为探究隧道初期支护喷射混凝土孔隙渗透作用下钙析出规律与水环境改变特征，考虑隧道排水路径和加压渗透作用，研制隧道初期支护喷射混凝土钙析出与水环境变化试验装置，开展隧道初期支护喷射混凝土加压渗透试验，分析围岩水渗流作用下喷射混凝土渗透断面酸碱度分布特征，明确初期支护水钙离子体积质量与水质参数的时间历程变化规律，并与文献对比验证了装置的可靠性与试验结果的正确性。研究表明： 1）该试验装置由围岩水密封加压仓、初期支护喷射混凝土试件仓和排水管回液仓组成，可实现200 kPa加压渗透下初期支护喷射混凝土钙析出与水环境变化的模拟。2）渗流断面内喷射混凝土pH值降低，钙流失明显，钙析出流失引起的喷射混凝土劣化呈不均匀性。3）喷射混凝土渗透作用下初期支护水呈现高钙离子体积质量（大于100 mg/L）、高碱性（大于3 000 mg/L）、高pH值（大于11.5）和高可溶解性固体总量（大于8×10-6 mg/L）特征； 其钙离子体积质量与水质参数均经历1~4 h极速增大、4~18 h短暂稳定、18~68 h波动下降及68 h后基本稳定4个发展阶段，各阶段变化特征与试验开始时间、渗透水量与钙离子结晶沉淀相关。

To investigate the calcium precipitation and change characteristics of water environment during pore infiltration into the shotcrete of tunnel primary support shotcrete, a test device is developed considering the tunnel drainage path and pressurized infiltration. A pressurized infiltration test is conducted on the shotcrete to determine the distribution of acidity and alkalinity under water infiltration into the surrounding rock. The change laws of the time course of the calcium ion concentration and water quality parameters of the primary support are determined and the results are verified by comparison with the literature to validate the reliability of the device. The following conclusions are drawn from the test results. (1) The developed test device comprises a watersealed pressure chamber placed in the surrounding rock, a specimen chamber placed in the shotcrete of the primary support, and a drain pipe as a return chamber. The device can simulate calcium precipitation and changes of water environment of the shotcrete of the primary support under 200kPa pressurized infiltration. (2) Lower the pH of the shotcrete in the seepage crosssection, leads to more severe calcium loss. The loss of calcium by precipitation deteriorates the shotcrete unevenly. (3) The primary support water under the action of shotcreting has high calciumion concentration (greater than 100 mg/L), high alkalinity (greater than 3 000 mg/L), high pH (greater than 11.5), and high total dissolved solids (greater than 8×10-6 mg/L); There are four stages in the development of the calcium ion concentration and water quality parameters: a rapid rise in the first four hours, shortterm stability during 4 to 18 h, fluctuating decline in 18 to 68 h, and stability after 68 h. The change characteristics of each stage are related to the start time of the experiment, the quantity of infiltrated water, and the precipitation of calciumion crystals.