Development Of Hydraulic Expandable Control Anchor

In order to overcome many deficiencies of existing grouting bolts,such as long construction period,polluted underground space,and non-recyclability,the innovative design of recyclable bolts has been paid attention by experts and scholars at home and abroad.This paper mainly proposes a new type of hydraulic expandable control anchor,which uses a hydraulic cylinder as the anchor expansion device.By applying hydraulic pressure to the anchor rod,the anchor rod can quickly achieve the anchoring effect.The hydraulic expandable control anchorhas the characteristics of convenient installation,complete recovery and rapid anchoring effect,and has certain engineering practicability and economy.In this paper,the hydraulic expandable control anchor is made into finished products,and the influencing factors of the pulling force of the bolt are analyzed through the indoor pullout test.The internal expansion mechanism and the pullout force formula of the bolt are obtained through mechanical analysis,The main contents include:(1)The type of surrounding rock and the relevant specifications of the anchor are analyzed to determine the performance requirements and design parameter requirements for the hydraulic expandable control anchor.(2)The structural design and material selection of the anchor rod are determined,and the finished anchor rod is manufactured,and the anchor rod assembly is completed.(3)The test procedures and precautions for indoor pull-out test are introduced in detail,and the supporting test equipment is designed.(4)A comparative pull-out test was carried out on thehydraulic expandable control anchorunder different hydraulic pressures and different lengths of expansion arms.It can be known from the test data that the pulling force of the anchor rod increases with the increase of the hydraulic pressure and decreases with the increase of the length of the expansion aem.(5)Through mechanical analysis,the internal expansion mechanism of the hydraulic expandable control anchoris analyzed and the mechanical formula of the relationship between the hydraulic expansion anchorconfining pressure and the oil pressure received by the anchor is obtained.According to the formula,it can be seen that changing some design parameters of the anchor rod,for example,increasing the bottom area of the anchor cylinder piston can provide a higher confining pressure under the same hydraulic pressure to obtain a better anchoring effect,which is an improvement of the hydraulic expandable control anchor provided directions.(6)The anchoring mechanism of the hydraulic expandable control anchoris analyzed,and it is divided into four stages: the anchor expansion stage,the elastic zone soil elastic stage,the anchor zone soil body elastoplastic stage and the anchor zone soil The destruction stage of the body.The formula of the pull-out bearingcapacity of the hydraulic expandable control anchor is also put forward,and the failure form of the hydraulic expandable control anchoris analyzed.