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在软土地基上修建低路堤时,软土地基经常会出现失稳、变形过大等问题,从而造成路面开裂,在此情况下通常会通过修建人工硬壳层对软基进行处治。目前,对于软土地基人工硬壳层相应的设计参数和处治方法并未进行深入的研究,且大部分处理方法都是通过工程实践和室内试验总结得到的。为优化用于处治软土路基的人工硬壳层设计方案,并提出软土地基上人工硬壳层设计参数的推荐取值范围,首先利用有限元软件ABAQUS在基于大、小变形理论基础上建立软土地基上路基路面有限元模型,对比分析软土地基模型对计算结果的影响程度,选定能够合理模拟软土地基的有限元模型;然后分析人工硬壳层的模量、厚度、宽度等参数对软土地基和路面力学响应的影响;最后推荐软土地基上人工硬壳层设计参数的合理取值范围。研究结果表明:含人工硬壳层软基上修建低路堤后,主要有软基整体承载力不足导致的剪切破坏、软基沉降变形过大和路基当量模量过低引起的路面提前开裂3种破坏形式;与扩展的Drucker-Prager模型相比,基于大变形理论的多孔介质弹性模型在模拟软土地基时表面沉降增大45.1%,附加应力降低4.9%,采用大变形理论模拟软土地基更合理;硬壳层的模量、厚度和宽度在一定范围内变化时,随着其数值的增加,软土地基的应力和位移逐渐降低,路面承受的附加应力逐渐增大;推荐软土地基上人工硬壳层的设计模量为150~300 MPa,处治深度为1~2m,每侧宽度比路基边坡增加1m。
When constructing low embankments on soft soil foundation, the problems of soft soil foundation such as instability and excessive deformation often occur, resulting in cracking of the pavement. In this case, the soft foundation is usually treated through the construction of artificial hard shell. At present, the corresponding design parameters and treatment methods for artificial crust in soft ground are not studied in depth, and most of the treatment methods are obtained through engineering practice and laboratory tests. In order to optimize the design scheme of artificial hard shell for treating soft soil roadbed and to propose the recommended value range of artificial hard shell design parameters on soft soil foundation, firstly, the finite element software ABAQUS was used to establish the artificial hard shell based on the theory of large and small deformation The finite element model of roadbed and pavement on soft soil foundation is contrasted and analyzed, and the influence of soft soil foundation model on the calculation results is contrasted and analyzed. The finite element model which can simulate the soft soil foundation is selected reasonably. Then the modulus, thickness and width of the artificial hard shell are analyzed. The influence of parameters on the dynamic response of soft soil foundation and pavement; Finally, reasonable design range of artificial hard shell design parameters on soft soil foundation is recommended. The results show that: after the construction of low embankment with artificial crust soft foundation, there are mainly three kinds of pre-cracking caused by the insufficient settlement of the soft foundation due to the insufficient overall bearing capacity, the excessive settlement of the soft foundation settlement and the too low equivalent moduli of the subgrade, Compared with the extended Drucker-Prager model, the elastic deformation of porous media model based on large deformation theory increases the surface settlement by 45.1% and the additional stress by 4.9% when simulating soft soil foundation, and simulates the deformation of soft soil foundation by using large deformation theory When the modulus, thickness and width of the hard shell change within a certain range, the stress and displacement of the soft ground gradually decrease with the increase of the numerical value, and the additional stress on the pavement increases gradually. The designed modulus of the artificial crust is 150-300 MPa and the treatment depth is 1-2 m, and the width of each side is increased by 1 m compared with the slope of the embankment.