轴向静应力对一维弹性杆中入射波的影响研究
本文选题:轴向静应力 + 波长 ; 参考:《江西理工大学》2015年硕士论文
【摘要】:近年来,针对地震频繁发生和爆破拆除建(构)筑物和开挖各类地下岩土体工程的实际,为了达到防灾减灾和安全高效施工的目的,应力波在各类岩土体或混凝土介质中的传播特性一直是研究的热点领域之一。爆破应力波在地下岩体中传播时,距震源不同距离的围岩已具有大小不等的静应力,这主要有以下两方面引起的:一是原岩应力大小本身随空间的变化而变化;二是地下工程岩体开挖卸荷导致附近围岩体中的应力场发生较大变化。针对此工程背景,本文提出研究轴向静应力对入射应力波的影响,首先分析了轴向均匀静应力对入射半正弦波的振幅、角频率和波初相的影响规律;接着分析了轴向均匀静应力对应力波畸变的影响;最后将变化的初始应力简化为线性梯度载荷,研究梯度应力对弹性杆中应力波幅值、波长的影响。主要研究内容与结论如下:(1)通过理论推导,研究了弹性杆中轴向均匀静应力的大小与入射半正弦波的振幅、角频率、初相的关系。当冲头以相同的速度共轴撞击具有轴向均匀静应力的弹性杆时,轴向均匀静应力的大小影响入射半正弦波的角频率,随着轴向均匀静应力的增大,入射半正弦波的角频率逐渐的增大;轴向均匀静应力的大小影响入射半正弦波的初相,轴向均匀静应力越大,入射正弦波的初相的绝对值越大,但增量很小,表现为起跳点越滞后。(2)针对在实验中获得的入射波在卸载段出现负值(“翘起”)情况进行了简要分析,研究了轴向均匀静应力对透射波波长、幅值的影响。轴向均匀静应力使得入射波在卸载段时出现应力不平衡,使得入射杆中质点反向振动,从而出现“翘起”现象,且轴向均匀静应力越大,“翘起”值也越大,其值也为轴向均匀静应力的一半;轴向均匀静应力也会影响透射波的幅值,轴向均匀静应力越大,幅值越小;轴向均匀静应力还会影响透射波的波长,轴向均匀静应力越大,波长越小。(3)取均质圆杆中的单位长度进行受力分析,利用牛顿第二定律推导出在具有梯度应力细长杆中应力波的波动方程,通过行波法求解该波动方程的通解,并与无梯度应力波动方程的通解比较,可得:细长圆杆中的梯度应力影响应力波幅值,梯度应力越大,应力波的幅值衰减的越快,表现在应力波的幅值随着k的增大而减小;细长圆杆的弹性模量也会影响应力波幅值的衰减速度,在梯度应力不变的情况下,弹性模量越大,应力波幅值衰减的越慢;细长圆杆中的梯度应力还会影响应力波的波长,梯度应力越大,应力波的波长越小,表现在应力波的波长随着k的增大而减小。
[Abstract]:In recent years, in order to achieve the purpose of disaster prevention and mitigation and safe and efficient construction, in view of the frequent occurrence of earthquakes and blasting demolition of building (construction) and excavation of various underground rock and soil engineering, The propagation characteristics of stress waves in various rock, soil and concrete media have been one of the hot research fields. When the blasting stress wave propagates in the underground rock mass, the surrounding rock with different distance from the earthquake source already has the different static stress, which is mainly caused by the following two aspects: first, the original rock stress itself changes with the change of the space; Second, the stress field of surrounding rock mass in the surrounding rock is changed greatly by excavation and unloading of underground engineering rock mass. In view of this engineering background, the influence of axial static stress on incident stress wave is studied. Firstly, the influence of axial uniform static stress on the amplitude, angular frequency and initial phase of incident semi-sinusoidal wave is analyzed. Then the influence of axial uniform static stress on the distortion of force wave is analyzed and the change of initial stress is reduced to linear gradient load. The influence of gradient stress on the amplitude and wavelength of stress wave in elastic rod is studied. The main contents and conclusions are as follows: (1) by theoretical derivation, the relationship between the magnitude of axial uniform static stress and the amplitude, angular frequency and initial phase of the incident semi-sinusoidal wave is studied. When the punch impinges the elastic rod with uniform axial static stress at the same velocity, the magnitude of the axial uniform static stress affects the angular frequency of the incident half-sine wave, and increases with the increase of the axial uniform static