| With the continuous expansion of the construction of coastal ports in China,the application of dredger fill is becoming more and more extensive.Depending on the source of the dredger fill and the dredging process,the artificial dredger may be a single silt or sand,or a mixture of sand and clay.According to the type and source of sand in the mixture,the dredger fill can be divided into land-source dredger fill and sea-source dredger fill.At present,the research on the osmotic consolidation characteristics of sand-clay mixture is mostly focused on land-sourced dredgers.The research on sea-source dredgers is still rare.Therefore,in order to meet the needs of the construction of the South Island reef,it is urgent to carry out in-depth research on the osmotic consolidation characteristics of the sea source dredger.In this paper,the calcareous sand-clay mixture was used to simulate the sea-source dredger fill,and the conventional consolidation instrument was modified to carry out the osmotic consolidation test on the calcareous sand-clay mixture samples with different clay contents and different initial void ratios,in order to study the sea-source dredger fill's osmotic consolidation characteristics and its influencing factors,the main results are as follows:(1)The modified osmosis consolidation instrument has a good sealing property and can perform a penetration test at the time of holding.At the same time as the unidirectional consolidation test,the pore water pressure is automatically measured and recorded using the pore pressure automatic acquisition module.The two-way drainage consolidation test can be carried out by controlling the test drainage conditions by the water stop clamp.(2)Under the action of stepwise pressure,the deformation-time curve of the calcareous sand-clay mixture sample is stepped,and the variation of the compression amount is gradually reduced.Under a certain pressure,the deformation-time curve is an "S" curve.The change trend of the compression curve is obviously affected by the initial void ratio,and the degree of influence decreases as the pressure increases.The compressibility index increases with the increase of clay content and initial void ratio.The consolidation coefficient increases with increasing pressure and eventually stabilizes.Calculating the consolidation factor using the new three-point method is applicable in this paper.(3)The pore pressure dissipation law of the calcareous sand-clay mixture in the consolidation test is: under the action of 100 kPa consolidation pressure,there is a “depression phenomenon” in the pore pressure dissipation;when the consolidation pressure exceeds 100 kPa,the pressure is instantaneous.There is a “hysteresis effect” in the bottom pore water pressure response,and the bottom pore water pressure peak is much lower than the consolidation pressure.(4)The permeability coefficient of the calcareous sand-clay mixture sample decreases with the increase of consolidation pressure and consolidation deformation,and the rate of decrease gradually decreases.The permeability coefficient decreases with the decrease of the compressibility index,and gradually increases with the decrease of the consolidation coefficient.In addition,as the clay content and initial pore ratio increase,the permeability coefficient decreases gradually,and the permeability is affected by the clay content to a greater extent than the initial void ratio.(5)There is a significant linear relationship between the logarithmic value of the permeability coefficient of calcareous sand-clay mixture and the void ratio.there is a significant secondary water relationship between the consolidation coefficient and the logarithm of the consolidation pressure.The research results in this paper can further improve the conventional osmotic consolidation device and promote the deep understanding of the osmotic consolidation characteristics of calcareous sand-clay mixture and its influencing factors. |
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