基坑开挖旁侧盾构隧道结构横向受力与变形研究

陈仁朋; 刘慕淳; 孟凡衍; 李忠超; 吴怀娜; 程红战

doi:10.11779/CJGE20211420

基坑开挖旁侧盾构隧道结构横向受力与变形研究 English Version

陈仁朋^{1, 2,},
刘慕淳^{1, 2},
孟凡衍^{1, 2, ,},
李忠超³,
吴怀娜^{1, 2},
程红战^{1, 2}

1.
湖南大学土木工程学院, 湖南长沙 410082
2.
湖南大学建筑安全与节能教育部重点实验室, 湖南长沙 410082
3.
武汉市市政建设集团有限公司, 湖北武汉 430023

基金项目:

国家自然科学基金项目 52090082

国家自然科学基金项目 51938005

博士后科学基金面上项目 2020M672489

武汉市市政建设集团有限公司隧道工程公司科研课题

湖湘高层次人才聚集工程创新团队项目 2019RS1030

详细信息

作者简介:
陈仁朋(1972—)，男，博士，教授，主要从事城市地下空间和交通岩土工程方面的研究工作。E-mail: chenrp@hnu.edu.cn

通讯作者:
孟凡衍, E-mail: fymeng@hnu.edu.cn

中图分类号: TU432
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出版历程
- 收稿日期: 2021-11-29
- 网络出版日期: 2023-02-03
- 发布日期: 2021-11-29
- 刊出日期: 2022-12-31

Circumferential forces and deformations of shield tunnels due to lateral excavation

CHEN Renpeng^{1, 2,},
LIU Muchun^{1, 2},
MENG Fanyan^{1, 2, ,},
LI Zhongchao³,
WU Huaina^{1, 2},
CHENG Hongzhan^{1, 2}

1.
College of Civil Engineering, Hunan University, Changsha 410082, China
2.
Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education, Hunan University, Changsha 410082, China
3.
Wuhan Municipal Construction Group Company Limited, Wuhan 430023, China

摘要

摘要: 针对基坑开挖旁侧盾构隧道结构横向受力和变形规律，提出了一种考虑围护结构变形影响的盾构隧道横向受力理论计算方法，并通过某实际工程三维有限元计算结果和干砂地层隧道旁侧基坑开挖离心模型试验结果，验证了隧道径向附加荷载理论计算方法的可靠性。结合该工程获取的围护桩水平位移、地表沉降、隧道变形和应变现场实测数据，探究了隧道横向受力-变形-内力之间的关联机制。结果表明：①隧道初始径向荷载呈“葫芦形”对称分布，侧方开挖引起隧道近基坑侧和拱顶外荷载减小，而远基坑侧和拱底外荷载增大，这与开挖引起的自由场地层位移和隧道位移相对大小有关，水平和竖向不均衡荷载由隧道纵向差异变形引起的环间剪切力平衡。②隧道椭圆形变形、朝基底方向的顺时针旋转角度和正负弯矩值随开挖不断增大。③隧道环向弯矩分布与螺栓相对位置关系密切相关，研究断面处近基坑侧拱腰附近存在螺栓，其将承担更多的环向拉应力；远基坑侧拱腰附近为混凝土管片，环向拉应力主要由管片承担，从而使得研究断面处隧道管片最大环向弯矩发生在远基坑侧拱腰位置。
- 深基坑 /
- 旁侧盾构隧道 /
- 横向受力 /
- 变形 /
- 弯矩
Abstract: To investigate its transverse forces and deformations subjected to lateral excavation, a theoretical approach for estimating the transverse forces of a shield tunnel considering the influences of deflections of retaining wall proposed. The calculated radial additional loads on the tunnel is compared with the results of three-dimensional finite element analysis of a case history and centrifuge modeling of excavation effects on a nearby existing tunnel in dry sand, which verifies the reliability of this approach. Based on the measured pile deflections, ground settlements, tunnel deformations and structural strains from this case history, the interaction mechanisms of the transverse forces, deformations and internal forces of the tunnel are analyzed. The results show that: (1) The initial radial loads on the tunnel are symmetrically distributed in a "gourd shape". The lateral excavation results in the decrease in the loads on the tunnel crown and right springline near excavation, while the loads on the tunnel invert and left springline away from excavation increase. This phenomenon is related to the relative values of the free-field ground displacements and measured tunnel displacements caused by excavation. The horizontal and vertical unbalanced loads are balanced by the shear force between neighboring rings caused by longitudinal differential deformations of the tunnel. (2) The elliptical deformations, clockwise rotations and bending moments of the tunnel all increase as the excavation proceeds. (3) The distribution of the circumferential bending moment of the tunnel is closely related to the relative position of the bolts. There are bolts near the right tunnel springline closer to the excavation at the investigated cross section, which bear more circumferential tension stress. In comparison, there are no bolts adjacent to the left tunnel away from the excavation, and thus the circumferential tension stress is mainly undertaken by the segments. Hence, the maximum circumferential bending moment of the tunnel at the investigated cross section occurs at the left springline.
- deep excavation /
- lateral shield tunnel /
- circumferential force /
- deformation /
- bending moment

