锚固力损失与岩土体时效变形耦合模型研究

Study on coupling model of anchorage force loss and time-dependent deformation of rock-soil mass

预应力锚索的锚固力损失是造成锚固工程失效的关键因素,研究锚固力时效变化规律至关重要。锚索与岩土体长期相互作用时,两者受力相等而变形不同,锚固力的损失需要同时考虑锚索自由段和锚固段分别与岩土体相互作用的影响。采用胡克体和广义开尔文体分别模拟锚索和岩土体,考虑锚索自由段与相应的岩土体并联,锚固段与岩土体串联,建立锚索与岩土体蠕变的耦合模型,推导其本构方程、松弛方程和蠕变方程。对比已有计算模型和试验值,验证该模型的合理性和精准性,分析锚索和岩土体的参数对锚固力损失率的影响。结果表明:锚固力损失率随锚索等效弹性模量增大而增加,随岩土体的滞后弹性模量和黏滞系数增大而减小;自由段和锚固段岩土体的瞬时弹性模量或黏滞系数等量变化时,引起的损失率改变量相等;自由段的岩土体滞后弹性模量等量变化引起的损失率改变量比锚固段更大。该模型能更真实地反映锚固力损失规律。

The anchorage force loss of prestressed anchor cables is the key factor causing the failure of engineering.It is vital to study the time-dependent variation law of the anchorage force.When the anchor cable interacts with rock-soil mass for a long time,the stress is equal but the deformation is different.The loss of the anchorage force needs to consider the influence of the interaction between free and anchorage sections of the anchor cable with the rock-soil mass respectively.The Hooke and the Generalized Kelvin bodies are used to simulate the anchor cable and the rock-soil mass respectively.Considering that the free section of the anchor cable is in parallel with the corresponding rock-soil mass but the anchorage section is in series with the rock-soil mass,a coupling model of the anchor cable and rock-soil mass creep is established,and its constitutive,relaxation and creep equations are derived.The rationality and accuracy of the model are verified by comparing with the existing models and experiment data,and the influence of parameters of the anchor cable and the rock-soil mass on the anchorage force loss rate is analyzed.The results show that the loss rate of the anchorage force increases with increasing the equivalent elastic modulus of the anchor cable but decreases with increasing the hysteretic elastic modulus and the viscosity coefficient of the rock-soil mass.When the instantaneous elastic modulus or the viscosity coefficient of the rock-soil mass in free and anchorage sections changes by the same amount,the change of the loss rate is equal.The change of the loss rate caused by the change of the hysteretic elastic modulus in the free section is more than that in the anchorage section.The model can more truly reflect the regular of the anchorage force loss.