边坡预应力锚索结构拉力松弛分析模型

Analysis model of tension relaxation of prestressed anchor cable used to reinforce slopes

摘要

为合理解决预应力锚索加固边坡的锚索拉力松弛分析问题，考虑锚索、锚固段地层、自由段滑体和坡面抑制构件的相互作用特征，建立了一种采用胡克体模拟锚索或坡面抑制构件、开尔文体模拟滑床、开尔文体或广义开尔文体模拟土质或岩质滑体的并联-串联组合分析模型，推导了锚索拉力松弛计算表达式。室内试验与现场实测结果表明，本法计算的锚拉力松弛后稳定值与实测值误差在6%以内，而其松弛历时的最大误差为7.7%，本法优于既有方法的计算结果。锚索拉力的松弛效应随锚孔间距、锚固段地层的滞后弹性模量和初期黏滞系数的增大呈非线性减弱，但随着锚索的直径和弹性模量的增大呈线性增强，而锚固段地层的瞬时弹性模量、自由段滑体的瞬时弹性模量、滞后弹性模量和黏滞系数均对锚索松弛效应影响很小；实际中一般可采用忽略自由段滑体影响的“坡面抑制构件-锚索-锚固段地层”的串联分析模型，以便捷估算锚索拉力松弛效应。

Abstract

In order to reasonably solve the problem of anchor cable tension relaxation analysis of slope reinforced by prestressed anchor cable, considering the interaction characteristics of anchor cable, stable layer, potential slide mass and surface restraint member, a parallel-series combined analysis model of anchor cable tension relaxation using Hooke body to simulate the anchor cable or surface restraint member, Kelvin body to simulate the stable layer, Kelvin body or generalized Kelvin body to simulate the slide mass is established. The calculation expression of the tension is derived. The results of laboratory test and field observation show that the errors between the proposed and observed tensions after the cable relaxation are within 6%, and the maximum error of the relaxation duration is 7.7%. The proposed results are better than those using the existing methods. The relaxation effect of anchor cable tension decreases nonlinearly with the increase of anchor hole spacing, hysteresis elastic modulus and initial viscosity coefficient of the stable layer, but increases linearly with the anchor cable diameter and elastic modulus. However, the instantaneous elastic modulus of the stable layer, and the instantaneous elastic modulus, hysteresis elastic modulus and viscosity coefficient of the slide mass have little influence on the relaxation effect of anchor cable. In practical engineering, the ‘surface restraint member-anchor cable-stable layer' series analysis model, which ignores the influence of the slide mass, can be used to simply estimate the tension relaxation.

关键词

预应力锚索 / 边坡 / 锚拉力松弛 / 串联模型 / 并联模型

Key words

prestressed anchor cable / slope / anchor tension relaxation / series model / parallel model

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基金资助

国家自然科学基金资助项目(51578466)

四川省交通运输科技资助项目(2020-A-01)