深圳典型潜水地层地铁车站基坑降水引起水位变化机理的试验研究
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摘要
以深圳某地铁车站基坑工程为背景,进行基坑不完整井降水模型试验。结果表明:在降水条件相同的情况下,由于绕渗作用的影响,基坑内降水有效影响深度大于基坑外;由于群井效应的影响,基坑内双井降水有效影响深度大于单井降水;在地连墙深度范围内,基坑外土层中孔隙水压变化值随深度的增加而增大,基坑内不完整井降水引起基坑外降水曲线为"先下凹再上凸"型。基于巴布什金潜水层完整井和不完整井涌水量理论计算公式,推导不完整井降水有效影响深度计算公式。基于模型试验数据,通过曲线拟合得到基坑外降水曲线方程。以实际基坑工程为案例,将采用理论计算公式计算得到的基坑内不完整井降水有效影响深度和基坑外降水曲线与数值模拟结果进行对比,发现有效影响深度误差较小,降水曲线基本吻合,从而验证了理论计算公式的正确性和合理性。
Based on the foundation pit engineering of a subway station in Shenzhen,the model tests of partially penetrating well precipitation of foundation pit were carried out.Results show that,in the case of the same precipitation conditions,due to the influence of by-pass seepage,the effective influence depth inside foundation pit is greater than that outside foundation pit.Due to the influence of well group effect,the effective influence depth of two wells inside foundation pit is greater than that of single well.Within the depth range of diaphragm wall,the variation of pore water pressure in the outer soil layer of foundation pit increases with the increase of depth,and the precipitation of partially penetrating well inside foundation pit leads to the precipitation curve outside foundation pit showing a type of"first concave and then convex".Based on the theoretical calculation formula by Babushkin for the water inflow in the phreatic layer of fully penetrating well and partially penetrating well,the calculation formula for the effective influence depth of partially penetrating well precipitation is derived.Based on model test data,the equation of precipitation curve outside foundation pit is obtained through curve fitting.Taking the actual foundation pit engineering as the case,the effective influence depth of partially penetrating well precipitation inside foundation pit and the precipitation curve outside foundation pit obtained by theoretical calculation formulas are compared with the results of numerical simulation.It is found that the error of effective influence depth is relatively small and the precipitation curve is basically consistent,which has verified the correctness and rationality of the theoretical calculation formulas.
Based on the foundation pit engineering of a subway station in Shenzhen,the model tests of partially penetrating well precipitation of foundation pit were carried out.Results show that,in the case of the same precipitation conditions,due to the influence of by-pass seepage,the effective influence depth inside foundation pit is greater than that outside foundation pit.Due to the influence of well group effect,the effective influence depth of two wells inside foundation pit is greater than that of single well.Within the depth range of diaphragm wall,the variation of pore water pressure in the outer soil layer of foundation pit increases with the increase of depth,and the precipitation of partially penetrating well inside foundation pit leads to the precipitation curve outside foundation pit showing a type of"first concave and then convex".Based on the theoretical calculation formula by Babushkin for the water inflow in the phreatic layer of fully penetrating well and partially penetrating well,the calculation formula for the effective influence depth of partially penetrating well precipitation is derived.Based on model test data,the equation of precipitation curve outside foundation pit is obtained through curve fitting.Taking the actual foundation pit engineering as the case,the effective influence depth of partially penetrating well precipitation inside foundation pit and the precipitation curve outside foundation pit obtained by theoretical calculation formulas are compared with the results of numerical simulation.It is found that the error of effective influence depth is relatively small and the precipitation curve is basically consistent,which has verified the correctness and rationality of the theoretical calculation formulas.
引文
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[12]刘俊龙.潜水含水层中的非完整井降水设计计算探讨[J].岩土工程技术,2002(5):297-301.(LIU Junlong.Research on the Simplified Method of Design for Dewatering by Annular Partially Penetrated Wells in Phreatic Aquifer[J].Geotechnical Engineering Technique,2002(5):297-301.in Chinese)
[13]郑刚,曾超峰.基坑开挖前潜水降水引起的地下连续墙侧移研究[J].岩土工程学报,2013,35(12):2153-2163.(ZHENG Gang,ZENG Chaofeng.Lateral Displacement of Diaphragm Wall by Dewatering of Phreatic Water before Excavation[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2153-2163.in Chinese)
[14]DIAO Yu,ZHENG Gang.Numerical Analysis of Effect of Friction between Diaphragm Wall and Soil on Braced Excavation[J].Journal of Central South University of Technology,2008,15(Supplement 2):81-86.
[15]ZHENG G,DIAO Y,NG C W W.Parametric Analysis of the Effects of Stress Relief on the Performance and Capacity of Piles in Nondilative Soils[J].Canadian Geotechnical Journal,2011,48(9):1354-1363.
