矿井喷射混凝土抗压强度的现场试验研究

Field test study on compressive strength of shotcrete in mine

为真实还原混凝土的喷射工艺和养护环境,通过在井下现场将施工用的喷射混凝土制成标准试块,开展不同龄期条件下的单轴压缩试验,测定煤矿真实环境下的喷射混凝土强度参数。试验结果表明,喷射混凝土24 h早期抗压强度随时间呈指数式增长规律,前期增长缓慢、后期增长迅速,24 h强度终值为3.68 MPa,占设计强度的18.4%;现场试验测得的喷射混凝土28 d抗压强度数据离散性小,强度最大值为28.2 MPa,最小值为25.2 MPa,平均为26.6 MPa,是设计强度的106.4%;现场测试得到的喷射混凝土抗压强度与实验室测试结果存在0.8%~3.3%的差异,前者更接近真实值。试验方法为获取喷射混凝土真实强度提供了一条理想的途径。

In order to truly restore the shotcrete process and curing environment,the shotcrete used for construction is made into standard test blocks at the underground site,and the uniaxial compression test under different age conditions is carried out to determine the strength parameters of shotcrete under the real environment of the coal mine.The test results show that the 24 hours early compressive strength of shotcrete increases exponentially with time,with slow growth in the early stage and rapid growth in the late stage.The final 24 hours strength is 3.68 MPa,accounting for 18.4% of the design strength.The 28 days compressive strength data of shotcrete measured in the field test have little dispersion,the maximum strength is 28.2 MPa,the minimum strength is 25.2 MPa,and the average strength is 26.6 MPa,which is 106.4% of the design strength.The compressive strength of shotcrete obtained in the field test is 0.8%~3.3% different from the laboratory test results,and the former is closer to the true value.The test method provides an ideal way to obtain the real strength of shotcrete.