深基坑抗突涌的有限元模拟及分析
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摘要
近年来,随着我国城市建设的发展,基坑工程大量涌现,开挖深度不断增加,使基坑朝着超大超深的规模发展,由此也带来了许多基坑稳定性问题。研究表明,地下水是影响基坑稳定性主要的因素,尤其在沿海地区,地下水是导致基坑工程事故发生直接的原因之一。基坑工程在开挖施工时,若基底有承压水含水层则易产生基底突涌、基底隆起、管涌或流砂等工程事故。
本文主要研究承压水对深基坑底部及周围的影响,采用有限元软件Plaxis模拟分析基坑突涌和渗流对深基坑的影响。由于实际工程在沿海地区,土体主要为粘性土,则在模拟计算时采用软土蠕变模型模拟土体,并对软土蠕变模型进行试验验证,确保模拟的土体与实际情况相符。因为目前设计方法中采用压力平衡法时未考虑土体的抗剪强度,在模拟深基坑抗突涌时采用均质连续体法。对深基坑的渗流模拟得出土层在含有潜水及承压水的情况下,根据有效应力原理计算出的抗渗系数则更接近于实际情况。对实际工程的模拟分析得出深基坑的开挖降水对基坑及其周围的影响很大,其中降水能够提高土的物理力学性质指标,增加土体的有效应力,但是也会引起基坑底部土体的附加沉降。
In recent years, with the development of urban construction, excavation engineering have proliferated and the excavation of the foundation pit is much deeper. It makes the scale of excavation engineering be much larger,and also brings more problems about the stability of foundation pit.According to the research, the important factor of stability is the groundwater. It is one of the direct cause of foundation stability in coastal areas vigorously. The confined aquifer under the basement will be easy to cause inrush, basement uplift, piping or the flow of sand and other engineering accident in the excavation of foundation.
This paper studies the influence of confined groundwater on the bottom of deep foundation and the surrounding, simulates and analyzes the inrush of foundation pit and the influence of seepage flow by using Plaxis.Using the soft soil creep model to simulate the soil as the actual works in coastal areas,because the chief soil is clay in that areas. Author tested and verified the soft soil creep model through the full size field test to ensure the simulation consistents with the actual situation. Because the pressure balance method in current design manual does not take the shear strength of soil into account, author used the homogeneous continuum method instead of the pressure balance method in the simulation on the anti-inrushing stability of deep foundation pit. According to the simulation of seepage flow, the permeability coefficient which calculated based on the principle of effective stress is more close to the actual situation when the groundwater exists in soil layer. According to the simulation and analysis of the actual project,the excavation pit and dewatering has great impact on foundation and its surrounding. Dewatering can improve the indicators of physical and mechanical properties of soil and increase the effective stress of soil.While it also lead to additional settlement of the soil at the bottom of the pit
本文主要研究承压水对深基坑底部及周围的影响,采用有限元软件Plaxis模拟分析基坑突涌和渗流对深基坑的影响。由于实际工程在沿海地区,土体主要为粘性土,则在模拟计算时采用软土蠕变模型模拟土体,并对软土蠕变模型进行试验验证,确保模拟的土体与实际情况相符。因为目前设计方法中采用压力平衡法时未考虑土体的抗剪强度,在模拟深基坑抗突涌时采用均质连续体法。对深基坑的渗流模拟得出土层在含有潜水及承压水的情况下,根据有效应力原理计算出的抗渗系数则更接近于实际情况。对实际工程的模拟分析得出深基坑的开挖降水对基坑及其周围的影响很大,其中降水能够提高土的物理力学性质指标,增加土体的有效应力,但是也会引起基坑底部土体的附加沉降。
In recent years, with the development of urban construction, excavation engineering have proliferated and the excavation of the foundation pit is much deeper. It makes the scale of excavation engineering be much larger,and also brings more problems about the stability of foundation pit.According to the research, the important factor of stability is the groundwater. It is one of the direct cause of foundation stability in coastal areas vigorously. The confined aquifer under the basement will be easy to cause inrush, basement uplift, piping or the flow of sand and other engineering accident in the excavation of foundation.
