基于随机介质理论的基坑地表沉降计算方法研究
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摘要
针对深基坑开挖及降水过程引起的地表沉降问题,文章引入随机介质理论中的地层损失概念,推导了基坑开挖引起的地表沉降计算公式,推导并改进了容重变化和渗透力变化引起的地表沉降公式,并考虑了支护结构-土界面摩阻力对沉降的影响,探讨了随机介质理论在基坑开挖计算中关键参数的确定问题,最后与文献[10]计算结果及实测地表沉降结果进行了对比分析。结果表明:本文计算方法得到的基坑周边地表沉降分布与实测沉降更为接近,能更准确地预估基坑开挖及降水引起的地表沉降;因考虑了土体的持水度和支护结构侧摩阻力的影响,在1.5倍开挖深度范围内的计算精度远高于传统方法,在基坑1.5倍开挖深度范围外的计算精度得到进一步提高;对于有支护结构并使用坑内降水的敞口基坑,应用本文计算方法预测地表沉降,能取得较好的效果。
In view of the surface settlement caused by excavation and dewatering of deep foundation pit,the concept of ground loss in random medium theory was introduced,the calculation formula for the surface settlement caused by foundation pit excavation was deduced,and the formula for surface settlement caused by changes of unit weight and penetration was deduced and improved,the determination of key parameters of random medium theory applied in calculation of foundation pit excavation was discussed by taking the effect of frictional resistance at support structure-soil interface on settlement into consideration,and a contrastive analysis of the calculation results by the methods proposed in this paper and reference[10]and the measured settlements was conducted.The results show that the surface settlement near foundation pit calculated by the method proposed in this paper is closer to the measured ones,the surface settlement caused by excavation and dewatering of foundation pit can be predicted more accurately using the proposed method;compared with the traditional methods,the calculation accuracy of this method is much higher within the scope of 1.5 times excavation depth while the calculation accuracy would be further improved beyond the scope of 1.5 times excavation depth by considering the effect of specific water retention of soil mass and frictional resistance at the side of support structure;as for the open foundation pit with support structure and dewatering in the pit,good prediction of surface settlement can be achieved with the calculation method proposed in this paper.
In view of the surface settlement caused by excavation and dewatering of deep foundation pit,the concept of ground loss in random medium theory was introduced,the calculation formula for the surface settlement caused by foundation pit excavation was deduced,and the formula for surface settlement caused by changes of unit weight and penetration was deduced and improved,the determination of key parameters of random medium theory applied in calculation of foundation pit excavation was discussed by taking the effect of frictional resistance at support structure-soil interface on settlement into consideration,and a contrastive analysis of the calculation results by the methods proposed in this paper and reference[10]and the measured settlements was conducted.The results show that the surface settlement near foundation pit calculated by the method proposed in this paper is closer to the measured ones,the surface settlement caused by excavation and dewatering of foundation pit can be predicted more accurately using the proposed method;compared with the traditional methods,the calculation accuracy of this method is much higher within the scope of 1.5 times excavation depth while the calculation accuracy would be further improved beyond the scope of 1.5 times excavation depth by considering the effect of specific water retention of soil mass and frictional resistance at the side of support structure;as for the open foundation pit with support structure and dewatering in the pit,good prediction of surface settlement can be achieved with the calculation method proposed in this paper.
引文
[1]薛莲,傅晏,刘新荣.深基坑开挖对临近建筑物的影响研究[J].地下空间与工程学报, 2008,(5):847-851.XUE Lian, FU Yan, LIU Xinrong. Study on Influence of Foundation Ditch Excavation to Adjacent Building[J]. Chinese Journal ofUnderground Space and Engineering, 2008,(5):847-851.
[2]刘勇健,李彰明,张建龙,等.基于遗传-神经网络的深基坑变形实时预报方法研究[J].岩石力学与工程学报, 2004,(6):1010-1014.LIU Yongjian, LI Zhangming, ZHANG Jianlong, et al. Real Time Prediction Method Based on Genetic Algorith and Neural Networkfor Deformation Caused by Deep Excavation[J]. Chinese Journal of Rock Mechanics and Engineering, 2004,(6):1010-1014.
