泡沫改良砂卵石土的试验研究
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摘要
砂卵石土具有内摩擦角大、流动性差、渗透系数大等特点,在砂卵石地层的盾构施工时会引起出土困难、刀盘磨损、地下水喷涌等问题。通过泡沫优化试验,得到泡沫半衰期及发泡倍率最优时的发泡液浓度为2%~3%。基于四川成都地铁7号线茶店子站至一品天下站区间砂卵石地层,配制卵、砾石含量为20%、40%、60%、80%的土体,掺入泡沫进行室内大型剪切试验、坍落度试验和渗透试验,发现随着泡沫注入率的增加,包裹在砂卵石土周围泡沫土的含量增加,砂石分离现象逐渐消失,抗剪强度和内摩擦角呈非线性降低,坍落度逐渐增大,抗渗性能明显提高,并得到了不同含石量砂卵石土满足盾构施工中"理想状态土体"要求的泡沫注入率。研究成果对砂卵石地层盾构掘进中的相关问题解决具有一定的意义。
Sandy pebble soil has the characteristics of large internal friction angle, poor mobility and high permeability coefficient. It will be excavation difficulties, cutter head wear, groundwater spewing and other problems in the construction of shield in sandy cobble stratum. Through foam optimization test, the foam liquid concentration is 2%-3% when the foam half-life and foam expansion ratio are optimum. Based on the sand-pebble stratum of Chengdu metro line 7 in Sichuan Province, the soil with 20%, 40%, 60% and 80% of the gravel content is prepared. Large-scale indoor shearing test, slump test and permeability test are carrie out, it is shown that with the increase of foam injection ratio, the content of foam soil wrapped around sand and pebble soil increased, the phenomenon of sand and stone separation gradually disappeared; the shear strength and internal friction angle decreased nonlinearly; and the slump gradually increased. The impermeability can be obviously improved; and the foam injection ratio of different stone contents gravel soil satisfying the requirements of "ideal state soil" in shield construction is obtained. The result can be of great importance in solving the problems encountered in the construction of shield in sand pebble stratum.
Sandy pebble soil has the characteristics of large internal friction angle, poor mobility and high permeability coefficient. It will be excavation difficulties, cutter head wear, groundwater spewing and other problems in the construction of shield in sandy cobble stratum. Through foam optimization test, the foam liquid concentration is 2%-3% when the foam half-life and foam expansion ratio are optimum. Based on the sand-pebble stratum of Chengdu metro line 7 in Sichuan Province, the soil with 20%, 40%, 60% and 80% of the gravel content is prepared. Large-scale indoor shearing test, slump test and permeability test are carrie out, it is shown that with the increase of foam injection ratio, the content of foam soil wrapped around sand and pebble soil increased, the phenomenon of sand and stone separation gradually disappeared; the shear strength and internal friction angle decreased nonlinearly; and the slump gradually increased. The impermeability can be obviously improved; and the foam injection ratio of different stone contents gravel soil satisfying the requirements of "ideal state soil" in shield construction is obtained. The result can be of great importance in solving the problems encountered in the construction of shield in sand pebble stratum.
引文
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[18]PSOMAS S.Properties of foam/sand mixtures for tunneling applications[D].Oxford:St Hughˊs College,2001.
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[20]BORIO L,PEILA D.Study of the permeability of foam conditioned soil with laboratory tests[J].American Journal of Environmental Sciences,2010,6(4):365-370.
[2]黄德中.超大直径土压平衡盾构施工土体改良试验研究[J].现代隧道技术,2011,48(4):65-71.HUANG De-zhong.Research of soil improvement during super large diameter earth pressure balance shield[J].Modern Tunnelling Technology,2011,48(4):65-71.
[3]肖超,王树英,叶新宇,等.泥质粉砂岩地层土压平衡盾构碴土改良技术研究[J].现代隧道技术,2015,52(5):165-170.XIAO Chao,WANG Shu-ying,YE Xin-yu,et al.Study on soil conditioning technology for an EPB shield in an argillaceous siltstone formation[J].Modern Tunnelling Technology,2015,52(5):165-170.
[4]姜厚停,龚秋明,周永攀,等.北京地铁盾构施工遇到的工程地质问题[J].工程地质学报,2010,18(增刊1):126-132.JIANG Hou-ting,GONG Qiu-ming,ZHOU Yong-pan,et al.Encountered engineering geological problems of shield tunneling during Beijing subway construction[J].Journal of Engineering Geology,2010,18(Supp.1):126-132.
[5]丛恩伟.北京地铁10号线砂卵石地层盾构法隧道施工关键技术[J].铁路标准设计,2009,12(12):168-170.CONG En-wei.Key studies for EPB shield in sandy cobble layer in Beijing subway line 10[J].Railway Standard Design,2009,12(12):168-170.