stress. The angular frequency of the incident half-sine wave increases gradually, the magnitude of axial uniform static stress affects the initial phase of the incident half-sine wave, the greater the axial uniform static stress is, the greater the absolute value of the initial phase of the incident sine wave is, but the increment is very small. The effect of axial uniform static stress on the length and amplitude of transmission wave is studied. The axial uniform static stress makes the incident wave unbalance in the unloading section, which causes the reverse vibration of the particle in the incident rod, thus the phenomenon of "warping" occurs, and the greater the axial uniform static stress, the greater the "warp" value. The axial uniform static stress also affects the amplitude of the transmission wave, the larger the axial uniform static stress, the smaller the amplitude, and the greater the axial uniform static stress will affect the wavelength of the transmission wave, the greater the axial uniform static stress. The smaller the wavelength is, the smaller the unit length of the circular rod is, and the second Newton's law is used to deduce the wave equation of the stress wave in the slender rod with gradient stress. The general solution of the wave equation is solved by the traveling wave method. Compared with the general solution of the non-gradient stress wave equation, it can be concluded that the gradient stress affects the amplitude of the stress wave in the slender circular rod. The larger the gradient stress, the faster the amplitude attenuation of the stress wave, which is shown in that the amplitude of the stress wave decreases with the increase of k; The elastic modulus of slender circular rod will also affect the attenuation speed of stress wave amplitude. The larger the elastic modulus is, the slower the attenuation of stress wave amplitude is, and the gradient stress in slender circular rod will also affect the wavelength of stress wave. The larger the gradient stress, the smaller the wavelength of the stress wave, which is manifested in that the wavelength of the stress wave decreases with the increase of k.
【学位授予单位】:江西理工大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:TU45
【参考文献】
相关期刊论文 前10条
1 喻军;刘松玉;童立元;;浅埋隧道爆破振动空洞效应[J];东南大学学报(自然科学版);2010年01期
2 聂建新;杨顶辉;巴晶;;含泥质低孔渗各向异性黏弹性介质中的波频散和衰减研究[J];地球物理学报;2010年02期
3 俞缙;钱七虎;宋博学;赵晓豹;李晓昭;;不同应力波穿过多条非线性变形节理时的透射特性[J];工程力学;2012年04期
4 金解放;李夕兵;尹土兵;周学进;;轴向冲击下弹性杆中轴向静载对入射波的影响[J];工程力学;2013年11期
5 巫绪涛,胡时胜,杨伯源,董钢;SHPB技术研究混凝土动态力学性能存在的问题和改进[J];合肥工业大学学报(自然科学版);2004年01期
6 房士波;;新羊石隧道坍方处理施工技术[J];铁道建筑;2007年09期
7 李夕兵;周子龙;叶州元;马春德;赵伏军;左宇军;洪亮;;岩石动静组合加载力学特性研究[J];岩石力学与工程学报;2008年07期
8 巩思园;窦林名;何江;贺虎;陆菜平;牟宗龙;;深部冲击倾向煤岩循环加卸载的纵波波速与应力关系试验研究[J];岩土力学;2012年01期
9 殷志强;李夕兵;金解放;贺显群;杜坤;;围压卸载下高应力岩石动力扰动的破坏特性(英文)[J];Transactions of Nonferrous Metals Society of China;2012年01期
10 李夕兵;姚金蕊;宫凤强;;硬岩金属矿山深部开采中的动力学问题[J];中国有色金属学报;2011年10期
相关硕士学位论文 前1条
1 刘涛;岩石在静应力状态下的循环冲击实验及损伤特性研究[D];中南大学;2013年
,本文编号:1926565
本文链接:https://www.wllwen.com/kejilunwen/diqiudizhi/1926565.html