| Dyke strengthening by desilting is an important measure to reinforce the dyke of the lower Yellow River,it reduces the risk of flooding,and the Yellow River has played an important role in flood control in recent years.This is because it can excavate the bottom of the river to reduce the elevation of the river bed and backfill the river bank to reinforce the Yellow River dam.Because the physical properties and consolidation law of hydraulic fill is complex in the design and construction of the silt area flushing project,it is difficult to regulate the construction speed and control the construction process.At the same time,it is difficult to achieve the expected construction period,resulting in waste of resources.In this paper,the actual dyke strengthening by desilting of jinan section in the lower reaches of the Yellow River is studied.In order to study the design rate of the hydraulic fill in the silt area,the construction process of dyke strengthening by desilting is analyzed by means of laboratory test,theoretical calculation and numerical calculation.This paper studies the pore water pressure,consolidation rule of the hydraulic fill in the silt area under construction load,and puts forward a safe,scientific and reasonable construction plan for the hydraulic fill of the silt area.It provides technical guidance and theoretical reference for the construction of the silt in the lower reaches of the Yellow River.First of all,in order to explore the physical mechanical properties of the hydraulic fill used in dyke strengthening by desilting and mechanical properties and for dyke strengthening by desilting engineering theory calculation and numerical calculation to provide reliable data,the jinan section the hydraulic fill used in dyke strengthening by desilting to carry out the indoor experiment study in this paper.The soil was classified by experimental data,and the soil was named as low liquid limit clay.According to the variation law of permeability coefficient and void ratio with different soil pressure,the k-p curve of the soil sample were obtained.Secondly,based on the shaki single direction consolidation theory,this paper makes a theoretical calculation of the simplified dyke strengthening by desilting engineering model.In this paper,in order to provide more accurate construction intervals for site construction,the law of dissipation of excess pore-water pressure and the consolidation rule of hydraulic fill are investigated.Silt area soil permeability coefficient is taken into account in the theoretical analysis with the rule of variation of consolidation pressure.It found that with the increase of stack thickness of filling soil,considering area soil permeability coefficient changing with consolidation pressure of silt area at the bottom of the the effects of dissipation of excess pore-water pressure rate is more and more obvious.However,due to the theoretical calculation of the average index,considering the change of soil permeability coefficient of the silt area has less influence on the consolidation of silt.Finally,the finite difference software's FLAC3D is used to simulate and study the construction process of dyke strengthening by desilting.The numerical model of dyke strengthening by desilting is established by using the reasonable displacement boundary condition and the hydraulic boundary condition.By means of fluid-solid coupling two-phase calculation method,the construction process of the silt area is simulated.The dissipation process of pore water pressure and consolidation rule in the silt area under construction load are analyzed,and the change law of soil permeability coefficient in the silt area varies with the consolidation pressure and the different construction rate are considered.According to the results of numerical calculation,it is suggested that the construction process of the hydraulic fill in the silt area should be intermittent,and a reasonable construction plan for the silt area should be put forward.The results show that the influence of the soil permeability coefficient in the silt area varies with the consolidation pressure is significant,and the uneven settlement of embankment and silt area caused by continuous construction is obviously greater than that of the layered construction. |
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