Study On Bearing Characteristics Of Enlarged Head Reinforcement Cage Anti-Floating Anchors Rod On Three Main Types Of Stratum In Guangxi

Guangxi is an area where it has abundant water resources,so its groundwater level in the adjacent water area is high.The groundwater will cause the building to float up,damaging the beam-column nodes and the basement floor.All above non-safety factors are going to pose a threat to a building.With the development of anchoring technology,anchor rods as a standard support method for slopes and foundation has widely used to solve anti-floating problems.Incipient anti-floating anchors have a small bearing capacity.So the enlarged head reinforcement cage anti-floating anchors rod were gradually used in Guangxi,which has a large bearing capacity and standardized factory production.However,the actual bearing characteristics of the new technique is not clear in any Guangxi practical project.Besides,the change law of bearing characteristics factors are also not precise in Guangxi stratum.Therefore,it is of great engineering significance to study the bearing characteristics of enlarged head reinforcement cage anti-floating anchor in the three main types of stratum in Guangxi,which can lay the foundation for its subsequent popularization and application.In this paper,field tests and finite element numerical simulation are used to study bearing characteristics of the enlarged head reinforcement cage anti-floating anchor rod.First of all,a simple comparative analysis is made between the anti-floating anchor rod and the enlarged head anti-floating anchor rod in theoretical calculation of bearing capacity,both of anchor rods have the same cross-section.Secondly,field tests were conducted in the three main types of stratum in Guangxi.In this test,it compares three types of anti-floating anchor rods bearing capacity in each stratum.Besides,different sizes of enlarged head reinforcement cage anti-floating anchor rods were going to install in the same stratum and study their bearing characteristics and Influencing factors.Finally,Midas(a finite element numerical simulation software)was used for establishing a model to analyze the axial force transmission laws in the three types of anti-floating anchors and the bearing characteristics of the anti-floating anchors with different size parameters.Moreover,the influence of the internal friction angle and cohesion of the soil on the bearing capacity characteristics of the enlarged head reinforcement cage anti-floating anchor rod.In the end,the field test and numerical simulation results are compared.The results show:(1)Normal anti-floating anchors mainly provide the anti-floating bearing capacity from two aspects.One is the bonding force between the anchor rod body and the grouting body,and the second source comes from the friction between the grouting body and the rock and soil layer.In the above situation,the calculation results of the "Technical standard for building engineering against uplift" are more accurate.The enlarged head reinforcement cage anti-floating anchor rod has better pull-out bearing capacity is due to the end resistance and greater friction provided by the enlarged head section.The main influencing factors of the end resistance of the enlarged head anti-floating anchor rod are related to the depth of the enlarged head,the cohesion of the soil and the angle of internal friction.(2)Field test results show that the load-bearing characteristics of the enlarged head reinforcement cage anti-floating anchor rod are better than the standard enlarged head anti-floating anchor rod and it also will show significant advantages in the standard anti-floating anchor rod.Furthermore,the primary influence factors of enlarged head reinforcement cage anti-floating anchor rod related to two aspects,the total length of the bolt and the diameter of the enlarged head.The minor factor is the length of the enlarged head.(3)Numerical simulation studies show that the axial force of the enlarged head reinforcement cage anti-floating anchor rod is gradually transferred to the end of the anchor rod as the load increases.However,the axial force drops obviously when it transferred to the cross-section,where it starts to enlarge.Then,it became to zero at the end of anchor rod.The frictional resistance mainly provides the initial pull-out bearing capacity of the bolt.When the load-bearing exceeds frictional resistance,the exceed parts of force will be provided by end resistance.The influence factors in the bearing characteristics of the enlarged head reinforcement cage anti-floating bolt are the total length of the bolt,the diameter of the enlarged head.Moreover,providing optimal recommended parameters for the anti-floating anchor rod of the enlarged head reinforcement cage.The diameter parameter of the enlarged head reinforcement cage anti-floating anchor rod is a crucial key factor to improve the bearing capacity of the anchor rod.Internal friction has a greater impact on the enlarged head reinforcement cage’s bearing characteristics.Therefore,the increase of soil cohesion and internal friction angle has a positive impact on the anchoring effect.