多振次循环动荷载作用下软黏土变形与孔压特性试验研究  

Study on deformation and pore pressure characteristics of soft clay under multiple vibration cyclic loading

作　　者：杨爱武[1] 钟晓凯 张兆杰[1,2] 

机构地区：[1]天津城建大学天津市软土特性与工程环境重点实验室,天津300384 [2]天津城大岩土工程技术有限公司,天津300384

出　　处：《地震工程与工程振动》2017年第1期25-31,共7页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(41372291);天津市科技计划项目(15JCZDJC40600;15ZCZDSF00220)~~

摘　　要：动荷载作用下土体累积变形、孔压的发展不仅与动应力幅值有关,还与振动次数密切相关。本文通过GCTS空心圆柱扭剪仪对天津海积软土进行循环三轴试验,研究了多振次不同循环动应力下土体的累积变形与孔压特性。试验结果表明:在多振次循环荷载作用下,临界动应力前后土体累积变形发展趋势不同。动应力幅值小于临界动应力,累积应变呈稳定型发展;动应力幅值大于临界动应力,累积应变呈破坏型发展。按照累积应变发展形态的不同,分段建立考虑动应力幅值影响的长期变形公式。同样根据孔压发展趋势,也相应地分段建立了孔压增长预测公式,拟合值与试验值较为吻合。Accumulated deformation of soils under dynamic loading is not only associated with the stress amplitude, but also closely related with the number of vibration. Through the cyclic triaxial test on marine soft soil in Tianjin by dynamic hollow cylinder device, the influence of long-term dynamic deformation under multiple vibration number different cyclic dynamic stress was researched. Results show that the soil＇s dynamic deformation displays different changing trend before and after the critical dynamic stress as the changes of dynamic stress amplitude. Regular sug- gest that the development of dynamic strain is stable when the dynamic stress amplitude is less than the critical dy- namic stress, but develops in destructive type when it is greater than the critical dynamic stress. In accordance with the difference of the forms of dynamic strain＇s development, the model of long-term deformation was set up in two stages considered the influences of dynamic stress amplitude. Exponential function and hyperbolic function were a- vailable to description the relationship between pore pressure and the vibration cycle time according to the dynamic stress amplitude, and the fitted values fit well with experimental values.

关 键 词：多振次 软黏土 循环动荷载 孔压 长期变形 

分 类 号：TU411.8[建筑科学—岩土工程] P315.93[建筑科学—土工工程]