关键词: 道路工程；红黏土；干湿循环试验；抗剪强度；神经网络模型

Abstract: In the humid and rainy southern region, red clay roadbed was prone to diseases such as excessive settlement and uneven settlement. Polypropylene fiber was incorporated into red clay to form fiber-modified red clay, aiming to investigate its shear strength characteristics under dry-wet cycles. Direct shear test was employed to investigate the effects of fiber content (0 ‰, 2 ‰, 6 ‰, 106 ‰), fiber length (0, 3, 6, 9mm), and dry-wet cycles (0, 2, 4, 6 times) on the shear strength characteristics of red clay. The results indicate that the shear strength of red clay is significantly enhanced by the incorporation of fibers, and within the range of dosage and length studied, the shear strength increases with the increase of fiber dosage and length. Fibers have a noteworthy impact on increasing the cohesion value of red clay, while their improvement of internal friction angle is limited. When the fiber length is 6mm, the shear strength of red clay reaches its maximum value. The dry-wet cycle significantly reduces the strength of red clay and its deterioration of cohesion exceeds the internal friction angle. Under the action of dry-wet cycle, fiber and normal pressure can reduce the deterioration effect of dry-wet cycle on red clay. Based on the above experimental results, the strength prediction model of red clay under the action of dry-wet cycle is established using the back propagation (BP) neural network technique, and the relative error value of its prediction is below 10%.

Key words: road engineering; red clay; dry-wet cycle test; shear strength; neural network model