基于均匀设计的高地温隧洞衬砌混凝土抗压强度影响规律研究

Study on the influence of high temperature tunnel lining concrete on its compressive strength based on uniform design

以分析高地温隧洞环境对衬砌混凝土性能的影响规律为目标,采用高地温湿度养护箱模拟高地温隧洞中的温湿环境,进行衬砌混凝土的养护,利用均匀设计的试验方法获得较为全面的试验数据,通过回归分析得到不同养护龄期的回归方程,归纳出温度、水胶比、砂率三个主要因素对衬砌混凝土单轴抗压强度的影响规律。结果表明:通过回归方程,温度、水胶比及砂率均可找到一个最优值(如水胶比为0.42、砂率为45%、养护温度为57℃)使得衬砌混凝土的单轴抗压强度达到最大值;随养护温度的升高,最大衬砌混凝土单轴抗压强度对应的水胶比及砂率均有所增大,如养护龄期为28 d时,水胶比为0.31(养护温度55℃)、0.52(养护温度115℃)。因此,混凝土养护温度较高时,应适当增大水胶比及砂率。

In order to analyze the impact of high ground temperature tunnel on the concrete performance,high/low temperature humidity curing box is adopted for simulating the thermal and humid environment inside of tunnel under high ground temperature and carrying out the curing of the lining concrete,and then more comprehensive testing data are obtained with the testing method of the uniform design. Furthermore,the regression equations for different curing ages are got through the relevant regression analyses,from which the laws of the impacts from the factors,i. e. temperature,water-cement ratio and sand percentage,on the uniaxial compression strength of the lining concrete are summed up. The result shows that an optimal value for each of the temperature,the water-cement ratio and sand percentage can be found out through the regression equations（ e. g. water-cement ratio is to be 0. 42,sand percentage is to be 45% and curing temperature is to be 57 ℃）,and thus make the uniaxial compression strength of the lining concrete reach to its maximum value. Along with the rise of the curing temperature,both the water-cement ratio and the sand percentage corresponding to the maximum uniaxial compression strength of the lining concrete are somewhat increased;for instance,the water-cement ratio is to be 0. 31（ the curing temperature of 55 ℃） and 0. 52（ the curing temperature of 115℃）,when the curing age is 28 d. Therefore,when the curing temperature is higher,both the water-cement ratio and the sand percentage must be appropriately increased as well.