1. Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China 2. Beijing Urban Rapid Transit Development Co. Ltd, Beijing 100027, China
A series of 2D model tests on slurry fracturing of shield tunnels in the sandy stratum with different cover depths were conducted to investigate the slurry fracturing mechanism, the displacements of the ground surface, and the earth pressure distribution in the stratum. According to the test results, the slurry fracturing mechanism is that the dense sandy stratum and the filter cake on its surface (the filter cake-sandy stratum) is formed due to the pressurized slurry penetrating into the sandy stratum around excavation space, and then the filter cake-sandy stratum is pushed by the slurry to tensile and shear failure. The fracture pressure increases linearly with the increase of the cover depth. The fracture initiates on the top edge of the cutter head and propagates up to the ground surface in acclivitous direction directly, or first in straight and then in acclivitous direction. Based on a self-developed finite element program for simulating slurry fracturing, the 2D numerical models were established referring to the model tests, the numerical results including the morphology of the fracture propagation which agreed with the test results, and the vertical and horizontal displacements in the stratum were obtained. The numerical results show that the vertical displacement mainly distributes in a triangle region bounded by the fracture surface above the cutter head, while the horizontal displacement mainly distributes in the excavation face.
Jing-jing LIU,Tie-lin CHEN,Mao-hong YAO,Yu-xin WEI,Zi-jian ZHOU. Experimental and numerical study on slurry fracturing of shield tunnels in sandy stratum. Journal of ZheJiang University (Engineering Science), 2020, 54(9): 1715-1726.
Fig.1Schematic diagram of model test device for slurry fracturing of shield tunnels
Fig.2Model test device for slurry fracturing of shield tunnels
Fig.3Shield model and open pore of cutter head
C/cm
p1 / kPa
p2 / kPa
p3 / kPa
4.5
120
82
186
9.0
142
219
149
18.0
450
417
344
27.0
501
426
248
Tab.1Experimental value of slurry fracture pressure under different cover depths conditions
Fig.4Slurry fracture morphology under different cover depths conditions
Fig.5Process chart of slurry fracturing of shield tunnels in sandy stratum
Fig.6Filter cake and fracture morphology on excavation face
Fig.7Top-view images of slurry fracture morphology in stratum above shield model under smaller cover depths (C=0.5 D, 1.0 D) conditions
Fig.8Top-view images of slurry fracture morphology in stratum above shield model under larger cover depths (C=2.0 D, 3.0 D) conditions
Fig.9Mechanical analysis for direction of fracture propagation
Fig.10Uplift displacement of ground surface varying with time
Fig.11Uplift displacement of ground surface at moment of fracture propagating to ground surface under different cover depths conditions
Fig.12Curves of variations in earth pressure during slurry fracturing process
Fig.13Photo of slurry fracture propagating to earth pressure sensor #3
材料
ρ / (kg·m?3)
e
Sr
k / (m·s?1)
邓肯-张模型参数
K
Kur
n
c/kPa
$\phi $
Rf
Kb
m
砂土
1 560
0.80
0.20
1×10?10
276
552
0.57
1
31.88
0.87
50
0.2
泥膜-砂层结构
2 000
0.50
1.00
1×10?20
500
1 000
0.60
500
30.00
0.90
100
0.3
Tab.2Material parameters in numerical simulation
Fig.14Schematic diagram of numerical model of slurry fracturing of shield tunnels in sandy stratum
Fig.15Numerical results of slurry fracture morphology under different cover depths conditions
Fig.16Distribution of experimental and numerical slurry fracture pressure under different cover depths conditions
Fig.17Numerical results of horizontal displacement at moment of slurry fracture propagating to ground surface under different cover depths conditions
Fig.18Numerical results of vertical displacement at moment of slurry fracture propagating to ground surface under different cover depths conditions
[1]
朱金才, 卢珂, 杨进超, 等 砂土地层中隧道失稳机理验证[J]. 地下空间与工程学报, 2015, 11 (5): 1175- 1179 ZHU Jin-cai, LU Ke, YANG Jin-cao, et al Verification of the failure mechanism of tunnel in sandy soil[J]. Chinese Journal of Underground Space and Engineering, 2015, 11 (5): 1175- 1179
[2]
朱永全, 宋玉香. 隧道工程: 第2版[M]. 北京: 中国铁道出版社, 2007: 30.
