残积土MICP灌浆结石体冻融损伤的核磁共振特性试验研究
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摘要
微生物诱导碳酸钙沉淀(MICP)可有效胶结残积土并形成一定强度的结石体,在地基加固工程中具有广阔的应用前景,但针对冻土地区残积土MICP灌浆结石体的耐久性目前还不明确,因此开展结石体的冻融循环损伤特征研究对MICP技术在该地区的适用性评价具有重要意义。在试验确定微生物灌浆周期和灌浆速率的基础上,成功制备出页岩残积土的MICP灌浆结石体,并对试样开展不同含水率下的气体冻融循环试验,对比分析结石体在冻融循环过程中的损伤破坏机制与表观演化特征,重点结合核磁共振技术(NMR)研究结石体冻融后损伤裂隙发育的变化规律。结果表明:结石体的冻融破坏主要表现为孔隙水结冰产生的冻胀力大于MICP胶结强度时,胶结作用失效导致表面碎屑颗粒大量脱落,且脱落面积随含水量和循环次数的增加而增大。不同含水率结石体的T2谱曲线特征差异显著,分析波峰随循环次数增加的迁移规律可知结石体内部裂隙在冻融循环过程中的发育情况。低含水率条件下主要表现为中、小裂隙的发育,而高含水率时则体现出大裂隙的不断扩张。结石体的破坏均由试样中部逐渐向两端发展,随着循环次数的增加,结石体中间部位的大裂隙增加速率高于两端,且含水率越高速率越大,高含水率结石体T2分层曲线的初始阶段中部"尖点"效应显著,但随着冻融循环的发展"尖点"逐渐消失,曲线渐趋平缓,此时试样中部的大裂隙逐渐向两端扩展并贯穿,最终达到冻融损伤破坏的极限状态。
Microbial-induced calcite precipitation(MICP) is a good approach for cementing residual soil to the bio-claystone with high strength,and hence,is widely applied in the subgrade improvement. However,the durability of the bio-claystone in the frozen regions is still uncharted. Therefore,it is necessary to study damage characteristics of the bio-claystone under freezing-thawing cycles,which will provide references for the further engineering application of MICP. Samples of the bio-claystone of shale residual soil were prepared after grouting period and rate were determined,and freezing-thawing tests with different moistures were performed. The damage characteristics and epigenetic features of the bio-claystone samples were analyzed,and the developing process of internal pore and fissure of the bio-claystone was investigated using the nuclear magnetic resonance(NMR). It is shown that the damage of the bio-claystone under freezing-thawing cycles is resulted from that the frost heave force of pore water exceeds the bond strength of MICP. Clastic particles fall down from the surface of samples due to the invalidation of cementation,and the damage area increases with increasing the water content and the number of cycles. T2 spectral curves of the bio-claystone remarkably vary with different water contents. The development of the internal crack of the bio-claystone can be evaluated by analyzing waveform alteration with cycles. It is also indicated that lower moisture causes the development of medium and small fissures while that higher moisture results in the continuous expansion of large fissures. The destruction of the bio-claystone gradually develops from the central part to both ends of the sample. With the increment of the cycle number, the growth rate of large fractures in the central part of the sample is greater than that at both ends. In the initial stage,the"sharp point"effect occurs in the middle of the T2 curve with high moisture. With increasing cycles,however,the"sharp point"gradually disappears and the curve becomes flat. Large fractures expand from the central part to both ends and then penetrat gradually,which finally causes the failure of the bio-claystone.
