黄河三角洲粉土循环剪切特性的试验研究
摘要
利用土工静力-动力液压三轴-扭转多功能剪切仪,对黄河三角洲埕北海域原状粉土试样进行了循环三轴和循环扭剪试验,以此探讨了原状海底粉土的动力变形与强度特性,确定了最大动剪切模量及动力变形参数随剪应变的变化规律。基于循环三轴试验结果,建立了残余孔隙水压力发展变化规律的双曲线经验模式,对动强度关于循环次数的依赖性提出了经验关系,确定了有关试验参数及其关于固结应力比的依赖性。与循环三轴试验结果相对比,认为在土工抗震设计中采用循环三轴试验结果稍偏于保守。
The soil static and dynamic universal triaxial and torsional shear apparatus was employed to perform both undrained cyclic triaxial tests and cyclic torsional tests for undisturbed silty soil samples.Based on the experimental test results,dynamic characteristics of both deformation and strength of undisturbed marine silty soil is investigated.The maximum dynamic shear modulus and the dependency of dynamic shear modulus and damping ratio on shear strain are defined through cyclic triaxial shear tests.An empirical pattern is established for residual pore water pressure generated during cyclic shear which is represented by a hyperbolic function with respect to the number of cycles of dynamic stress.And an empirical formula is developed to describe the cyclic strength with respect to the number of cycles.The related parameters involved in both patterns of pore water pressure and cyclic strength are determined by experimental tests;and their dependency on the consolidation stress ratio is clarified.The experimental data achieved from cyclic torsional shear tests are used to validate the results from the triaxial shear tests.It should be more conservative using the cyclic strength determined by triaxial shear tests in geotechnical earthquake design.
The soil static and dynamic universal triaxial and torsional shear apparatus was employed to perform both undrained cyclic triaxial tests and cyclic torsional tests for undisturbed silty soil samples.Based on the experimental test results,dynamic characteristics of both deformation and strength of undisturbed marine silty soil is investigated.The maximum dynamic shear modulus and the dependency of dynamic shear modulus and damping ratio on shear strain are defined through cyclic triaxial shear tests.An empirical pattern is established for residual pore water pressure generated during cyclic shear which is represented by a hyperbolic function with respect to the number of cycles of dynamic stress.And an empirical formula is developed to describe the cyclic strength with respect to the number of cycles.The related parameters involved in both patterns of pore water pressure and cyclic strength are determined by experimental tests;and their dependency on the consolidation stress ratio is clarified.The experimental data achieved from cyclic torsional shear tests are used to validate the results from the triaxial shear tests.It should be more conservative using the cyclic strength determined by triaxial shear tests in geotechnical earthquake design.
引文
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[3]王建华,要明伦.循环应变下饱和砂(粉)土衰化动力特性研究[J].水利学报,1997,(7):24-30.WANG Jian-hua,YAO Ming-lun.Degradation behavior of saturated sand and sandy loam under cyclic strain[J].Journal of Hydraulic Engineering,1997,(7):24-30.
[4]黄博,陈云敏,殷建华,等.粉土的动力特性及液化势研究[J].工程勘察,2000,(2):7-9,17.
[5]栾茂田,郭莹,李木国,等.土工静力-动力液压三轴-扭转多功能剪切仪研发及应用[J].大连理工大学学报,2003,43(5):670-675.LUAN Mao-tian,GUO Ying,LI Mu-guo,et al.Development and application of soil static and dynamic universal triaxial and torsional shear apparatus[J].Journal of Dalian University of Technology,2003,43(5):670-675.
[6]何昌荣.动模量和阻尼的动三轴试验研究[J].岩土工程学报,1997,19(2):39-48.HE Chang-rong.Dynamic triaxial test on modulus and damping[J].Chinese Journal of Geotechnical Engineering,1997,19(2):39-48.
[7]周小文,刘鸣.砂土振动液化循环次数取值方法探讨[C]//土动力学理论与实践(第五届全国土动力学学术会议论文集).大连:大连理工大学出版社,1998,124-127.
[8]沈瑞福,王洪瑾,周克骥,等.动主应力旋转下砂土孔隙水压力发展及海床稳定性判断[J].岩土工程学报,1994,16(3):70-78.SHEN Rui-fu,WANG Hong-jin,ZHOU Ke-ji,et al.Building-up of pore water pressure under cyclic rotation of principal stress and evaluation of stability of seabed deposit[J].Chinese Journal of Geotechnical Engineering,1994,16(3):70-78.
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