温湿耦合作用下喷射混凝土孔隙结构与强度试验研究

Experimental Study on Pore Structure Characteristics and Strength of Shotcrete under Coupling Effect of Temperature and Humidity

为分析隧洞围岩温度和洞室环境湿度对喷射混凝土细观孔隙结构特征及单轴抗压强度的影响,采用室内CT扫描和无侧限压缩试验的方法,测试不同围岩温度、湿度条件下喷射混凝土细观孔隙结构的分布特征和单轴抗压强度,建立基于细观结构参数的喷射混凝土单轴抗压强度预测模型。研究结果表明:1)低湿环境(湿度25%)下,高岩温诱发喷射混凝土孔隙结构和力学性能劣化,温度越高劣化影响越显著,喷射混凝土单轴抗压强度可采用Schiller模型预测;2)高湿环境(湿度95%)下,60℃岩温是喷射混凝土力学性能和孔隙结构特征发生劣化转变的临界温度;3)引入相对湿度影响系数建立的高湿环境喷射混凝土抗压强度预测模型,其预测结果与试验结果较吻合。

In order to analyze the influence of surrounding rock temperature and humidity on the micro pore structure characteristics and uniaxial compressive strength of shotcrete,indoor CT scanning and unconfined compression test are carried out,and the prediction model of uniaxial compressive strength of shotcrete is established based on micro structural parameters.The results show that:(1)Under the low humidity environment(with humidity of 25%),high rock temperature induces the deterioration of shotcrete pore structure and mechanical properties,and the higher the temperature,the more obvious the effect of deterioration;the uniaxial compressive strength of shotcrete is predicted by Schiller model.(2)Under the high humidity environment(with humidity of 95%),60℃rock temperature is the critical temperature for deterioration of mechanical properties and pore structure characteristics of shotcrete.(3)The prediction model of compressive strength of shotcrete in high humidity environment is established by introducing the influence coefficient of relative humidity,of which the prediction results are in good agreement with the test results.