Microbial-induced calcite precipitation(MICP) is a good approach for cementing residual soil to the bio-claystone with high strength,and hence,is widely applied in the subgrade improvement. However,the durability of the bio-claystone in the frozen regions is still uncharted. Therefore,it is necessary to study damage characteristics of the bio-claystone under freezing-thawing cycles,which will provide references for the further engineering application of MICP. Samples of the bio-claystone of shale residual soil were prepared after grouting period and rate were determined,and freezing-thawing tests with different moistures were performed. The damage characteristics and epigenetic features of the bio-claystone samples were analyzed,and the developing process of internal pore and fissure of the bio-claystone was investigated using the nuclear magnetic resonance(NMR). It is shown that the damage of the bio-claystone under freezing-thawing cycles is resulted from that the frost heave force of pore water exceeds the bond strength of MICP. Clastic particles fall down from the surface of samples due to the invalidation of cementation,and the damage area increases with increasing the water content and the number of cycles. T2 spectral curves of the bio-claystone remarkably vary with different water contents. The development of the internal crack of the bio-claystone can be evaluated by analyzing waveform alteration with cycles. It is also indicated that lower moisture causes the development of medium and small fissures while that higher moisture results in the continuous expansion of large fissures. The destruction of the bio-claystone gradually develops from the central part to both ends of the sample. With the increment of the cycle number, the growth rate of large fractures in the central part of the sample is greater than that at both ends. In the initial stage,the"sharp point"effect occurs in the middle of the T2 curve with high moisture. With increasing cycles,however,the"sharp point"gradually disappears and the curve becomes flat. Large fractures expand from the central part to both ends and then penetrat gradually,which finally causes the failure of the bio-claystone.
引文
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[17]王升福,杨平,刘贯荣,等.人工冻融软黏土微观孔隙变化及分形特性分析[J].岩土工程学报,2016,38(7):1 254-1 261.(WANGShengfu,YANG Ping,LIU Guanrong,et al.Micro pore change and fractal characteristics of artificial freeze thaw soft clay[J].Chinese Journal of Geotechnical Engineering,2016,38(7):1 254-1 261.(in Chinese))
[18]RADZI A A S M,YUSOP S F M,RUSOP M,et al.Structural and nitrogen gas adsorption-desorption studies of bragg grating waveguide fabricated on porous silicon nanostructure[C]//International Conference on Structural Nano Composites(NANOSTRUC 2012).Bedfordshire,UK:Materials Science and Engineering,2016:2 046.
[19]D'AGOSTINO C,BR?UER P,CHAROEN-RAJAPARK P,et al.Effect of paramagnetic species on T1,T2 and T1/T2 NMR relaxation times of liquids in porous Cu SO4/Al2O3[J].RSC Advances,2017,57(7):36 163-36 167.
[20]LI Yang,Li Jianyu.Experimental NMR T2 distribution properties of tight carbonate reservoir,Da′anzhai Formation,Sichuan Basin,Southwest China[C]//SEG Workshop:Rock Physics and Borehole Geophysics.[S.l.]:[s.n.],2016:56-59.
[21]邱继业.MICP技术固化页岩残积土的可行性试验与效果评价[硕士学位论文][D].福州:福州大学,2018.(QIU Jiye.Feasibility experiment and evaluation of shale residual soil improvement based on MICP[M.S.Thesis][D].Fuzhou:Fuzhou University,2018.(in Chinese))
[22]HARKES M P,VAN PAASSEN L A,Booster J L,et al.Fixation and distribution of bacterial activity in sand to induce carbonate precipitation for ground reinforcement[J].Ecological Engineering,2010,36(2):112-117.
[23]HARTER T,JIM YEH T C.Flow in unsaturated random porous media,nonlinear numerical analysis and comparison to analytical stochastic models[J].Advances in Water Resources,1998,22(3):257-272.
[24]AGUIRRE C G,HAGHIGHI K.Stochastic modeling of transient contaminant transport[J].Journal of Hydrology,2003,276(1):224-239.
[25]LIU S,ZHOU F,SHEN Y,et al.Fluid shear stress induces epithelial-mesenchymal transition(EMT)in Hep-2 cells[J].Oncotarget,2016,7(22):32 876-32 892.
[26]AL QABANY A,SOGA K,SANTAMARINA C.Factors affecting efficiency of microbially induced calcite precipitation[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,138(8):992-1 001.
[27]CHENG L,CORD-RUWISCH R,SHAHIN M A.Cementation of sand soil by microbially induced calcite precipitation at various degrees of saturation[J].Canadian Geotechnical Journal,2013,50(1):81-90.
