考虑水泥土桩增强作用的灌注桩水平承载性能现场试验研究

Field experimental study of lateral load capacity of filling pile enhanced by soil-cement pile

结合淤泥土地基中的三洋港挡潮闸工程,研究水泥土桩增强灌注桩水平承载特性的效果,在现场进行水平静载荷试验。试验时,为量测钢筋应力,在钻孔形成灌注桩时将钢筋计焊接在钢筋笼的不同高程,测得在施加水平荷载时桩身的应力分布情况,从而得到弯矩的分布;将土压力盒埋入桩侧土体中,测试在水平荷载下桩周土体的土压力分布规律。试验结果表明,打设水泥土桩能够控制灌注桩水平位移的发展,并能提高灌注桩水平承载能力;灌注桩桩身弯矩值和桩周土体的土压力的分布情况都呈现先增加后减小的变化规律,并且都主要集中在上部桩体和土体中,其最大值约为泥面以下3 m左右的位置;水泥土桩的打设能够有效地减小桩身弯矩值,并且可以减弱底部反弯矩的出现;打设有水泥土桩的灌注桩桩周土体能够提供更大的土压力。另外,灌注桩的水平承载力受上部土体的影响较大,即提高上部土体的物理力学性质可以有效增大灌注桩水平承载力。

Based on the project in the tidal gate of Sanyang port in silt foundation, a field experimental study was conducted on lateral load capacity, in order to study the effect of filling pile enhanced by the soil-cement pile. For measuring the pile stress distribution of the body in the horizontal load and getting the distribution of bending moment, reinforcement meter were welded to the steel cage at different elevations when the filling piles were being driven; Soil pressure cells were buried on both sides of pile; in order to get the distribution of the soil pressure while the lateral load test was under way. The results show that, filling pile enhanced by soil-cement piles can control the development of horizontal displacement and increase the level of pile bearing capacity. Distribution of the bending moment value and the soil pressure of the soil around the pile are presented the developing trend of increasing initially and decreasing afterwards, and are mainly concentrated in the upper part of the pile and soil, and go to the maximum value of about 3m below the soil surface. Soil-cement pile can effectively reduce the value of bending moment of the pile, and can also weaken the emergence of anti-bottom. The soil around pile can provide greater soil pressure when the filling pile is surrounded by the soil-cement pile. The lateral load capacity of filling pile is impacted greatly by the upper level of soil, that is, raising the upper soil physico-mechanical properties can increase the level of lateral bearing capacity.