压力型锚索锚固段荷载传递特征及影响因素研究

Study on the Load Transfer Characteristics and Influence Factors of Anchorage Segment of Pressure-type Anchor Cable

为了研究土层压力型锚索锚固段的荷载传递特征及滑脱过程,在理论分析的基础上推导出压力型锚索在外荷载作用下的剪应力和轴力分布规律公式,详细分析了各影响因素对轴向力和剪应力的影响程度。研究结果表明:锚索锚固段的剪应力和轴力分布函数均为幂函数;剪应力和轴力大小及分布范围取决于锚固力,并与锚固体直径、锚固体弹性模量和泊松比、土的压缩模量和泊松比以及锚固体和土间界面的摩擦角有关;预应力锚索锚固段的最大剪应力位置仅与锚固体直径、土体性质、锚固体材料参数和半径有关;锚固体直径的大小对剪应力和轴力均有显著影响;在不同荷载作用下,锚固体界面剪应力的分布形式、范围和峰值位置均相同。现场原位试验结果表明:理论分析结果与工程实践结果吻合性较好。研究结果可为分析土体锚固工程的受力状态及优化设计提供依据。

In order to study the load transfer characteristics and the slippage process of anchorage segment of the pressure-type anchor cable in soil strata,the formula of shear stress and axial force distribution of the anchor cable under external load was derived based on theoretical analysis.In addition,the load transfer characteristics was analyzed.The influence degree of soil compressive modulus,anchor diameter,load and Poisson’s ratio on axial force and shear stress were analyzed in detail.The shear stress and axial force in the anchorage segment of the cable has the same distribution function and is all power functions.The shear stress and axial force are the largest near the bearing plate,but far from the bearing plate,the shear stress and axial force gradually decrease to zero.The magnitude and distribution range of the shear stress and axial force in the anchorage segment mainly depend on the anchorage force,and are related to the diameter,elastic modulus and Poisson ratio of anchor body,the compressibility modulus and Poisson ratio of soils,and friction angle of the interface between anchors and soils.In the form of the formula,if the anchorage segment is infinite,the anchoring force P can be infinite in theory.The ultimate anchoring force depends on the strength of the anchors around the bearing plate,the soil and the interface.The position of the maximum shear stress is only related to the soil properties,material parameters and radius of anchorage in anchorage segment of prestressed cable,not related to the magnitude of load.The diameter of anchors also has significant influence on the distribution of shear stress and axial force.With different loads,the distribution form,range and peak position of shear stress is the same,which is independent of load.Under the same conditions,the larger the compressive modulus of soil,the larger of shear stress,and the faster the shear stress decline trendation.The Poisson’s ratio has little effect on the shear stress.When the value of Poisson’s ratio is different,the mechanical property of the whole anchorage system under external load is basically unchanged,and also the value of shear stress.The range of action remains and the axial force is unchanged.In order to verify the correctness of the theoretical analysis results,the load transfer test results of the anchor cable were obtained by in-situ tests of clay and sandy soil.The in-situ test results show that the theoretical analysis results are in good agreement with the engineering results.The research results can provide a basis for analyzing the stress state and optimizing design of soil anchorage engineering.