无填料振冲法在液化粉细砂中的应用研究
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摘要
结合某电厂工程大面积吹填土的地基处理实践,从振冲法处理地基的加固机理出发,根据振动荷载作用下孔隙水压力的增长方式,由理论公式推导孔压变化的解析式,并由此得到砂土地基达到临界液化状态所需条件。考虑到孔压解析式为单调波动函数,求解困难,故在计算过程中将其分解为单调函数及波动函数两部分,利用图解法求解,得到一定条件下砂土地基临界液化时间的精确值。根据文献中最优密度的概念,经分析认为临界液化时间即为砂土达到最优密度所需的时间,据此可对振冲法施工中的留振时间进行优化设计。对振冲法的预振效应进行了分析,认为预振效应的机理是经过振动处理后,砂土地基的微观结构得到了优化。最后结合工程实例,探讨了无填料振冲法处理液化粉细砂地基的适宜性及处理效果。
The application of vibroflotation without backfill in the improvement of liquefiable silty and fine sand at a power plant ground treatment is presented.On the basis of vibroflotation strengthening principle and the rising mode of vibration pore water pressure,the analytic solution of pore water pressure is deduced from the theoretical formula,and the sand critical liquefaction condition is presented.In view of the monotonic fluctuation function,the analytic solution is detached as monotonic function and fluctuation function and solved by the graphical method to get the exact solutions of sand critical liquefaction time.The paper takes the critical liquefaction time as the time to get the best density of sand and then optimization design for the vibroflotation load time can be made on the basis of the critical liquefaction time.The underlying mechanism of pre-vibration effect is also discussed,which is thought to be useful to improve the microstructure of sand.Finally,the suitability and effectiveness of vibroflotation without backfill on silty and fine sand are dicussed.
The application of vibroflotation without backfill in the improvement of liquefiable silty and fine sand at a power plant ground treatment is presented.On the basis of vibroflotation strengthening principle and the rising mode of vibration pore water pressure,the analytic solution of pore water pressure is deduced from the theoretical formula,and the sand critical liquefaction condition is presented.In view of the monotonic fluctuation function,the analytic solution is detached as monotonic function and fluctuation function and solved by the graphical method to get the exact solutions of sand critical liquefaction time.The paper takes the critical liquefaction time as the time to get the best density of sand and then optimization design for the vibroflotation load time can be made on the basis of the critical liquefaction time.The underlying mechanism of pre-vibration effect is also discussed,which is thought to be useful to improve the microstructure of sand.Finally,the suitability and effectiveness of vibroflotation without backfill on silty and fine sand are dicussed.
引文
[1]叶书麟,叶观宝.地基处理与托换技术[M].北京:中国建筑工业出版社,2005.(YE Shu-lin,YE Guan-bao.Ground treatment and underpinning technique[M].Beijing:China Architecture&Building Press,2005.(in Chinese))
[2]林宗元.岩土工程治理手册[M].沈阳:辽宁科学技术出版社,1993.(LIN Zong-yuan.Geotechnical investigation and design[M].Shenyang:Liaoning Science and Technology Publishing House,1993.(in Chinese))
[3]周健,胡寅,林晓斌,等.粉细砂的室内无填料振冲试验研究[J].岩土力学,2003,24(5):790–795.(ZHOU Jian,HU Yin,LIN Xiao-bin,JIA Min-cai,et al.Laboratory test of vibroflotation on hydraulic backfilled silty and fine sand without backfill[J].Rock and Soil Mechanics,2003,24(5):790–794.(in Chinese))
[4]周健,贾敏才,池永.无填料振冲法加固粉细砂地基试验研究及应用研究[J].岩石力学与工程学报,2003,22(8):1350–1355.(ZHOU Jian,JIA Min-cai,CHI Yong.Vibroflotation compaction of silty fine sands without additional backfill materials[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(8):1350–1355.(in Chinese))
[5]周健,姚浩,贾敏才.大面积软弱地基浅层处理技术研究[J].岩土力学,2005,26(10):1685–1688.(ZHOU Jian,YAO Hao,JIA Min-cai.Research on technology for shallow treatment of large-area soft soils[J].Rock and Soil Mechanics,2005,26(10):1685–1688.(in Chinese))
[6]牟宏彬,章奕峰,杨小宝,等.振冲法在加固粉细砂地基中的应用[J].浙江建筑,2006,23(10):33–35.(MOU Hong-bin,ZHANG Yi-feng,YANG Xiao-bao,et al.The application of vibroflotation on silty and fine sands[J].Zhejiang Construction,2006,23(10):33–35.(in Chinese))
[7]刘金韬,金晓媚,武强.地震液化饱和砂土层内部超静孔压理论分析[J].工程勘察,2000(5):6–8.(LIU Jin-tao,JIN Xiao-mei,WU Qiang.Analysis of the ultra-static pore water pressure theory in earthquake liquefaction sature sands[J].Geotechnical Investigation&Surveying,2000(5):6–8.(in Chinese))
[8]缪林昌,刘松玉.振冲动力法加固地基的机理[J].东南大学学报(自然科学版),2001,31(4):71–74.(MIAO Lin-chang,LIU Song-yu.Mechanism of vibro-flotation dynamic method for improving foundation[J].Journal of Southeast University(Natureal Science Edition),2001,31(4):71–74.(in Chinese))
[9]MARTIN G H,FINN W D,SEED H B.Fundamentals of liquefaction under cyclic loading[J].Journal of the Geotechnical Division.American Society of Civil Engineering,1975,101(5):427–437.
