锚索预应力初期与长期损失的预测模型研究

采用预应力锚索加固边坡是一种切实有效的方法。考虑锚索预应力变化与坡体蠕变之间的耦合效应,建立两种耦合模型并推导模型的本构方程和有效预应力的变化公式。基于实际锚固工程的预应力监测数据,采用反分析方法得到坡体的蠕变参数,划分预测阶段后采用相应的理论模型,通过理论计算值与实际监测值的对比分析,验证了分段预测模型的合理性和准确性。研究表明:在预应力预测的全周期采用单一的耦合模型,随着时间发展产生的偏差也随之增大;弹性模型与广义Kelvin模型并联(H-K模型)预应力曲线下降较快,适用于预测锚索锚固初期的预应力损失;弹性体上并联广义Kelvin(H-2K模型)能更好地拟合锚索预应力的长期变化。合理的分阶预测能够准确地评价锚索预应力的损失变化,为及时采取措施以保证边坡的稳定与安全提供科学依据。

Prediction models for short-term and long-term pre-stress loss of anchor cable

It is a practical and effective method to strengthen the slope using pre-stressed anchor cables. Complicated coupling effect exists between the anchorage force loss of anchor cable and creep of rock and soil. Two coupling models are established. The constitutive equations of the model and the formulas for the effective pre-stress are derived. Based on the pre-stress monitoring data in a practical engineering, the creep parameters of the slope are obtained by inverse analysis methods. The corresponding theoretical models are adopted after the division of the prediction stages. The comparison between theoretical calculation value and the actual monitoring value is used to verify the rationality and accuracy of the models. The results show that a single coupled model leads to an increase in prediction of error as time goes on. The curve of H-K model, which is made up of the elastic model and the generalized Kelvin model in parallel, declines quickly, so it is suitable for predicting the early pre-stress loss of anchor cable. H-2K model, elastomer parallel with generalized Kelvin body to consider the stress relaxation of anchor cable, can fit the late changes of anchor cable pre-stress better. Reasonable staged prediction can accurately evaluate the loss of anchor cable pre-stress, and thus to provide references for the prevention and treatment of landslides