喷射混凝土力学性能试验研究及预测模型建立

以喷射混凝土单层永久衬砌隧道为背景,采用干喷大板法,开展喷射混凝土力学性能试验。以宝鸡至兰州高速铁路麦积山隧道衬砌喷射混凝土配合比为基础,考虑水胶比、粉煤灰和钢纤维影响,研究喷射混凝土抗压强度和劈裂抗拉强度经时变化规律,建立相应的预测模型。结果表明:喷射混凝土早龄期强度较高。随着龄期增大,同配合比模筑混凝土强度增大并超过喷射混凝土,且二者差值逐渐增大。水胶比增大及钢纤维掺量减小,喷射混凝土强度减小;随粉煤灰掺量增大,强度先增大后减小。采用13组数据对抗压强度模型进行验证,其相对偏差的标准差为5. 55,说明模型具有较好的适用性。喷射混凝土抗压强度和劈裂抗拉强度均呈正态分布,且二者之间呈指数关系。

Study on Mechanical Properties and Prediction Model Establishing of Dry-mix Shotcrete

As background of shotcrete single layer lining tunnel,mechanical properties of shotcrete were investigated by using dry-mix method.Based on the shotcrete mixture of Maijishan Mountain tunnel on high-speed railway from Baoji to Lanzhou,the time-dependent of compressive and splitting tensile strength were studied in term of water-binder ratio,dosage of fly ash and steel fiber content.After that,the strength prediction model of compressive and splitting tensile strength were established.The results show that shotcrete has higher strength at early hydration age.With curing age increased,the strength of formed concrete is over shotcrete and the difference also increases.The strength increases with w/b increased and steel fiber content decreased,and that is first increased and then decreased with dosage of fly ash increased.Compressive and splitting tensile strength are obey normal distribution.Moreover,there has exponential distribution between compressive strength and splitting tensile strength.