This paper studies the influence of confined groundwater on the bottom of deep foundation and the surrounding, simulates and analyzes the inrush of foundation pit and the influence of seepage flow by using Plaxis.Using the soft soil creep model to simulate the soil as the actual works in coastal areas,because the chief soil is clay in that areas. Author tested and verified the soft soil creep model through the full size field test to ensure the simulation consistents with the actual situation. Because the pressure balance method in current design manual does not take the shear strength of soil into account, author used the homogeneous continuum method instead of the pressure balance method in the simulation on the anti-inrushing stability of deep foundation pit. According to the simulation of seepage flow, the permeability coefficient which calculated based on the principle of effective stress is more close to the actual situation when the groundwater exists in soil layer. According to the simulation and analysis of the actual project,the excavation pit and dewatering has great impact on foundation and its surrounding. Dewatering can improve the indicators of physical and mechanical properties of soil and increase the effective stress of soil.While it also lead to additional settlement of the soil at the bottom of the pit
引文
[1]龚晓南,高有潮.深基坑设计施工手册[M].北京：中国建筑工业出版社,1998.
[2]刘利民.基坑工程事故的原因与对策[J].建筑安全,2001,08：9-10.
[3]王曙光,温文.深基坑工程事故分析与工程实践[J].地基基础工程,2001,10(6)：1-9.
[4]蒋红星,李龙,冯芳.深基坑支护工程中的地下水防治问题研究[J].中国煤田地质,2003,15(1)：41-43.
[5]叶琳昌.要重视基坑围护中的防水问题[J].中国建筑防水,2000,01：18-22.
[6]郑剑升,张克平,章立峰.承压水地层基坑底部突涌及解决措施[J].隧道建设,2003,05：25-27.
[7]陈希哲.土力学地基基础[M].北京：清华大学出版社,2004.
[8]刘国彬,王洪新.上海浅层粉砂地层承压水对基坑的危害及治理[J].岩土工程学报,2002,24(6)：790-792.
[9]李守德,张晓海,刘志祥.基坑开挖工程管涌发生过程的模拟[J].工程勘察,2003,02：14-17.
[10]叶志德.基坑工程流砂处理方案及效果[J].建筑技术,2005,(08)：625.
[11]孙向明,胡艳荣,赵小文.基坑突涌事故的分析与处理[J].水利科技与经济,2006,07：460-461.
[12]马丽丽.深基坑开挖中的水文地质问题[J].工程勘察,1996,02：25-29.
[13]丁春林.软土地区承压水基坑突涌稳定计算法研究综述[J].地下空间与工程学报,2007,3(2)：333-338.
[14]潘泓,曹洪等.基坑抗突涌计算方法的对比分析及应用探讨[J].岩石力学与工程学报,2006,25(Supp2)：3529-3534.
[15]叶国强,陈杰生.深基坑施工中承压水的危害、预防及紧急应对措施[J].建筑施工,2005,07：22-25.
[16]黄春娥,龚晓南.承压含水层对基坑边坡稳定性影响的初步探讨[J].建筑技术,2002,02：92.
[17]李玲玲,冯曹毅.有限元法在硬壳层软土地基应力分析中的应用[J].西部交通科技.2008,06：26-29.
[18]栾茂田,许成顺,刘占阁等.一般应力条件下土的抗剪强度参数探讨[J].大连理工大学学报,2004,02：271-276.
[19]蒋坤,夏才初.基于不同节理模型的岩体边坡稳定性分析[J].同济大学学报(自然 科学版),2009,11：1440-1445.
[20]叶为民,万敏,陈宝等.深基坑承压含水层降水对地面沉降的影响[J].2009,S2：1799-1805.
[21]王常明,王清,张淑华.滨海软土蠕变特性及蠕变模型[J].岩石力学与工程学报,2004,02：227-230.
[22]杨林德,张向霞.基于广义塑性力学的Cam-clay模型的改进[J].科学技术与工程,2005,18：1282-1286.
[23]Buisman,K. Results of long duration settlement tests. Proceedings 1st International Conference on Soil Mechanics and Foundation Engineering. Cambirdge Mass,1936,1:103-107.
[24]Bjerrum, L. Engineering geology of Norwegian normally consolidated marine clays as related to settlements of buildings. Seventh Rankine lecture. Geotechnique,1967,17:81-118.
[25]Garlanger, J. E. The consolidation of soils exhibiting creep under constant effective stress. Geotechnique.1972,22:71-78.
[26]Butterfield, R. A natural compression law for soils(an advance on e-log p'). Geotechnique,1979,29:469-480.
[27]Den haan, E. J. vertical compression of Soils. Thesis, Delft University. 1994.
[28]Janbu, N. The resistance concept applied to soils. Proceedings of the 7h ICSMFE, Mexico City,1969,1:191-196.
[29]卢萍珍.饱和软粘土蠕变特性研究：[硕士学位论文].武汉：武汉岩土力学研究所,2008.
