基于理论承载性能与应力扩散计算的高强预应力锚索适配垫板设计方法

Design method of adapted face plate for high-strength prestressed anchor cable based on theoretical load bearing performance and stress diffusion calculation

垫板是高强预应力锚索系统的核心组成构件,当其与锚索间适配性不足时,会出现结构可靠性低以及围岩支护效果差等问题。基于垫板的承载力学特性及其应力扩散作用,提出适配高强预应力锚索的垫板设计方法。为此,首先分析垫板的应力扩散作用与锚索的支护效应间的关联性。其次,基于不同形式垫板的结构受力特征,提出碗形垫板和平板形垫板的理论承载力计算公式,并由此计算得到满足高强预应力锚索承载性能需求的垫板型式及其结构参数。接着,通过建立“垫板(碗形、平板形)-围岩”三维数值仿真模型,分析不同型式及结构参数垫板的围岩应力扩散效果,并由此优选得到适配高强预应力锚索的垫板型式及其结构参数。最后,通过现场应用案例,分析适配垫板下高强预应力锚索系统支护效果。研究结果表明:提出的垫板设计方法实现了对高强预应力锚索系统中垫板的有效选用,适配加载300 kN的高强预应力锚索系统垫板为25 cm×25 cm×16 mm的碗形垫板,其拱高35 mm、孔口半径32 mm、碗底半径75 mm;同时,适配垫板下高强预应力锚索系统的围岩变形控制效果提升了11.9%~15.2%。研究结果有助于提升高强预应力锚索系统的可靠性与支护效果,并为预应力锚固系统中垫板的设计提供了一种可行且有效的方法。

The face plate is the core component of high-strength prestressed anchor cable system.When its adaptability to the anchor cable is insufficient,problems such as low structural reliability and poor perimeter rock support will occur.The purpose of this paper was to propose the design method of face plate for high-strength prestressed anchor cable based on the load bearing characteristics and stress diffusion of the face plate.Firstly,the correlation between the stress diffusion effect of the face plate and the support effect of the anchor cable was analyzed.Secondly,the theoretical bearing capacity calculation formulas of bowl-shaped face plate and flatshaped face plate were proposed based on the structural force characteristics of different face plates.The face plate type and its structure parameters to meet the demand of the bearing performance of high-strength prestressed anchor cable were obtained by calculating.The stress diffusion effect of different types and structure parameters of face plates was analyzed through the establishment of the three-dimensional numerical simulation model of“face plate(bowl-shaped,flat-shaped)-surrounding rock”,and the adapted face plate type and its structure parameters for high-strength prestressed anchor cable were optimized.Finally,the support effect of highstrength prestressed anchor cable system under the adapted face plate was analyzed through the on-site application cases.The results are shown as follows.The proposed face plate design method realizes the effective selection of face plate for high-strength prestressed anchor cable system.The face plate of the high-strength prestressed anchor cable system suitable for loading 300 kN is a bowl-shaped face plate of 25 cm×25 cm×16 mm,with an arch height is 35 mm,aperture radius of 32 mm,and a radius of 75 mm at the bottom of the bowl.Meanwhile,the rock deformation control effect of the high-strength prestressed anchor cable system under the adapted face plate is improved by 11.9%~15.2%.The results can improve the reliability and support effect of the high-strength prestressed anchor cable system,and provide a feasible and effective method for the face plate design of the prestressed anchorage system.