Accumulative deformation law and control of the compacted lateritic soil under the coupled action of wetting and dynamic loading

To address the problem that in-service lateritic soil subgrade is prone to wetting and excessive additional deformation under the combined effect of traffic loading in southern rainy areas of China. Static triaxial tests with different moisture contents and dynamic triaxial tests with different wetting times, wetting amplitudes, and dynamic stresses were conducted. The effect of varying moisture content on cohesive force and angle of internal friction were analyzed, the influence of dynamic stress amplitude, wetting number, and wetting amplitude on the accumulative deformation and dynamic resilience modulus were investigated, and a prediction model for accumulative deformation was established by considering dynamic stress amplitude, number and amplitude of wetting, and cohesive force and angle of internal friction. Based on the spectrum method, a transverse isotropic dynamic response model of lateritic soil was established, and the validity of the analytical model was verified by comparing with the results of the field vehicle test, and the law of vertical compressive strain on the top of subgrade was analyzed under effect of wetting and dynamic loading. The results show that the accumulative plastic strain increases nonlinearly with increasing wetting amplitude. The dynamic resilient modulus decreases with the initial moisture content and the wetting number. The vertical compressive strain on the top of subgrade increases approximately double after wetting three times. The empirical relationship between the vertical compressive strain on the top of subgrade and the accumulative strain is established, and the control value of accumulative strain is proposed in combination with the existing specification of the permissible value of accumulative deformation of subgrade, which gives the controlling method of the lateritic soil subgrade deformation. The proposed method is verified by the cement treated upper roadbed filler and the dynamic resilient modulus test in the test section of an expressway. The research results can provide reference for the design and service performance evaluation of durable subgrade in lateritic soil areas.