摘要
对于既有工程桩,其顶面非裸露自由,常规低应变法难以有效检测其桩底深度,而旁孔透射波法则对此有着良好的应用前景。旁孔透射波法可以在桩侧采用竖向、斜向和水平横向敲击的激振方式。通过建立三维有限元模型,对既有工程桩在桩侧竖向、斜向下45°、水平向敲击下进行旁孔透射波法测试模拟分析。读取不同深度信号的首至波走时并进行分段线性拟合的结果表明:在桩侧竖向或斜向敲击时,主要是基于桩身一维P波信号进行分析;在桩侧水平向敲击时,应主要基于桩身的弯曲波信号进行测试。当地基土饱和时,桩身弯曲波波速与土的P波波速相差较小,采用现行的桩身和桩底土拟合直线交点法难以较为可靠地确定桩底深度,而采用在桩侧竖向或斜向敲击方式更为适宜。
For existing project pile with unexposed pile head, it is difficult to use the regular low- strain method to detect depth of the pile bottom. Parallel seismic （PS） method, however, has shown a great potential. PS method can be conducted by exciting the pile side vertically, oblique- ly, or horizontally. A three dimension （3D） finite element （FE） model was developed to model the procedures of the PS testing by use of lateral knock on the pile side surface vertically, ob- liquely at an angle of 45°, and horizontally, respectively. The travel time of first arrival ware at different depths were red and segmental linear fitting were carried out. The results show that by knock on the pile side surface vertically or obliquely at an angle of 45°, the testing is based on one dimensional P wave signal of the pile, whereas by knock on the pile side surface horizontally, the testing is based on flexural wave signal of the pile. As flexural wave velocity of the pile is close to the P wave velocity of the saturated soil, it is difficult to identify the initial pile bottom depth by the intersection of the two fitting lines. Vertical or oblique knock on the pile side is more suit- able.
出处
《防灾减灾工程学报》
CSCD
北大核心
2015年第2期180-185,共6页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(51178267)
交通运输部西部交通科技项目(20113182231390)资助
关键词
旁孔透射波法
既有桩
低应变检测
激振方式影响
parallel seismic test
existing pile
low strain deteetion
effect of exciting mode
