Calculation Method of Pullout Capacity of Recyclable Sawtooth Anchor

In order to solve the problems of unrecyclable anchor bearing head and low recovery efficiency,which are commonly found in recyclable anchor used for foundation pit,a new supporting structure of fully recyclable sawtooth anchor is proposed,its structure and working mechanism are described,and its bearing capacity are analyzed.Firstly,according to the structural characteristics of the sawtooth anchor,the expansion model of the shear fork type anchorage mechanism is established.It is solved by using the complex function method of elasticity plane problem and Tresca plastic yield criterion that the elastoplastic solution of the surrounding soil and the ultimate rotation angle of the shear fork arm when the shear fork type anchorage mechanism is expanded,and the calculation formulas of the uplift bearing capacity and the threshold value of rotation angle of the rotation element of the new type of anchor are derived.Then,the expansion process and pullout characteristics of the new anchor are analyzed by using the finite element method,and the theoretical value is compared with the simulation value.The results show that:(1)The influence range of the shear fork anchorage mechanism on the soil stress is about 2~3 times of its expanded width.The boundary of the plastic deformation zone of the soil around the anchorage mechanism is elliptical,and the ratio of the long axis to the short axis radius remains unchanged during the expansion of the anchorage mechanism;(2)Within the range not exceeding the limit rotation angle,the increase of the rotation angle of the anchoring mechanism can improve the pullout resistant property of the recyclable sawtooth anchor;(3)Compared to ordinary anchor rod,recyclable sawtooth anchor have stronger pullout capacity.