不同能级强夯置换处理软土地基现场试验
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摘要
依托广西钦州港区某大型工程软土地基处理实践,开展8 000和15 000kN·m能级强夯置换处理软土地基的现场试验;基于强夯置换过程中超孔隙水压力测试、强夯置换前后多道瞬态面波测试及重型动力触探试验、强夯置换后钻孔检测及静载试验结果,对地基承载力和土体工程特性变化进行详细分析。研究结果表明:2个能级强夯置换后,地基承载力均明显提高,土体工程特性得到改善,置换后复合地基承载力均大于200kPa,变形模量分别大于20和15 MPa,满足地基处理设计要求;8 000和15 000kN·m能级强夯置换第1遍强夯超孔隙水压力消散时间分别为6~7d和为7~8d;8 000和15 000kN·m能级强夯有效加固深度约为8.0和9.5m,水平振动影响安全距离约为18.0和25.0m;强夯置换后,置换墩体与墩间土间存在明显的不均性,设计时应充分考虑到强夯置换后地基土的不均匀性。
Based on foundation treatment practice of large-scale engineering in Qinzhou port,field test of dynamic replacement method on soft soil foundation under 8 000 and 15 000 kN·m energy-level was carried.Excess pore water pressure monitoring during replacement process,multichannel transient surface wave test and heavy dynamic penetration test before and after dynamic replacement,drilling test and static load test after dynamic replacement were finished in field test.Changing of bearing capacity and engineering characteristics of soil during replacement process was analyzed in details.Conclusions obtained were as following.Firstly,the bearing capacity of foundation and engineering characteristics of soil was improved after dynamic replacement.The bearing capacity of foundation was larger than 200 kPa with compression modulus of 8 000 and 15 000 kN·m dynamic replacement larger than 20 and 15 MPa.Secondly,dissipation time of excess pore water pressure of 8 000 and 15 000 kN·m dynamic replacement was 6 to 7 days and 7 to 8 days.The reinforcement depth of 8 000 and 15 000 kN·m energy-level replacement was about8.0 and 9.5 m.Thirdly,safety distance of horizontal vibration for 8 000 and 15 000 kN·m energy-level replacement was about 18.0 and 25.0 m.Finally,difference existed between replacement piers and surrounding soil.Therefore,non-uniformity of foundation soil after dynamic replacement should be considered fully during building design.The experience and results in this paper could be referred in foundation treatment under similar geotechnical condition.
Based on foundation treatment practice of large-scale engineering in Qinzhou port,field test of dynamic replacement method on soft soil foundation under 8 000 and 15 000 kN·m energy-level was carried.Excess pore water pressure monitoring during replacement process,multichannel transient surface wave test and heavy dynamic penetration test before and after dynamic replacement,drilling test and static load test after dynamic replacement were finished in field test.Changing of bearing capacity and engineering characteristics of soil during replacement process was analyzed in details.Conclusions obtained were as following.Firstly,the bearing capacity of foundation and engineering characteristics of soil was improved after dynamic replacement.The bearing capacity of foundation was larger than 200 kPa with compression modulus of 8 000 and 15 000 kN·m dynamic replacement larger than 20 and 15 MPa.Secondly,dissipation time of excess pore water pressure of 8 000 and 15 000 kN·m dynamic replacement was 6 to 7 days and 7 to 8 days.The reinforcement depth of 8 000 and 15 000 kN·m energy-level replacement was about8.0 and 9.5 m.Thirdly,safety distance of horizontal vibration for 8 000 and 15 000 kN·m energy-level replacement was about 18.0 and 25.0 m.Finally,difference existed between replacement piers and surrounding soil.Therefore,non-uniformity of foundation soil after dynamic replacement should be considered fully during building design.The experience and results in this paper could be referred in foundation treatment under similar geotechnical condition.
