Failure Modes And Design Methods Of Hard Crust Reinforcement Under Traffic Load

Soft soil foundation is widely distributed in china, and a lot of methods is proposed todeal with it. Building artificial hard shell layer on the soft soil foundation is one of the mostcommon approaches. However, early damages occurred due to the uncertain using conditionsand the imperfect design method, which bring impact on the pavement performance.The hazards of moisture migration internal road structure and the importance of roadbedwaterproof were pointed out by introducing the influence of presence of water, water energystate and the moisture migration on roadbed, then the one-dimensional moisture diffusivityequation was used to study the influence of moisture migration on sudgrade modulus.Theextended Drucker-Prager model and porous media elastic model were used to simulate thesoft soil foundation and structure model were established. The influence of two models onsettlement of roads was analyzed. At last, the mechanical response of low embankmendtpavement with hard shell layer under traffic loads was analyzed.According to the review of research results of soft soil roadbed damages at home andabroad, several failure modes and the corresponding forecast models were proposed. A failuresurface of soft soil roadbed was proposed by analyzing failure models of soft soil roadbedunder roles of rigid roadbed. Then finite element model for soft soil roadbed damage undertraffic loads was established. The effects of different hard shell layer and subgrade modulus,thickness, on the damage of soft soil roadbed were studied with the model. At last, design andconstruction method of the technology using hard shell to deal with soft soil roadbed wereproposed.The research showed that the porous media elastic model was more accurate than thecommonly used extended Drucker-Prager model, which could reflect the characteristics ofsoft soil well. Destroy of soft soil roadbed with hard shell is mainly due to insufficientanti-shear. The best modulus of soft soil roadbed with hard shell rang from150MPa to300MPa, and the depth rang from1m to2m,The spray powder pile was proposed to deal withsoft foundation when the requirement still can not met with a dealed modulus was300MPaand depth was2m.