饱和黏性土和砂砾石料振动孔压的试验研究
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摘要
在国内外主要孔压发展模型的基础上,对某土石坝心墙防渗黏性土和坝基砂砾石料饱和试样进行动三轴试验,提出了两种材料的顾淦臣孔压模型,并对砂砾石料的孔压发展规律作了深入地分析,提出了不同固结比Kc时振动孔压比和振次比的函数关系。试验结果表明,动孔压随振动周数和振动强度的增加而增加,随固结应力比或初始剪应力比的增加而减小;无论等压或偏压固结,黏性土均不会出现动孔压ud等于围压力σ3c的液化现象,其孔压比Ru均小于0.5,多数试样Ru=0.1~0.4;当等压固结Kc=1.0时,砂砾石料最终孔压值均可达到围压;偏压固结Kc≥1.5后,试样是否达到Ru=ud/σ3c=1.0取决于动应力σd是否大于主应力差(σ1c-σ3c),即σd是否形成拉应力,使试件伸长,但当Kc很大后,σ1c和σ3c相差太大,需施加非常大的σd才能使其应力应变反向,试样的大变形先于Ru=1.0的应力状态出现,即不可能达到初始液化;固结比Kc对不同土料动孔压的影响是不同的。
The research outcomes at home and abroad about dynamic pore water pressure developing models are firstly reviewed; then the dynamic triaxial tests which used saturated core cohesive soil and dam foundation gravel of a rockfill dam were performed; and Gu Gan-chen models of these two materials were put forward. And dynamic pore water pressure developing rules of gravel were analyzed in detail. The results of dynamic intensity tests show that with the increasing of vibration times and vibration intensity, dynamic pore water pressure increases. While with the increasing of consolidated stress ratio, dynamic pore water pressure decreases. For cohesive soil, in spite of equivalent-pressure or unequivalent-pressure consolidation, liquefaction phenomenon didn’t appear. For gravel, final dynamic pore water pressure could all reach confining pressure under equivalent-pressure consolidation, and when consolidated stress ratio Kc exceeds or equals to 1.5, whether samples could liquefy lied on that dynamic stress σd could make samples stretch or not. And the effects of consolidated stress ratio Kc on various soils were different.
The research outcomes at home and abroad about dynamic pore water pressure developing models are firstly reviewed; then the dynamic triaxial tests which used saturated core cohesive soil and dam foundation gravel of a rockfill dam were performed; and Gu Gan-chen models of these two materials were put forward. And dynamic pore water pressure developing rules of gravel were analyzed in detail. The results of dynamic intensity tests show that with the increasing of vibration times and vibration intensity, dynamic pore water pressure increases. While with the increasing of consolidated stress ratio, dynamic pore water pressure decreases. For cohesive soil, in spite of equivalent-pressure or unequivalent-pressure consolidation, liquefaction phenomenon didn’t appear. For gravel, final dynamic pore water pressure could all reach confining pressure under equivalent-pressure consolidation, and when consolidated stress ratio Kc exceeds or equals to 1.5, whether samples could liquefy lied on that dynamic stress σd could make samples stretch or not. And the effects of consolidated stress ratio Kc on various soils were different.
引文
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[4]Geoffrey R.Martin W D,Liam Finn H.Bolton Seed.Fundamentals of liquefaction under cyclic loading[J].Journal of Geotechnical Engineering Division,ASCE,1975,101(GT5):423-438.
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[12]于濓洪,王波.饱和粉土振动孔隙水压力的试验研究[J].大连大学学报,1999,20(4):59-62.YU Lian-hong,WANG Bo.Study on pore water pressure of saturated and disturbed sandy loam during cyclic loading[J].Journal of Dalian University,1999,20(4):59-62.
[13]孙明权,顾淦臣.堤坝边坡地震液化失稳有效应力法分析研究[J].水利学报,1994,(4):63-68.SUN Ming-quan,GU Gan-chen.Embankment slope failure due to earthquake induced liquefaction[J].Journal of Hydraulic Engineering,1994,(4):63-68.
[14]张建红,何昌荣.往返荷载作用下非饱和砂性土的液化强度和孔压规律[J].成都科技大学学报,1994,(1):1-8.ZHANG Jian-hong,HE Chang-rong.Liquefaction strength and pore pressure distribution of a nonsaturated sandy soil under cyclic loading[J].Journal of Chengdu University of Science and Technology,1994,(1):1-8.