[30]Roscoe,, K. B. and J. B. Burland, On the generalized stress-strain behavior o 'fwet' olay, in Ennineorina Plasticity, J. Heymann and F. A. Leokie. Rds., Cambridge Univ. Press, Cambridge,1968,535-608.
[31]王秋生.K_O固结软黏土的临界不排水强度研究[J].岩土力学.2008,12：3179-3185.
[32]王海波,徐明,宋二祥.基于硬化土模型的小应变本构模型研究[J].岩土力学,2011,01：39-43.
[33]李国维,盛维高,蒋华忠等.超载卸荷后再压缩软土的次压缩特征及变形计算[J].岩土工程学报.2009,01：118-123.
[34]郑颖人等著.岩土塑性力学原理[M].中国建筑工业出版社.
[35]Brinkgreve, R. B. J. Geomaterial Models and Numerical Analysis of Softening. Dissertation. Delft University of Technology,1994.
[36]张茹,何昌荣,费文平等.饱和黏性土和砂砾石料振动孔压的试验研究[J].岩土力学.2006,10：1805-1810.
[37]-汪中卫,刘国彬.基于超固结比与变形的基坑被动区土压力计算[J].建筑结构,2005,09：88-91.
[38]Stolle, D. F. E., Bonnier, P. G., Vermeer, P. A. A soft soil model and experiences with two integration schemes. Numerical Models in Geomechanics. Numog 1997:123-128
[39]Kulhawy, F. H., Mayne, P. W. Manual on Estimating Soil Preperties for Foundation Design. Cornell University, Ithaca, New York,1990.
[40]郑刚,杨建.抗突涌稳定验算公式分析[J].土木工程学报.2011,02：123-127.
[41]杨建民,郑刚.基坑降水中渗流破坏归类及抗突涌验算公式评价[J].岩土力学,2009,30,01：261-264.
[42]马石城,印长俊,邹银生.抗承压水基坑底板的厚度分析与计算[J]工程力学,2004,02：204-208.
[43]谭松林.考虑土体强度的建筑基坑突涌问题分析[J].地球科学—中国地质大学学报,2002.27(2)：209-216.
[44]李建交,屠厚泽.关于矩形基坑中突涌问题的分析与探讨[J]地质科技情报,1998,03：91-94.
[45]李琳,杨敏,张慧.承压水作用下圆形基坑底板突涌的临界厚度计算公式[J].勘察科学技术,2006,05：13-15.
[46]李广信.深基坑支护结构上的水土压力的分算与合算.岩土工程学报,2000,Vol.22,No.3：348-352.
[47]韩红霞,窦远明,王喜燕等.基坑支护中水土压力合算与分算的综合分析[J].河北工业大学学报,2002,31(6)：62-65.
[48]高颂东.土工分析中水土分算、水土合算的概念、原理与应用实例[J],建筑科学,2004,20(4)：33-42.
[49]刘建军,杨前雄,史沛元.基坑降水过程中地下水渗流数值模拟[J].地下水,2005,(()5)：342-343.
[50]吕德洪.不稳定渗流法在堤防工程设计中的应用[J].岩土工程技术,2001,03：159-160.
[51]谢春红,赵文良,张天岭等.地下水不稳定渗流达西速度计算新方法[J].岩土工程学报,1996,01：68-74.
[52]陈仲颐,周景星,王洪瑾.土力学[M].北京：清华大学出版社,2004.
[53]孙淑贤.考虑渗流力的基坑涌砂分析[J].工程勘察,1998,02：32-35.
[54]杨进良.土力学[M].北京：中国水力水电出版社,2004.
[55]张在明.地下水与建筑基础工程[M].北京：中国建筑工业出版社,2001.
[56]Desai C. S. Finite element residual schemes for unconfined flow. Int. J. Geotechnical Eng,1976,109(7):946-960.
[57]Li G. C, Desai C.S.stress and seepage analysis of earth dams. J. Geotechnical Eng,1983.
[58]Bakker k.J. Analysis of groundwater flow through revetments Proc.3rd International Symposium on Numerical Models in Geomechanics. Niagara Falls, Canada.1989:367-374.
[59]李学山,田微微,李芒原.渗流对深基坑工程的影响研究[J].广西大学学报(自然科学版).2008,S1：192-194.
[60]魏汝龙,基坑内外的水压力和渗流力[J],岩土工程师,1998,10(1)：23-25.
[61]王钊,邹维列,李广信,挡土结构上的土压力和水压力.岩土力学,2003,24(2)：143-150.
[62]刘建航,候学渊.基坑工程手册[M].北京：中国建筑工业出版社,1997.
