针对土砂互层隧道易出现大变形问题，以浩吉铁路阳城隧道为例，通过分析大变形原因、围岩预加固和逐榀换拱等方面，对大变形控制技术进行研究，最后以现场监测结果对大变形段的施工效果进行评价。研究结果表明： 1）土砂互层地层围岩性质差，围岩强度不均导致应力集中、偏压以及施工针对性不足等是隧道大变形发生的主要原因。2）围岩压力和格栅钢架应力总体表现为前期波动变化、后期逐步趋于稳定的变化趋势，而喷射混凝土则表现为明显的迅速增长、增长放缓和逐渐稳定3个阶段。围岩压力和支护结构受力变化范围均处于安全状态。3）大变形段支护结构的材料性能未被充分利用。喷射混凝土的最大压应力为1 523 kPa，为混凝土极限强度的6.3%；格栅钢架最大压应力值为24 553 kPa，是其极限强度的6.1%。4）对大变形段进行整治后的围岩压力为0~85 kPa，喷射混凝土应力为-2 400~420 kPa，钢架应力为-33 000~1 600 kPa，表明隧道结构处于稳定状态且具有较大的安全储备。隧道现场试验结果表明，本文提出的大变形控制技术对整治土砂互层隧道的大变形问题具有较大的可行性。

When tunneling in soilsand interbeded strata, large deformation often occurs. Hence, the causes and control techniques (such as surrounding rock prereinforcement and arch replacement) of large deformation of Yangcheng tunnel of HaolebaojiJi′an railway are studied. The site monitoring results are used to evaluate the control effect of large deformation section. The research results show the following: (1) The poor properties of soilsand interbeded surrounding rock and uneven strength would cause stress concentration and asymmetrical pressure, and improper countermeasures are adopted, which are the main causes of large deformation. (2) The pressure of surrounding rock and the stress of grid steel frame generally show a fluctuation in the early stage and stabilization in the late stage trend, whereas the shotcrete shows obvious rapid growth, slow growth, and stabilization trend. The variation range of the pressure of surrounding rock and the stress of supporting structure is within the safe state. (3) The material properties of the support structure in large deformation section are not fully utilized. The maximum compressive stress of shotcrete is 1 523 kPa, which is 6.3% of the ultimate strength, and that of grid steel frame is 24 553 kPa, which is 6.1% of the ultimate strength. (4) After the treatment of the large deformation section, the pressure of surrounding rock varies in the range of 0 ~ 85 kPa, the shotcrete stress varies in the range of -2 400 ~ 420 kPa, and the steel frame stress varies in the range of -33 000 ~ 1 600 kPa, indicating that the tunnel structure is in a stable state with large safety reserve. The monitoring results show that the control techniques of large deformation proposed is feasible in controlling the large deformation of tunnel in soilsand interbedded strata.