摘要
通过现场原位观测试验,研究波浪、潮流水动力作用对快速堆积的黄河口沉积物固结强度的影响。在黄河三角洲刁口叶瓣潮坪上,开挖2 m×1 m×1 m的试坑,现场取土配置流状堆积物,以铁板部分覆盖试坑隔绝波浪和潮流作用,利用微型贯入、静力触探、十字板剪切试验、孔隙水压力监测等原位测试手段,实时测定快速沉积的海床土强度发展以及孔隙水压力消散情况,研究快速沉积的粉质海床土分别在自重条件下以及在波浪和潮波等水动力作用下的固结过程。研究发现:海床土固结速度很快,自重作用下固结度72 h内达到37%,142 h左右孔隙水压力消散完毕,水动力作用下固结度72 h内达到52%,195 h左右孔隙水压力消散完毕;在沉积物固结过程中,水动力作用在固结初始阶段具有决定性作用,对沉积物强度的改变最大可为自重固结作用的5倍,随深度延伸水动力作用逐渐降低;随着固结过程的延续,表层沉积物在水动力作用下强度增加的趋势逐渐减缓,50 cm以下深度沉积物在水动力作用下强度逐渐降低,使得快速沉积粉质土强度逐渐沿深度出现非均匀变化,并且逐渐形成硬壳层。研究结果对了解水动力在沉积物固结中的作用具有借鉴意义。对于不同水动力在沉积物固结中的作用尚需进一步的研究。
Based on in-situ tests,the impact of marine hydrodynamics,such as waves and tides,on the consolidation process of rapidly deposited sediments is studied.On the tidal flat of Diaokou delta-lobe,a 2 m×1 m×1 m test pit filled with fluid sediments prepared by the in-situ silt is excavated.The test pit is divided into two parts,one of which is covered with a plate to eliminate the influence of the hydrodynamics.By some field test methods,static cone penetration tests,field vane shear tests and pore water piezometer tests,the variation of sediments strength and pore water pressure of the both parts are real-time measured to study the consolidation process of the prepared sediment under the gravity and marine hydrodynamics.It is shown that the self-consolidated sediments have a high consolidation rate which can reach 37% in 72 h and so does the pore water pressure which nearly disperses over in about 142 h,while under the hydrodynamics,the consolidation rate reaches 52% in 72 h and the pore water pressure disperses over in about 195 h.In the consolidation process,the waves and tides whose ability to raise the strength of the sea-bed soils is five times as much as that of self-consolidated play a decisive role at the initial stage,and with the extension of the depth,the role of the hydrodynamics is reduced.With the continuation of the consolidation process,the trend of the strength increase of the surface sediments gradually slows down under the water dynamics,while the sediments whose depth is below 50 cm is in an opposite way.As a result,the rapidly deposited silts show a non-uniform consolidation state,and the crust is gradually formed.The results provide a reference for studying the role of the hydrodynamics in the soil consolidation process.The impact of different hydrodynamics on the soil consolidation requires further studies.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2010年第4期630-637,共8页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(40876042)
关键词
黄河口
海床土
水动力作用
固结过程
Yellow River estuary
seabed soil
marine hydrodynamics
consolidation process