黄河三角洲潮滩孔压对循环振动荷载响应研究

Study on Pore Pressure Response to Cyclic Viberation in Yellow River Delta Tidal Flat

为了研究黄河三角洲潮滩孔压对循环振动荷载的响应过程,在现场潮滩上利用循环振动荷载作用于海床,实时监测了振动过程中孔压的发展过程。研究结果表明:在每一轮振动过程中,超孔压并非是一直升高的,其发展过程主要可以分成3个阶段:首先是累积阶段,在此期间内超孔压迅速积累并达到一峰值,即"超孔压最大响应值";其次是过渡阶段,在此期间超孔压基本保持稳定;而后是消散阶段,即超孔压从最大响应值开始缓慢消散。在振动过程中,产生的最大超孔压是振动能量的指数函数,而且不同深度所产生的最大超孔压不同,存在一极值响应深度。在超孔压累积阶段,尽管不同深度超孔压的累积历程不同,但其累积形式具有一致性,即超孔压是以振动次数为自变量的二次函数,而且,超孔压的累积速率是线性降低的。

In order to study the pore pressure response to the cyclic viberation loads on the seabed,the pore pressure development process is in situ monitored in the tidal flat of the Yellow River Delta.It is shown in the study results that the excessive pore pressure does not keep continously increased in each cycle of the viberation.The development process of the pore pressure can be divided into the 3 stages.They are（1） the progressive increase stage,in which the excessive pore pressure is going up to a peak value i.e.the maximum response value,（2） the transition stage,in which the excessive pore pre-ssure keeps relatively steady,and（3） the dissipation stage,in which the excessive pore pressure is going to disappear.The maximum of the excessive pore pressure in response to the viberation can be expressed as an exponential function of the viberation energy,and it depends on the subbottom depth and there exists a most active response depth.In the progressive increase stage,the excessive pore pressure can be unifomed as a quadratic function of the viberation frequency although its increase depends on the subbottom depth.The progressive increase of the excessive pore pressure becomes linearly weakened as the viberation is more frequent.