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图 1 旁侧卸载后隧道外荷载分布图

Figure 1. Circumferential loads on jointed tunnel linings after lateral excavation

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图 2 基坑与隧道平面图

Figure 2. Plan view of excavation and adjacent twin tunnels

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图 3 X0+364断面示意图

Figure 3. Cross section of X0+364

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图 4 X0+348—X0+480地质剖面图

Figure 4. Longitudinal geological profile (X0+348 to X0+480)

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图 5 隧道监测横断面图

Figure 5. Instrumentation at tunnel circumferential section

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图 6 X0+364断面围护桩水平位移图

Figure 6. Displacements of retaining pile at X0+364

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图 7 地表沉降与围护桩体位移的关系

Figure 7. Relationship between ground settlement and displacement of retaining pile

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图 8 X0+364断面隧道变形图（隧道变形放大1000倍）

Figure 8. Deformations of tunnel at X0+364 (scale =1∶1000)

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图 9 X0+364断面开挖前后隧道径向荷载分布图

Figure 9. Distribution of radial loads around tunnel before and after lateral braced excavation at X0+364

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图 10 X0+364断面隧道内侧环向附加应变分布图

Figure 10. Profile of additional internal circumferential strain of tunnel at X0+364

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图 11 X0+364断面底板浇筑完后隧道环向附加弯矩分布图

Figure 11. Additional internal circumferential bending moment of tunnel at X0+364 after base slab constructed

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图 12 右线隧道纵向水平挠度

Figure 12. Longitudinal horizontal displacements of right tunnel

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图 13 隧道水平剪切力纵向分布曲线

Figure 13. Distribution of horizontal shear stress along tunnel

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图 14 离心模型试验隧道径向荷载变化实测值^[9]与理论值

Figure 14. Calculated and measured radial load changes around tunnel in centrifuge tests^[9]

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表 1 主要土体物理力学参数

Table 1 Physical and mechanical parameters of main soils

土层	w/%	γ/(kN·m^-3)	E_s/MPa	c/kPa	ϕ/(°)
①₁杂填土	27.8	17.9	6.0	8	18
④_c碎石	22.2	19.5	11.3	52	32
⑤₁残积土	23.5	19.4	12.5	39	20
⑩₁强风化含粉砂泥岩	—	20.5	46.0	50	18
⑩_2-2中风化含粉砂泥岩	—	22.9	62.0	70	20
注：w为含水率；γ为重度；E_s为压缩模量；c为黏聚力（固结快剪）；ϕ为内摩擦角（固结快剪）。

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表 2 X0+364施工顺序

Table 2 Construction sequence at X0+364

工序	施工时间	开挖或支撑深度/m
第一层土方开挖	07-22—08-18	1.0~8.4
第二道混凝土支撑浇筑	08-19—08-29	7.4~8.4
第二层土方开挖	08-30—10-12	8.4~13.7
第三道钢支撑安装	10-12—10-15	13.1~13.7
第三层土方开挖	10-16—10-31	13.7~17.7
底板浇筑	11-01—11-08	16.0~17.7

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表 3 隧道外荷载

Table 3 Magnitudes of external loads on tunnel 单位：kPa

初始荷载	数值	附加荷载	数值
${p_1}$	228.1	${p_7}$	-21.7
${p_2}$	255.1	${p_8}$	+7.0
${p_3}$	41.1	${p_9}$	-3.3
${p_4}$	57.5	${p_{10}}$	+13.9
${p_5}$	8.6	—	—
${p_6}$	20.7	—	—

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表 4 有限元计算土体参数

Table 4 Soil parameters for finite element calculations

土层	$\gamma$ /(kN·m^-3)	E_oed^ref/MPa	E₅₀^ref/MPa	E_ur^ref/MPa	m	$c'$ /kPa	$\varphi '$ /(°)	${\gamma _{0.7}}$ /10^-4	G₀^ref/MPa
①₁	17.9	6.0	6.0	18.0	0.50	7	15	—	—
④_c	19.5	11.3	11.3	33.9	0.50	32	15	—	—
⑤₁	19.4	12.5	12.5	50.0	0.65	32	14	2.1	103.2
⑩₁	20.5	38.3	38.3	114.9	0.50	34	17	1.0	120.5
⑩_2-2	22.9	51.7	51.7	155.1	0.50	48	20	—	—
注：E_oed^ref为参考切线模量；E₅₀^ref为参考割线模量；E_ur^ref为参考卸载再加载模量；m为模量应力水平相关幂指数； $c'$ 为有效黏聚力； $\varphi '$ 为有效内摩擦角； ${\gamma _{0.7}}$ 为剪切模量衰减到初始剪切模量70%时所对应的剪应变；G₀^ref为初始剪切模量。

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