锚索预应力长期损失与岩土体蠕变耦合模型研究

锚索通过反力支座与边坡岩土体紧密接触,当给锚索施加一定预应力后,岩土体同样受到预应力作用而发生形变。该形变不会瞬时完成,而是随时间变化,将导致锚索预应力出现长期损失。将锚索等效成弹性体和广义Kelvin体(考虑锚索应力松弛) 这2种模型,并假设岩土体为考虑蠕变特性的H+nK体(n≤3),结合锚索与岩土体的耦合变形和初始条件,推导出锚索张拉力随时间变化的计算式。经与以往研究成果对比,验证了模型的正确性。同时,研究分析表明,在理论模型中增加岩土体蠕变模型的K体个数及考虑锚索应力松弛现象,可使得拟合曲线更接近于实测的锚索预应力变化。

Coupled Model for the Long-term Pre-stress Loss of Anchor Cable and Geotechnical Creep

Anchor cable is closely contacted with geotechnical body through reaction support.After a certain pre-stress is applied on anchor cable,the geotechnical body also deforms under the action of pre-stress.Due to the creep property of geotechnical body,its deformation doesn’t complete instantaneously but changes with time,which causes the long-term loss of pre-stress.In this research,anchor cable is equivalent to two models (elasticity body and generalized Kelvin body),and geotechnical body is assumed to be model of H +nK (n≤3)which could simu-late the creep property of geotechnical body.According to the coupling deformation between anchor cable and geotechnical body and the initial conditions,formulas of calculating the pre-stress of anchor cable with the change of time are obtained.Through comparison with the results of previous studies,the correctness of this model is veri-fied.Moreover,the fitting curve could be more consistent with the measured pre-stress variation if the number of K in creep model of geotechnical body is increased and the relaxation of anchor cable stress is considered in the theo-retical model.