[28]QIN X C,MENG S P,CAO D F,et al.Evaluation of freeze-thaw damage on concrete material and prestressed concrete specimens[J].Construction and Building Materials,2016,125:892-904.
[29]FURSA T V,DANN D D,OSIPOV K Y.Evaluation of freeze-thaw damage in concrete by the parameters of electric response under impact excitation[J].Construction and Building Materials,2016,102:182-189.
[2]ACHAL V,MUKHERJEE A,BASU P C,et al.Strain improvement of Sporosarcina pasteurii for enhanced urease and calcite production[J].Journal of Industrial Microbiology and Biotechnology,2009,36(7):981-988.
[3]PHILLIPS A J,CUNNINGHAM A B,GERLACH R,et al.Fracture sealing with microbially-induced calcium carbonate precipitation:Afield study[J].Environmental Science and Technology,2016,50(7):4 111-4 117.
[4]YUSUF C E,NELE D B,NICO B.Microbially induced Ca CO3precipitation through denitrification:an optimization study in minimal nutrient environment[J].Biochemical Engineering Journal,2015,101:108-118.
[5]DHAMI N K,REDDY M S,MUKHERJEE A.Significant indicators for biomineralisation in sand of varying grain sizes[J].Construction and Building Materials,2016,104:198-207.
[6]DHAMI N K,REDDY M S,MUKHERJEE A.Improvement in strength properties of ash bricks by bacterial calcite[J].Ecological Engineering,2012,39(39):31-35.
[7]MONTOYA B M,DEJONG J T.Stress-strain behavior of sands cemented by microbially induced calcite precipitation[J].Journal of Geotechnical and Geoenvironmental Engineering,2015,141(6):4015019.
[8]SALIFU E,MACLACHLAN E,IYER K R,et al.Application of microbially induced calcite precipitation in erosion mitigation and stabilisation of sandy soil foreshore slopes:a preliminary investigation[J].Engineering Geology,2016,201(4):96-105.
[9]ACHAL V,MUKERJEE A,REDDY M S.Biogenic treatment improves the durability and remediates the cracks of concrete structures[J].Construction and Building Materials,2013,48(19):1-5.
[10]程晓辉,麻强,杨钻,等.微生物灌浆加固液化砂土地基的动力反应研究[J].岩土工程学报,2013,35(8):1 486-1 495.(CHENGXiaohui,MA Qiang,YANG Zuan,et al.Study on dynamic response of liquefied sandy soil reinforced by microbial grouting[J].Journal of Geotechnical Engineering,2013,35(8):1 486-1 495.(in Chinese))
[11]RAMAKRISHNAN V,PANCHALAN R K,BANG S S.Improvement of concrete durability by bacterial mineral precipitation[C]//Proceedings of the 11th International conference on Fracture.Turin,Italy:[s.n.],2005.
[12]荣辉,钱春香,李龙志.微生物水泥胶结机理[J].硅酸盐学报,2013,41(3):314-319.(RONG Hui,QIAN Chunxiang,LI Longzhi.Cementation mechanism of microbe cement[J].Journal of the Chinese Ceramic Society,2013,41(3):314-319.(in Chinese))
[13]王掌权,许健,郑翔,等.反复冻融条件下黄土边坡稳定性分析[J].中国地质灾害与防治学报,2017,28(2):15-21.(WANGZhangquan,XU Jian,ZHENG Xiang,et al.Analysis on freezingthawing stability of slope in loess region[J].The Chinese Journal of Geological Hazard and Control,2017,28(2):15-21.(in Chinese))
[14]姜磊,牛荻涛.硫酸盐与冻融环境下混凝土损伤破坏准则研究[J].防灾减灾工程学报,2017,37(1):148-153.(JIANG Lei,NIU Ditao.Study on damage failure criterion of concrete under sulfate attack and freeze-thaw environment[J].Journal of Disaster Prevention and Mitigation Engineering,2017,37(1):148-153.(in Chinese))
[15]阎锡东,刘红岩,邢闯锋,等.基于微裂隙变形与扩展的岩石冻融损伤本构模型研究[J].岩土力学,2015,36(12):3 489-3 499.(YANXidong,LIU Hongyan,XING Chuangfeng,et al.Constitutive model research on freezing-thawing damage of rock based on deformation and propagation of microcracks[J].Rock and Soil Mechanics,2015,36(12):3 489-3 499.(in Chinese))
[16]YU J,CHEN X,LI H,et al.Effect of freeze-thaw cycles on mechanical properties and permeability of red sandstone under triaxial compression[J].Journal of Mountain Science,2015,12(1):218-231.