[15]许才军,周红波.不排水循环荷载作用下饱和软黏土的孔压增长模型[J].勘察科学技术,1998,(1):3-7.XU Cai-jun,ZHOU Hong-bo.Pore pressure increase model of saturated soft clay under undrained cyclic load[J].Site Investigation Science and Technology,1998,(1):3-7.
[16]章克凌,陶振宇.饱和软黏土在循环荷载作用下的孔压预测[J].岩土力学,1994,15(3):9-17.ZHANG Ke-ling,TAO Zhen-yu.The prediction of pore pressure of saturated clay under cyclic loading[J].Rock and Soil Mechanics,1994,15(3):9-17.
[2]Finn W D L,Lee K W,Martin G R.An effective stress model for liquefaction[J].Journal of Geotechnical Engineering Division,ASCE,1977,103(GT6):517-533.
[3]孙锐,袁晓铭,石兆吉.建筑物地基中地震孔压的计算分析[J].世界地震工程,1999,(3):63-68.
[4]Geoffrey R.Martin W D,Liam Finn H.Bolton Seed.Fundamentals of liquefaction under cyclic loading[J].Journal of Geotechnical Engineering Division,ASCE,1975,101(GT5):423-438.
[5]汪闻韶.饱和砂土振动孔隙水压力的产生、扩散和消散[A].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集[C].北京:中国建筑工业出版社,1964.
[6]吴世明.土动力学[M].北京:中国建筑工业出版社会,2000.
[7]Ishihara K,Tatsuoka,Yasuda S.Undrained deformation and liquefaction of sand under cyclic stress[J].Soils and Foundations,1975,15(1):29-44.
[8]Nasser S N,Shokooh A.A unified approach to densification and liquefaction of cohesionless sand in cyclic shearing[J].Canadian Geotechnical Journal,1979,(16):659-678.
[9]曹亚林,何广讷,林皋.土中振动孔隙水压力升长程度的能量分析法[J].大连理工大学学报,1987,(3):83-89.CAO Ya-lin,HE Guang-na.An energy approach for analysing the development of cyclic proe water pressure[J].Journal of Dalian University of Technology,1987,(3):83-89.
[10]Finn W D L,Bhatia S K.Endochronic theory of sand liquefaction[A].Proceedings of the7th Word Conference on Earthquake Engineering[C].Turkey:Istanbul,1980.
[11]谢定义,张建民.往返荷载下饱和砂土强度变形瞬态变化的机理[J].土木工程学报,1987,(3):59-72.XIE Ding-yi,ZHANG Jian-min.Developing mechanism on transient strength-deformation of saturated sand under cyclic loading[J].China Civil Engineering Journal,1987,(3):59-72.
[12]于濓洪,王波.饱和粉土振动孔隙水压力的试验研究[J].大连大学学报,1999,20(4):59-62.YU Lian-hong,WANG Bo.Study on pore water pressure of saturated and disturbed sandy loam during cyclic loading[J].Journal of Dalian University,1999,20(4):59-62.
[13]孙明权,顾淦臣.堤坝边坡地震液化失稳有效应力法分析研究[J].水利学报,1994,(4):63-68.SUN Ming-quan,GU Gan-chen.Embankment slope failure due to earthquake induced liquefaction[J].Journal of Hydraulic Engineering,1994,(4):63-68.
[14]张建红,何昌荣.往返荷载作用下非饱和砂性土的液化强度和孔压规律[J].成都科技大学学报,1994,(1):1-8.ZHANG Jian-hong,HE Chang-rong.Liquefaction strength and pore pressure distribution of a nonsaturated sandy soil under cyclic loading[J].Journal of Chengdu University of Science and Technology,1994,(1):1-8.
[15]许才军,周红波.不排水循环荷载作用下饱和软黏土的孔压增长模型[J].勘察科学技术,1998,(1):3-7.XU Cai-jun,ZHOU Hong-bo.Pore pressure increase model of saturated soft clay under undrained cyclic load[J].Site Investigation Science and Technology,1998,(1):3-7.
[16]章克凌,陶振宇.饱和软黏土在循环荷载作用下的孔压预测[J].岩土力学,1994,15(3):9-17.ZHANG Ke-ling,TAO Zhen-yu.The prediction of pore pressure of saturated clay under cyclic loading[J].Rock and Soil Mechanics,1994,15(3):9-17.
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