Study On The Distribution Characteristics Of The Stress Load Of Highway Subgrade In Arid Area Of Xinjiang

With in-depth implement of China’s Western Area Development Strategy and Silk Road Economic Zone Strategy, both of which contributed to rapid development of Xinjiang regional economy, traffic flow and axle load of Xinjiang Highway has changed fundamentally. What’s more, overloading phenomenon is becoming more and more serious. However, the asphalt pavement was designed in accordance with current theory and criteria that can not meet future traffic demand. Consequently, the pavement usually gets damaged before its service deadline. And road maintenance will be in need. Survey shows more than 70% of structure damage has close connection with subgrade deformation.Facing the trend of busy traffic flow and overloading in Xinjiang, to improve the instability of the subgrade disease, prolong the service life of the road, according to actual proportion of single lane road, we built an outdoor test cell model, containing 3 pavement structures: semi-rigid base, soft base, and composite pavement structure. Fiber Bragg grating pressure sensor were embedded in the different depth of each pavement structure to monitor the standard shaft of 100 KN, 150 KN, 200 KN, 250 KN, 300 KN in different conditions, and the test vehicle in the static load, dynamic load conditions under the condition of combination of vertical load stress in the subgrade compressive stress; bias conditions within the range of 0~2.2m to load the stress of transverse transfer distance. Analysis of static load of semi-rigid base, soft base, composite pavement structure, under the different load, vertical compressive stress variation along the depth of the subgrade. Different pavement structures, different load in the different load cases, the formation of traffic load in subgrade compressive stress transfer rule with depth is non-linear, the mathematical model of = a2+ + (0.9<R2<1), and obtained the fitting solution; in the same depth, the vertical compressive stress is a linear change with the load change, and speed on the vertical compressive stress is linear relationship; application of multivariate statistical analysis to establish the model of = a + + + , explored the effects of load, speed, depth of three factors on the stress of subgrade vertical pressure, through the significant test showed that, in the test cell impact factor ranking scheme is the depth, speed, load.Finally, using the BISAR3.0 software analysis the effects of the depth of Subgrade under different load stress, and the theoretical values are consistent with the observed results.