三轴冲击荷载作用下淤泥力学响应研究  

Mechanical responses of muck under triaxial impact loading

作　　者：林伟弟 李彰明[1] 罗智斌[1] 

机构地区：[1]广东工业大学岩土工程研究所,广东广州510006

出　　处：《岩土力学》2015年第7期1966-1972,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51178122)

摘　　要：利用SPAX-2000(改进型)静动真三轴系统,针对淤泥类超软土进行静动力排水固结试验,研究包括较高频率在内的各冲击荷载频率(1、8、16 Hz)与不同围压(200、250、300 k Pa)作用下淤泥的力学响应;此外,结合三轴剪切试验研究不同固结条件对淤泥不排水强度的影响。试验结果表明:(1)在相同冲击频率作用下,试样抗剪强度随着围压增大而提高;围压增大,使得球应力增大,体应变随着增大,有效地促进试样排水固结。(2)相同围压作用下,存在着一个冲击荷载频率阈值,当冲击频率低于这一阈值时,随着冲击荷载频率的提高,轴向应变量逐渐变小,反之逐渐变大。(3)冲击瞬间,体应变为负值,表现为体胀,这与原位试验夯击瞬间的孔隙水压力变化曲线一致,从而验证了高含水率淤泥在冲击作用下的孔压负增长现象。Using the improved true triaxial testing system SPAX-2000, the static and dynamic drainage consolidation tests on muck are carried out. And then the mechanical responses of muck are investigated at different impact loading frequencies of 1 Hz, 8 Hz and 16 Hz and different confining pressures of 200 k Pa, 250 k Pa and 300 k Pa. With combining the triaxial shear tests, this paper studies the undrained strength development of muck under different consolidation conditions. The experimental results are drawn as follows.（1） At the same impact loading frequency, the shearing strength of the specimen continuously increases as confining pressure increases. The increasing confining pressure also can result in an increase in the spherical stress and the volumetric strain increase, effectively promoting the specimen drainage consolidation.（2） Under the same confining pressure, there is a threshold of impact loading frequency. When the frequency is lower than the threshold, with the increase of impact load frequency, the axial strain gradually tends to become smaller, and vice versa.（3） At the instant of the impact, the volumetric strain is negative and characterized by volumetric expansion. The development law of volumetric strain is in agreement with that of pore water pressure at tamping moment in a field test. The fact is confirmed that a negative growth in pore water pressure would occur as the muck with high water content is subjected to the impact.

关 键 词：三轴试验 冲击荷载 不同频率 淤泥 力学响应规律 

分 类 号：TU411.7[建筑科学—岩土工程]