[63]刘建刚,王军,陈永战.越流条件下基坑降水的有限元计算[J]门.勘察科学技术,2002,(02)：10-12.
[64]张秀勇,刘汉龙,刘广明等.南通市长江堤防渗透性能数值模拟研究[J].防灾减灾工程学报,2004,03：283-287.
[2]刘利民.基坑工程事故的原因与对策[J].建筑安全,2001,08：9-10.
[3]王曙光,温文.深基坑工程事故分析与工程实践[J].地基基础工程,2001,10(6)：1-9.
[4]蒋红星,李龙,冯芳.深基坑支护工程中的地下水防治问题研究[J].中国煤田地质,2003,15(1)：41-43.
[5]叶琳昌.要重视基坑围护中的防水问题[J].中国建筑防水,2000,01：18-22.
[6]郑剑升,张克平,章立峰.承压水地层基坑底部突涌及解决措施[J].隧道建设,2003,05：25-27.
[7]陈希哲.土力学地基基础[M].北京：清华大学出版社,2004.
[8]刘国彬,王洪新.上海浅层粉砂地层承压水对基坑的危害及治理[J].岩土工程学报,2002,24(6)：790-792.
[9]李守德,张晓海,刘志祥.基坑开挖工程管涌发生过程的模拟[J].工程勘察,2003,02：14-17.
[10]叶志德.基坑工程流砂处理方案及效果[J].建筑技术,2005,(08)：625.
[11]孙向明,胡艳荣,赵小文.基坑突涌事故的分析与处理[J].水利科技与经济,2006,07：460-461.
[12]马丽丽.深基坑开挖中的水文地质问题[J].工程勘察,1996,02：25-29.
[13]丁春林.软土地区承压水基坑突涌稳定计算法研究综述[J].地下空间与工程学报,2007,3(2)：333-338.
[14]潘泓,曹洪等.基坑抗突涌计算方法的对比分析及应用探讨[J].岩石力学与工程学报,2006,25(Supp2)：3529-3534.
[15]叶国强,陈杰生.深基坑施工中承压水的危害、预防及紧急应对措施[J].建筑施工,2005,07：22-25.
[16]黄春娥,龚晓南.承压含水层对基坑边坡稳定性影响的初步探讨[J].建筑技术,2002,02：92.
[17]李玲玲,冯曹毅.有限元法在硬壳层软土地基应力分析中的应用[J].西部交通科技.2008,06：26-29.
[18]栾茂田,许成顺,刘占阁等.一般应力条件下土的抗剪强度参数探讨[J].大连理工大学学报,2004,02：271-276.
[19]蒋坤,夏才初.基于不同节理模型的岩体边坡稳定性分析[J].同济大学学报(自然 科学版),2009,11：1440-1445.
[20]叶为民,万敏,陈宝等.深基坑承压含水层降水对地面沉降的影响[J].2009,S2：1799-1805.
[21]王常明,王清,张淑华.滨海软土蠕变特性及蠕变模型[J].岩石力学与工程学报,2004,02：227-230.
[22]杨林德,张向霞.基于广义塑性力学的Cam-clay模型的改进[J].科学技术与工程,2005,18：1282-1286.
[23]Buisman,K. Results of long duration settlement tests. Proceedings 1st International Conference on Soil Mechanics and Foundation Engineering. Cambirdge Mass,1936,1:103-107.
[24]Bjerrum, L. Engineering geology of Norwegian normally consolidated marine clays as related to settlements of buildings. Seventh Rankine lecture. Geotechnique,1967,17:81-118.
[25]Garlanger, J. E. The consolidation of soils exhibiting creep under constant effective stress. Geotechnique.1972,22:71-78.
[26]Butterfield, R. A natural compression law for soils(an advance on e-log p'). Geotechnique,1979,29:469-480.
[27]Den haan, E. J. vertical compression of Soils. Thesis, Delft University. 1994.
[28]Janbu, N. The resistance concept applied to soils. Proceedings of the 7h ICSMFE, Mexico City,1969,1:191-196.
[29]卢萍珍.饱和软粘土蠕变特性研究：[硕士学位论文].武汉：武汉岩土力学研究所,2008.
[30]Roscoe,, K. B. and J. B. Burland, On the generalized stress-strain behavior o 'fwet' olay, in Ennineorina Plasticity, J. Heymann and F. A. Leokie. Rds., Cambridge Univ. Press, Cambridge,1968,535-608.
[31]王秋生.K_O固结软黏土的临界不排水强度研究[J].岩土力学.2008,12：3179-3185.
