Lei-Yi Expressway Subgrade Condition And Its Impact On The Fatigue Life Of The Grassroots

In recent years, the research on the expressway subgrade condition and its impact on the fatigue life of the grassroots is an very important applied area in road engineering.Its purpose is to having a comprehensive and in-depth understanding of expressway subgrade conditions by studying engineering geology, climate, hydrology, traffic, road construction, load and other factors,based on which we can form a scientific and rational roadbed situation analysis method and having a comprehensive and in-depth understanding of expressway subgrade conditions;By analyzing the different loads under different conditions of soil resilient modulus of pavement subgrade layers bend each structural changes in tensile stress, establish the relationship between the flexural stress and fatigue life, and analyze the influence of load and subgrade resilient modulus and other elements on the fatigue life, to guide the treatment of high grade expressway.This article relies on the Lei-Yi expressway heavy maintance and takes the key research on the high grade expressway. According to the field test data and related research fruits, and combined with our current asphalt pavement design specifications and technical indicators, it analyzes the expressway subgrade resilient modulus decay and its impact on pavement and grass. The main research results are as follows:(1) By the loading plate test, we can see that when compared with normal sections, where there is pavement diseases, the grass-roots modulus attenuation degree is much greater than attenuation degree of surface modulus. It can be seen that the pavement disease relates great to the damage to the grass-roots or the overall strength reduction at the grass-roots level.(2)The NDT test results shows that the Lei-Yi expressway roadbed diseases are widely distributed, and disease epidemic period were mostly dominated by two or more diseases. From the testing data, the Lei-Yi expressway has such serious diseases that the grass-roots level is not dense, collapsed and with high water content, and the degree of attenuation of the soil base resilience modulus is greater in disease area.(3) By BISAR software calculation, it is found that the effect of the intensity on the soil base of asphalt pavement structural layers of of bottom stress is linear, and the load effect is very obvious. As the soil base resilience modulus decreases, the decrease of pavement fatigue life is great no matter under the influence of standard axle load or overload, while the attenuation amplitude is 20～40MPa, the fatigue life increases slowly, and after 20～40MPa, it increases rapidly. Only control the soil base resilience modulus at the proper level.can the roadbed suffers no early diseases or damages that affects the high grade expressway of the traffic capacity.