[3]
王梦恕 中国盾构和掘进机隧道技术现状、存在的问题及发展思路[J]. 隧道建设, 2014, 34 (3): 179- 187 WANG Meng-shu Tunneling by TBM/shield in China: state-of-art, problems and proposals[J]. Tunnel Construction, 2014, 34 (3): 179- 187
doi: 10.3973/j.issn.1672-741X.2014.03.001
[4]
闵凡路, 宋航标, 柏煜新, 等 泥水盾构隧道开挖面被动破坏研究进展[J]. 隧道建设, 2018, 38 (4): 575- 581 MIN Fan-lu, SONG Hang-biao, BAI Yu-xin, et al Research progress of passive failure of excavation face during slurry shield tunneling[J]. Tunnel Construction, 2018, 38 (4): 575- 581
doi: 10.3973/j.issn.2096-4498.2018.04.007
[5]
LV X L, ZHOU Y C, HUANG M S, et al Experimental study of the face stability of shield tunnel in sands under seepage condition[J]. Tunnelling and Underground Space Technology, 2018, 74: 195- 205
doi: 10.1016/j.tust.2018.01.015
[6]
WONG K S, Ng C W W, Chen Y M, et al Centrifuge and numerical investigation of passive failure of tunnel face in sand[J]. Tunnelling and Underground Space Technology, 2012, 28: 297- 303
doi: 10.1016/j.tust.2011.12.004
[7]
李昀. 软土中超大直径泥水平衡盾构开挖面稳定性研究[D]. 上海: 同济大学, 2008: 53. LI Yun. Stability analysis of large slurry shield-driven tunnel in soft clay [D]. Shanghai: Tongji University, 2008: 53.
[8]
袁大军, 黄清飞, 小泉淳, 等 水底盾构掘进泥水喷发现象研究[J]. 岩石力学与工程学报, 2007, 26 (11): 2296- 2301 YUAN Da-jun, HUANG Qing-fei, XIAO Quan-chun, et al Study on slurry-water gushing during underwater shield tunnel construction[J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26 (11): 2296- 2301
doi: 10.3321/j.issn:1000-6915.2007.11.016
[9]
LIU X Y, YUAN D J An in-situ slurry fracturing test for slurry shield tunneling[J]. Journal of Zhejiang University-SCIENCE A: Applied Physics and Engineering, 2014, 15 (7): 465- 481
[10]
ADACHI J, SIEBRITS E, PEIRCE A, et al Computer simulation of hydraulic fractures[J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44 (5): 739- 757
doi: 10.1016/j.ijrmms.2006.11.006
[11]
KUMAR S, ZIELONKA M, SEARLES K, et al Modeling of hydraulic fracturing in ultra-low permeability formations: the role of pore fluid cavitation[J]. Engineering Fracture Mechanics, 2017, 184: 227- 240
doi: 10.1016/j.engfracmech.2017.08.020
[12]
CHEN T L, PANG T Z, ZHAO Y, et al Numerical simulation of slurry fracturing during shield tunnelling[J]. Tunnelling and Underground Space Technology, 2018, 74: 153- 166
doi: 10.1016/j.tust.2018.01.021
[13]
MIN F L, ZHU W, HAN X R Filter cake formation for slurry shield tunneling in highly permeable sand[J]. Tunnelling and Underground Space Technology, 2013, 38: 423- 430
doi: 10.1016/j.tust.2013.07.024
[14]
尹鑫晟. 泥水盾构成膜规律及开挖面稳定性[D]. 杭州: 浙江大学, 2017: 27. YIN Xin-sheng. Cake filtration and face stabilitv of slurry shield tunnel[D]. Zhejiang: Zhejiang University, 2017: 27.
[15]
XU T, BEZUIJEN A. Bentonite slurry infiltration into sand: filter cake formation under various conditions[J]. Geotechnique. 2019, 69(12): 1095-1106.
[16]
CUI W, LIU D, SONG H F, et al Development and experimental study on environmental slurry for slurry shield tunneling[J]. Construction and Building Materials, 2019, 216: 416- 423
doi: 10.1016/j.conbuildmat.2019.04.265
[17]
阮文军, 王文臣, 胡安兵 新型水泥复合浆液的研制及其应用[J]. 岩土工程学报, 2001, 23 (2): 212- 216 RUAN Wen-jun, WANG Wen-chen, HU An-bing Development and application of new kind of cement composite grout[J]. Chinese Journal of Geotechnical Engineering, 2001, 23 (2): 212- 216
doi: 10.3321/j.issn:1000-4548.2001.02.018
[18]
闵凡路, 魏代伟, 姜腾, 等 泥浆在地层中的渗透特性试验研究[J]. 岩土力学, 2014, 35 (10): 2801- 2806 MIN Fan-lu, WEI Dai-wei, JIANG Teng, et al Experimental study of law of slurry infiltration in strata[J]. Rock and Soil Mechanics, 2014, 35 (10): 2801- 2806
