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沉井加桩基础作为深水地区大型桥梁常用的基础形式,其稳定性直接关系到桥梁的安全。为分析砂土中水平循环加载条件下冲刷对基础水平承载力和滞回圈刚度的影响,本文对沉井加桩复合基础进行了冲刷条件下的静载和循环后静载模型试验,得到了基础的水平荷载位移曲线和循环滞回圈。试验结果表明:冲刷对沉井加桩复合基础的水平承载力削弱严重。试验在中密砂、低围压条件下,循环加载会提高基础的水平承载力。对比循环后的静载曲线得知,无冲刷条件下的循环后基础水平承载力高于有冲刷条件下的该值。比较循环加载中的荷载位移曲线得到,无冲刷时滞回圈水平刚度高于有冲刷时的水平刚度,随着循环荷载次数的增加,滞回圈的水平刚度有所提高,但趋势减缓,并逐步稳定。
As a commonly used foundation form for large bridges in deepwater areas, the stability of caisson plus pile foundation is directly related to the safety of bridges. In order to analyze the effect of scouring on horizontal bearing capacity and hysteretic stiffness under horizontal cyclic loading in sandy soil, static loading and post-cycle static loading test of composite foundation with caisson and pile were carried out. Fundamental horizontal load displacement curves and cyclic hysteresis loops. The test results show that the horizontal bearing capacity of scouring on the caisson plus pile composite foundation is severely weakened. Test in the sand, low confining pressure conditions, cyclic loading will increase the basic horizontal bearing capacity. Comparing the static load curve after the cycle, it is found that the horizontal bearing capacity of the foundation under the no-scouring condition is higher than that under the scouring condition. Comparing the load displacement curves in cyclic loading, the horizontal stiffness of non-scouring lag lag is higher than that of horizontal lashing. With the increasing of cyclic load, the horizontal stiffness of hysteresis loop is increased but the trend is slowed down. Gradually stable.