纤维尺寸效应对深井井壁衬砌支护层力学特性的影响  

Influence of fiber size effect on mechanical properties of deep shaft linerconcrete

作　　者：汪小东[1] 王勇兵 方旭刚 李地元[3] 蒋京泰 王蜜蜜 WANG Xiaodong;WANG Yongbing;FANG Xugang;LI Diyuan;JIANG Jingtai;WANG Mimi(CINF Engineering Co.Ltd.,Changsha 410019,China;Yunnan Chihong Zn&Ge Co.Ltd.,Qujing 655011,Yunnan,China;School of Resources and Safety Engineering,Central South University,Changsha 410083,China)

机构地区：[1]长沙有色冶金设计研究院有限公司,长沙410019 [2]云南驰宏锌锗股份有限公司,云南曲靖655011 [3]中南大学资源与安全工程学院,长沙410083

出　　处：《矿冶》2024年第2期173-180,共8页Mining And Metallurgy

基　　金：国家自然科学基金资助项目(52074349);国家重点研发计划项目(2016YFC0801605)。

摘　　要：为探究纤维尺寸效应对深井井壁钢纤维混凝土力学特性及应变演化的影响,设计三种不同钢纤维尺寸和掺量的混凝土配方,通过测试试样的力学特性后得知,随着钢纤维尺寸、掺量的增加,试样单轴抗压强度、抗拉强度、抗折强度以及弹性模量提升。借用数字图像相关技术对试验过程监测发现,钢纤维的加入使得试样破坏时表面裂纹数量、长度远大于素混凝土试样,随着钢纤维尺寸的增加,试样破坏时试样表面裂纹宽度有所下降,混凝土试样的轴向变形降低。当试样到达峰值荷载时,素混凝土迅速失稳破坏,而钢纤维混凝土试样在到达峰值荷载时仍然存在一定残余强度。运用随机森林模型对钢纤维混凝土测试强度进行训练、测试与预测,结果表明训练、测试、预测样本精度较高,R 2>0.8,均方根误差值较小,改进随机森林模型对钢纤维混凝土强度的预测较精确,利用此预测模型,可大幅度降低优化钢纤维混凝土配方所需要的人力与物力成本,结果可为现场混凝土配方强度预测提供参考。To explore the impact of fiber size effect on the mechanical properties and strain evolution of deep shaft liner steel fiber reinforced concrete,three concrete formulations with different steel fiber sizes and admixtures were designed.After testing the sampl′s tensile and compressive mechanical properties,it was found that with the increase of steel fiber size and admixtures,the uniaxial compressive strength,tensile strength,flexural strength,and elastic modulus of the samples increased.Using non-contact digital image correlation technology to monitor the damage process of the sample,it was found that the addition of steel fibers significantly increased the number and length of surface cracks when the sample was damaged,compared to plain concrete samples.With the increase in the size of steel fibers,the width of surface cracks decreased when the sample was damaged,and the axial deformation of the concrete sample decreased.When the sample reaches the peak load,the plain concrete loses its stability quickly and is damged,while the steel fiber concrete sample still has a certain residual strength when it reaches the peak load.Then,the random forest model is used to train,test,and predict the testing strength of steel fiber concrete.The results show that the training,testing,and prediction accuracy of the samples is high,with the R 2>0.8,and the root mean square error value is small.This indicates that the improved random forest model is more accurate in predicting the strength of steel fiber concrete.Using this prediction model,the labor and material costs required for optimizing the steel fiber concrete formula can be greatly reduced,it can provide a reference for predicting the strength of concrete formulations in on-site application.

关 键 词：纤维尺寸 深井 井壁 钢纤维 混凝土 抗拉强度 数字图像相关 力学特性 随机森林 

分 类 号：TU528.572[建筑科学—建筑技术科学] TD35[矿业工程—矿井建设]