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对软黏土与粉土互层中静压预应力混凝土管桩的相关性状进行了现场试验研究。试验结果显示,桩周土体中不同深度处的超孔隙水压力在沉桩过程中呈现不同的变化规律。回归分析得出两个不同深度处的对数表达式,用以描述最大超孔隙水压力与初始竖向有效应力的比值随距离参数的变化规律。测斜试验结果说明,群桩施工过程中土体最大水平位移发生在渗透性相对较差的淤泥质黏土层中。单桩沉桩过程中,地面的隆起量随沉桩深度不断增加,但主要的隆起量发生在桩体位于浅层时。贯入过程中,开口管桩的管壁端阻与静力触探锥尖阻力显示出极为相似的变化规律,且两者之间的比值不随贯入深度和土塞高度的变化而改变。上硬下软的土层分布易形成闭塞现象,而上软下硬的情况则易导致土塞的滑动。分析认为开口管桩直径越大管壁越薄,形成的土塞高度则越大。
The field experiment on the related characters of static pressure prestressed concrete pipe piles between soft clay and silt interbed was carried out. The test results show that the excess pore water pressure at different depths in the soil around the pile presents different variation rules during pile driving. The logarithmic expression at two different depths was obtained by regression analysis to describe the variation of the ratio of the maximum excess pore water pressure to the initial vertical effective stress with distance parameters. The test results of incline test indicate that the maximum horizontal displacement of soil mass during the construction of pile groups occurs in the relatively impermeable muddy clay layer. During the pile piling process, the uplift of the ground increases with the depth of pile sinking, but the main uplift occurs when the piles are in the shallow layer. During the penetration process, the end-of-pipe resistance of the open pipe pile and the cone resistance of the static probe show a very similar variation, and the ratio between them does not change with the penetration depth and the height of the soil plug. On the soft under the soil distribution of the formation of easy to occlusion, while the soft under the hard case is easy to cause the earth plug sliding. It is considered that the larger the diameter of the open pipe pile is, the thinner the pipe wall is and the larger the height of the soil plug is formed.