[10]汪闻韶.饱和砂土震动孔隙水压力的产生、扩散和消散[C]//中国土木工程学会第一届土力学及基础工程学术会议论文选集.天津:中国工业出版社,1964.(WANG Wen-shao.The generation,diffusion and dissipation of vibration pore water pressure in sature sands[C]//The Memoir of the First Soil Mechanics and Foundation Engineering Academic Conference of China Civil Engineering Society.Tianjin:China Industry Press,1964.(in Chinese))
[11]汪闻韶.土的液化机理[J].水利学报,1981(5):22–34.(WANG Wen-shao.The liquefaction mechanism of soil[J].Journal of Hydraulic Engineering,1981(5):22–34.(in Chinese))
[12]刘洋,周健,吴顺川.循环荷载下砂土变形的细观数值模拟Ⅰ:松砂试验结果[J].岩土工程学报,2007,29(7):1035–1041.(LIU Yang,ZHOU Jian,WU Shun-chuan.Micro-numerical simulation of cyclic biaxial textⅠ:results of loose sand[J].Chinese Journal of Geotechnical Engineering,2007,29(7):1035–1041.(in Chinese))
[13]GB 50011—2001建筑抗震设计规范[S].2001.(GB 50011—2001 Code for seismic design of buildings[S].2001.(in Chinese))
[14]DGJ08—37—2002上海市岩土工程勘察规范[S].2002.(DGJ08—37—2002 Code for investigation of geotechnical engineering[S].2002.(in Chinese))
[2]林宗元.岩土工程治理手册[M].沈阳:辽宁科学技术出版社,1993.(LIN Zong-yuan.Geotechnical investigation and design[M].Shenyang:Liaoning Science and Technology Publishing House,1993.(in Chinese))
[3]周健,胡寅,林晓斌,等.粉细砂的室内无填料振冲试验研究[J].岩土力学,2003,24(5):790–795.(ZHOU Jian,HU Yin,LIN Xiao-bin,JIA Min-cai,et al.Laboratory test of vibroflotation on hydraulic backfilled silty and fine sand without backfill[J].Rock and Soil Mechanics,2003,24(5):790–794.(in Chinese))
[4]周健,贾敏才,池永.无填料振冲法加固粉细砂地基试验研究及应用研究[J].岩石力学与工程学报,2003,22(8):1350–1355.(ZHOU Jian,JIA Min-cai,CHI Yong.Vibroflotation compaction of silty fine sands without additional backfill materials[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(8):1350–1355.(in Chinese))
[5]周健,姚浩,贾敏才.大面积软弱地基浅层处理技术研究[J].岩土力学,2005,26(10):1685–1688.(ZHOU Jian,YAO Hao,JIA Min-cai.Research on technology for shallow treatment of large-area soft soils[J].Rock and Soil Mechanics,2005,26(10):1685–1688.(in Chinese))
[6]牟宏彬,章奕峰,杨小宝,等.振冲法在加固粉细砂地基中的应用[J].浙江建筑,2006,23(10):33–35.(MOU Hong-bin,ZHANG Yi-feng,YANG Xiao-bao,et al.The application of vibroflotation on silty and fine sands[J].Zhejiang Construction,2006,23(10):33–35.(in Chinese))
[7]刘金韬,金晓媚,武强.地震液化饱和砂土层内部超静孔压理论分析[J].工程勘察,2000(5):6–8.(LIU Jin-tao,JIN Xiao-mei,WU Qiang.Analysis of the ultra-static pore water pressure theory in earthquake liquefaction sature sands[J].Geotechnical Investigation&Surveying,2000(5):6–8.(in Chinese))
[8]缪林昌,刘松玉.振冲动力法加固地基的机理[J].东南大学学报(自然科学版),2001,31(4):71–74.(MIAO Lin-chang,LIU Song-yu.Mechanism of vibro-flotation dynamic method for improving foundation[J].Journal of Southeast University(Natureal Science Edition),2001,31(4):71–74.(in Chinese))
[9]MARTIN G H,FINN W D,SEED H B.Fundamentals of liquefaction under cyclic loading[J].Journal of the Geotechnical Division.American Society of Civil Engineering,1975,101(5):427–437.
[10]汪闻韶.饱和砂土震动孔隙水压力的产生、扩散和消散[C]//中国土木工程学会第一届土力学及基础工程学术会议论文选集.天津:中国工业出版社,1964.(WANG Wen-shao.The generation,diffusion and dissipation of vibration pore water pressure in sature sands[C]//The Memoir of the First Soil Mechanics and Foundation Engineering Academic Conference of China Civil Engineering Society.Tianjin:China Industry Press,1964.(in Chinese))
[11]汪闻韶.土的液化机理[J].水利学报,1981(5):22–34.(WANG Wen-shao.The liquefaction mechanism of soil[J].Journal of Hydraulic Engineering,1981(5):22–34.(in Chinese))
[12]刘洋,周健,吴顺川.循环荷载下砂土变形的细观数值模拟Ⅰ:松砂试验结果[J].岩土工程学报,2007,29(7):1035–1041.(LIU Yang,ZHOU Jian,WU Shun-chuan.Micro-numerical simulation of cyclic biaxial textⅠ:results of loose sand[J].Chinese Journal of Geotechnical Engineering,2007,29(7):1035–1041.(in Chinese))
[13]GB 50011—2001建筑抗震设计规范[S].2001.(GB 50011—2001 Code for seismic design of buildings[S].2001.(in Chinese))
[14]DGJ08—37—2002上海市岩土工程勘察规范[S].2002.(DGJ08—37—2002 Code for investigation of geotechnical engineering[S].2002.(in Chinese))
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