Vibration energy harvesting from tunnel invert-filling using rubberized concrete

With the increasing operation mileage of urban rail transit, to ensure its operation safety, it is necessary to carry out health monitoring on the rail, tunnel, and other structures. How to capture the vibration energy generated by train operation and use it to monitor the power supply of sensors has become a research hotspot in recent years. In this paper, a new type of spherical energy harvester is designed for rubberized concrete tunnel invert-filling. Based on the calculation model of rubberized concrete tunnel invert-filling under train load, the vertical displacement, stress, voltage, and total electric energy are analyzed. The main conclusions are as follows: (1) The spherical energy harvester is embedded in the rubberized concrete tunnel invert-filling in the form of an array, and the optimal position is 5 mm below the sleeper. (2) Ten energy harvesters are set up in the scope of a 6-m-long rubberized concrete tunnel invert-filling. The electric energy of the millijoule level can be generated when an A-type train of 8-vehicle formation passes by. If the departure interval of 5 min/trip is calculated, the total electric energy harvesting in 1 h is 122.4 mJ. (3) Rubberized concrete tunnel invert-filling is more conducive to energy harvesting than ordinary concrete tunnel invert-filling. When the content of rubber is 10%, the total electric energy harvesting by the energy harvester array inside the tunnel invert-filling is 5% higher than that of the ordinary concrete, and the mechanical performance indexes such as stress are within the safe range. The research results of this paper have reference value for further exploration of electric energy harvesting in the running environment of rail transit trains.