloading is divided into four sections, and the Mohr-Coulomb yield criterion is selected to carry out one-element fitting and binary function fitting to the parameter AffU / rsquhbsp _ bsp _ r. Finally, the constitutive relation under unloading condition is obtained. The results show that the theoretical model is in good agreement with the experimental results.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;中铁十一局集团第五工程有限公司;西安建筑科技大学土木工程学院;重庆工商大学管理学院;
【基金】：煤矿灾害动力学与控制国家重点实验室资助项目(2011DA105287—MS201208) 陕西省自然科学基础研究计划资助项目(2016JQ4009) 重庆市科委自然科学基金基础与前沿研究计划资助项目(cstc2013jcyj A30005)
【分类号】：TU45

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