Experimental Study On Ultimate Bearing Capacity Of Anchor Uplift Pile

Anchor uplift pile used in the transmission tower structure can effectively resist the load on the pull.However,the experimental data of the anchor piles are few,the mechanism of force is to be further analyzed,and it is necessary to carry out the experimental study.In this paper,based on the Nanyang Nanzhao transmission tower anchor pile foundation project carried out a variety of anchor pile form of field test,the main conclusions are as follows:(1)The effect of the pedestal anchor piles on the resistance of the upper part of the uplift piles is larger than that of the normal anchor piles.And the latter stage is the main role.Under the same test conditions,the uplift bearing capacity is higher than 45% and the ultimate displacement of the bolt is also improved.(2)The ultimate bearing capacity of the normal anchor pile is most affected by the length of the pile.The tensile stress of the anchor is gradually reduced along the pile depth,The load increases and increases,when the load reaches a certain value,the anchor force tends to be stable;The longer the pile length,the faster the anchor side resistance decreases along the pile length,when the pull force is small,the side resistance is almost no play,the resistance of the bolt side is increased with the increase of the upper force;The effect of grouting material and anchor bar diameter on the ultimate loading capacity is small,but the reasonable selection of grouting material can improve the sudden change of pile edge resistance along pile depth.(3)The pile length has the greatest influence on the bearing capacity of the pedestal anchor piles,and the tensile stress of the anchor is gradually reduced with the pile depth,and the axial force of the pile top and the pile end is very different;The variation law of the anchorage resistance of the pedestal anchor piles along the pile depth is affected by the load grade,and it is found that the law of the force and lateral resistance of the anchor pile is clarified according to the load grade;Grouting material and anchor type have little effect on it.(4)The group anchoring effect reduces the total loading capacity of the group anchors and verifies the influence of anchor spacing on the group anchoring effect,the larger the anchorage distance is,the effect of the group anchoring effect is relatively small;The tensile stress of the upper part of the anchor pile is higher than the average bearing capacity of the upper part of the anchor pile,the tensile stress of the upper part of the anchor is increased,and then with the increase of the anchor depth,the tensile stress of the tendons is decreasing,which is the same as that of the ordinary single anchor pile;The resistance of the single pile anchorage varies,there is no obvious law;The joint foundation with the confinement of the platform-the group anchorage test shows that the effect of the cap on the lifting capacity of the group anchors is obviously improved,and the displacement of the foundation is greatly reduced,which is beneficial to the overall stability.