为探究粉土或粉质黏土地层中管幕法+CRD法隧道施工对地表或管线沉降的影响规律,依托郑州地铁3号线中州大道站出入口通道工程,对施工全过程进行分析。研究表明: 1)管幕法+CRD法隧道施工大致分为6个阶段,其中管幕施工对地表沉降的影响最为显著; 2)管幕顶推导致地表沉降的影响范围超过3倍隧道跨度,地层损失率超出3%; 3)3次地表注浆导致的地表抬升量分别占总抬升量的22.43%、28.25%、49.32%,注浆结束后回落量分别占每次抬升量的19.62%、23.03%、5.86%; 4)全断面注浆导致地表隆起的影响范围从隧道轴线向两侧扩展到1.6倍隧道跨度。建议管幕顶推时钢套筒壁后应及时注浆,并应实时调整注浆压力和配比;上半断面注浆率应根据地表沉降变化趋势在本工程注浆率的基础上适当下调,下半断面注浆率可以采用本工程建议值;各导洞开挖面应间隔约1倍隧道高度;地层加固施工时注浆率不建议超过6%。
Data collected
from the entire tunneling process of the passageway project at the portal of
Zhongzhou avenue station on Zhengzhou metro line 3 are analyzed to investigate
the influence of tunnel in silty or silty clay strata constructed by pipe roof
and cross diaphragm(CRD) methods on settlement of surface or pipelines. Results
reveal the following: (1) Tunneling by pipe roof and CRD methods can be roughly
divided into six stages. The influence of pipe roofing on the surface
settlement is the most significant. (2) The influence range of surface
settlement caused by pipe roofing is more than three times the tunnel span, and
the stratum loss rate is more than 3%. (3) Surface uplifts caused by three
times of surface grouting reinforcement account for 22.43%, 28.25%, and 49.32%
of the total uplift, respectively, and the surface falling back amounts after
each grouting account for 19.62%, 23.03%, and 5.86% of each uplift,
respectively. (4) The influence range of surface uplift caused by fullface
grouting ranges from the tunnel axial line to both sides (as much as 1.6 times
the tunnel span). Therefore, it is suggested that grouting should be timely
synchronized behind the wall of the steel sleeve, the grouting pressure should
be strictly controlled to prevent pipe blocking, the grouting rate of the upper
haft crosssection should be reasonably adjusted
according to surface settlement, the grouting rate of the lower haft crosssection can adopt the recommended values, the excavation face of
each guide tunnel should be spaced about one times the tunnel height, and the
grouting rate should not exceed 6% during the construction of strata reinforcement.