Stress Analysis and Critical Anchorage Length Calculation of Anchor Based on Hyperbolic Model
For the anchor bolt anchoring technology,it is mainly aimed at the construction of closed space such as rock and soil.The stress of the anchor bolt anchoring section is not completely clear,and the construction quality is difficult to guar-antee.The existing analytical solution of the stress distribution in the anchorage section of the bolt is relatively cumbersome,and the design length made by the current anchorage length design specification and the empirical method is relatively conser-vative.In order to clarify the stress mechanism of the anchorage section of the tensile anchor and obtain the calculation method of the critical anchorage length of the tensile anchor,based on the hyperbolic model of the relationship between the axial force of the bolt and the displacement of the anchor head,the nonlinear shear-slip model of the anchorage interface of the bolt is de-duced by analyzing the force of the micro element of the bolt.According to the basic equation of bolt load transfer,the analyti-cal solution of load transfer in anchorage section is solved,and the variation trend and distribution form of axial force and shear stress in anchorage range are explored through specific examples.Under the action of load,the anchorage interface of bolt shows obvious three processes:elastic bonding stage,elastic-plastic deformation stage and accelerated softening stage.The variation trend and distribution form of shear stress are different from those of axial force.With the gradual increase of load,it changes from a monotonic and nonlinear decreasing curve to a unimodal curve with a peak and the peak point gradually transmits to the anchorage depth.Based on the simplified model that the shear stress is inverted triangular distribution along the anchorage depth direction when the anchorage interface of the anchor bolt is in the elastic stage,the calculation formula of the critical an-chorage length of the tensile anchor bolt is obtained and the calculation results are verified.The load transfer equation solved by the relevant assumptions is simple in calculation and form,and can further understand the distribution form and transfer law of the anchorage interface of the tensile anchor rod.The calculation formula of critical anchorage length obtained by corresponding simplification provides a certain reference value for the design of anchorage length.
hyperbolic modelnonlinear shear-slip modelload transfer characteristicsinverted triangle distribution sim-plified modelcritical anchorage length
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