引文
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[8]刘红军,吴腾,马江,等.基于孔压监测的强夯置换和砂井-强夯处理饱和软土地基试验研究[J].中国海洋大学学报(自然科学版),2015,45(2):109-114.LIU Hong-jun,WU Teng,MA Jiang,et al.An experimental study on saturated soft ground improvement with dynamic compaction replacement and Dcm combined with sand-drain based on monitoring of pore water pressure[J].Periodical of Ocean University of China,2015,45(2):109-114.
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[10]谢仁追.强夯置换法应用关键技术[J].水运工程,2009(5):128-132.XIE Ren-zhui.Key technologies of application of dynamic replacement[J].Port and Waterway Engineering,2009(5):128-132.
[2]王宏祥,闫澍旺,冯守中.强夯置换墩法处理公路软基的机制研究[J].岩土力学,2009,30(12):3753-3758.WANG Hong-sheng,YAN Shu-wang,FENG Shou-zhong.Study of mechanism of dynamic compaction replacement for reinforcing highway soft roadbed[J].Rock and Soil Mechanics,2009,30(12):3753-3758.
[3]白冰,徐华轩,刘海波,等.强夯置换法处理松软土地基若干问题研究[J].岩石力学与工程学报,2010,29(增1):3001-3006.BAI Bing,XU Hua-xuan,LIU Hai-bo,et al.Some problems on dynamic replacement method to improve soft ground[J].Journal of Rock Mechanics and Engineering,2010,29(S1):3001-3006.
[4]张彧,房建宏,刘建坤,等.强夯置换复合地基加固盐渍土效果的试验研究[J].岩土工程学报,2011,33(增1):258-261.ZHANG Yu,FANG Jian-hong,LIU Jian-kun,et al.Field tests on reinforcement effects of ground treatment of composite foundation in saline soils by dynamic compaction replacement[J].Journal of Rock Mechanics and Engineering,2011,33(S1):258-261.
[5]水伟厚.对强夯置换概念的探讨和置换墩长度的实测研究[J].岩土力学,2011,32(增2):502-506.SHUI Wei-hou.Exploring concept of dynamic replacement and measured length of replacement pier[J].Rock and Soil Mechanics,2011,32(S2):502-506.
[6]郑凌逶,周风华,谢新宇.强夯置换中碎石运动机制和成墩过程的数值模拟[J].岩土工程学报,2013,35(11):2068-2075.ZHENG Ling-wei,ZHOU Feng-hua,XIE Xin-yu.Numerical simulation of forming of replacement piers during a dynamic replacement process[J].Chinese Journal of Geotechnical Engineering,2013,35(11):2068-2075.
[7]郑凌逶,周风华.强夯置换软土中碎石墩形成过程的试验研究[J].岩土力学,2014,35(1):90-97.ZHENG Ling-wei,ZHOU Feng-hua,.Experimental study of forming process of replacement pier in soft soil using dynamic replacement method[J].Rock and Soil Mechanics,2014,35(1):90-97.
[8]刘红军,吴腾,马江,等.基于孔压监测的强夯置换和砂井-强夯处理饱和软土地基试验研究[J].中国海洋大学学报(自然科学版),2015,45(2):109-114.LIU Hong-jun,WU Teng,MA Jiang,et al.An experimental study on saturated soft ground improvement with dynamic compaction replacement and Dcm combined with sand-drain based on monitoring of pore water pressure[J].Periodical of Ocean University of China,2015,45(2):109-114.
[9]张成光.抛石挤淤及强夯置换在软基处理中的应用[J].水运工程,2015(2):165-169.ZHANG Cheng-guang.Application of rock fill dumping and dynamic replacement method to soft soil foundation treatment[J].Port&Waterway Engineering,2015(2):165-169.
[10]谢仁追.强夯置换法应用关键技术[J].水运工程,2009(5):128-132.XIE Ren-zhui.Key technologies of application of dynamic replacement[J].Port and Waterway Engineering,2009(5):128-132.