黄土地区高边坡锚索预应力损失与土体蠕变耦合模型研究

预应力锚索锚固技术由于能有效控制边坡变形而得到广泛应用,但同时也出现大量因锚固力损失而造成工程失效的问题.建立以M-2K模型为基础,适用于黄土的锚索与边坡蠕变耦合的M-B-B模型,并推导其相应的本构方程、松弛方程和蠕变方程,从理论上解决了锚固力变化与坡体蠕变之间的关系问题.以兰州市城关区某不稳定斜坡治理工程为例,采用遗传算法反算出模型土体蠕变参数,与已有M-K-B模型拟合情况进行对比.结果表明:M-B-B模型更适用于黄土地区的高边坡,可以用来长期预测预应力变化;由于该工程部分为填土,填土部分水平变形较大,使得在预应力损失稳定阶段之前存在预应力缓慢上升阶段,而M-B-B模型则能完美契合该变化;其研究成果可供锚固工程的设计、施工和安全运行参考.

Study on coupling model of prestress loss of anchor cable and soil creep of high slope in loess area

The prestressed anchor cable anchoring technology is widely used because it can effectively control the slope deformation, but at the same time, there are also a lot of engineering failure problems caused by the loss of anchoring force. Based on M-2K model, this model is established, which is suitable for M-B-B model for creep coupling of anchor cable and slope in Loess. Meanwhile, the corresponding constitutive equation, relaxation equation and creep equation are derived, which theoretically solves the relationship between the change of anchorage force and slope creep. Taking an unstable slope treatment project in Chengguan District of Lanzhou City as an example, the genetic algorithm is adopted, which can reversely calculate the creep parameters of the model soil. The results are compared with the existing M-K-B model. The results show that the M-B-B model is more suitable for high slope in loess area, and it can be used to predict the change of prestress in the long run. The project is divided into filling soil, which leads to large horizontal deformation of filling soil. There is a slow rise stage of prestress before the stable stage of prestress loss, and the M-B-B model can perfectly fit this change. The research results can be used as reference for the design, construction and safe operation of anchorage engineering.