Performance And Failure Pattern On Enlarged Bottom Anchor Bolt Under Pullout Loading

Wind power is one of the most mature and most large-scale way in generating electricity. It is currently second only to hydroelectric renewable energy technologies. In recent years, many domestic wind power generation projects have been built or are under construction, but there has been no specific design specification involves the safety of wind turbine in wind turbine foundation design. Generally, the wind turbine foundation design learns from architectural design, electrical and other industries related specifications. Learning from other industry standards, caused wind turbine foundation design is conservative. Wind generators mainly affected by horizontal level wind, it is very important that foundation stability does not capsize under the horizontal action. The traditional wind power foundation is expand gravity foundation, but it can not play a good role on rock mass mechanical properties, so we improve a new kind of wind power foundation:rock anchor foundation.The enlarged bottom anchor bolt is a type of special figure anchor bolt. It is based on the straight anchor bolt, squeezed soil around the bottom of the anchor bolt with a hydraulic squeezed machine. Because of the higher bearing capacity, the enlarged bottom anchor bolts are widely used in recent years, such as the use in the power transmission towers and substructure.Up to now, the theory researches of anchor bolts with enlarged bottom can’t keep up with the level of application. The tradition measures of ensuring vertical bearing capacity of anchor bolts with enlarged bottom are the field loading tests. But it costs too much time and funds, and also difficult to gain the whole Q-S curve. So it is necessary to discuss the bearing character of the enlarged bottom anchor bolts and find out a more reasonable method of numerical simulation to ensure vertical bearing capacity of the anchor bolt.In this paper the FEM software ANSYS is used to model the anchor bolt-soil interaction and in-depth analyze bearing character of the enlarged bottom anchor bolt. The main research contents in this paper are as follows:(1)With the plane element, the axisymmetric model is established by ANSYS software, in witch, the contact elements are set between the anchor bolt and soil to simulate the separation and sliding. And then simulate the working mechanism of the anchor bolt under uplifting load(2)The mechanics mechanism of enlarged bottom anchor bolts, the load transmission behavior rand the failure mechanism of soil are analyzed. Then main factors affecting the bearing capacity and the uplift mechanism of anchor bolt in different kinds of soil are discussed.(3)3-D FEM model including the contact elements between the anchor bolt and soil of three enlarged bottom anchor bolts in complex load cases are established to analyze the bearing capacity. Discusses multiple reamed bearing bolt joint action mechanism and affects the anchor group reamed on vertical Loaded Bolt bearing capacity.Finally, this paper summarizes the work, summarized the main conclusions of this paper and gives future research directions.