Deformation Control Technology for New Shield Tunneling Overcrossing an Existing Tunnel with Extremely Small Spacing

doi:10.11988/ckyyb.20231220

Abstract

Abstract:

The new shield tunnel for Dongguan Metro Line 1 was constructed with an extremely small clearance of 1.73 meters over the existing Dongguan-Huizhou intercity tunnel. The upper and lower semicircles of the new tunnel are situated in fully and moderately weathered granite, respectively. Moreover, the shield path of the new tunnel encountered residual anchor cables from the existing tunnel, posing a significant threat to the shield operation. To ensure shield operation safety and minimize the impact of new tunnel construction on the existing tunnel, multiple control measures were implemented after specialized research. These measures included optimizing shield excavation parameters through trial interval tunneling and numerical simulation, reinforcing the overburden soil layers with pre-grouting, cutting anchor cables using a newly developed method of “shield stop-silo open-manual cutting”, and conducting in situ displacement monitoring. The construction of the new tunnel was successfully completed, and monitoring data show that displacement control was effective. This paper comprehensively details the construction control technologies used in this project, which should be valuable for similar future projects.

Key words: shield tunnel, granite, existing tunnel, anchor cable, deformation control

CLC Number:

U455

MU Yi-long, ZHOU Xiao-wen, LIU Huai-yu. Deformation Control Technology for New Shield Tunneling Overcrossing an Existing Tunnel with Extremely Small Spacing[J]. Journal of Changjiang River Scientific Research Institute, 2025, 42(2): 122-128.

Figures/Tables 16

Fig.1 Position relationship between Metro Line 1 and the existing Dongguan-Huizhou intercity tunnel

Fig.2 Variation processes of shield tunneling parame-ters and ground surface settlement at test section (right line)

Table 1 Positions of encountered anchor cables

锚索编号	图纸锚索桩号	实际桩号
1^#	ZDK20+142.22	ZDK20+142.62
2^#	ZDK20+143.84	ZDK20+144.13
3^#	ZDK20+145.46	ZDK20+145.75
4^#	ZDK20+147.08	ZDK20+147.20
5^#	ZDK20+148.70	ZDK20+149.12
6^#	ZDK20+149.54	ZDK20+149.51
7^#	ZDK20+150.32	ZDK20+150.56
8^#	ZDK20+151.16	ZDK20+151.38
9^#	ZDK20+152.78	ZDK20+152.65
10^#	ZDK20+154.40	ZDK20+154.53
11^#	ZDK20+156.02	ZDK20+156.18
12^#	ZDK20+157.64	ZDK20+157.88

Table 2 Treatment of 5# and 6# anchor cables

开仓原因	开仓方式	开仓时间	开仓位置	进仓作业人数	开仓作业内容
5^#锚索,里程ZDK20+148.7;6^#锚索,里程ZDK20+149.54。刀盘到达锚索区,出现掘进参数异常,扭矩波动大,掘进速度慢	常压	2021年 12月20日 10:35至 2021年 12月20日 12:01	左线1307 环行程 1 857 mm, 对应刀盘里程 ZDK20+ 150.112	3人	①更换单刃滚刀1把;②用砂轮切割机切断2根掌子面锚索(5^#、6^#)

Fig.3 Photo of cable cutting

Fig.4 Integral three-dimensional finite element model of soil strata and structures

Fig.5 Structural finite element model

Table 3 Physical and mechanical parameters of soil strata

土层名称	重度 $γ$ / (kN·m^-3)	黏聚力 c/ kPa	内摩擦角 $\begin{array}{l} φ / \\ (°) \end{array}$	弹性模量E/ GPa	泊松比 $μ$
①素填土	18.20	10	15	0.015	0.35
②硬塑砂质黏性土	18.64	16	26	0.022	0.33
③全风化花岗岩	19.10	30	28	0.200	0.29
④中风化花岗岩	25.40	400	35	20.000	0.25
⑤微风化花岗岩	25.97	1 200	40	30.000	0.22

Table 3 Physical and mechanical parameters of soil strata

土层名称	重度 $γ$ / (kN·m^-3)	黏聚力 c/ kPa	内摩擦角 $\begin{array}{l} φ / \\ (°) \end{array}$	弹性模量E/ GPa	泊松比 $μ$
①素填土	18.20	10	15	0.015	0.35
②硬塑砂质黏性土	18.64	16	26	0.022	0.33
③全风化花岗岩	19.10	30	28	0.200	0.29
④中风化花岗岩	25.40	400	35	20.000	0.25
⑤微风化花岗岩	25.97	1 200	40	30.000	0.22

Table 4 Physical and mechanical parameters of structures

材料名称	弹性模量 E/GPa	重度 $γ$ / (kN·m^-3)	泊松比 $μ$	厚度或直径/mm
盾壳	212.0	76.93	0.16	40
管片	29.3	24.40	0.25	350
既有隧道内立柱	34.5	25.00	0.22	600

Table 4 Physical and mechanical parameters of structures

材料名称	弹性模量 E/GPa	重度 $γ$ / (kN·m^-3)	泊松比 $μ$	厚度或直径/mm
盾壳	212.0	76.93	0.16	40
管片	29.3	24.40	0.25	350
既有隧道内立柱	34.5	25.00	0.22	600

Fig.6 Layout of cross-sectional surface settlement monitoring points

Fig.7 Plane layout of automatic monitoring section of existing tunnel settlements

Fig.8 Layout of automatic laser measuring points in existing tunnels

Fig.9 Installation of track bed (rail surface) and side wall monitoring points

Fig.10 Surface settlement trough at the area of shield tunnel overcrossing the existing tunnel

Fig.11 Numerically calculated vertical displacement of No.15-15 section of the existing tunnel

Fig.12 Vertical displacement processes of the left and right line monitoring points of the existing tunnel

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