滚石坡面碰撞破裂机理试验及数值模拟研究

发布时间：2018-06-02 01:16

本文选题：滚石 + 碰撞破裂机理　；参考：《浙江大学》2017年硕士论文

【摘要】：作为一种特殊的地质灾害,滚石灾害虽然规模较小,但是因其具有较大的突发性和不确定性,已经对国民经济和人民生命财产造成了巨大危害。开展滚石坡面碰撞研究对探究滚石坡面碰撞机理,分析滚石坡面碰撞破裂效应进而修正坡面碰撞模型有重大的意义。本文通过系统的坡面碰撞试验和数值模拟分析,探究了碰撞速度、滚石力学性质、碰撞角度和滚石尺寸对滚石碰撞破裂特征的影响,分析了滚石碰撞破裂条件下碰撞恢复系数的变化规律,主要内容和基本认识如下:(1)在文献调查的基础上,分析比较了各种岩石试样预损伤方法的优劣,提出高温加热的方法制备岩石试样,并通过一系列试验检验了高温损伤效果。试验表明:高温加热将导致花岗岩试样质量略微减小并产生不可逆的体积膨胀。花岗岩的单轴抗压强度、劈裂抗拉强度、弹性模量和纵波波速均随温度的升高而降低。一般在400℃以内,温度的影响较小;随着温度的升高,岩石性质损伤劣化程度加剧。综合比较各种力学参数,采用基于纵波波速的岩石完整性指标作为岩石试样损伤指标效果较好。(2)在自主研制的滚石碰撞系统上对不同特征的滚石试样进行一系列室内碰撞试验,详细分析了滚石力学性质、碰撞速度、入射角度和尺寸大小等因素耦合作用下的滚石坡面碰撞破裂机理,探讨了碰撞破裂对滚石运动特征的影响。结果表明:滚石力学性质和碰撞速度是控制滚石碰撞破裂的主要因素,滚石力学性质越差,碰撞速度越大,滚石碰撞越破碎。滚石破裂存在法向速度阈值,随着力学性质的劣化,破裂法向速度阈值减小。碰撞入射角对滚石碰撞破裂及能量恢复系数影响较大;碰撞破裂不但会引起滚石总的能量恢复系数减小,而且会造成个别碎块具有较大速度。(3)采用三维动力有限元软件LS-DYNA,对滚石坡面碰撞过程进行数值模拟分析,基于试验获得的滚石坡面碰撞破裂特征和结果,对数值模型及其参数进行调整与校验,结果表明:采用参数优化后的土/混凝土模型,可以较好的反映滚石碰撞破裂特征。滚石的抗拉强度对破裂特征影响较大,而坡面的结构形式、边界条件以及力学参数对滚石碰撞恢复系数有较大的影响。在此基础上,采用理想刚体坡面模型,进一步扩大了碰撞速度、滚石尺寸和力学性质等参数变化范围,研究了碰撞破裂对滚石运动特征的影响。数值模拟结果表明:滚石力学性质越差,滚石碰撞能量恢复系数越小;破裂前,碰撞恢复系数随碰撞速度的增大而略有减小,滚石碰撞破裂后,能量恢复系数急剧减小,碰撞速度大于某一值后,能量恢复系数平缓下降。
[Abstract]:As a special geological disaster, the rolling stone disaster, though small in scale, has caused great harm to the national economy and people's life and property because of its large unexpected and uncertainty. The research on the collision of rolling stone slope to explore the mechanism of the collision of rolling stone slope, analyze the impact and rupture effect of the rolling stone slope and then amend the slope surface The collision model is of great significance. In this paper, the impact velocity, the mechanical properties of the rolling stone, the impact angle and the rolling stone size have been investigated through the systematic slope impact test and numerical simulation analysis. The change law of the collision recovery coefficient under the conditions of the rolling stone collision and fracture is analyzed. The main contents and basic understanding are as follows. (1) (1) on the basis of the literature survey, the advantages and disadvantages of the pre damage methods of various rock samples were compared and compared, and the high temperature heating method was put forward to prepare the rock samples, and a series of tests were made to test the effect of high temperature damage. The uniaxial compressive strength, splitting tensile strength, modulus of elasticity and longitudinal wave velocity of the rock decreased with the increase of temperature. The temperature was less influenced by the temperature at 400 degrees C. With the increase of temperature, the deterioration degree of the rock properties was aggravated. The rock integrity index based on the longitudinal wave velocity was used as rock test. (2) a series of indoor collision tests are carried out on the rolling stones with different characteristics on the independently developed rolling stone collision system. The mechanism of the rolling stone collision and fracture mechanism under the coupling effect of the mechanical properties of the rolling stones, the velocity of the collision, the angle of incidence and the size of the rolling stones is analyzed in detail, and the collision rupture to the rolling stone is discussed. The results show that the mechanical properties of the rolling stones and the velocity of collision are the main factors to control the collision and rupture of the rolling stones. The worse the mechanical properties of the rolling stones, the greater the collision speed, the more crushing of the rolling stones. The fracture of the rolling stones has a normal velocity threshold, with the deterioration of the mechanical properties, the breaking method is reduced to the velocity threshold. The collision incidence angle has the impact on the rolling stone. The impact fracture and the energy recovery coefficient have great influence, and the collision rupture not only causes the reduction of the total energy recovery coefficient of the rolling stones, but also causes a large speed of the individual fragments. (3) the three-dimensional dynamic finite element software LS-DYNA is used to analyze the process of the rolling stone slope collision, and the fracture of the rolling rock slope based on the test is special. The results show that the numerical model and its parameters are adjusted and checked. The results show that the parameters optimized by the soil / concrete model can better reflect the fracture characteristics of the rolling stones. The tensile strength of the rolling stones has a great influence on the fracture characteristics, and the structural form of the slope, boundary conditions and the mechanical parameters have the coefficient of recovery of the rolling stone collision. On this basis, using the ideal rigid body slope model, the impact velocity, the rolling stone size and the mechanical properties are further expanded, and the impact of the collision rupture on the rolling stone motion characteristics is studied. The numerical simulation results show that the worse the mechanical properties of the rolling stones, the smaller the energy recovery coefficient of the rolling stone collision, and the collision before the collision. The recovery coefficient decreases slightly with the increase of the collision speed. After the rolling stone collision, the energy recovery coefficient decreases sharply. After the collision speed is greater than a certain value, the energy recovery coefficient decreases slowly.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

【参考文献】