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本文以黄河三角洲粉质土为研究对象,开展了波致海床剪切破坏过程中孔压响应与土体强度变化的室内水槽试验研究,试验过程中,先后在模拟海床床上施加5、10、15cm波高的模拟波浪荷载,同步测量海床内不同深度处的孔压变化,并对海床进行贯入阻力测试和不排水抗剪强度测试。研究发现:海床中孔压响应过程的规律为孔压快速累积-孔压缓慢消散,在该过程中海床内最容易形成大幅度的孔压累积、孔压响应最强烈的位置,也是海床内土体强度的逐渐丧失以及土体剪切破坏是处开始发育的深度;波浪作用下粉质海床剪切破坏后会在海床内部一定深度处出现明显的弧形破坏界面,破坏土体沿界面随波浪作振荡运动,且破坏范围经历先扩展后回缩的过程,剪切破坏界面以下会有强度硬层的发育,强度硬层的形成与演化直接受剪切破坏过程控制,最终整个海床出现明显的强度非均质化;在孔压响应过程中孔压比即超孔压与上覆有效应力比值存在临界值K(本文水槽试验所得K=0.5),当超过K值时,土体贯入阻力和不排水抗剪强度降低,发生剪切破坏,这是波浪作用提供的剪切力以及超孔压累积导致海床内部抗剪强度降低共同作用的结果。
In this paper, the Yellow River Delta silty soil as the research object, to carry out wave-induced seabed shear failure process of pore pressure and soil strength changes in the indoor tank test study, the test process, one after another in the simulated seabed bed imposed 5,10 , 15cm wave height of the simulated wave load simultaneously measured at different depths of the sea bed pore pressure changes, and on the seabed penetration resistance test and undrained shear strength test. It is found that the regularity of pore pressure response in the seafloor is the rapid accumulation of pore pressure and the slow dissipation of pore pressure. During this process, the most obvious pore pressure accumulation in the seabed is most likely, and the pore pressure response is the strongest and also the seabed The gradual loss of soil strength and the shear failure of soil are the depths at which development begins. After shearing and breaking of the silty seabed under wave, a clear arc-shaped failure interface appears at a certain depth inside the seafloor, destroying the soil Along the interface with the wave for oscillatory movement, and the scope of the failure to experience the first expansion after the retraction process, the shear failure interface will be the development of strength hard layer, the formation and evolution of the hard layer of strength directly under the control of shear failure process, and ultimately the entire There is a critical value K (the result of the experiment in this article is K = 0.5) when the ratio of pore pressure to pore pressure is the ratio of pore pressure to overlying effective stress. When the value exceeds K, Soil penetration resistance and undrained shear strength decrease and shear failure occurs, which is the result of the shear force provided by the wave action and the combined effect of excess pore pressure on the internal shear strength of the seabed.