低能量强夯–电渗法联合加固软黏土地基试验研究
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摘要
针对电渗过程中土样开裂造成电阻增大,阳极腐蚀造成界面电阻增大,能量消耗增大且加固效果减弱,极端情况下甚至造成电渗过程中断的问题,以及考虑到强夯法对开裂土体进行处理,不仅使开裂土体重新弥合,更可弥补电渗法的土骨架加密部分的功能缺失。因此,通过低能量强夯联合电渗法室内模型试验与单独电渗试验进行对比分析,分别获得2种试验条件下电路电流、土体出流、土体含水率、土体电导率、p H值等变化规律。研究结果表明:低能量强夯时改善了土体排水路径,使得土体出流表现强于单纯电渗的情况;低能量强夯能够增强电路电流、增强土体密实性以弥补土体裂纹的同时,促进土表沉降发展、改善环向土体处理的不均匀问题和减缓阳极腐蚀发展。在实际工程中,为提高加固效果,低能量强夯重点施加于阳极区土体开裂处,而不对阴极区土体进行强夯;在土体出流量突然变小且阳极区土体干燥时,选取阳极区土体干燥处作为夯点并开始强夯,待所有区域点夯完后,再针对阳极区土体进行低能量满夯,不对阴极区土体进行满夯处理。
The dynamic compaction with low energy was considered to deal with the problems of the increasing of the electrical resistance of soil samples due to cracking and of the interface between anode and soil,the increasing of energy consumption and the decreasing of the effect of consolidation due to anode corrosion in the electroomostic process, and in the extreme cases the interruption of the electro-osmotic process. Indoor model tests of electro-osmosis with and without the low-energy dynamic compaction were carried out respectively. The low energy dynamic compaction was found to improve the drainage paths of the soil and the water drainage was increased than that without dynamic compaction. The electrical circuit current was increased and soil compactness was enhanced due to low-energy dynamic compaction. The cracks in soils ample was closed,the surface settlementwas increased, and the uneven settlement of soil and the anode corrosion were reduced due to the low-energy dynamic compaction. Suggestions of carrying on dynamic compaction in the cracking soil of anode zone were thus made for application in the engineering practice. Dynamic compaction should start when the water flow become smaller and the anode zone become dry.
The dynamic compaction with low energy was considered to deal with the problems of the increasing of the electrical resistance of soil samples due to cracking and of the interface between anode and soil,the increasing of energy consumption and the decreasing of the effect of consolidation due to anode corrosion in the electroomostic process, and in the extreme cases the interruption of the electro-osmotic process. Indoor model tests of electro-osmosis with and without the low-energy dynamic compaction were carried out respectively. The low energy dynamic compaction was found to improve the drainage paths of the soil and the water drainage was increased than that without dynamic compaction. The electrical circuit current was increased and soil compactness was enhanced due to low-energy dynamic compaction. The cracks in soils ample was closed,the surface settlementwas increased, and the uneven settlement of soil and the anode corrosion were reduced due to the low-energy dynamic compaction. Suggestions of carrying on dynamic compaction in the cracking soil of anode zone were thus made for application in the engineering practice. Dynamic compaction should start when the water flow become smaller and the anode zone become dry.
引文
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[15]BURNOTTE F,LEFEBVRE G,GRONDIN G.A case record of electroosmotic consolidation of soft clay with improved soil-electrode contact[J].Canadian Geotechical Journal,2004,41(6):1 038–1 053.
[16]熊巨华,胡斌,冯世进,等.强夯法加固粉土地基室内模型试验研究[J].世界地震工程,2010,26(增):241–246.(XIONG Juhua,HU Bin,FENG Shijin,et al.Model test study on silt foundation improvement by dynamic compaction[J].World Earthquake Engineering,2010,26(Supp.):241–246.(in Chinese))
[2]ESRIG M I.Pore pressure,consolidation and electrokinetics[J].Journal of the SMFD,1968,94(SM4):899–921.
[3]SU J Q,WANG Z.The two-dimensional consolidation theory of electro-osmosis[J].Geotechnique,2003,53(8):759–763.
