粉砂地层中浓泥土压盾构泥膜效应引起的孔压变化规律试验研究
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摘要
为了减小盾构机在粉砂地层中掘进时对地层的扰动及地表沉降的影响,针对粉砂地层渗透性大、内摩擦角高的情况,提出一种新型浓泥土压盾构施工技术,使用自制的土舱渗透试验装置,开展了3组不同泥浆添加量下混合土中泥浆渗透试验,研究混合土及地层中孔压的变化,分析应力的传递规律。基于室内试验结果开展了现场孔压监测试验,研究泥浆的添加对地层中孔压的影响。研究结果表明:泥浆添加量大于25%时,在开挖面表层处中出现泥膜效应;盾构掘进过程中泥浆添加量越大,地层中孔压的变化率越小,当添加量达到8m~3/环时,其孔压变化率仅为25%～45%;浓泥土压盾构泥膜类型只有渗透型泥膜,且渗透成膜前伴随泥浆颗粒损失。该研究结果对浓泥土压盾构在实际工程中的应用以及向砂砾石及砂卵石地层的推广具有重要的意义。
To reduce stratum disturbance and settlement during shield tunneling in silty sand layer, a new construction technique of slurry-EPB shield was proposed for the silty sand layer with large permeability and high internal friction angle. 3 groups of slurry permeability test were carried out on mixed soils with different slurry additions using the self-made soil chamber penetrating test device. The variation of pore water pressure in mixed soil and stratum, and the distribution rule of pore water pressure were analyzed.Based on the laboratory testing results, in situ pore water pressure was monitored to study the effect of slurry addition on the pore water pressure in the stratum. The effect of filter cake appears on the excavation surface when the amount of slurry added is more than 25%. The larger the amount of slurry added during the tunneling process, the smaller the change rate of pore water pressure in the stratum. The change rate of pore pressure is only 25%-45% when the addition amount reaches 8 cubic meters per ring. Only the type of infiltration cake occurs in case of slurry-EPB shield, and undergoes slurry particles lost before the film formation. The research results have important significance for the application of slurry-EPB shield in practical engineering and extension to sandy gravel stratum.
To reduce stratum disturbance and settlement during shield tunneling in silty sand layer, a new construction technique of slurry-EPB shield was proposed for the silty sand layer with large permeability and high internal friction angle. 3 groups of slurry permeability test were carried out on mixed soils with different slurry additions using the self-made soil chamber penetrating test device. The variation of pore water pressure in mixed soil and stratum, and the distribution rule of pore water pressure were analyzed.Based on the laboratory testing results, in situ pore water pressure was monitored to study the effect of slurry addition on the pore water pressure in the stratum. The effect of filter cake appears on the excavation surface when the amount of slurry added is more than 25%. The larger the amount of slurry added during the tunneling process, the smaller the change rate of pore water pressure in the stratum. The change rate of pore pressure is only 25%-45% when the addition amount reaches 8 cubic meters per ring. Only the type of infiltration cake occurs in case of slurry-EPB shield, and undergoes slurry particles lost before the film formation. The research results have important significance for the application of slurry-EPB shield in practical engineering and extension to sandy gravel stratum.
引文
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[11]张亚洲,闵凡路,孙涛,等.硬塑性黏土地层泥水盾构停机引起的地表塌陷机制研究[J].岩土力学,2017,38(4):1141-1147.ZHANG Ya-zhou,MIN Fan-lu,SUN Tao,et al.Analysis of causes for ground subsidence induced by slurry shield shutdown in hard plastic clay[J].Rock and Soil Mechanics,2017,38(4):1141-1147.
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[13]魏代伟,朱伟,闵凡路.泥水盾构泥膜形成过程中超静孔隙水压力随时间的变化[J].水利与建筑工程学报,2013,11(3):36-40.WEI Dai-wei,ZHU Wei,MIN Fan-lu.Change laws of excess pore water pressure during forming of filter cake in slurry shield[J].Journal of Water Resources and Architectural Engineering,2011,11(3):36-40.
[14]闵凡路,朱伟,魏代伟,等.泥水盾构泥膜形成时开挖面地层孔压变化规律研究[J].岩土工程学报,2013,35(4):722-727.MIN Fan-lu,ZHU Wei,WEI Dai-wei,et al.Change of pore water pressure in soil as filter cakes formed on excavation face in slurry shield[J].Chinese Journal of Geotechnical Engineering,2013,35(4):722-727.
[15]钱勇进,朱伟,闵凡路,等.砂卵石地层中泥膜支护土压盾构施工试验[J].中国公路学报,2017,30(8):210-215.QIAN Yong-jin,ZHU Wei,MIN Fan-lu,et al.Test of construction method of filter membrane supporting EPBshield in sand and cobble stratum[J].China Journal of Highway and Transport,2017,30(8):210-215.
