双速度法在铁塔基础结构完整性检测中的应用研究

低应变法广泛应用于新建的桩基完整性检测。然而,针对铁塔桩基这种桩顶非自由情况的现役桩基,低应变法已经不能对基础结构的完整性进行准确地判断。在低应变法的基础上,提出了双速度方法,即通过排除次生应力波干扰,解析出只含有桩基信息的上行应力波,从而对桩基的完整性进行判断。主要通过茂名地区输电铁塔桩基的现场测量,对双速度法检测输电铁塔桩基的可靠性进行验证。结果表明:1)上行波可以用于铁塔基础结构的完整性检测;2)茂名地区港茂甲乙线铁塔基础结构的完整性较好。

Application of the double velocity method for the integrated detection of the subsurface structures in the iron towers

Aiming at the non-destructive testing of the pile foundation of the iron transmission tower,this paper intends to propose a doubling speed method based on the low strain non-destructive testing one.As a testing method,it is a rare case in the paper on the non-destructive testing of the pile foundations of the transmission iron towers.Therefore,the feasibility of the doubling speed method for detecting the pile foundation of the transmission iron tower has been illustrated through a theoretical analysis formula derivation.And,then,the pile foundation has been made simplified to a one-dimensional rod via the doubling speed method.According to the mono-dimensional stress wave theory,it is possible to judge the integrity of the pile foundation by the phase change of the reflected waves.That is to say,when the pile foundation has to be detected by the doubling speed method,it would be necessary to instal 2 acceleration sensors on the pile body,with one of the two being put at the top of the other pile body but with the other being put on its side.And,then,the vertical excitation method has to be given to the top of the pile body,while the pile foundation taken as an entity is expected to generate the stress waves,which may propagate along the pile body.Finally,the stress wave signals obtained by the 2 acceleration sensors can be processed to eliminate the interference of the secondary stress waves,with the upward stress waves keeping up merely the pile foundation information separated.And,then,the upward stress wave can help to assess the integrity of the pile foundation.Furthermore,the reliability of the pile foundation of the transmission iron tower can be tested and verified by the onsite measurement of the transmission tower pile foundation in Maoming area by the double speed method itself.The results of our investigation and examination prove that the upward waves can be used to detect the integrity of the tower infrastructure information whereas the structural integrity of the pile foundation of the transmission iron tower of the Gangmao a-b line in Maoming area prove to be more advantageous than the other equivalents.