双锚固段新型锚索锚固机理数值分析及应用

Numerical Analysis and Application on Anchorage Mechanism of New Pressure-type Anchor Cable with Double Anchoring

为了探究双锚固段新型锚索的锚固机理,从结构形式入手,分析受力模式与设计计算方法,采用有限差分数值软件进行数值模拟,建立不同外锚固段长度、自由段长度及内锚固段长度双锚固段新型锚索数值模型。在外锚头段锚固力不断损失时,新型锚索三段长度变化对锚索各段轴力、灌浆体与孔壁之间接触面上的剪应力影响规律研究,并通过工程实例验证。研究结果表明:(1)当外锚头锚固力损失时,外锚固段轴力自外锚头处开始逐渐降低,外锚固段灌浆体与孔壁间剪应力自外锚头处开始逐渐发展;(2)将外锚头锁定的预应力进行卸载的过程中,量测内锚固段注浆体的应变基本保持稳定,表明外锚头施加的预应力已完全由外锚固段与孔壁间粘结力承担,避免了因外锚头失效导致的锚索预应力损失,整个锚固系统实现了反向自锁的功能;(3)外锚头锚固力损失相同时,外锚固段长度越短,自由段锚索轴力变化越大;(4)新型锚索自由段长度大4 m。研究结果对正确分析双锚固段新型锚索加固作用机理和锚固工程设计具有一定的参考价值。

To explore the anchoring mechanism of new anchor cable with double anchoring,its force model and calculation method were studied by analyzing its structural characteristics.A numerical model of new anchor cable with double anchoring of different anchor length,free length and inner anchorage length was established by the finite difference numerical software.When the outside anchor head has the loading loss,the affect rule of the anchor length,free length and inner anchorage length change on the tension stress in anchor cable and the shear stress around the contact surface was studied.It is verified by the engineering example and comparative results show that:(1)when the outside anchor head has the loading loss,outside the anchoring tension stress begins to gradually reduce from the place of outside anchor head,and shear stress between the grouting section and the wall begins to develop from the place of outside anchor head;(2)the strain of the grouting in the inside anchor segment is basically stable in the whole process of unloading the outside anchor head,and it shows that the force of the inner anchorage segment is basically unchanged and the pre-stressing loss of free segment is smaller.The anchoring force exerted by the orifice is fully borne by the adhesion between the outer anchor and the wall,the outside anchor segment effectively serves as a double anchor.The whole anchor system realizes the function of reverse self-locking,avoiding the loss of the anchor cable due to the failure of the outer anchor.(3)when the outside anchor head has the same loading loss,the outside anchor length becomes shorter and the free-segment of anchor cable’s tension stress affect becomes greater;(4)new type of anchor cable free segment length is more than 4 m,and the research results have a good reference value for correct analysis of anchoring and reinforcing mechanism and engineering design of new anchor cable with double anchoring.