[17]王升福,杨平,刘贯荣,等.人工冻融软黏土微观孔隙变化及分形特性分析[J].岩土工程学报,2016,38(7):1 254-1 261.(WANGShengfu,YANG Ping,LIU Guanrong,et al.Micro pore change and fractal characteristics of artificial freeze thaw soft clay[J].Chinese Journal of Geotechnical Engineering,2016,38(7):1 254-1 261.(in Chinese))
[18]RADZI A A S M,YUSOP S F M,RUSOP M,et al.Structural and nitrogen gas adsorption-desorption studies of bragg grating waveguide fabricated on porous silicon nanostructure[C]//International Conference on Structural Nano Composites(NANOSTRUC 2012).Bedfordshire,UK:Materials Science and Engineering,2016:2 046.
[19]D'AGOSTINO C,BR?UER P,CHAROEN-RAJAPARK P,et al.Effect of paramagnetic species on T1,T2 and T1/T2 NMR relaxation times of liquids in porous Cu SO4/Al2O3[J].RSC Advances,2017,57(7):36 163-36 167.
[20]LI Yang,Li Jianyu.Experimental NMR T2 distribution properties of tight carbonate reservoir,Da′anzhai Formation,Sichuan Basin,Southwest China[C]//SEG Workshop:Rock Physics and Borehole Geophysics.[S.l.]:[s.n.],2016:56-59.
[21]邱继业.MICP技术固化页岩残积土的可行性试验与效果评价[硕士学位论文][D].福州:福州大学,2018.(QIU Jiye.Feasibility experiment and evaluation of shale residual soil improvement based on MICP[M.S.Thesis][D].Fuzhou:Fuzhou University,2018.(in Chinese))
[22]HARKES M P,VAN PAASSEN L A,Booster J L,et al.Fixation and distribution of bacterial activity in sand to induce carbonate precipitation for ground reinforcement[J].Ecological Engineering,2010,36(2):112-117.
[23]HARTER T,JIM YEH T C.Flow in unsaturated random porous media,nonlinear numerical analysis and comparison to analytical stochastic models[J].Advances in Water Resources,1998,22(3):257-272.
[24]AGUIRRE C G,HAGHIGHI K.Stochastic modeling of transient contaminant transport[J].Journal of Hydrology,2003,276(1):224-239.
[25]LIU S,ZHOU F,SHEN Y,et al.Fluid shear stress induces epithelial-mesenchymal transition(EMT)in Hep-2 cells[J].Oncotarget,2016,7(22):32 876-32 892.
[26]AL QABANY A,SOGA K,SANTAMARINA C.Factors affecting efficiency of microbially induced calcite precipitation[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,138(8):992-1 001.
[27]CHENG L,CORD-RUWISCH R,SHAHIN M A.Cementation of sand soil by microbially induced calcite precipitation at various degrees of saturation[J].Canadian Geotechnical Journal,2013,50(1):81-90.
[28]QIN X C,MENG S P,CAO D F,et al.Evaluation of freeze-thaw damage on concrete material and prestressed concrete specimens[J].Construction and Building Materials,2016,125:892-904.
[29]FURSA T V,DANN D D,OSIPOV K Y.Evaluation of freeze-thaw damage in concrete by the parameters of electric response under impact excitation[J].Construction and Building Materials,2016,102:182-189.