针对砂卵石地层中盾构穿越施工的地层变形控制问题，依托北京地铁新建17号线区间隧道上穿既有南水北调东干渠输水隧道工程，通过现场监测和数值模拟方法研究盾构上穿施工的合理掘进参数、特殊新型管片设计、施工前土体注浆预加固、施工后补注浆加固以及填充克泥效产品等措施的地层变形控制效果。研究结果表明： 1）新建地铁盾构的施工引起表层土体沉降，先行线施工通过后应补注浆充足，否则后行线施工将导致地层沉降变形显著增大； 2）深层土体的水平变形随着土层深度的增加由上到下逐渐减小，表层土体水平变形最大； 3）下伏既有东干渠输水隧道结构主要发生竖向隆起变形，基本无水平变形，变形最大值位于交叉点位置； 4）砂卵石地层中严格控制盾构掘进参数、注浆加固等措施，能够有效降低新建盾构隧道上穿施工对既有输水隧道结构变形的影响。
To effectively control the ground deformation induced
by shield tunneling in sandycobble strata, a case study is
conducted on the Beijing metro line 17 crossing above the existing SouthtoNorth water transfer tunnel project, and
the insitu monitoring and numerical simulation methods
are employed to examine the ground deformation control effect of tunneling
parameters, special new segment design, soil grouting prereinforcement, supplemental grouting reinforcement, and clay shock
products filling. The research results show the following: (1) The newlybuilt tunnel induces surface soil subsidence, as a result,
supplemental grouting should be conducted after the first tunnel passes to
avoid dramatic increasing in ground settlement induced by later tunnel
construction. (2) The horizontal deformation of deep soil decreases gradually
from top to bottom with increasing soil depth, and the surface soil deformation
is the largest. (3) Vertical lifting occurs to the lower existing water
transfer tunnel at the intersection of the two tunnels, and basically no
horizontal deformation occurs. (4) In sandycobble
strata, reasonable shield tunneling parameters and grouting reinforcement can
effectively reduce the impact of new shield tunneling on the existing tunnel
structure.
