Study on characterization of soft soil deposit in delta

在这项研究中，合作研究了越南南部湄公河三角洲谭安和坎托地区冲积层的土壤特性。从研究中得出以下结论。(1)沉积在蜿蜒的Bam Co Tay河滨江的Tan An粘土具有高度塑性，非常软，在约8 m的深度具有相对均匀的物理性质。(2)坎托软粘土沉积在湄公河主要河流之一的Hau河堤坝旁的洪水泛滥区。它在沉积方向上具有显著的非均质性，塑性相对较低，砂层较薄，可能是由于大洪水造成的。(3)鄂尔多斯粘土的沉积速度比潭安粘土快得多。Tan An粘土6.5m深度和坎托粘土19.5m深度的C14年龄几乎相同，为6，300 BP。(4)虽然两种粘土的机械和物理性质有很大不同， ...更多信息 这两种粘土都具有高度的微观结构，这已经从CRS试验中得到证实。如果试样质量良好，两种粘土在固结屈服应力后的最大压缩指数与在很大固结压力下的最大压缩指数之比均大于6。(5)对于不均匀和非常厚的软存款，如坎托粘土，连续土壤探测使用压电锥是必不可少的特征网站。(6)取样方法对样品质量有显著影响，特别是对于低塑性粘土，如坎托。JFP比谢尔比要高级上级得多。而对于高塑性粘土，谢尔比管采样器采集的样品可能与FFP采样器采集的样品质量相当。(7)除上述取样方法外，越南土壤调查过程中还存在一些问题，如从现场到实验室的样品处理和实验室样品制备不当。(8)湄公河三角洲地区软土种类繁多，物理化学性质各异。强烈建议进行连续的土壤调查研究和实践，并进行高质量的采样，例如固定活塞薄壁管采样器、实验室测试以及适当的现场测试，这将极大地有助于湄公河三角洲的适当发展。少

In this study collaboration researches about the soil characterization on the alluvial deposits at the Tan An and Can Tho sites in Mekong River Delta, South Vietnam. The following conclusions were drawn from the study.(1) The Tan An clay, which has been deposited at the riverside of meandering Bam Co Tay River, is highly plastic and very soft with relatively uniform physical properties to a depth of about 8m.(2) The Can Tho soft clay has been deposited at the flooding area beside the levee of Hau River, one of the major streams of Mekong River. It has significant heterogeneity in the depositional direction, having relatively low plasticity with thin sand seams, which might be created due to large floods.(3) Depositional speed of the Can To clay is much faster than that of the Tan An clay. C14 dating of the Tan An clay at depth of 6.5m and the Can Tho clay at depth of 19.5m are almost the same, 6,300BP.(4) Although mechanical and physical properties of the two clays are quite different, … More both clays have developed high degree of microstructures, which has been confirmed from CRS tests. The ratios of maximum compression index just after the consolidation yield stress to that at the very large consolidation pressure are more than 6 for both clays if excellent quality of sample can be retrieved.(5) For the non uniform and very thick soft deposit like the Can Tho clay, continuous soil sounding using piezocone is essential for characterizing the site.(6) Sampling method has significant effect on the sample quality especially for low plastic clay, like Can Tho. JFP is much more superior to Shelby. However, for high plastic clay, the sample collected by Shelby tube sampler might give similar quality to those collected by FFP.(7) Beside the above mentioned sampling method, there are some problems in the process of soil investigation in Vietnam, such as poor handling of the samples from the site to laboratory and specimen preparation in the laboratory.(8) Wide varieties of soft soils with different physical and chemical properties prevail in the huge area of Mekong River Delta. Continuous soil investigation studies and practices with good quality sampling, such as thin-walled tube sampler with fixed piston, and laboratory testing as well as appropriate field testing are highly recommended, which can greatly contribute to the proper development in Mekong River Delta. Less