[32]王海波,徐明,宋二祥.基于硬化土模型的小应变本构模型研究[J].岩土力学,2011,01：39-43.
[33]李国维,盛维高,蒋华忠等.超载卸荷后再压缩软土的次压缩特征及变形计算[J].岩土工程学报.2009,01：118-123.
[34]郑颖人等著.岩土塑性力学原理[M].中国建筑工业出版社.
[35]Brinkgreve, R. B. J. Geomaterial Models and Numerical Analysis of Softening. Dissertation. Delft University of Technology,1994.
[36]张茹,何昌荣,费文平等.饱和黏性土和砂砾石料振动孔压的试验研究[J].岩土力学.2006,10：1805-1810.
[37]-汪中卫,刘国彬.基于超固结比与变形的基坑被动区土压力计算[J].建筑结构,2005,09：88-91.
[38]Stolle, D. F. E., Bonnier, P. G., Vermeer, P. A. A soft soil model and experiences with two integration schemes. Numerical Models in Geomechanics. Numog 1997:123-128
[39]Kulhawy, F. H., Mayne, P. W. Manual on Estimating Soil Preperties for Foundation Design. Cornell University, Ithaca, New York,1990.
[40]郑刚,杨建.抗突涌稳定验算公式分析[J].土木工程学报.2011,02：123-127.
[41]杨建民,郑刚.基坑降水中渗流破坏归类及抗突涌验算公式评价[J].岩土力学,2009,30,01：261-264.
[42]马石城,印长俊,邹银生.抗承压水基坑底板的厚度分析与计算[J]工程力学,2004,02：204-208.
[43]谭松林.考虑土体强度的建筑基坑突涌问题分析[J].地球科学—中国地质大学学报,2002.27(2)：209-216.
[44]李建交,屠厚泽.关于矩形基坑中突涌问题的分析与探讨[J]地质科技情报,1998,03：91-94.
[45]李琳,杨敏,张慧.承压水作用下圆形基坑底板突涌的临界厚度计算公式[J].勘察科学技术,2006,05：13-15.
[46]李广信.深基坑支护结构上的水土压力的分算与合算.岩土工程学报,2000,Vol.22,No.3：348-352.
[47]韩红霞,窦远明,王喜燕等.基坑支护中水土压力合算与分算的综合分析[J].河北工业大学学报,2002,31(6)：62-65.
[48]高颂东.土工分析中水土分算、水土合算的概念、原理与应用实例[J],建筑科学,2004,20(4)：33-42.
[49]刘建军,杨前雄,史沛元.基坑降水过程中地下水渗流数值模拟[J].地下水,2005,(()5)：342-343.
[50]吕德洪.不稳定渗流法在堤防工程设计中的应用[J].岩土工程技术,2001,03：159-160.
[51]谢春红,赵文良,张天岭等.地下水不稳定渗流达西速度计算新方法[J].岩土工程学报,1996,01：68-74.
[52]陈仲颐,周景星,王洪瑾.土力学[M].北京：清华大学出版社,2004.
[53]孙淑贤.考虑渗流力的基坑涌砂分析[J].工程勘察,1998,02：32-35.
[54]杨进良.土力学[M].北京：中国水力水电出版社,2004.
[55]张在明.地下水与建筑基础工程[M].北京：中国建筑工业出版社,2001.
[56]Desai C. S. Finite element residual schemes for unconfined flow. Int. J. Geotechnical Eng,1976,109(7):946-960.
[57]Li G. C, Desai C.S.stress and seepage analysis of earth dams. J. Geotechnical Eng,1983.
[58]Bakker k.J. Analysis of groundwater flow through revetments Proc.3rd International Symposium on Numerical Models in Geomechanics. Niagara Falls, Canada.1989:367-374.
[59]李学山,田微微,李芒原.渗流对深基坑工程的影响研究[J].广西大学学报(自然科学版).2008,S1：192-194.
[60]魏汝龙,基坑内外的水压力和渗流力[J],岩土工程师,1998,10(1)：23-25.
[61]王钊,邹维列,李广信,挡土结构上的土压力和水压力.岩土力学,2003,24(2)：143-150.
[62]刘建航,候学渊.基坑工程手册[M].北京：中国建筑工业出版社,1997.
[63]刘建刚,王军,陈永战.越流条件下基坑降水的有限元计算[J]门.勘察科学技术,2002,(02)：10-12.
[64]张秀勇,刘汉龙,刘广明等.南通市长江堤防渗透性能数值模拟研究[J].防灾减灾工程学报,2004,03：283-287.