1, Road Quality Index (RQI)
Based on the analysis of the road driving quality index RQI= 10.5-0.75IRI of the experimental forest farm, the road conditions of the experimental forest farm were classified according to the driving quality evaluation standard. Where IRI=a+b*BI, where BI is the detection result of flatness detection equipment; A and b are calibration coefficients. In use, all localities can determine their values according to the actual calibration results. China's current specification "Code for On-site Inspection of Highway Subgrade Pavement (JTJO59-95)" stipulates that there are three methods for measuring pavement smoothness in China: 3m straightedge (TO93 1-95), continuous flatness meter (TO932-95) and vehicle-mounted bump integrator (to T0933-95). In this paper, according to the actual needs, the pavement smoothness of experimental forest farm is measured by continuous flatness instrument. RQI value range is 0~ 10, if there is a negative value, take 0; If the result is greater than 10, take 10.
2. Damage index
The experimental forest farm roads are graded by analyzing the damage index PCI=∑∑DPijkWij, where: c is the initial grading value, which is generally c =100; DPijk is a deduction system of type I injury, J severity and K range. Wij is a weight function when there are many kinds of damage types and severity. Different damage types and severity have different effects on pavement integrity (that is, its attenuation rate) and meeting the requirements of pavement use, so maintenance and reconstruction measures are not needed. It is difficult for the flagship to establish a clear quantitative relationship. Therefore, we can only use the method of combining subjective and objective (similar to the method used in driving quality evaluation) to determine the penalty system DPijk with different damage types, severity and scope. This paper can study the damage, severity, scope and density of pavement.
3. Anti-sliding performance evaluation
The most direct way to measure the anti-skid performance of pavement is to simulate the sliding friction or rolling friction state of wheel load on pavement, and to determine the relationship between friction force and test wheel pressure or test load at this time. The commonly used methods are braking distance method, wheel locking trailer method, eccentric wheel trailer method and simple pendulum instrument method. The evaluation index of anti-sliding performance is: lateral force coefficient (SFC)/ British pendulum value (BPN)
4、PQI
To evaluate the comprehensive service level of pavement, the pavement quality index PQI = S1XP1+S2XP 2+S3XP 3+S4XP 4 can be used. Among them, S 1, S2, S3 and S4 respectively represent the scores of pavement smoothness, damage condition, bearing capacity and skid resistance; P 1, P2, P3 and P4 respectively represent the weight values of pavement smoothness, damage, bearing capacity and skid resistance. This paper mainly uses the smoothness, damage and anti-skid ability of pavement.