中文摘要：

顶管始发与到达时的端头土体加固是隧道施工成败的关键。对现有的滑移失稳理论做出改进,得出了端头土体纵向加固厚度大于洞口高度时的稳定系数计算公式;使用三维有限元数值模拟,计算拔除洞口H型钢支护和机头穿越加固区后的端头土体地表沉降;最后采用正交试验法分析了纵向加固厚度、加固强度和上覆土厚度3种因素对端头土体加固效果影响的主次关系。结果表明：覆土厚度和加固强度对端头土体地表最大沉降值影响并不显著,而加固厚度对其影响很大,增加端头土体的纵向加固厚度可有效减小地表最大沉降值;覆土厚度与端头土体稳定系数呈负相关,加固厚度和加固强度与端头土体稳定系数呈正相关。

英文摘要：

The end soil reinforcement of pipe jacking launching and arrival is the key to successful tunnel construction.In this paper,the formula of stability coefficient is given when the longitudinal thickness of reinforced soil is greater than the height of the tunnel entrance,which is an improvement for the existing sliding instability theory; and then three dimensional FEM is used to calculate the surface settlement when the H-steel support is removed and when the shield crossed the reinforced area. Finally,the orthogonal experiment method is adopted to analyze the influence of longitudinal thickness of reinforced soil,the strength of reinforced soil and the thickness of cover on reinforcement effect of end soil.The results show that： 1） The thickness of cover and the strength of reinforced soil affect the maximum ground surface settlement slightly; but the thickness of reinforced soil affects the maximum ground surface settlement greatly. 2） The maximum ground surface settlement can be reduced by increasing the longitudinal thickness of end soil. 3） The thickness of cover is negatively correlated to the stable coefficient of end soil; and the thickness of reinforced soil and strength of reinforced soil is positively correlated to the stable coefficient of end soil. The results can provide an effective way to decide the scheme of end soil reinforcement in the future.