单轴压缩下不同尺寸充填体能量损伤演化特征试验研究

Experimental Study on Energy Damage Evolution Characteristics of Filling Specimens with Different Sizes Under Uniaxial Compression

对4种不同尺寸(40,70.7,100,150 mm)的充填体试件进行了室内单轴压缩试验,研究了尺寸变化对充填体能量演化规律和损伤破坏机制的影响,并得到了基于弹性能耗比的充填体破坏前兆判据。研究结果表明:单轴压缩下不同尺寸充填体的能量演化规律相似,体现为峰前以弹性应变能积蓄为主,峰后耗散能占比不断上升并迅速超越弹性应变能;随着试件尺寸的增加,充填体在峰值应力处总输入应变能、弹性应变能和耗散能均呈非线性下降趋势;根据耗散能曲线,可将充填体能量损伤演化过程划分为初始损伤、损伤加速、损伤稳定发展和损伤破坏4个阶段;试件尺寸越大,弹性能耗比K值变化幅度越大;弹性能耗比K值曲线整体先上升后下降,持续到一个较低值,在临近峰值应力处再转为上升。弹性能耗比K值曲线的这一变化规律可作为充填体临界破坏前兆特征。

The indoor uniaxial compression tests were carried out on four filling specimens with different sizes of 40 mm,70.7 mm,100 mm and 150 mm.The effects of size changes on the energy evolution law and damage mechanism of filling were studied,and the precursory criterion of filling body failure based on elastic energy consumption ratio was obtained.The results show that the energy evolution laws of different sizes of fillings under uniaxial compression are similar,which are reflected in that the elastic strain energy is mainly accumulated before the peak stress,the energy is released and dissipated during the failure process of the specimen,the curve of dissipated energy and elastic energy shows an alternating growth trend,and the proportion of dissipated energy increases continuously and exceeds the elastic strain energy rapidly after the peak stress.With the increase of specimen size,the total input strain energy,elastic strain energy and dissipation energy of the filling body at the peak stress show a nonlinear downward trend,indicating that the energy storage limit and bearing capacity of the filling body are decreasing with the increase of specimen size.The dissipative energy characteristics of the filling body can better reflect the four stages of damage evolution in the filling body.In the initial damage stage and the stable development stage of damage,the variation range of the dissipation energy curves of the sample with the size of 40 mm is slightly larger than that of the sample with other sizes.In the stage of damage acceleration and damage failure,the corresponding curves of 40 mm and 70.7 mm samples and 100 mm and 150 mm samples show two different growth trends.The smaller the size is,the more severe the damage is.The larger the size of the filling specimen is,the greater the change range of the elastic energy consumption ratio K value of the specimen is.The elastic energy consumption ratio K value curve increases first and then decreases,continues to a low value,and then increases near the peak stress.This variation law of K value curve of elastic energy consumption ratio can be used as the precursory characteristic of critical failure of filling body.