结合北京地铁四号线西单—灵境胡同渡线隧道工程，利用理论分析、数值模拟等研究手段，研究分析在粉细砂地层中修建大跨隧道时注浆管棚的预支护作用机理、围岩塑性区范围、地表沉降最大值及不同支护条件下的沉降比较，经过实践验证，取得了良好的效果。

Taking XidanLingjing Hutong crossover tunnel on line 4 of Beijing Metro as example, the author, by means of theoretical analysis and numerical simulation, studies on the advance reinforcement mechanism of grouted roof pipes, the scope of the plasticized zones of the ground, the maximum ground surface settlement values and the comparison of the settlement under different reinforcement modes in the construction of largespan tunnels located in fine silt sand ground. The construction practice confirms that the study has achieved good results.