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湿陷性黄土地基渠道抗冻胀衬砌结构优化模拟

Structural Optimization Simulation of Frost Swell Resistant Lining for Channels with Wet Sinking Loess Foundation

  • 摘要: 由于西北地区衬砌渠道在冬季受冻胀土体挤压破坏发生渠道渗漏,加之湿陷性黄土遇水易下沉导致以湿陷性黄土为地基的衬砌渠道冻害情况复杂。针对这一问题,研究以宁夏固海灌区改造前后的东一支干渠为原型,通过分析渠道改造前后受冻胀破坏的劣化规律以及混凝土材料塑性损伤本构,建立了简化的渠道三相耦合数学模型。考虑湿陷性黄土力学特性和渠基土与衬砌板之间的接触行为,基于实测数据采用ABAQUS软件构建改造前后衬砌渠道热-力耦合数值模型,分别进行模拟并对比分析其冻胀的具体情况和变形规律。通过对比两个耦合模型模拟的3个物理场,结果表明:改造后的刚柔衬砌渠道冻害情况得到了大幅度的改善,在一定程度上避免了出现应力集中的情况;将改造前的现场数据与研究结果相比较,验证了数值耦合模型的准确性和可行性,模拟得出的热-力-位移3个物理场能够较好地反映实际衬砌渠道的冻胀机理,为灌区渠道冻胀破坏治理与改造设计提供参考。

     

    Abstract: As the lined channels in Northwest China are subject to frost heave soil extrusion damage in winter, coupled with the easy sinking of wet-submerged loess in water, the frost damage of lined channels with wet-submerged loess as foundation is complicated. To address this problem, this paper takes the East First Trunk Canal before and after the renovation of Ningxia Guhai Irrigation District as a prototype, and establishes a simplified three-phase coupled mathematical model of the channel by analyzing the deterioration law of the channel before and after the renovation by frost damage and the plastic damage structure of concrete material. Considering the mechanical properties of wet-submerged loess and the contact behavior between canal base soil and liner plate, the numerical model of thermal-force coupling of lined channels before and after renovation is constructed by ABAQUS software based on the measured data, and the specific situation and deformation law of frost swelling are simulated and analyzed in comparison. By comparing the three physical fields simulated by the two coupled models, the results show that the frost damage of the modified rigid-flexible lined channels has been substantially improved and the stress concentration has been avoided to a certain extent; comparing the field data before modification with the research results, the accuracy and feasibility of the numerical coupled model are verified, and the three physical fields of heat-force-displacement simulated can better reflect the frost swelling mechanism of the actual lined channels, which serves as a reference for the management and modification design of the frost damage of the irrigation channels.

     

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