摘要
钢花管是管棚超前支护中的核心承力构件.采用有限元仿真分析了低频纵向导波模态在钢花管中的传播特性和检测能力.建立带注浆小孔的钢花管中低频纵向导波模态传播的有限元模型.选取频率30kHz的L(0,2)模态用于钢花管检测.当注浆小孔直径为10mm时,孔数的变化对频率30kHz的L(0,2)模态第一次和第二次端面回波信号幅值影响较小.但随着孔数增加,该模态的群速度呈线性下降,每增加1个孔,该模态的群速度下降0.76m/s.研究孔数不变时孔径对频率30kHz的L(0,2)模态传播能力和传播速度的影响,结果显示孔径变化对该模态的能量传播影响较小.孔数和孔径对端面回波幅值影响较小,表明低频纵向超声导波具有对钢花管进行长距离检测的潜力.然而,随着孔径的增加,该模态的群速度也逐渐下降,但下降幅度不一致.研究结果为将低频纵向模态应用于钢花管结构的无损检测奠定了一定的基础.
Steel floral pipe is one of the key load-carrying components of advanced pipe supporting structures. Propagation characteristics and inspection potential of low frequency longitudinal guided wave modes in steel floral pipes were investigated by using finite element analysis. Finite element model of low frequency longitudinal guided wave mode propagation in steel floral pipe distributing small grouting holes was established. L(0, 2) mode at 30 kHz was optimized for the inspection of steel floral pipes. The change of hole number had no significant effect on the amplitudes of the first and second end-reflected echoes of L(0, 2) mode at 30 kHz when the diameter of small grouting hole was kept to be 10 mm. However, group velocity of this mode linearly decreases with the increase of the hole and to be 0.76 m/s with the increase of every hole. The effect of hole diameter on propagation velocity of longitudinal guided waves mode was also simulated when the hole number kept constant. It was shown that the change of hole diameter had limited effect on the energy propagation of this mode. Number and diameter of holes less affect to the amplitude of end-reflected echo. It was shown that low frequency longitudinal guided waves had potentials to inspect long range steel floral pipes nondestructively. However, with the increase of the hole diameter, group velocity of this mode will decrease gradually in varying degree. These simulation results provide a basic foundation for nondestructive inspection of steel floral pipes by using low frequency longitudinal guided wave modes.
出处
《应用基础与工程科学学报》
EI
CSCD
北大核心
2012年第5期930-939,共10页
Journal of Basic Science and Engineering
基金
国家自然科学基金项目(50975006
10772009
10972014)
NSFC-RGC联合资助项目(60831160523)
北京市自然科学基金项目(1122007)
北京市教委项目(KM201010005003)
关键词
钢花管
纵向导波模态
注浆小孔
孔径
数值仿真
Computer simulation
Concrete construction
Finite element method
Grouting
Inspection
Light velocity
Mortar
作者简介
吴斌(1962-),男,博士,教授.E-mail:wb@bjut.edu.cn;
