1. The introduction of dynamic truck scale

1.1 Type:

At present, we can see that there are four main types of dynamic electronic truck scales: complete vehicle type, axle weight type, bending plate type and quartz crystal type. Only when the “complete vehicle type” is weighing, the whole vehicle stays on the carrier, while when “axle weight type”, “bending plate type” and “quartz crystal type” are weighed, most of the vehicle stays on both sides of the road surface at both ends of the load carrier.

1.2 Characteristic

1) It is necessary to get various weights of the vehicle by measuring the vehicle through a carrier installed in the road surface of the vehicle information;

2) The weight information obtained is different due to the different structure of the various scale carriers;

3) For now, since various scale carriers are installed in highway pavement, the composition characteristics of highway pavement determine the performance indicators of the scale;

4) The whole vehicle type and axle load type are relatively stable compared to their performance indicators due to the installation on the recast reinforced concrete foundation;

5) The bending plate type and the quartz crystal type are installed directly on the road surface, and there is no special modification to the road surface.the performance varies greatly, especially for the asphalt concrete road.

2. The cause of the problem

2.1 Pavement structure

The pavement structure layer generally consists of a surface layer, a base layer and a cushion layer. The asphalt concrete pavement may further divide the surface layer into a wear layer, an upper layer of the surface layer, a lower layer of the surface layer, and a joint layer as needed; the base layer may also be divided into an upper base layer and a base layer. The surface layer may consist of one or several layers, the cement concrete surface layer usually consists of a single layer, and the asphalt concrete surface layer often consists of several layers. The asphalt concrete surface layer of the high-grade road is a combination of the reinforcing surface layer and the base layer.

2.2 Pavement quality requirements

For asphalt concrete pavement, the quality of the pavement is required to form the thickness, width, transverse slope and flatness of the contours of each layer of the pavement, and whether the inherent material composition ratio, compaction degree, deflection value, etc. are within the allowable deviation.

For the scales installed on the expressway, the indicator that affects the weighing performance is mainly the “bending value”.

Deflection value: The deformation of the subgrade/road surface before and after the load on the subgrade/road surface, using 1/100 mm as the calculation unit.

The “bending value” is measured by a vehicle with a certain axle load (usually with a rear axle load of 6 tons or 10 tons of vehicles) on a certain section, before and after the action on the roadbed/road surface. A weighted average of the amount of deformation. Calculating the deflection value has a direct relationship with the design strength of the subgrade/road surface. The smaller the calculation of the deflection value, the higher the strength. The deflection value reflects the overall strength of each level of the road surface as a whole, and the strength of the roadbed is generally reflected by the rebound modulus. If the deflection value is too large, the deformation will be larger, and the layers on the road surface will be easily broken.

The “bending value” is too large, and the reason is generally related to the material properties, thickness, integrity (whether or not), compactness, etc. of each layer of the pavement, and is also related to climatic conditions, and the rainy season will be too large.

The "bending value" is related to the pavement structure, to the composition of the pavement material, to the load of the detected vehicle, and to the detection of the tire pressure of the vehicle. The smaller the "bending value", the better. In theory, zero deflection will never produce a rut. The larger the “bending value”, the less the road quality is suitable for the installation of related weighing