[3]王平卫,彭振斌,何忠明.基于灰色理论的基坑变形预测[J].地质与勘探, 2006,(6):94-97.WANG Pingwei, PENG Zhenbin, HE Zhongming. Prediction of Deformationof Deep Excavation Based on Grey Theory[J]. Geologyand Prospecting, 2006,(6):94-97.
[4]代春泉,王磊.深基坑施工变形预测VAR建模与应用分析[J].岩土力学, 2012,(增2):395-400.DAI Chunquan, WANG Lei. VAR Modeling of Construction Deformation Prediction of Deep Foundation Pit and Application[J].Rock and Soil Mechanics, 2012,(S2):395-400.
[5]张尚根,袁正如.软土深基坑开挖地表沉降分析[J].地下空间与工程学报, 2013,(增1):1753-1757.ZHANG Shanggen, YUAN Zhengru. Analysis of Ground Settlement Induced by Excavation of Deep Foundation Pit in Soft Soil[J].Chinese Journal of Underground Space and Engineering, 2013,(S1):1753-1757.
[6]李小青,王朋团,张剑.软土基坑周围地表沉陷变形计算分析[J].岩土力学, 2007, 28,(9):1879-1882.LI Xiaoqing, WANG Pengtuan, ZHANG Jian. Calculation Analysis of Circumferencial Surface Settlement of Soft Soil Foundation Pit[J]. Rock and Soil Mechnaics, 2007, 28,(9):1879-1882.
[7] HASHASH Y M A, WHITTLE A J. Ground Movement Prediction for Deep Excavations in Soft Clay[J]. Journal of Geotechnical En?gineering, ASCE, 1996, 122,(6):474-486.
[8]刘小丽,周贺,张占民.软土深基坑开挖地表沉降估算方法的分析[J].岩土力学, 2011,(增1):90-94.LIU Xiaoli, ZHOU He, ZHANG Zhanmin. Computation of Surface Settlement for Deep Excavation in Soft Areas[J]. Rock and SoilMechanics, 2011,(S1):90-94.
[9]阳军生,刘宝琛.城市隧道施工引起的地表移动与变形[M].北京:中国铁道出版社, 2002.YANG Junsheng, LIU Baocheng. Ground Surface Movement and Deformation Induced by Urban Tunnel Construction[M]. Beijing:China Railway Publishing House, 2002.
[10]施成华,彭立敏.基坑开挖及降水引起的地表沉降预测[J].土木工程学报, 2006,(5):117-121.SHI Chenghua, PENG Limin. Ground Surface Settlement Caused by Foundation Pit Excavation and Dewaterting[J]. China Civil En?gineering Journal, 2006,(5):117-121.
[11]苑莲菊,李振栓,武胜忠,等.渗流工程力学及应用[M].北京:中国建材工业出版社, 2001.YUAN Lianju, LI Zhenshuan, WU Shengzhong, et al. Seepage Engineering Mechanics and Application[M]. Beijing:China BuildingMaterials Press, 2001.
[12]姚天强,石振华.基坑降水手册[M].北京:中国建筑工业出版社, 2006.YAO Tianqiang, SHI Zhenhua. Manual of Foundation Pit Dewatering[M]. Beijing:China Architecture&Building Press, 2006.
[13]中华人民共和国建设部.建筑桩基技术规范:GB/JGJ 94-2008[S].北京:中国建筑工业出版社, 2008.Ministry of Housing and Urban-rural Delopment of the People′s Republic of China. Technical Code for Building Pile Foundations:GB/JGJ 94-2008[S]. Beijing:China Architecture&Building Press, 2008.
[14]陈鹏飞.城际铁路车站深基坑地表沉降估算方法研究[D].长沙:中南大学, 2012.CHEN Pengfei. Rearch on the Surface Settlement Estimation Methods of Deep Foundation Pit on the Interurban Railway[D]. Chang?sha:Central China University, 2012.
[15]邓聚龙.灰色系统理论[M].武汉:华中科技大学出版社, 2002.DENG Julong. Grey System Theory[M]. Wuhan:Huazhong Unversity of Science&Technology Press, 2002.
[2]刘勇健,李彰明,张建龙,等.基于遗传-神经网络的深基坑变形实时预报方法研究[J].岩石力学与工程学报, 2004,(6):1010-1014.LIU Yongjian, LI Zhangming, ZHANG Jianlong, et al. Real Time Prediction Method Based on Genetic Algorith and Neural Networkfor Deformation Caused by Deep Excavation[J]. Chinese Journal of Rock Mechanics and Engineering, 2004,(6):1010-1014.
