| It has become a very urgent technical problem that the skid resistance of asphalt pavement in Road Engineering. But the key to skid problem is contact characteristics of tires and rough surface. When the microscopic structure contacts with the tire rubber, it is adhesive friction that occurs between the top of asperity smooth and tread rubber, it offers about 90% of the tire and the road surface friction throughout. Therefore, by studying the characteristic and performance of the common tire pavement contact surface and the actual effect of the sub micro scope, to find out the actual contact surface texture and structural features of the contact area and pressure distribution, so as to find out the influence of pavement skid fundamental factors of friction, to improve the anti slide pavement safety objective.Starting from the material tribology、the surface contact mechanism between tire and road, research focus on the microscopic and submicroscopic behavior. Through using the two innovative analytical methods which includes pressure-sensitive film and laser texture measuring, it is common asphalt pavement surface characteristics that were statistically analyzed, and then evaluation and design-related were compared with conventional skid performance testing methods to verify. In the study of aspects related to decay mechanism for skid resistance of asphalt mixture, this paper firstly used self-developed simulation-based asphalt pavement traffic load pattern tester tire rub, with rubbing at different times for different gradations specimens skid performance evaluation, in order to obtain the desired skid asphalt mixture gradation design. The study can significantly improve the conventional asphalt pavement skid surface backward situation of over-reliance on experience, and science design of asphalt pavement skid resistance, so as to improve road traffic safety. The main processes and innovations of this dissertation are as follows:1. In order to explore the interface of the pressure distribution characteristics between the tire and the road surface and skid resistance of the road surface on the contact characteristics, The study used the prescale pressure-sensitive film in high accuracy (0.016mm2), designed the skid evaluation test of tires and asphalt pavement in different contact states to obtain the tire/road real pressure distribution in the contact interface, combined with MATLAB program implements the visualization of contact surface pressure distribution. Given the pressure limitations and the range of tire contact pressure values in the pressure range of film distribution, the author designed the test methods for the joint analysis of the film, which is selected LLLW type and LLW type of the pressure film at the same time, the pressure film of LLLW type can be detected [0,0.6] MPa pressure distribution range, and LLW type can be detected [0.6,3.06] MPa pressure distribution range, so that it is the skid resistance of contact surface between the actual tire and road that was fully satisfied.2. Combined with effective area of stress concentration and stress distribution, stress concentration ratio was proposed indicators to quantitatively describe the adhesive friction surface rough pavement structure asperity. Tests showed that the average ground pressure of asphalt pavement is 1.15 to 1.4 times of smooth steel contact pressure; increasing the proportion of coarse aggregate of larger than 4.75mm may increase the stress concentration rate, so as to effectively improve the adhesion friction of pavement skidding; when the skeleton wedging of grading 4.75 stall aggregate is about 30%,9.5 stall aggregate is about 35%, the aggregate skeleton will be more stable, the durability against sliding will be better.3. The researchers will R&D the three-dimensional laser texture analyzer in high-precision (0.001mm) to estimate the complicated degree of surface microscopic texture tortuous of aggregate particles, analysis showed that the peak angle laser profiler had obvious correlation with conventional test methods, the greater the peak angle, The wider and flatter the macro outline of pavement, the worse the skid resistance, on the contrary, the better the skid resistance. The peak angle of new pavement focused on 10°～30°ange, and effectively guarantee the basic rate of less than 90°n more than 70%. With the increase of rubbing time, dense suspension type AC-13 has outline peak maximum angle of decay, SMA-13 decay amplitude is small, which further validates not only regardless of the initial performance but also anti-skid sliding durability of SMA-13 are superior to AC-13. When the effective guaranteed rate (the percentage is less than outline peak angle of 90 degrees) of outline of the peak angle of asphalt pavement reaches more than 60%, asphalt mixture can provide adequate skid resistance.4. Under the different test stages rub, in order to reveal variation which include contact area and contact angle of Asphalt sliding layer as well as the surface within the depth of 2cm coarse aggregate particles in the rolling movement of the role, using digital image processing technology, aggregate particles were extracted from the surface within the depth of 2cm coarse, and along the longitudinal direction the angle was analyzed. Tests showed that SMA-13 of the skeleton fitted with sliding layer extrusion grade has more "upright" coarse aggregate number of states than AC-13 of the dense suspension skid type gradation, so as to get much better skid resistance performance. For the purposes of SMA-13 in the rub test, compaction and wear effects wheel led to stress concentration rate of decay, while sliding layer of coarse aggregate inclination irregularities affected the stress concentration changes monotony. The results showed that intermittent stall 2.36, an increase of 4.75 stalls aggregates can make SMA-13 asphalt mixture has better stability, better wedging effect which will help improve the overall stability of the skeletal structure, keeping skid road performance, further validates the above 4.75mm coarse aggregate can provide a more stable contact with the main skeleton. |
PDF Full Text Request