Abstract
Sensors of stress or strain currently used in geotechnical and civil engineering applications have the disadvantage that a large quantity of measuring points would result in large bundles of cables. Based on the principle of resistive strain gauge, a type of smart sensor that supports serial communication over RS-485 is developed for the measurement of strain or stress of foundation piles, which has the benefit of good noise tolerance. All the sensors installed along a pile could share a common cable for power supply and communication, and there is no actual limits to pile length. The installation in the field is simple, convenient and efficient. The sensor has a compact structure with reliable waterproof protection. The internal measurement circuit mainly consists of a Wheatstone bridge excitation module, a signal conditioning module, a microcontroller with ADC, a precision voltage reference, and a RS-485 communication module. A group of sensors were calibrated after being assembled, and the calibration results obtained have shown their functionality and reliability.
Highlights
Among all the assessment testing methods of deep foundations used in geotechnical investigation, the static load testing is an in situ testing method widely used to evaluate the quality and bearing capacity of foundation piles
The sensor consists of a shell, a Wheatstone bridge of four resistive strain gauges, a bridge excitation module, a signal conditioning module, a precision voltage reference, a microcontroller and a RS-485 communication module
The strain sensor consists of a sensing element, and data acquisition and processing capabilities provided by a microcontroller
Summary
Among all the assessment testing methods of deep foundations used in geotechnical investigation, the static load testing is an in situ testing method widely used to evaluate the quality and bearing capacity of foundation piles. Vibrating wire strain gauges have been used in geotechnical and civil engineering applications[1,2,3]. Widely used sensors of stress or strain have some disadvantages. A large quantity of measuring points of stress or strain could result in large bundles of cables, and make the installation and the data acquisition more difficult and less efficient, or even damage the integrity of the pile[7]. The proposed axial smart strain sensor features simple structure, easy installation and convenience for testing. The sensor consists of a shell, a Wheatstone bridge of four resistive strain gauges, a bridge excitation module, a signal conditioning module, a precision voltage reference, a microcontroller and a RS-485 communication module. The calibration of a group of strain sensors was carried out in the laboratory environment for the verification of their functionality and reliability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