[4]ZHUANG Y F,WANG Z.Interface electric resistance of electroosmotic consolidation[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,2007,133(12):1 617–1 624.
[5]GLENDINNING S,LAMONT-BLACK J,JONES C J F P.Treatment of sewage sludge using electrokinetic geosynthetics[J].Journal of Hazardous Materials,2007,139(3):491–499.
[6]GLENDINNING S,JONES C J F P,PUGH R C.Reinforced soil using cohesive fill and electrokinetic geosynthetics[J].International Journal of Geomechanics,ASCE,2005,5(2):138–146.
[7]MICIC S,SHANG J Q,LO K Y,et al.Electrokinetic strengthening of a marine sediment using intermittent current[J].Canadian Geotechical Journal,2001,38(22):287–302.
[8]李瑛,龚晓南,焦丹,等.软黏土二维电渗固结性状的试验研究[J].岩石力学与工程学报,2009,28(增2):4 034–4 039.(LI Ying,GONG Xiaonan,JIAO Dan,et al.Experimental study on two-dimensional electro-osmotic consolidation of soft clay[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(Supp.2):4 034–4 039.(in Chinese))
[9]曹永华,高志义.电渗法中排水固结理论与实践的若干问题[J].中国港湾建设,2010,(1):22–24.(CAO Yonghua,GAO Zhiyi.Some problems on theory and application of drainage consolidation in electroosmotic for ground improvement[J].China Harbour Engineering,2010,(1):22–24.(in Chinese))
[10]郑颖人,陆新,李学志,等.强夯加固软黏土地基的理论与工艺研究[J].岩土工程学报,2000,22(1):18–22.(ZHENG Yingren,LU Xin,LI Xuezhi,et al.Research on theory and technology of improving soft clay with DCM[J].Chinese Journal of Geotechnical Engineering,2000,22(1):18–22.(in Chinese))
[11]赵建国,朱文凯.电渗–强夯综合法加固软土地基的实践[J].地质与勘探,1994,30(2):76–80.(ZHAO Jianguo,ZHU Wenkai.A practice consolidating soft formations with an electric osmosizingstrong ramming composite method[J].Geology and Prospecting,1994,30(2):76–80.(in Chinese))
[12]刘凤松,刘耘东.真空–电渗降水–低能量强夯联合软弱地基加固技术在软土地基加固中的应用[J].中国港湾建设,2008,(1):43–47.(LIU Fengsong,LIU Yundong.Application of combined weak soil improvement technology of vacuum preloading-dewatering by electro-osmosis-low energy dynamic compaction to improve soft soils[J].China Harbour Engineering,2008,(1):43–47.(in Chinese))
[13]廖敬堂,廖宏志.真空电渗井点降水及低能量强夯加固技术在软基加固中的应用[J].华南港工,2009,(1):30–36.(LIAO Jingtang,LIAO Hongzhi.Water level lowing technique using vacuum electrical point well and low energy dynamic compaction on soft ground of berth 5 and 6 of shatian port zone of humen port[J].South China Harbour Engineering,2009,(1):30–36.(in Chinese))
[14]高有斌,曾国海,徐步兴,等.双控动力固结法加固软黏土地基的应用研究[J].防灾减灾工程学报,2009,29(6):632–637.(GAO Youbin,ZENG Guohai,XU Buxing,et al.Research on application of double-control dynamic consolidation method in strengthening soft clays[J].Journal of Disaster Prevention and Mitigation Engineering,2009,29(6):632–637.(in Chinese))
[15]BURNOTTE F,LEFEBVRE G,GRONDIN G.A case record of electroosmotic consolidation of soft clay with improved soil-electrode contact[J].Canadian Geotechical Journal,2004,41(6):1 038–1 053.
[16]熊巨华,胡斌,冯世进,等.强夯法加固粉土地基室内模型试验研究[J].世界地震工程,2010,26(增):241–246.(XIONG Juhua,HU Bin,FENG Shijin,et al.Model test study on silt foundation improvement by dynamic compaction[J].World Earthquake Engineering,2010,26(Supp.):241–246.(in Chinese))
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