基于近场动力学单轴压缩下宏观孔隙混凝土的损伤破裂模拟

Damage and fracture of macro-porous concrete under uniaxial compression based on peridynamic theory

基本蒙特卡罗方法,采用MATLAB程序生成随机孔隙结构的物理模型,通过自编近场动力学程序模拟了单轴压缩下宏观孔隙混凝土的裂纹萌发与扩展,并结合混凝土单轴压缩试验对计算结果进行了对比验证。结果表明:宏观孔隙混凝土抗压强度与孔隙率近似呈线性负相关关系,当孔隙率由0增加到5%时,抗压强度下降幅度最为显著;随着孔隙率的增加,混凝土压缩破坏形式由剪切剥落破坏转变为孔隙导向连通形成柱状劈裂破坏或剪切滑移破坏;当孔隙率达到20%后,试件两端表现为压溃现象,并随着孔隙率的增加,试件端部出现了大块混凝土的破裂滑移,当孔隙达到30%后,试件在应力峰值前均有不同程度的应力跌落现象。另外,当孔隙均为20%时,混凝土抗压强度与弹性模量随着孔隙粒径的增大而减小。试件压缩试验结果验证了近场动力学计算模型的准确性。

Based on the Monte Carlo method,the physical model of random pore structure is generated by MATLAB program,and the crack germination and propagation of macro porous concrete under uniaxial compression are simulated by peri-dynamic programself-made,and the calculation results are compared with the concrete uniaxial compression experiment.The results show that there is a linear negative correlation between the compressive strength and porosity of macro porous concrete,when the porosity increases from 0 to 5%,the compressive strength decreases most significantly.With the increase of porosity,the compression failure mode of concrete changes from shear spalling failure to pore oriented connection,resulting in columnar splitting failure or shear failure.When the porosity reaches 20%,the two ends of the specimen behave as shear failure with the increase of porosity,the fracture slip of large rock appears at the end of the specimen.When the porosity reaches 30%,the specimen has different degrees of stress drop before the peak stress.In addition,when the porosity is 20%,the compressive strength and elastic modulus of rock decrease with the increase of pore size.The accuracy of the model is verified by the compression test results.