The Research And Development Of A Portable Pile Integrety Decting Instrument

In recent years, with the domestic infrastructure construction being underway vigorously,the detection of the quality of construction has been particularly important. Pile foundation, as an important part of the basic building form, is widely used in large plants, buildings, ports and bridge engineering. Pile foundation has a variety of forms in which the bored concrete pile is the most frequently used form, especially for the large-scaled engineering.Because the construction work of pile foundation itself is conducted invisibly and is quite easy to be affected by some factors like terrain environment, construction conditions, the quality problems of pile itself and the consequential potential safety problems will probably emerge.Therefore, it is pretty important to design a detector which enables to detect the completeness of pile quickly and accurately.The most commonly used method for pile completeness testing is the low strain reflected wave method, which is based on the stress wave theory.Because the detector produced by the method is characterized by being convenient, reliable and economical, it has been widely used in the world. Based on the wave theory and the embedded system theory, in this paper, the author designs a set of portable pile foundation detection instrument with the features of low cost and easy operation. With 32 bit microcontroller, STM32F103 series as the main controller unit, the detector works by applying floating point amplifier technology to improve the data collection of dynamic magnification range in data acquisition.The author designs the testing system by making use of the favorable interactive environment in the touchable serial screen.When the instrument is connected with the acquired reflected wave of speed sensor, the data acquired will be displayed on the screen. The on-site staff can process the waveform through the serial port touchable screen operation, which assists the staff in making judgment for the pile.This paper first elaborates on the methods of pile foundation detection and the advantages and disadvantages, mainly focusing on the description of pile testing principle of low strain reflected wave method. Secondly, based on the functional requirements of detecting instrument, in this paper, the author designs the functional ingredients, working principle and realization scheme for the whole detection system.The testing hardware part is composed of data acquisition module, the main controller and the man-machine interface module.And the data acquisition module employs floating point amplifier technology wave form to be undistorted, at the same time, the main controller fulfills the task of controlling the data acquisition module and man-machine interaction module. As for software part, it is mainly developed by using STM32F103 database.Meanwhile, the author conducts detailed design for the initial equipment, serial screen driver, serial display interface, application function and the data acquisition module of the main control chip STM32F103.Finally, the detecting system is debugged and tested on the function with the findings that the system runs well, waveform displays clearly, and the expected design requirements has been met.The selected processor of detecting system is quite powerful in data processing with low power consumption, so it is especially suitable for portable devices with the various touchable screen interface functions and with the feature of easy operation.The on-site staff can complete the entire testing process just by touching a serial screen with the related functions.To sum up, the detector, being portable with a wide range of signal acquisition and various functions and easy operation, has a good application prospects and value.