The Research Of Subgrade Moisture’s Distribution And Changing Regularity In Hot And Humid Areas

With the influence of climate, groundwater and roadbed drainage conditions, the subgrade moisture in hot and humid area will change over time and space, even the stiffness of the subgrade and pavement will be directly affected, etc. Thus it is very significant in hot and humid area that launching the moisture division situation, taking effective moisture stability control measures to control the change of subgrade moisture and providing a reference about subgrade soil moisture design.In this paper, the influence factors of subgrade moisture in hot and humid area are analyzed. Excavating the subgrade section, testing and analysing the subgrade moisture of the test section, and combining with the study of subgrade under the hard shoulder moisture, the distribution of subgrade moisture is relatively complete obtained. And fitting the plastic limit equilibrium moisture, the low liquid limit clay and sandy clay balance moisture forecasting formula is obtained..Through the long-term observation of subgrade moisture of subgrade soil, The moisture and temperature changes of subgrade soil internal are analyzed, the change laws of subgrade moisture and temperature is got. These provide a favorable prerequisite for the following works, such as the subgrade moisture simulation and stability of subgrade moisture control technology.The subgrade moisture to simulate the required parameters have been obtained by simulation testing and investigating the subgrade moisture parameter of the low liquid limit clay and sandy clay in hot and humid area. Whether to consider the effect of the soil water characteristic curve under the vertical stress when to simulate two kinds of soil moisture, had been comparatively and simulated analyzed. Finally it is concluded that considering the effect of the vertical stress is more in line with the actual. On this basis, the two subgrade models considering soil vertical stress of water characteristic curve were analyzed. Finally, took an overall consideration, there is a suggestion that considering the effect of vertical stress on the soil water characteristic curve when the subgrade moisture is simulated, and dividing the slope surface layering in parallel when dealing with the numerical modeling.Based on the analysis of the source of the subgrade moisture and the infiltration of moisture content, the method of control the subgrade moisture is obtained. With different properties tipping soil simulated analysis, it is concluded that the tipping soil of clay, which permeability coefficient is small, has good effects on the stability of the subgrade moisture control. Analysis of simulating different thickness of sand cushion layer, the result shows sand cushion layer has little effect on reducing the water level and the control of subgrade moisture stability in hot and humid area.