抗拔荷载作用下锚固体与岩土体界面剪切作用

Shear interaction of anchorage body and rock and soil interface under the action of uplift load

为了加深对锚固机理的研究,通过建立锚杆在受到拉拔荷载作用下锚固体界面侧阻力产生软化的数学模型,分析了锚固体与周围土体界面分别处于弹性状态、塑性状态、部分进入滑移状态、全部进入滑移状态4个阶段锚杆的轴力、位移和锚固界面剪应力,推导了锚杆产生松动的临界荷载、拉拔荷载与松动长度的关系及锚杆极限抗拔荷载的理论公式。结果表明,当锚杆在受到拉拔作用后滑移破坏首先在端部产生,然后荷载向锚杆里端传递,致使锚固体进一步破坏;根据拉拔荷载与锚杆松动长度之间的关系,当锚固体界面的侧阻力大于临界滑移的侧阻力时,在拉拔荷载作用下锚杆表现为渐进性破坏,当锚固体界面的侧阻力小于临界滑移的侧阻力时,则为突发性破坏。

In order to improve the mechanism study of anchorage,according to the established mathematical model on the interface of the anchoring and surrounding soil turning into softening when under the load of pullout,to analysis the displacement and axial force of anchor when the soil close to the interface of the anchoring body was in the elastic state,the plastic state and slip state. The theoretical formula for the critical loose pullout load of soil anchors and an inherent relationship formula between anchor pullout load and loose length are derived and at last deduced the ultimate pullout load. The results show that the first failure position was at the anchor head and then transmitted to the remote end of anchor system,which further aggravates the deterioration of interior anchor. According to the relationship between loose length and pullout,when the interfacial resistance is greater than the critical lateral side slip resistance,the anchor showed progressive destruction,and on the contrary,the anchor showed sudden destruction. Finally,the theoretical calculations and the actual test results were compared to verify the correctness of thetheoretical methods.