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边坡、挡土墙等结构中的土体一般存在初始剪应力的作用,同时在地震、波浪等动荷载作用下,土体的初始剪应力与动荷载之间往往会存在一定的夹角。为了研究初始剪应力与循环荷载之间的夹角(剪切方向角)对土体软化指数的影响,采用多向循环单剪仪对温州软黏土进行一系列的循环单剪试验研究。研究结果表明,在特定剪切方向角下,随着循环应力比rc的增加,软化指数?逐渐降低,且在相同软化指数条件下,相邻循环应力比对应的循环圈数相差的幅度逐渐减小;循环应力比一定时,当剪切方向角在0°~90°范围内增加时,软化指数依次递增,当90°<θ≤180°时,软化指数的变化趋势与0°~90°时相反;循环应力比rc=0.15时,在加载初期,θ=120°,150°,180°时,软化指数均分别较θ=60°,30°,0°时大。对试验数据进行回归分析,建立土体的软化指数模型和孔压–软化模型。
Soil, such as slope, retaining wall and so on, generally have initial shear stress. At the same time, under the action of earthquake, wave and other dynamic loads, there exists a certain angle between the initial shear stress of soil and dynamic load. In order to study the influence of the angle (shear direction angle) between the initial shear stress and cyclic loading on the softening index of soil, a series of cyclic single-shear tests on Wenzhou soft clay were carried out by using a multi-cycle single shearer. The results show that with the increase of cyclic stress ratio rc, the softening index decreases gradually with the specific shear direction angle. And under the same softening index, the amplitude of the difference between the adjacent cyclic stress and the corresponding loop decreases gradually When the cyclic stress ratio is constant, the softening index increases as the shear direction angle increases from 0 ° to 90 °. When 90 ° <θ≤180 °, the trend of softening index changes from 0 ° to 90 ° On the other hand, when the cyclic stress ratio rc = 0.15, the softening indexes are all higher than those of θ = 60 °, 30 ° and 0 °, respectively, at the initial stage of loading and at θ = 120 °, 150 ° and 180 °. Regression analysis of the experimental data to establish soil softening index model and pore pressure - softening model.