摘要
钢纤维混凝土是一种常用的喷层支护材料,其抗弯性能的强弱是决定喷层材料是否发生开裂的重要因素之一。目前,钢纤维混凝土抗弯性能测试采用的试样多以浇筑成型方法获取。为了更真实地反映工程中处于真实工作状态的喷射混凝土的抗弯性能,采用工程现场原位取样、室内切割加工成型的方法制作试样,并采用四点弯曲试验的方法进行抗弯性能测试。基于抗弯强度和残余抗弯强度试验结果,发现取样取自不同区域时,上述强度指标有所差异。通过试样的钢纤维含量分析,发现钢纤维含量与试件的抗弯强度总体上呈线性正相关关系,钢纤维的含量是导致喷射混凝土抗弯强度差异的重要因素。进一步与既有文献的混凝土抗弯强度测试成果对比分析,发现基于原位取样获得的混凝土抗弯强度值,在整体上要小于采用浇筑成型方法制作试样获得的抗弯强度。认为采用原位取样方法获得试件更能反映地下洞室喷混凝土结构的实际工作性态。
Fiber reinforced concrete is a commonly used shotcrete support material in underground engineering.The bending strength of the fiber reinforced concrete is an important factor that determines whether the spray layer cracks or not.Currently,the bending properties of fiber reinforced concrete are usually obtained by test samples prepared in laboratory by pouring and direct molding method.In order to study the actual bending performance of shotcrete in practical engineering,bending test samples were made following a new two-step procedure.The first step was to collect in-situ shotcrete blocks and the second step was to cut the blocks into samples complying with required dimensions for bending test.The four-point bending test method was used to study the bending strength and residual bending strength of these samples.The results showed that the bending strength and residual bending strength of samples collected from different parts of the underground cavern were different.Based on analyzing the steel fiber content,it was found that the steel fiber content had a linear positive relationship with the bending strength,which meant the variation of the steel fiber content was an important factor that led to the difference of bending strength of the shotcrete.Further analysis on current literature regarding bending strength tests showed that concrete bending strength magnitudes based on the proposed method were generally lower than those prepared by pouring and direct molding method.It reveals that the proposed method demonstrates more realistic results because it considers the practical working conditions of shotcrete.
作者
马雨峰
黄书岭
王兰普
吕风英
孔张宇
何军
MA Yufeng;HUANG Shuling;WANG Lanpu;LYU Fengying;KONG Zhangyu;HE Jun(HebeiFengning Pumped Storage Co.,Ltd,Chengde 068350,China;Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan 430010,China)
出处
《人民长江》
北大核心
2021年第1期190-195,共6页
Yangtze River
基金
国家自然科学基金重点项目(51539002)
国家自然科学基金面上项目(51779018,51979008)
中央级公益性科研院所基本科研业务费项目(CKSF2019434/YT)。
关键词
抗弯性能
喷射混凝土
钢纤维混凝土
四点弯曲试验
bending performance
shotcrete
steel fibre reinforced concrete
four-point bending test
