不同形式变水头作用下土体的管涌特性
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摘要
为探究不同形式变水头作用下无黏性砂土的管涌特性,选取12种不同的变水头形式,利用自行研制的管涌三轴仪选择向上管涌的方法模拟管涌实际.通过管涌试验分析了变水头的周期和振幅对渗透系数和累计涌砂量的影响规律.结果表明:不同形式周期和峰值的正弦水头条件下,土体渗透系数均随着时间的推移而逐渐增加,当达到一定时间后,渗透系数趋于稳定;管涌相同的时间,渗透系数值随着正弦水头周期的减小而逐渐增加,随着峰值的增加而逐渐增加,土体抗渗性能下降;土体管涌3 h后,不同周期和峰值正弦水头条件下的渗透系数在常水头渗透系数线两边呈近似对称分布.土体管涌3 h内累计涌砂量随时间的增长基本呈线性增长,变水头周期越小峰值越大,累计涌砂量越大;通过扩大系数α,得到土体管涌3 h后的变水头累计涌砂量公式和马鞍形状的拟合曲面图.
In order to explore the piping characteristics of graded soil under different types under variable water head,twelve different types of variable head are selected to simulate the actual piping by using self-developed piping triaxial apparatus and selecting the method of upward piping. The influence of period and amplitude of variable head on permeability coefficient and cumulative sand inflow is analyzed by piping test. The results show that the permeability coefficient of soils is increased gradually with time under sinusoidal head with different periods and peaks. When the permeability coefficient reaches a certain time,it tends to be stable. With the same piping time,the permeability coefficient is increased with the decrease of sinusoidal head period,increased with the increase of peak value,and decreased with the impermeability of soil. After 3 hours of soil piping,the permeability coefficient of sinusoidal head with different periods and peak values is approximately symmetrical on both sides of the constant head permeability coefficient line. The cumulative amount of sand inrush is increased linearly with time in 3 hours of soil piping,and the smaller the period of variable head,the larger the peak value and the cumulative amount of sand inrush. The formula of cumulative amount of sand inrush with variable head after 3 hours of soil piping and the fitting curve of saddle shape are obtained by enlarging coefficient α.
In order to explore the piping characteristics of graded soil under different types under variable water head,twelve different types of variable head are selected to simulate the actual piping by using self-developed piping triaxial apparatus and selecting the method of upward piping. The influence of period and amplitude of variable head on permeability coefficient and cumulative sand inflow is analyzed by piping test. The results show that the permeability coefficient of soils is increased gradually with time under sinusoidal head with different periods and peaks. When the permeability coefficient reaches a certain time,it tends to be stable. With the same piping time,the permeability coefficient is increased with the decrease of sinusoidal head period,increased with the increase of peak value,and decreased with the impermeability of soil. After 3 hours of soil piping,the permeability coefficient of sinusoidal head with different periods and peak values is approximately symmetrical on both sides of the constant head permeability coefficient line. The cumulative amount of sand inrush is increased linearly with time in 3 hours of soil piping,and the smaller the period of variable head,the larger the peak value and the cumulative amount of sand inrush. The formula of cumulative amount of sand inrush with variable head after 3 hours of soil piping and the fitting curve of saddle shape are obtained by enlarging coefficient α.
引文
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[3]梁成彦,许合伟,李亚,等.边坡管涌现象及坡地安全的探讨[J].价值工程,2018,37(25):107-109.
[4]李汉华,戴文彬,邓明伟.浅谈对深基坑开挖管涌灾害的治理及预防[J].四川建材,2017,43(7):92-93.
[5]常东升,张利民.土体渗透稳定性判定准则[J].岩土力学,2011,32(S1):253-259.
[6]陈亮,雷文,张红宇,等.非稳定流作用下管涌发生发展的室内试验及理论分析[J].岩土工程学报,2013,35(4):655-662.
[7]姚志雄,周健,张刚,等.颗粒级配对管涌发展的影响试验研究[J].水利学报,2016,47(2):200-208,218.
[8]梁越,陈亮,陈建生.考虑流固耦合作用的管涌发展数学模型研究[J].岩土工程学报,2011,33(8):1265-1270.
[9]罗玉龙,吴强,詹美礼,等.渗流-侵蚀-应力耦合管涌试验装置的研制及初步应用[J].岩石力学与工程学报,2013,32(10):2108-2114.
[10]罗玉龙,速宝玉,盛金昌,等.对管涌机理的新认识[J].岩土工程学报,2011,33(12):1895-1902.
[11] CHANG D S,ZHANG L M. A stress-controlled erosion apparatus for studying internal erosion in soils[J]. Geotechnical Testing Journal,2011,34(6):1-11.
[12] CHEN C,ZHANG L M,CHANG D S. Stress-strain behavior of granular soils subjected to internal erosion[J]. Journal of Geotechnical and Geoenvironmental Engineering,2016,142(12):060160141-060160146.
[13] LIN K,AKIHIRO T. Triaxial erosion test for evaluation of mechanical consequences of internal erosion[J]. Geotechnical Testing Journal,2014,37(2):1-18.
[14] OUYANG M,AKIHIRO T. Influence of initial fines content on fabric of soils subjected to internal erosion[J]. Canadian Geotechnical Journal,2016,53(2):299-313.
[15]毛昶熙,段祥宝,蔡金傍,等.洪峰过程非稳定渗流管涌试验研究与理论分析[J].水利学报,2005,36(9):1105-1120.
[16]段祥宝,谢罗峰.水位降落条件下非稳定渗流试验研究[J].长江科学院院报,2009,26(10):7-12.
[17]魏建飞.三亚大隆水利枢纽施工汛期土石坝局部管涌现象探讨[J].城市道桥与防洪,2011(2):45-49,113.
[18]倪小东,赵帅龙,王媛.非稳定流作用下管涌发生发展的细观数值模型试验研究[J].中南大学学报(自然科学版),2016,47(9):3154-3161.
[19] KENNEY T C,LAU D. Internal stability of granular filters[J]. Canadian Geotechnical Journal,1985,22:215-225.
[20] LADD R S. Preparing test specimens using undercompaction[J]. Geotechnical Testing Journal,1978,1(1):8-16.