基于孔隙分布模型的垫层料冻胀变形规律探讨

垫层料冻胀变形过大会影响面板坝的正常使用，研究表明，垫层料冻胀变形量大小与其级配及孔隙分布有关。为了研究寒冷环境下垫层料冻胀变形机制和规律，基于土颗粒为理想球体且完全均匀分布的假定，提出了垫层料孔隙分布模型，确定了等效孔隙直径及等效孔隙数量的计算办法。利用单向固结仪，进行了不同孔隙尺寸和不同孔隙数量垫层料的冻融循环试验，冻胀试验结果表明：垫层料冻胀量大小随孔隙尺寸和孔隙数量变化而变化。存在一个临界孔隙尺寸，小于该尺寸的孔隙越小、小孔隙越多，冻胀量越大；反之，冻胀量越小。基于孔隙分布模型，构造定义了孔隙分布指数，发现垫层料冻胀变形量与孔隙分布指数呈线性正相关关系。研究结果可为工程设计确定合理的垫层料级配提供参考。

Discussion on frost heave deformation of cushion material based on pore distribution model

Concrete-faced-rockfill-dam (CFRD) cannot work properly if the cushion material has too much frost heave deformation. Recent researches have shown that: frost heave deformation of cushion material relates to its pore distribution and gradation. In order to reveal the mechanism of the frost heave of cushion material in cold environment, assumptions are adopted that soil particles are ideal spheres and their distribution is completely uniform, a pore distribution model of cushion material is put forward; and the methods are given for determining the equivalent pore diameter and equivalent pore number. Freeze-thaw cycling tests are carried out on one-way oedometer for different pore sizes and different pore quantities of cushion material. Laboratory frost heave tests results show that the frost heave deformation varies with the size and the quantity of the pore. There exists a critical pore size, when the pore is smaller than the critical size, the smaller the pore and the more the small pores, the greater the frost heave, and vice versa. Based on the proposed pore distribution model, a pore distribution index is defined; it is found to have linear positive correlation between the frost heave deformation of cushion material and this index. The results can be applied for the graduation design of cushion material.