[2]袁大军,尹凡,王华伟,等.超大直径泥水盾构掘进对土体的扰动研究[J].岩石力学与工程学报,2009,28(10):2074-2080.YUAN Da-jun,YIN Fan,WANG Hua-wei,et al.Study of soil disturbance caused by super large diameter slurry shield tunneling[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):2074-2080.
[3]张顶立,李倩倩,房倩,等.隧道施工影响下城市复杂地层的变形机制及预测方法[J].岩石力学与工程学报,2014,33(12):2504-2516.ZHANG Ding-li,LI Qian-qian,FANG Qian,et al.Deformation mechanism and prediction method for tunneling in complex urban ground conditions[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(12):2504-2516.
[4]莫振泽,王梦恕,罗跟东,等.土压盾构在富水粉砂地层中浓泥渣土改良技术研究[J].隧道建设(中英文),2018,38(12):2026-2031.MO Zhen-ze,WANG Meng-shu,LUO Gen-dong,et al.Study of ground conditioning by thick slurry for earth pressure balance shield in water-rich silty sand stratum[J].Tunnel Construction,2018,38(12):2026-2031.
[5]郭涛.盾构用发泡剂性能评价方法研究[D].南京:河海大学,2005.GUO Tao.Study on the performance evaluation of foaming agents in EPBS[D].Nanjing:Hohai University,2005.
[6]魏康林.土压平衡盾构施工中泡沫和膨润土改良土体的微观机理分析[J].现代隧道技术,2007,44(1):73-77.WEI Kang-lin.Micro-mechanism analysis for the soil improvement by foam and bentonite in EPB shield tunneling[J].Modern Tunneling Technology,2007,44(1):73-77.
[7]王海波,王树英,胡钦鑫,等.盾构砂性渣土-泡沫混合物渗透性影响因素研究[J].隧道建设(中英文),2018,38(5):833-838.WANG Hai-bo,WANG Shu-ying,HU Qin-xin,et al.Study of influencing factors of permeability of sand-foam mixture for shield tunneling[J].Tunnel Construction,2018,38(5):833-838.
[8]WATANABE T,YAMAZAKI H.Giant size slurry shield is a success in Tokyo[J].Tunnels and Tunnelling,1981,13(1):13-17.
[9]FRITZ P.Additives for slurry shields in highly permeable ground[J].Rock Mechanics and Rock Engineering,2007,40(1):81-95.
[10]韩晓瑞.基于泥浆与地层匹配性的泥水盾构泥膜形成规律研究[D].南京:河海大学,2009.HAN Xiao-rui.Study on the filter-cake forming low of slurry shield based on the matching of slurry and the ground[D].Nanjing:Hohai University,2009.
[11]张亚洲,闵凡路,孙涛,等.硬塑性黏土地层泥水盾构停机引起的地表塌陷机制研究[J].岩土力学,2017,38(4):1141-1147.ZHANG Ya-zhou,MIN Fan-lu,SUN Tao,et al.Analysis of causes for ground subsidence induced by slurry shield shutdown in hard plastic clay[J].Rock and Soil Mechanics,2017,38(4):1141-1147.
[12]闵凡路,徐静波,宋航标,等.反压条件下泥水盾构开挖面泥膜致密性评价试验[J].中国公路学报,2017,30(8):216-221.MIN Fan-lu,XU Jing-bo,SONG Hang-biao,et al.Evaluating test on compactness of filter cakes of excavation face in slurry shield under reverse water pressure[J].China Journal of Highway and Transport,2017,30(8):216-221.
[13]魏代伟,朱伟,闵凡路.泥水盾构泥膜形成过程中超静孔隙水压力随时间的变化[J].水利与建筑工程学报,2013,11(3):36-40.WEI Dai-wei,ZHU Wei,MIN Fan-lu.Change laws of excess pore water pressure during forming of filter cake in slurry shield[J].Journal of Water Resources and Architectural Engineering,2011,11(3):36-40.
[14]闵凡路,朱伟,魏代伟,等.泥水盾构泥膜形成时开挖面地层孔压变化规律研究[J].岩土工程学报,2013,35(4):722-727.MIN Fan-lu,ZHU Wei,WEI Dai-wei,et al.Change of pore water pressure in soil as filter cakes formed on excavation face in slurry shield[J].Chinese Journal of Geotechnical Engineering,2013,35(4):722-727.
[15]钱勇进,朱伟,闵凡路,等.砂卵石地层中泥膜支护土压盾构施工试验[J].中国公路学报,2017,30(8):210-215.QIAN Yong-jin,ZHU Wei,MIN Fan-lu,et al.Test of construction method of filter membrane supporting EPBshield in sand and cobble stratum[J].China Journal of Highway and Transport,2017,30(8):210-215.