Vehicle Weigh-In-Motion Technology Research Based On Piezoelectric Smart Pavement

With the gradual formation of expressway network and rapid development of transportation, vehicle overloading is increasing and already become a widespread social problem in China. Vehicle Weigh-in-Motion (W1M) technology gradually plays more and more important role in traffic management and the tendency of replacing the static weighing technology is visible. Although the existing sensors adopted by vehicle WIM system have excellent dynamic performance, high accuracy and preferable durability, they are hard to be widely used in our county’s highway network, especially in the lower level of roads and bridges for their high cost of application and maintenance as well as technical complexity. In this paper, a vehicle WIM technology based on piezoelectric smart pavement is proposed. The technology has the characteristics of low cost, easy to implement. Based on principle of piezoelectric, arrays of compressive stress sensors-smart aggregates(SA for short)made by piezoelectric ceramic piece, epoxy and marble are installed in surface layer of pavement. Then, self-sensing pavement embedded with arrays of smart aggregates has a great potential for detection and measurement of the dynamic vehicle’s axle weight. The following is studied in this paper.(1) Based on measurement principle of SA, the feasibility of SA used for dynamic load monitoring is analyzed.(2) The dynamic mechanical properties for a single SA embedded in the asphalt concrete (AC for short) are studied seriously. The cyclic stress is applied on an AC block embedded a piece of SA by a servo-hydraulic machine. During the loading, a variety of frequencies is used to consider the vehicle speed variation. The SA sensitivity in the given boundary condition is obtained and the influence of the loading rate on the sensitivity is studied. The finite element (FE) model of the AC block embedding the SA is established with the real boundary condition of the loading test. The stress distribution in SA is analyzed and the SA sensitivity is obtained based on the numerical method. The influence of the AC Young’s modulus variation on its sensitivity is studied through the numerical simulation approach.(3) Piezoelectric smart pavement made by arrays of SA is used for on-site measurement of vehicle’s wheel load. The response of SA array in different structure layers of pavement under vehicle load is respectively explored, characteristics of the stress signal of each channel of SA are analyzed, when different axle loads and different types of vehicles crossed over them; Changing range of sensitivity of each channel’s SA under different vehicles" speed is compared. The FE model is made to check the result; The gross vehicle weight algorithm is explored, and preliminary estimation has been carried on.