深厚软土层盾构近距下穿既有隧道沉降控制研究  

Study on Settlement Control of Shield Tunnel Under-passing Existing Subway at Close Range in Deep and Thick Soft Ground Layers

作　　者：李端[1] 姜和远 李盼盼 钱磊雄 吴联棒 Li Duan;Jiang Heyuan;Li Panpan;Qian Leixiong;Wu Lianbang(China Railway First Group Co.,Ltd.,Ningbo 315100,Zhejiang,China;Institute of Rock Mechanics,Ningbo University,Ningbo 315211,Zhejiang,China)

机构地区：[1]中铁一局集团有限公司,浙江宁波315100 [2]宁波大学岩石力学研究所,浙江宁波315211

出　　处：《科技通报》2024年第12期84-90,共7页Bulletin of Science and Technology

摘　　要：新建地铁近距下穿时会引起既有隧道结构和地表的不均匀沉降,严重时会影响地铁运营及周边建筑安全,这种现象在深厚软土层中更为显著。本文依托宁波轨道交通8号线近距下穿5号线工程,通过数值模拟分析了地表及既有隧道拱顶沉降规律,并结合现场试验提出了近距下穿的沉降控制措施。主要结论有:(1)下穿既有隧道时地面及拱顶沉降均逐渐增大,但变化率呈现先增大后减小规律,沉降主要发生在下穿开始至离开既有隧道2D区段;(2)既有隧道地表及拱顶沉降最大值分别是6.95 mm和4.42 mm,既有隧道地表最终沉降约为拱顶的1.57倍,与实测结果接近,最大沉降位置会向后续下穿隧道偏移;(3)盾构技术参数是控制沉降的关键因素,由现场试验可知,其近距下穿盾构施工参数宜设定为:土仓压力1.97~2.03 bar,推进速度10~20 mm/min,盾构推力1500~1600 t;(4)盾尾空隙是引起地层沉降的主要因素,宜设定同步注浆量2.0~2.2 m^(3),注浆压力0.25~0.3 MPa,在管片脱出盾尾后进行二次注浆和深层注浆加固。The new subway will cause the uneven settlement of the existing tunnel structure and ground surface,which will seriously affect the subway operation and the safety of the surrounding buildings,and this phenomenon is more significant in the deep soft soil layer.This paper relies on the Ningbo Railway Line 8 under-passing Line 5 project,through numerical simulation to analyze the ground surface and the existing tunnel vault settlement law,and combined with the field test to put forward the settlement control measures for under-passing in close proximity.The main conclusions are:(1)The ground and vault settlement gradually increase when going through the existing tunnel,but the rate of change shows the law of increasing first and then decreasing,and the settlement mainly occurs at the beginning of going through and leaving the existing tunnel in the 2D section;(2)The maximum settlement of the ground surface and the vault of the existing tunnel is 6.95 mm and 4.42 mm,respectively,and the final settlement of the ground surface of the existing tunnel is 1.57 times of that of the vault,which is close to the measured results,and the maximum settlement location will move to the subsequent tunnel;(3)The shield technical parameters are the key factors to control the settlement,and it is known from the field test that it is appropriate to set the construction parameters of its proximity downward penetrating shield:soil chamber pressure of 1.97-2.03 bar,propulsion speed of 10-20 mm/min,shield thrust 1500-1600 t;(4)The shield tail gap is the main factor to cause the settlement of the stratum,it is appropriate to set the synchronized grouting volume of 2.0 to 2.2 m^(3),grouting pressure 0.25-0.3 MPa,and carry out secondary grouting and deep grouting reinforcement after the tube sheet is taken off the shield tail.

关 键 词：深厚软土层 盾构近距下穿 既有隧道 数值模拟 沉降控制 现场试验 

分 类 号：U455[建筑科学—桥梁与隧道工程]