摘要
为探究土石交界地层双侧壁导坑法施工围岩变形与压力分布规律,通过现场监测对白塔山隧道围岩压力与收敛沉降变形进行研究分析。结果表明:下台阶施工易导致拱腰和拱脚围岩压力产生突变,最大增量可达70%,而对拱肩影响较小;相较于岩石地层,黄土层稳定性差,更易受隧道施工扰动影响导致围岩变形大、稳定距离长,黄土层稳定距离比岩石层长4~9 m;土石交界地层围岩压力呈现快速增加→缓慢增加→逐渐稳定的变化趋势,在快速增长阶段岩石层荷载释放率高达80%,大于黄土层荷载释放率;断面围压分布呈现出明显的不对称性,表现为“黄土侧大,岩石侧小”的分布规律。因此,双侧壁导坑法下穿土石交界地层时,建议在下台阶工序交替时保留部分土体进行反压控制,并提高下台阶锚杆布设密度,黄土层应做好超前支护预加固,并提高初期支护强度。
In order to explore the law of deformation and pressure distribution of the surrounding rock in the construction of the double side heading method in the soil-rock boundary layer,the surrounding rock pressure and convergent settlement deformation of the Baitashan Tunnel were studied and analyzed through on-site monitoring.The results show that the construction of lower steps will easily lead to sudden changes in the surrounding rock pressure of the arch waist and arch foot,and the maximum increase can reach 70%,but the impact on the spandrel is small.Compared with rock formations,the loess layer is less stable and more susceptible to tunnel construction.The influence of the disturbance leads to large deformation of the surrounding rock and a long stable distance.The stable distance of the loess layer is 4~9 m longer than that of the rock layer.The release rate is 80%higher than the load release rate of the loess layer.The distribution of confining pressure on the section presents an obvious asymmetry,showing the distribution law of"the loess side is large and the rock side is small".Therefore,when the double side heading method is used to penetrate the soil-rock boundary stratum,it is recommended to retain part of the soil for back pressure control when the steps are alternated,and to increase the density of anchor bolts at the lower steps.The loess layer should be pre-reinforced with advanced support,and increase the initial support strength.
作者
段旭晗
张明礼
蒋春海
郑钊
马昭
DUAN Xuhan;ZHANG Mingli;JIANG Chunhai;ZHENG Zhao;MA Zhao(College of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Shanghai Municipal Engineering Design Research Institute(Group)Co.,Ltd.,Shanghai 200092,China;Shanghai Municipal Engineering Design Research Institute Group Tenth Municipal Design Institute Co.,Ltd.,Lanzhou 730000,China)
出处
《甘肃科学学报》
2024年第3期114-121,145,共9页
Journal of Gansu Sciences
基金
甘肃省高等学校产业支撑计划项目(2020C-40)。
关键词
隧道工程
土石交界地层
现场监测
围岩压力
控制措施
Tunnel engineering
Soil-rock boundary layer
Field monitoring
Surrounding rock pressure
Control measures
