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通过对青藏饱和粉质黏土进行开放条件下的单向冻结试验,并结合土样冻结过程的图像数据,分析土样在单向冻结过程中冷生构造的发育和冻胀变形的发展规律,得到以下结论:试样冻结稳定所需时间为26 h左右,基本不受顶板温度变化的影响,但土样冻结后形成不同冷生构造带的位置及薄厚与土样顶板温度(顶底板温度梯度)密切相关,顶板温度越低,微薄层状和薄层状构造带的厚度越大,最暖端厚层冰透镜体以及未冻土部分整体状构造带的厚度越小。研究结果还表明,土样的冻胀变形经历了快速冻胀、稳定冻胀和线性冻胀3个阶段,其中线性冻胀阶段是冻胀发展最快的阶段,也是冰透镜体生长最快的阶段。研究成果揭示了土样单向冻结过程中冷生构造发育和冻胀发展的动态过程,为冻胀机制的认识以及冻胀模型的建立与验证提供了试验基础。
Based on the one-way freezing test of open saturated Qinghai-Tibetan silty clay and the image data of freezing process, the development of cold-accretion structure and the frost heave deformation during the unidirectional freezing process were analyzed. The following conclusions: The time required for the sample to freeze steadily is about 26 h, which is basically unaffected by the change of the roof temperature. However, the location and thickness of the different cold-formed tectonic belts and the roof temperature (top and bottom temperature gradient) Is closely related to the lower the roof temperature, the thinner the laminar and thin layer structure with the greater the thickness of the warmest end of the thick layer of ice lens body and the part of the whole frozen zone structure with less thickness. The results also show that the frost heave deformation of soil samples undergoes three stages: rapid frost heave, steady frost heave and linear frost heave. The linear frost heave stage is the fastest developing stage of frost heave and also the fastest ice body growth stage. The research results reveal the dynamic process of cold-accrete tectonics and frost heave during the unidirectional freezing process of soil samples, and provide experimental basis for the understanding of frost heave mechanism and the establishment and verification of frost heave model.