内蒙古塔木素地区粘土岩力学特性研究

发布时间：2018-01-20 14:37

  本文关键词： 塔木素 粘土岩 力学特性研究 高放废物 地质处置　出处：《东华理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：粘土岩是高放废物地质处置库的重要候选围岩之一,内蒙古巴音戈壁盆地塔木素地区是我国高放废物地质处置粘土岩场址的重点筛选区域,粘土岩的物理性能及力学特性是评价候选围岩场址中重要的参数之一。本文通过试验研究了巴音戈壁盆地塔木素地区粘土岩的物理化学性能及力学性能,根据实验数据探讨了该粘土岩的力学特性的产生机理,分析其产生的原因。主要获得以下几点认识:(1)塔木素粘土岩宏观特征上表现为结构致密,岩石固结程度非常高。岩石主要由粘土矿物、钠长石、白云石以及方沸石组成,矿物颗粒细小,分布均匀。(2)通过试验研究得到塔木素地区粘土岩的天然含水率为1.11~2.52%、天然块体密度为2.25~2.65 g/cm3、颗粒密度为2.41~2.72 g/cm3、孔隙率为2.58~6.64%。该粘土岩的吸附性能优异,岩土材料的比表面积为10.24~39.78 m2/g之间。该粘土岩的渗透系数为10-8~10-9 cm/s,渗透率为10-13~10-14 cm2,属于极微透水的岩土材料。该粘土岩各方面特性满足高放废物处置库的基本要求。(3)塔木素地区粘土岩具有较高的声波速度、点荷载强度、抗拉强度和单轴抗压强度,并且其声波速度、抗拉强度、单轴抗压强度均与块体密度表现出良好的正相关性。由于粘土岩本身的结构非常致密,其力学强度的变化趋势与埋深没有显著的相关性。通过热—力耦合条件下的三轴试验,发现该粘土岩的力学强度和变形会随着围压的增加而增加,破坏后峰值应力迅速下降,并伴有体积的迅速膨胀现象,呈现应变软化特征,岩石中的裂隙属于非稳定破裂传播,变形属于脆性破坏的特征;此外由于粘土矿物受到温度条件的影响,导致该岩石的力学强度会随着温度的升高而下降,并在90℃、30MPa围压条件下呈现出明显的塑性变形特征。(4)通过FLAC 3D模拟塔木素粘土岩在受力后的变性特征,并记录在加载过程中岩石材料所发生的位移变化。再与实际试验中的所记录的结果进行对比,发现两者有类似的变化趋势,说明摩尔-库伦本构模型及相关的材料参数在一定程度上能够反映该粘土岩的受力后的状况。(5)综合对比瑞士Mont Terri高放废物地质处置地下实验室Opalinus粘土岩和法国高放废物地质处置库Meuse/Haunt Marn场址Callovo-Oxfordian粘土岩的力学特性,塔木素地区粘土岩具有更高的力学强度、弹性模量和内摩擦角。为我国高放废物地质处置库围岩的筛选提供了重要的依据。
[Abstract]:Clay rock is one of the important candidate rock rocks for geological disposal of high-level radioactive waste, and the Tashu area of Bayingobi Basin in Inner Mongolia is the key screening area for the geological disposal of clay rock of high-level radioactive waste in China. The physical and mechanical properties of clay rocks are one of the important parameters in evaluating candidate surrounding rock sites. The physical and chemical properties and mechanical properties of clay rocks in Tashu area of Bayingobi Basin have been studied by experiments in this paper. Based on the experimental data, the mechanism of the mechanical properties of the clay rock is discussed, and the causes are analyzed. The main results are as follows: 1) the macroscopical characteristics of the lignin clay rock of the tower are densified. The rock is mainly composed of clay minerals, albite, dolomite and donites, and the mineral particles are fine. The natural moisture content of clay rock is 1.112.52 and the density of natural block is 2.25 ~ 2.65 g / cm ~ 3. The particle density is 2.41 ~ 2.72 g / cm ~ 3 and the porosity is 2.58 ~ 6.64. The clay rock has excellent adsorption performance. The specific surface area of the rock and soil materials is between 10.24 ~ 39.78 m2 / g and the permeability coefficient of the clay rock is 10-8 ~ (-9) cm/s. The permeability is 10-13 ~ 10 ~ (-14) cm2. The characteristics of the clay rock meet the basic requirements of the high-level radioactive waste repository. The clay rock in the area of the tower lignin has high acoustic velocity and point load strength. The tensile strength and uniaxial compressive strength, and the sound velocity, tensile strength and uniaxial compressive strength all show a good positive correlation with the bulk density. Through triaxial tests under thermal-mechanical coupling conditions, it is found that the mechanical strength and deformation of the clay rock will increase with the increase of confining pressure. After failure, the peak stress decreases rapidly, accompanied by rapid expansion of volume, showing strain-softening characteristics, cracks in the rock belong to the propagation of non-stable fracture, deformation belongs to the characteristics of brittle failure; In addition, due to the influence of temperature on the clay minerals, the mechanical strength of the rock will decrease with the increase of temperature, and the mechanical strength of the rock will decrease at 90 鈩，

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