桩基倾斜度对低应变反射波法割桩损伤的影响

低应变反射波法用于已建高桩码头的桩身结构完整性检测时,需要割桩设置传感器和激振两个平台,因而对桩身产生一定损伤。运用大型通用有限元软件ANSYS对比了不同倾斜度桩基在完好状态和检测状态下桩身应力的变化,分析了有割桩损伤侧桩身应力集中程度。结果表明:割桩损伤会导致割桩处出现应力集中,其影响范围主要在割桩处1.0 m之内,桩身受力最不利截面从桩基与横梁联接处移至割桩平台处。割桩处的应力集中程度与桩基的倾斜度相关:正斜桩应力集中程度最高,直桩次之,反斜桩应力集中程度最低。因此,对于以船舶撞击力为控制荷载的高桩码头,在低应变检测桩数目的前提下可增大抽检桩中反斜桩的比例。低应变检测桩基后应对割桩处1.0 m范围内进行修补,以确保桩基水平承载性能。

Effects of pile inclination on pile cutting damage by low strain reflected wave method

When applying a low strain reflected wave method to the high-pile wharf in service life, two platforms are cut in the pile in order to set up the sensor and excitation, thus a certain damage to the pile can be created. Based on a finite element software ANSYS, this paper compares the stress change of piles with different inclination when piles are in good conditions and detecting conditions. It also makes analyses of the degree of stress concentration in the cut side. Analysis results show that the pile cutting damage can lead to the stress concentration at the cutoff, and the impact range of cutting is mainly close to the cutting of 1.0 m. The most disadvantaged section of the pile moves from the connection of the pile with the beam at the top of the pile to the cut platform. The stress concentration is related to the pile inclination. The highest stress concentration occurs in the battered pile, then the vertical pile, and finally the backslash pile. Therefore in the case of the high-pile wharf where the impact force given by ships is taken as a control load, the proportion of backslash piles to be detected can be increased under the conditions of the low strain detection. The range of 1.0 m to the cutting damage should be repaired in order to ensure the horizotal bearing capacity of the piles foundation. The research results can be taken as a reference for detection of the piles in high-pile wharfs.