火灾（高温）后破碎卵石混凝土三轴受力性能研究

Triaxial Mechanical Performance of Broken Pebble Concreteafter Fire（High Temperature）

摘要:

为研究火灾（高温）后破碎卵石混凝土的三轴受力性能，以温度及侧向围压为参数，完成了30个100×200mm的圆柱体试件在经历不同高温后的常规三轴加载试验.结果表明：火灾（高温）后破碎卵石混凝土试件在单向应力下的应力应变曲线有明显的峰值点，随着温度的增加，峰值点逐渐向右下角移动；在三向应力下试件的破坏形态分为斜面剪切破坏与层状劈裂破坏；随着围压的不断增加，试件的应力应变曲线逐渐平缓，峰值点也越来越不明显，温度的影响逐渐减小，其弹性模量、峰值应力、峰值应变均显著增加；随着温度的上升，试件的峰值应力与弹性模量整体呈下降趋势；基于试验数据建立了相关计算公式及火灾（高温）后破碎卵石混凝土在三轴应力下的应力应变本构方程，可为相关研究提供参考.

Abstract:

To investigate the triaxial stress of broken pebble concrete after fire（high temperature）, 30 100×200mm cylinder specimens with temperature and lateral confining pressure as parameters under conventional triaxial loading test were measured. The results show that after fire（high temperature）, when under uniaxial stress, the stress strain curve has an obvious peak. With the increase of temperature, the peak point declines and moves to the right; when under triaxial stress, the failure pattern of broken pebble concrete can be divided into cant shear failure and layered splitting failure. With increase of lateral confining pressure, the stress strain curve becomes smooth and plump and the peak point becomes more and more unobvious, and the elastic modulus, peak stress and peak strain of specimens are significantly increasing. With the increase of temperature, the peak stress and elastic modulus present a downward trend. Based on experimental data, the relational calculation formula and stress strain constitutive relation formula are given, the results can provide reference for related work.