为研究高铁隧道全断面机械化施工下围岩的稳定性，优化初期支护参数，首先，以黄(冈）黄（梅）高速铁路刘元隧道为依托工程，通过岩石常规三轴试验获得准确可信的数值计算参数； 其次，采用强度折减法求解依托工程的安全系数，以安全系数作为评价指标，评价围岩的稳定性； 再次，以拱顶沉降位移及边墙收敛位移作为评价围岩稳定性的定量指标，对依托工程进行支护参数优化研究，得到适用于依托工程的合理初期支护参数； 最后，通过现场监测数据对隧道围岩的稳定性进行验证。结果表明： 1）双线高速铁路隧道全断面机械化开挖时围岩具有良好的自稳能力，且在强度折减法分析中，拱顶沉降及边墙收敛对折减系数变化较为敏感； 2）可将拱顶沉降及边墙收敛作为评价指标，得到适用于依托工程的初期支护优化参数； 3）现场监测数据验证了优化后支护参数的安全性和合理性。

To study the stability of surrounding rock and support parameter optimization under fullface mechanization of highspeed railway tunnels, accurate and credible numerical calculation parameters are obtained through routine rock triaxial tests based on the Liuyuan tunnel of the HuanggangHuangmei highspeed railway. Under engineering conditions, the strength reduction method is used to numerically calculate the safety factor, which is used as an evaluation index for the stability of surrounding rock. Additionally, the crown settlement and sidewall convergence displacements are taken as quantitative indicators to evaluate the stability of the surrounding rock. Further, the optimization of the supporting parameters of the supporting project is performed, and the reasonable primary supporting parameters suitable for the supporting project are obtained. Finally, the stability of the surrounding rock with the optimized support parameters is verified using onsite monitoring data. The following results are obtained. (1) The fullface mechanized excavation of the doubletrack highspeed railway tunnel has a good selfstabilizing ability, and the crown settlement and sidewall convergence are sensitive to the change in reduction coefficient. (2) The crown settlement and sidewall convergence can be used as evaluation indicators to obtain the optimal support parameters suitable for supporting projects. (3) The onsite monitoring data verify the rationality of the optimized support parameters.