考虑各向异性的压实膨胀土细观膨胀力模型及其验证

If the swelling pressure of compacted expansive soils is too big, it will cause unfavorable consequence to restraint. Moreover, the values of swelling pressure in different orientation are various because of the microstructure of soils. So it is necessary to further study the generation mechanism and the action law of swelling pressure. According to the anisotropic of swelling pressure of expansive soils, in local project, a swelling pressure model for the compacted expansive soils will be built, which could describe the influences of microscopic swelling of montmorillonite particles and the microstructure of soils on the macroscopic anisotropic. Based on the micromechanical mechanics of composite materials, the soils are regarded as the composite materials. Then the montmorillonite particles have the same direction are treated as one phase of inclusion. Consequently, the swelling pressure at the boundary produced by the single inclusion will be calculated by the application of characteristic strain theory. Furthermore, the total swelling pressure of expansive soils will be obtained in the help of probability density function of exponential distribution， which pulsing the boundary pressure generated by all the inclusions. Finally the two-dimensional swelling pressure experiments will be made to verify the model. The research of this project is helpful to reveal the swelling mechanism and to grasp the swelling laws of expansive soils, and also can provide references for the treatment of expansive soils and can introduce new idea for the theoretical study of expansive soils. So it has important engineering significances and theoretical values.

压实膨胀土吸水后产生的膨胀力如若过大，将会对外界约束造成不利后果，而且由于细观结构的影响，各向膨胀力大小会有所差异，因此有必要深入研究膨胀力产生的细观机理及作用规律。本项目针对膨胀土膨胀力的各向异性，以压实膨胀土为研究对象，拟建立膨胀力模型，用以描述蒙脱石颗粒细观膨胀、土体细观结构对宏观膨胀力各向异性的影响。基于复合材料细观力学，将土体视为复合材料，取向相同的蒙脱石颗粒作为一相夹杂，运用本征应变理论求得单相夹杂在土体边界产生的膨胀力；引入指数分布的概率密度函数，将各单相夹杂产生的膨胀力进行求和即可得土体膨胀力；开展二维膨胀力试验研究，对所建模型进行验证。本项目的研究将有助于揭示膨胀土的膨胀机理、准确掌握膨胀规律，为处理工程中的膨胀土问题提供参考，为膨胀土理论研究提供新的思路，具有重要的工程意义及理论价值。

压实膨胀土吸水后产生的膨胀力如若过大，将会对外界约束造成不利后果，而且由于细观结构的影响，各向膨胀力大小会有所差异，因此有必要深入研究膨胀力产生的细观机理及作用规律。蒙脱石颗粒晶层膨胀是膨胀土产生膨胀的根本原因，首先建立了蒙脱石晶层膨胀阶段的经验公式，该公式避免了计算晶层间各种复杂的水合力及静电力。其次针对膨胀土膨胀力的各向异性建立了细观膨胀力模型，该模型以压实膨胀土为研究对象，基于复合材料细观力学，将土体视为复合材料，取向相同的蒙脱石颗粒作为一相夹杂，运用本征应变理论求得单相夹杂在土体边界产生的膨胀力；引入指数分布的概率密度函数，将各单相夹杂产生的膨胀力进行求和即可得土体膨胀力。开展了膨胀土一维及常规三轴膨胀试验，并建立了宏观尺度的三轴膨胀经验公式。自行设计了可测二维膨胀力及膨胀变形的膨胀土二维膨胀仪，并已获实用新型专利。本项目的研究有助于揭示膨胀土的膨胀机理、准确掌握膨胀规律，为处理工程中的膨胀土问题提供参考，为膨胀土理论研究提供新的思路，具有重要的工程意义及理论价值。