基于高分子复合材料改良砂土三轴剪切试验研究

为研究剑麻纤维和高分子固化剂复合改良对砂土工程特性影响，通过一系列三轴剪切试验，对不同掺量和长度的剑麻纤维与高分子固化剂改良砂土的剪切强度特性进行了研究，从峰值偏应力、应力应变曲线特征和抗剪强度参数等方面分别对改良机理进行了研究。研究结果表明，纯高分子固化剂改良砂土的峰值偏应力和黏聚力明显提升，由于固化剂粘结砂土颗粒，限制了变形过程中颗粒的相对滑动，内摩擦角略微降低。随纤维掺量的增加，不同围压下固化剂改良土体的峰值偏应力明显增加，应力硬化特征愈加明显，土体的黏聚力和内摩擦角随纤维掺量的增加保持单调递增趋势。在单纯添加固化剂的情况下，土体强度与固化剂浓度呈正相关的关系；在给定0.4%的纤维含量下，随着纤维长度的加长，纤维和高分子固化剂复合改良砂土的剪切强度先增强后降低；在纤维长度为18 mm时，土体的剪切强度达到最大，黏聚力达到最大207.57 kPa；纤维长度的改变对试样破坏时的轴向应变和土体的内摩擦角基本没有影响。

Triaxial shear test of sand improved by polymer composite

The effect of sisal fiber and polymer curing agent on the engineering properties of sandy soil is examined in this paper. Through a series of triaxial shear tests, the shear strength characteristics of sand improved by sisal fiber and polymer curing agent with different content and lengths are studied. The improvement mechanism is studied in terms of peak deviation stress, stress-strain curve characteristics and shear strength parameters. The results show that the peak deviating stress and cohesion of pure polymer curing agent improved sandy soil are obviously increased. Because the curing agent binds sand particles, the relative sliding of particles during deformation is limited, and the internal friction angle is slightly reduced. With the increasing fiber content, the peak deviation stress and stress hardening characteristics of the soil improved by curing agent increase obviously under different confining pressures. The cohesion and internal friction angle of the soil keep a monotonous increasing trend with the increasing fiber content. Given the fiber content of 0.4%, with the increasing fiber length, the shear strength of composite sand improved by fiber and polymer curing agent increases first and then decreases. When the fiber length is 18 mm, the shear strength of soil reaches the maximum and cohesion reaches the maximum of 207.57 kPa. The change in fiber length has little effect on the axial strain and the internal friction angle of soil when the sample is damaged.