根式基础竖向承载性能的现场试验及数值模拟

Field Test and Numerical Simulation of Vertical Bearing Capacity of Root Foundation

为深入研究根式基础的竖向承载性能,首先通过现场静载试验对普通桩基础和根式桩基础的竖向承载性能进行测试,获得了相应的Q-s曲线和轴力曲线。结果表明根式桩基础竖向极限承载力明显增大且沉降减小。本试验中,在基础长度和直径相同的条件下,根式桩基础竖向极限承载力比普通桩提高约23.75%~33.33%。而后基于数值模拟方法对比研究了根键长度、根键直径、根键位置和根键层间距对根式桩基础竖向承载性能的影响。发现其竖向承载力随根键长度增加而增大,而根键直径对其竖向承载力的影响较小;根键位置对其竖向承载特性有较大影响,当根键在基础下部时其竖向承载能力提高最大;随着根键层间距的增加,其竖向承载力呈增加趋势。总之,根键的存在充分调动了桩基础周围土体的承载力,加强了桩基础-土体之间的耦合作用。

In order to study the vertical bearing capacity of the root foundation,the field static load test is made to test the vertical bearing behavior of the ordinary pile foundation and root pile foundation,and the corresponding Q-s curves and axial force curves are obtained.The result shows that the vertical bearing capacity of the root pile foundation increases evidently and the subsidence decreases.In this test,with the same pile foundation length and diameter,the vertical bearing capacity of the root pile foundation increases by 23.75%~33.33%that of the ordinary pile foundation.Then the numerical simulation method is adopted to study the effect of the root length,root diameter,root position and layer interval of the neighboring roots on the vertical bearing capacity of the root pile foundation.It is found that its vertical bearing capacity increases with increasing the root length,while the root diameter has rather less effect on its vertical bearing capacity.The root position has much effect on its vertical bearing capacity,and when the vertical bearing capacity of the pile foundation increases the most when the root is at the bottom of the pile foundation.With increasing layer interval of the neighboring roots,its vertical bearing capacity has an increase trend.In all,the existence of the roots fully mobilizes the capacity of the neighboring soil of the pile foundation and strengthens the coupling effect between the pile foundation and soil.