[3]王平卫,彭振斌,何忠明.基于灰色理论的基坑变形预测[J].地质与勘探, 2006,(6):94-97.WANG Pingwei, PENG Zhenbin, HE Zhongming. Prediction of Deformationof Deep Excavation Based on Grey Theory[J]. Geologyand Prospecting, 2006,(6):94-97.
[4]代春泉,王磊.深基坑施工变形预测VAR建模与应用分析[J].岩土力学, 2012,(增2):395-400.DAI Chunquan, WANG Lei. VAR Modeling of Construction Deformation Prediction of Deep Foundation Pit and Application[J].Rock and Soil Mechanics, 2012,(S2):395-400.
[5]张尚根,袁正如.软土深基坑开挖地表沉降分析[J].地下空间与工程学报, 2013,(增1):1753-1757.ZHANG Shanggen, YUAN Zhengru. Analysis of Ground Settlement Induced by Excavation of Deep Foundation Pit in Soft Soil[J].Chinese Journal of Underground Space and Engineering, 2013,(S1):1753-1757.
[6]李小青,王朋团,张剑.软土基坑周围地表沉陷变形计算分析[J].岩土力学, 2007, 28,(9):1879-1882.LI Xiaoqing, WANG Pengtuan, ZHANG Jian. Calculation Analysis of Circumferencial Surface Settlement of Soft Soil Foundation Pit[J]. Rock and Soil Mechnaics, 2007, 28,(9):1879-1882.
[7] HASHASH Y M A, WHITTLE A J. Ground Movement Prediction for Deep Excavations in Soft Clay[J]. Journal of Geotechnical En?gineering, ASCE, 1996, 122,(6):474-486.
[8]刘小丽,周贺,张占民.软土深基坑开挖地表沉降估算方法的分析[J].岩土力学, 2011,(增1):90-94.LIU Xiaoli, ZHOU He, ZHANG Zhanmin. Computation of Surface Settlement for Deep Excavation in Soft Areas[J]. Rock and SoilMechanics, 2011,(S1):90-94.
[9]阳军生,刘宝琛.城市隧道施工引起的地表移动与变形[M].北京:中国铁道出版社, 2002.YANG Junsheng, LIU Baocheng. Ground Surface Movement and Deformation Induced by Urban Tunnel Construction[M]. Beijing:China Railway Publishing House, 2002.
[10]施成华,彭立敏.基坑开挖及降水引起的地表沉降预测[J].土木工程学报, 2006,(5):117-121.SHI Chenghua, PENG Limin. Ground Surface Settlement Caused by Foundation Pit Excavation and Dewaterting[J]. China Civil En?gineering Journal, 2006,(5):117-121.
[11]苑莲菊,李振栓,武胜忠,等.渗流工程力学及应用[M].北京:中国建材工业出版社, 2001.YUAN Lianju, LI Zhenshuan, WU Shengzhong, et al. Seepage Engineering Mechanics and Application[M]. Beijing:China BuildingMaterials Press, 2001.
[12]姚天强,石振华.基坑降水手册[M].北京:中国建筑工业出版社, 2006.YAO Tianqiang, SHI Zhenhua. Manual of Foundation Pit Dewatering[M]. Beijing:China Architecture&Building Press, 2006.
[13]中华人民共和国建设部.建筑桩基技术规范:GB/JGJ 94-2008[S].北京:中国建筑工业出版社, 2008.Ministry of Housing and Urban-rural Delopment of the People′s Republic of China. Technical Code for Building Pile Foundations:GB/JGJ 94-2008[S]. Beijing:China Architecture&Building Press, 2008.
[14]陈鹏飞.城际铁路车站深基坑地表沉降估算方法研究[D].长沙:中南大学, 2012.CHEN Pengfei. Rearch on the Surface Settlement Estimation Methods of Deep Foundation Pit on the Interurban Railway[D]. Chang?sha:Central China University, 2012.
[15]邓聚龙.灰色系统理论[M].武汉:华中科技大学出版社, 2002.DENG Julong. Grey System Theory[M]. Wuhan:Huazhong Unversity of Science&Technology Press, 2002.
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