Research On Drawing Bearing Characteristics And Calculation Method Of Inclined Bar Anchor Plate In Sand

Anchor plates have the advantages of strong bearing capacity,simple construction,and good economy.They are widely used in the practice of anti-uplift foundation engineering such as signal communication towers,slope anti-sliding reinforcement,and high-rise structures.Usually,the anchor plate with the aspect ratio L/B>5 is regarded as a strip anchor plate and works under plane strain conditions.Many anchor plate design theories start with strip-shaped anchor plates,obtain the formula for calculating the pull-out bearing capacity,and then introduce shape factors to extend the calculation formula of strip-shaped anchor plates to rectangular anchor plates,circular anchor plates,and so on.In the current domestic and foreign research,horizontal anchor plate research is the majority,vertical anchor plate research is relatively rare,and inclined anchor plate research is rare.Different scholars have not yet formed a unified understanding of the bearing characteristics affected by the embedded inclination angle and depth,and the bearing mechanism is not fully revealed.As a result,the existing research is not enough to provide a sufficient theoretical basis for the engineering application of inclined anchor plates.Therefore,it is particularly important to study the pull-out bearing mechanism of the inclined anchor plate and establish the corresponding bearing capacity calculation method.In this paper,a self-made visual pull-out test device is used to carry out indoor model tests,and pull-out tests under 5 embedding angles and 7 embedding depths are carried out on the strip anchor plate under a total of 35 test conditions.According to the load-displacement curve,the influence of the embedding depth and the inclination angle on the ultimate drawing bearing capacity of the anchor plate is analyzed.The results show that the ultimate drawing bearing capacity increases with the increase of the buried depth,and the growth rate gradually decreases.Theoretically,when the buried depth approaches infinity,the ultimate drawing bearing capacity approaches a gradual value.Under the same burying depth,the ultimate drawing bearing capacity increases with the increase of the burying angle,the bearing capacity of the horizontal slab is the smallest,and the bearing capacity of the vertical slab is the largest.The digital image obtained in the experiment was processed by the digital photogrammetry system tools Photo Infor and Post Viewer software to obtain the displacement field and the shear strain field of the soil around the anchor,and analyze the failure sliding surface morphology of the soil around the anchor during the ultimate drawing.The shear strain cloud diagram shows that the sliding surface of a horizontal anchor plate can be described by a partial circumference of an ellipse.As the buried depth ratio increases,the sliding surface shrinks toward the anchor plate,and the long and short axes of the curve corresponding to the ellipse gradually decrease.The sliding surface of the inclined anchor plate under the same buried depth is composed of a straight line segment and a large elliptical part contour line corresponding to the horizontal anchor plate on one side of the drawing direction.The straight line segment is generally the end point of the anchor plate and a point on the ellipse.Connect the line,and the other side is described by the elliptical part contour corresponding to the sliding surface of the horizontal anchor plate.Based on the above-mentioned sliding surface change law,the elliptic function is selected as the basic morphological function of the sliding surface,and the shrinkage law of the sliding surface with the buried depth ratio is reflected by the change of the ratio of its long axis to the short axis.The position of the anchor plate corresponds to a chord on the ellipse,and the change of the angle setting of the former is described by the change of the position of the latter.Further combining the length of the anchor plate and the intersecting relationship between the ground and the ellipse,it is divided into four categories and a total of 23 working conditions to establish a unified mechanical model of the drawing load bearing of the inclined strip anchor plate,which can cover the characteristics of the sliding surface under any setting of the buried depth and inclination angle.The surface is composed of a part of an elliptical circumference and an oblique straight line inside it.On this basis,the limit equilibrium analysis is carried out with the area enclosed by the sliding surface,the ground and the anchor plate as the isolator,and the calculation method of the ultimate drawing bearing capacity of the inclined anchor plate is derived and established.The comparative analysis with the existing test and calculation method shows that the calculation method in this paper has certain applicability.