[2]黄雅虹,吕悦军,周毅,等.北京亦庄轻轨工程场地水位下降引起地面沉降量的评估方法探讨[J].岩土力学,2009,30(8):2457-2462.(HUANG Yahong,LYuejun,ZHOU Yi,et al.A Method for Estimating Land Subsidence Induced by Groundwater Extraction and Its Application to Site Evaluation of Yizhuang Light Railway in Beijing[J].Rock and Soil Mechanics,2009,8(30):2457-2462.in Chinese)
[3]原华,张庆贺,张建伟.侧摩阻力约束下降水引起的地面沉降估算方法[J].上海交通大学学报,2013,47(8):1329-1334.(YUAN Hua,ZHANG Qinghe,ZHANG Jianwei.Estimation Method for Surface Subsidence Induced by Dewatering under the Constraint of Lateral Friction[J].Journal of Shanghai Jiaotong University,2013,47(8):1329-1334.in Chinese)
[4]王建秀,吴林高,朱雁飞,等.地铁车站深基坑降水诱发沉降机制及计算方法[J].岩石力学与工程学报,2009,28(5):1010-1019.(WANG Jianxiu,WU Lingao,ZHU Yanfei,et al.Mechanism of Dewatering-Induced Ground Subsidence in Deep Subway Station Pit and Calculation Method[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(5):1010-1019.in Chinese)
[5]吴意谦,朱彦鹏.考虑疏干带非饱和土影响下基坑降水引起地面沉降的计算[J].工程力学,2016,33(3):179-187.(WU Yiqian,ZHU Yanpeng.Calculation of Settlement Considering Unsaturated Soil Influence on the Dewatering of Foundation Pits[J].Engineering Mechanics,2016,33(3):179-187.in Chinese)
[6]ROY Debasis,ROBINSON Keith E.Surface Settlements at a Soft Soil Site Due to Bedrock Dewatering[J].Engineering Geology,2009,107:109-117.
[7]陈崇希,林敏.地下水动力学[M].武汉:中国地质大学出版社,1999.(CHEN Chongxi,LIN Min.Groundwater Dynamics[M].Wuhan:China University of Geosciences Press,1999.in Chinese)
[8]王军辉,陶连金,韩煊,等.悬挂式帷幕入土深度对涌水量影响及优化设计[J].北京工业大学大学报,2015,41(9):1390-1398.(WANG Junhui,TAO Lianjin,HAN Xuan,et al.Effect of Suspended Curtain Depth into Stratum on Discharge Rate and Its Optimum Design[J].Journal of Beijing University of Technology,2015,41(9):1390-1398.in Chinese)
[9]顾大钊.相似材料和相似模型[M].徐州:中国矿业大学出版社,1995.(GU Dazhao.Similar Materials and Similar Models[M].Xuzhou:China University of Mining and Technology Press,1995.in Chinese)
[10]刘丰敏.考虑初始水力坡度和层间补给的降水引起地面沉降研究[D].北京:中国建筑科学研究院,2016.(LIU Fengmin.Research on Ground Settlement Caused by Dewatering Considering the Initial Hydraulic Gradient and Interlayer Recharge[D].Beijing:China Academy of Building Research,2016.in Chinese)
[11]王志佳,张建经,付晓,等.模型试验的分离相似设计方法——以锚索格构加固边坡模型试验为例[J].岩土力学,2016,37(9):2617-2623.(WANG Zhijia,ZHANG Jianjing,FU Xiao,et al.Isolated Similar Design Method for a Scaled Model Test and Its Application to Slope-Anchor Cable-Lattice Beam System[J].Rock and Soil Mechanics,2016,37(9):2617-2623.in Chinese)
[12]刘俊龙.潜水含水层中的非完整井降水设计计算探讨[J].岩土工程技术,2002(5):297-301.(LIU Junlong.Research on the Simplified Method of Design for Dewatering by Annular Partially Penetrated Wells in Phreatic Aquifer[J].Geotechnical Engineering Technique,2002(5):297-301.in Chinese)
[13]郑刚,曾超峰.基坑开挖前潜水降水引起的地下连续墙侧移研究[J].岩土工程学报,2013,35(12):2153-2163.(ZHENG Gang,ZENG Chaofeng.Lateral Displacement of Diaphragm Wall by Dewatering of Phreatic Water before Excavation[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2153-2163.in Chinese)
[14]DIAO Yu,ZHENG Gang.Numerical Analysis of Effect of Friction between Diaphragm Wall and Soil on Braced Excavation[J].Journal of Central South University of Technology,2008,15(Supplement 2):81-86.
[15]ZHENG G,DIAO Y,NG C W W.Parametric Analysis of the Effects of Stress Relief on the Performance and Capacity of Piles in Nondilative Soils[J].Canadian Geotechnical Journal,2011,48(9):1354-1363.