Pouring Pile Integrity Test Research Based On Optical Fiber Sensing Technology

Piles have many advantages,such as large diameter,high bearing capacity,no vibration when the construction of pile,the construction site noise,economic and reasonable.So in urban areas,building-intensive sites piles are widely used.But the pile construction process requires high,slightly inadvertently,there will be a variety of quality problems,so take an effective method to check the quality of the pile is essential.However,today's detection methods exist heavy equipment,high cost,large error,can not be fast,online,long-term monitoring and other issues.Distributed fiber-optic temperature measurement technology has a great advantage in the detection of pile foundation,and its small volume,light weight,high sensitivity,anti-electromagnetic interference,long-term,online real-time rapid distributed detection of pile quality,So much attention.In this paper,the principle and basic theory of the method of detecting the integrity of the pile foundation are introduced.Based on the existing research,the design of the wiring system of the detection system is discussed and studied.The experimental study on the influence range of the fiber is carried out.The field test of the pile integrity and the comparative study of the model test are carried out.Under the study results:(1)This paper briefly introduces the methods and problems of pile foundation detection and summarizes the research status of pile foundation detection technology and introduces the research status of distributed optical fiber temperature measurement technology and the advantages of optical fiber temperature measurement technology to test pile integrity.The basic principle and method are introduced.(2)Optimum design of fiber optic layout.The shortcomings of the model test and the field test in the early stage of the research group are analyzed.According to the one-dimensional radial heat conduction theory,the determinants of the critical radius of heat conduction and the characteristics of the thermal conduction temperature distribution are analyzed.The design of the wiring system of the detection system is discussed and studied.It is concluded that the fiber is "U" The radius is equal to half the radius of the pile.When laying out a number of fiber detection,to separate the interval of heating detection.(3)Model test study on the influence of fiber.According to the radial conduction theory of one-dimensional internal heat source,the theoretical formula of the critical radius of fiber heat conduction is deduced.The experimental results show that the critical radius has the conclusion that the heating power has a decisive effect on the critical radius,but the theoretical formula of the critical radius of optical fiber is calculated The results show that the theoretical formula is further modified and perfected,and further research will be done in the follow-up study.(4)Comparative study on field test and model test of filling pile integrity.Taking the bored pile of a project to study the integrity of the cast-in-place pile by heating the optical fiber.The experimental results show that the average stable temperature rise value of the field test is larger than the average stable temperature rise value of the model test under different heating power.A method of quantitative analysis of the mud content of the mud pile is put forward.