悬索桥的重力式锚碇在混凝土与碎石土接触面的摩擦强度特性,对锚碇体的抗滑稳定性具有决定性影响。为了深入研究碎石土与锚碇混凝土接触面的摩擦强度特性,并确定接触面的摩擦系数,本文进行了混凝土与碎石土接触面的抗剪断试验、抗剪试验和往复剪切试验,分析了3个试验阶段的应力—位移变化规律,利用最小二乘法拟合τ与σ关系曲线获取接触面摩擦系数。结果表明:在抗剪断试验中,接触面呈现出应变软化现象,并在剪断破坏过程中出现压嵌效应,压嵌深度介于2~5 mm之间;在抗剪试验和往复剪切试验中,接触面并未出现显著的应变软化现象,混凝土主要在接触面上水平滑动;在抗剪段、抗剪和往复剪试验的3个阶段中,混凝土与接触面的黏聚力(c)显著下降,摩擦系数f值以1%~2%的速率递减,表明接触面的咬合和嵌固作用正在减弱;建议选取往复剪切试验中的纯摩擦强度参数f值(0.48)为混凝土与碎石土接触面的摩擦系数。
The friction strength characteristics of gravity anchorages of suspension bridges at the contact surface between concrete and gravel soil have a decisive influence on the slip resistance stability of the anchorages. In order to study the friction strength characteristics of the contact surface between gravel soil and anchor concrete and to determine the friction coefficient of the contact surface, this paper carried out the shear fracture test, shear test, and reciprocating shear test of the contact surface between concrete and gravel soil, analyzed the change rule of the stress-displacement law of the three test phases, and utilized the least-squares method to fit the τ vs. σ relationship curve to obtain the friction coefficient of the contact surface. The result shows that in the shear resistance test, the contact surface showed strain softening phenomenon and pressure embedding effect in the shear damage process, and the depth of pressure embedding ranged from 2 mm to 5 mm; in the shear resistance test and reciprocating shear test, the contact surface did not show significant strain softening phenomenon, and the concrete was mainly sliding horizontally on the contact surface; in the shear section, the shear resistance, and the three phases of reciprocating shear test, the friction coefficient of the contact surface was calculated by the relationship curve between the concrete and the adhesion (c) of the contact surface decreased significantly, and the value of the friction coefficient f decreased at a rate of 1% to 2%, indicating that the occlusion and embedment of the contact surface was weakening; the value of the pure friction strength parameter f (0.48) in the reciprocating shear test was selected as the friction coefficient of the contact surface between concrete and gravel soil.
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