干湿循环作用下约束泥质白云岩力学特性试验研究

发布时间：2018-06-14 13:16

本文选题：干湿循环 + 约束　；参考：《贵州大学》2015年硕士论文

【摘要】：在实际工程中,工程岩体受到约束的情况很多,例如在边坡支护时,当锚杆打入岩体内部之后,锚杆周边的岩体随即受到约束作用。工程实践表明这些处理好的边坡中常有边坡坍塌等灾害发生,说明处理好的边坡岩石在自然环境条件下其性质在发生变化,据此本文以受约束岩体作为研究对象,探究其物理力学特性在干湿循环作用下的变化规律,为岩体工程的设计、施工和维护安全运行提供理论依据,具有重大的现实意义和理论意义。本文是建立在3个主要试验的基础之上,一是受约束的泥质白云岩的物理特性实验,二是干湿循环作用下受约束的泥质白云岩的力学特性实验,三是预应力损失观测试验。取7组岩样,在饱水状态下进行室内干湿循环试验,饱水和干燥各12小时为1周期,总共循环30周期。在循环过程中,通过观察记录岩样的外观变化情况,并跟踪其质量和纵波波速等物理特性参数;另外对每增加5个循环周期进行了单轴压缩试验,从而获得岩样的单轴抗压强度、弹性模量、泊松比等力学特性参数,得出了泥质白云岩在干湿循环作用下物理参数和力学参数的变化规律。预应力损失观测试验是本文的一个主要创新点,这个试验中模拟了一种对岩体施加约束的方法。在试样两端放置两块10mm厚的方形钢板,钢板通过4根高强度螺杆连接,通过调节螺栓的松紧来改变施加应力的大小。对这种施加了约束的岩样进行干湿循环试验,在螺杆上贴上应变片,采用江苏东华测试技术股份有限公司生产的DH3816N静态应变测试系统采集螺杆的应变,由此探究预应力的衰减规律。试验结果表明:泥质白云岩在干湿循环作用下有明显的损伤劣化现象,岩样纵波波速、单轴抗压强度、弹性模量等参数呈现明显的下降趋势。约束岩体的预应力损失呈现比较明显的规律性,即循环周期的初始段和结束段损失比较明显,中间段变化比较小,本文对这种规律性做了初步的分析探讨,认为预应力会受到岩体自身性质和外部自然环境双重因素的影响。
[Abstract]:In practical engineering, the engineering rock mass is subjected to many constraints. For example, when the bolt is inside the rock mass, the rock mass around the anchor rod will be restrained when the slope is supported. Engineering practice shows that slope collapse and other disasters often occur in these treated slopes, indicating that the nature of the treated slope rock is changing under the natural environment. Therefore, the confined rock mass is taken as the research object in this paper. It is of great practical and theoretical significance to explore the variation of its physical and mechanical properties under the action of dry-wet cycle, which provides the theoretical basis for the design, construction and safe operation of rock mass engineering. This paper is based on three main experiments, one is the physical characteristic experiment of the confined muddy dolomite, the other is the mechanical characteristic experiment of the confined muddy dolomite under the action of dry-wet cycle, and the third is the observation test of the prestress loss. Seven groups of rock samples were taken for indoor dry and wet cycle tests under the condition of saturated water. The water saturation and drying were 1 cycle for 12 hours each, and the total cycle was 30 cycles. During the cycle, the appearance changes of rock samples are recorded, and the physical characteristic parameters such as mass and longitudinal wave velocity are tracked, and the uniaxial compression tests are carried out for each additional five cycles. The uniaxial compressive strength, elastic modulus and Poisson's ratio of rock samples are obtained, and the variation of physical and mechanical parameters of muddy dolomite under dry and wet cycles is obtained. The observation test of prestress loss is one of the main innovations in this paper. In this experiment, a method of imposing constraint on rock mass is simulated. Two square steel plates with 10mm thickness were placed at both ends of the specimen. The plates were connected by four high strength screws and the applied stress was changed by adjusting the fastening of bolts. The dry-wet cycle test was carried out on the rock samples with constraints. Strain gauges were attached to the screw, and the strain of the screw was collected by the DH3816N static strain testing system produced by Jiangsu Donghua testing Technology Co., Ltd. Thus, the attenuation law of prestress is explored. The test results show that the muddy dolomite has obvious damage deterioration phenomenon under the action of dry and wet cycle. The longitudinal wave velocity, uniaxial compressive strength and elastic modulus of the rock sample show an obvious downward trend. The prestress loss of confined rock mass shows obvious regularity, that is, the loss of initial and end stages of cycle is obvious, and the change of middle section is relatively small. This paper makes a preliminary analysis and discussion on this regularity. It is considered that the prestress will be affected by both the nature of rock mass and the external natural environment.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU452

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