[6]魏康林.土压平衡盾构施工中“理想状态土体”的探讨[J].城市轨道交通研究,2007,10(1):67-70.WEI Kang-lin.On the“Ideal soil”in the earth pressure balanced shield tunneling[J].Urban Mass Transit,2007,10(1):67-70.
[7]魏康林.土压平衡式盾构施工中喷涌问题的发生机理及其防治措施研究[D].南京:河海大学,2003.WEI Kang-lin.Earth pressure balance type shield tunnel beneath the happening of the problems in the mechanism and its prevention and control measures[D].Nanjing:Hohai University,2003.
[8]宋克志,汪波,孔恒,等.无水砂卵石地层土压平衡盾构施工泡沫技术研究[J].岩石力学与工程学报,2005,24(13):2327-2332.SONG Ke-zhi,WANG Bo,KONG Heng,et al.Study on foam technology during shield excavation in sandy cobble bed without water[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(13):2327-2332.
[9]姜厚停,龚秋明,杜修力.卵石地层土压平衡盾构施工土体改良试验研究[J].岩土工程学报,2013,35(2):284-292.JIANG Hou-ting,GONG Qiu-ming,DU Xiu-li.Experimental study on soil conditioning in cobble layer by use of earth pressure balanced machine[J].Chinese Journal of Geotechnical Engineering,2013,35(2):284-292.
[10]郭彩霞,孔恒,王梦恕.无水大粒径漂卵砾石地层土压平衡盾构施工渣土改良分析[J].土木工程学报,2015,48(增刊1):201-205.GUO Cai-xia,KONG Heng,WANG Meng-shu.Study on muck improvement of EPB shield tunneling in waterless sandy-cobble-boulder stratum[J].China Civil Engineering Journal,2015,48(Supp.1):201-205.
[11]姜厚停,闫鑫,龚秋明.土压平衡盾构施工中泡沫改良圆砾地层试验研究[J].现代隧道技术,2008,45(增刊):187-190.JIANG Hou-ting,YAN Xin,GONG Qiu-ming.Use of chemical foam for earth pressure balanced shields excavation in gravel layer[J].Modern Tunnelling Technology,2008,45(Supp.):187-190.
[12]乔国刚,陶龙光,刘波,等.泡沫改良富水砂层工程性质的实验研究[J].现代隧道技术,2009,46(6):79-84.QIAO Guo-gang,TAO Long-guang,LIU Bo,et al.Study on engineering properties of foam-conditioned water-soaked sand strata[J].Modern Tunnelling Technology,2009,46(6):79-84.
[13]汪国锋.北京地铁十号线土压平衡盾构土体改良技术应用研究[J].现代隧道技术,2009,46(4):74-82.WANG Guo-feng.Soil improvement technologies and implementation for EPB shield in Beijing subway[J].Modern Tunnelling Technology,2009,46(4):74-82.
[14]PEILA D,PICCHIO A,CHIEREGATO A.Earth pressure balance tunnelling in rock masses:laboratory feasibility study of the conditioning process[J].Tunnelling and Underground Space Technology,2013,35:55-66.
[15]建设部综合勘察研究设计院.GB/50021–2001岩土工程勘察规范[S].北京:中国建筑工业出版社,2001.Reconnaissance and Design Research Institute of the Ministry of Construction.GB50021-2001 Code for investigation of geotechnical engineering[S].Beijing:China Architecture and Building Press,2001.
[16]闫鑫,龚秋明,姜厚停.土压平衡盾构施工中泡沫改良砂土的试验研究[J].地下空间与工程学报,2010,6(3):449-453.YAN Xin,GONG Qiu-ming,JIANG Hou-ting.Soil conditioning for earth-pressure balanced shields excavation in sand layer[J].Chinese Journal of Underground Space and Engineering,2010,6(3):449-453.
[17]张明晶.土压平衡式盾构施工闭塞问题的发生机理与防治措施研究[D].南京:河海大学,2004.ZHANG Ming-jing.Study on the mechanism and curing method of blocking in EPBS[D].Nanjing:Hohai University,2004.
[18]PSOMAS S.Properties of foam/sand mixtures for tunneling applications[D].Oxford:St Hughˊs College,2001.
[19]张文萃.土压平衡式盾构穿越含砂土层渣土改良试验研究[D].西安:西安建筑科技大学,2013.ZHANG Wen-cui.Study on ground conditioning in EPB shield tunnelling through sandy stratum[D].Xi’an:Xi’an University of Architecture and Technology,2013.
[20]BORIO L,PEILA D.Study of the permeability of foam conditioned soil with laboratory tests[J].American Journal of Environmental Sciences,2010,6(4):365-370.