基于双参数弹性地基梁理论的梯形渠道冻胀力学模型

为克服已有梯形渠道弹性地基梁模型未考虑土体连续性及需要预先假定切向冻结力分布的不足,该研究在Winkler模型的基础上,用土弹簧的伸缩来描述法向冻胀力与法向冻结力,引入剪切层和接触界面层构建了梯形渠道双参数冻土地基梁模型。通过引入剪切层考虑土弹簧间的相互作用,引入接触界面层把切向冻结力计算纳入模型中一体化求解。以甘肃省靖会总干渠梯形渠道为例,计算了衬砌板法向冻胀位移,并将计算值与Winkler模型、有限元法计算结果及试验值进行对比分析,最后对衬砌板各点切向位移及切向冻结力分布进行计算。结果表明：本文模型计算值与Winkler模型、有限元法计算结果的总体变化趋势一致,且关键点上与试验值更加符合,当剪切系数g=0时双参数模型则退化为Winkler模型,验证了模型合理性;衬砌板各点切向位移及切向冻结力呈非线性分布,且随切向刚度增大,各点切向位移总体呈减小趋势,与实际相符。本研究可为梯形渠道抗冻胀设计提供参考。

Frost-heaving mechanical model of concrete lining trapezoidal canal based on two-parameter elastic foundation beam theory

Abstract: An elastic foundation beam theory can be used to properly and effectively deal with the interaction between soil and structure. The theory application has also been gradually promoted in the frost-heaving mechanical analysis of frozen soil engineering structures in recent years. However, the existing Winkler model cannot consider the continuity of frozen soil. It is very necessary to presuppose the distribution of tangential freezing force. In this study, the governing differential equations were presented for the normal and tangential directions. The Pasternak shear layer was also introduced to connect the adjacent soil springs and contact interface layer between the frozen soil and concrete lining plate. Then, the frost-heaving mechanical model of the trapezoidal concrete lining canal was established using the two-parameter Pasternak elastic frozen soil foundation. The model was effectively connected with the SL23-2006"Specification for Design of Anti-freeze of Canal Engineering". The frost-heaving mechanical analysis was applied to the concrete lining canals with the deep groundwater table. The computational accuracy of the frost-heaving mechanical model was improved significantly, where the shear layer was introduced to describe the interaction between the Winkler soil springs. The distribution of tangential freezing force was incorporated into the elastic foundation beam theory through the introduction of the contact interface layer. As such, there was no need for an improved model for the distribution of tangential freezing force. Taking the trapezoidal main canal of the Jinghui irrigation area in Gansu Province of China as the prototype, the improved model was applied to calculate the normal frost-heaving displacement of each point on the concrete lining plate. A comparison was then made on the Winkler model, the finite element (FEM) and test values. The comparative analysis indicated that there was consistent overall variation and tendency in the presented model, Winkler model, and FEM simulation. The critical test points were set on the concrete lining plates. The two-parameter elastic foundation beam model was much more consistent with the test values than those in the Winkler model and FEM. Furthermore, the two-parameter elastic foundation beam model was reduced to the Winkler model, when the shearing factor of frozen soil g was equal to 0. These results demonstrated the rationality and reliability of the presented model. The presented model was also applied to calculate the tangential displace and tangential freezing force of each section of the concrete lining plate. A parameter analysis was then carried out for the tangential contact stiffness. Among them, different tangential contact stiffness was set as the contact surface layer between concrete lining plates and frozen soil. Consequently, there was a nonlinear distribution in the section tangential displace and tangential freezing force along the concrete lining plates. A general decreasing trend was found in the tangential displace of each section with the increment of tangential contact stiffness. The distribution of tangential freezing force showed that "when one side is relatively large, then the other side is small". In addition, there was a linear and uniform distribution of tangential freezing force, when the tangential contact stiffness was smaller. By contrast, the more nonlinear and non-uniform distribution was observed with the increase of tangential contact stiffness. The finding can provide a strong reference to designing the frost heave damage resistance of canals.