Experimental Study On Scouring Of Modified Dispersive Soil In Cold Regions

Dispersed soil is widely used in water conservancy projects as an indigenous material.However,the nature of dispersive soil self-dispersing in low-salt water results in the destruction of water in the presence of dispersed soil.Taking a dispersive earth embankment project in the fat head storage and detention area of Heilongjiang Province as an example,this paper focuses on the problem of scouring damage caused by scattered earth embankment,combined with the theory of rainfall erosion,and uses experimental analysis as a means to develop decentralized land reform.On the basis of the sexual scheme,the model test is carried out to study the modification effect of dispersive soil,which has certain reference value for the research and engineering governance of dispersive soil.The main contents are as follows:(1)Firstly,the dike soil was identified by the fragment test and the pinhole test.The results show that the embankment soil has strong dispersion.Then,based on the economic applicability of the project,cement,quicklime and fly ash are selected as modifiers for the dispersive soil,and two combined modification schemes are selected through the fragment test and the pinhole test,and finally the unconfined compression is carried out.The uniaxial compressive strength was measured by a strength test.The results suggest that the preliminary modification scheme is feasible,among which: S1 scheme is a combination modifier of 1% cement + 1% quicklime + 4% fly ash mixed with dispersible soil quality,and S2 scheme is the quality of dispersible soil.Combination modifier of 2% quicklime + 4% fly ash.(2)According to the freeze-thaw cycle damage theory,the rainfall scouring test after 0 and 7 freeze-thaw cycles was used to study whether the damage of the soil by freezethaw cycles affected its anti-scour ability,and whether the modification scheme was suitable for cold regions.Firstly,the model of the finished slope was placed in a low temperature laboratory for 3 days,then the temperature in the laboratory was adjusted,and the freeze-thaw cycle test was started.Finally,the slope model after the freeze-thaw cycle test was placed in the independently designed rainfall.Equipment and complete the rainfall flush test.The test results show that the freeze-thaw cycle has certain damage to the modified soil,especially the soil within 1cm of the slope surface.However,the freezethaw cycle does not affect the modification effect of the modifier on the dispersive soil,that is,the modified soil still has no dispersibility,and the anti-rain erosion ability of the soil is significantly higher than that of the dispersive soil.The results of the study suggest that the two modification schemes can be applied to decentralized soil embankment projects in cold regions.(3)According to the theory of dry-wet cycle degradation,25 dry-wet cycle model tests were carried out to study whether the deterioration effect of dry-wet cycle on soil affected its anti-scour ability,and the anti-scour effect of modification scheme under multiple dry-wet cycles was analyzed.stability.Firstly,the equipment for simulating the dry-wet cycle model test was designed independently,and then the rainfall mode and the drying mode were determined.Finally,two sets of dry-wet cycle model tests were carried out.In each set of model tests,a comparative test of dispersive soil and modified soil slope was set up to study the rainfall erosion and drying deterioration of dispersed soil and modified soil under the same working conditions.Among them,in the M1 group,it was found that the slope of the dispersive soil appeared splashing damage,surface erosion and gully damage,and the slope of S1 modified soil appeared splashing and surface erosion;under dry conditions,dispersed Cracking and cracking occurred on the slope of the soil,and this phenomenon did not occur on the slope of the modified soil.In the process of dry and wet circulation,only the amount of sediment loss of the S1 modified soil was greater than that of the dispersed soil.Others are smaller than the modified soil;the test results show that the S1 modified soil has better anti-raining ability than the dispersive soil under dry and wet cycles.The dry-wet cycle model test of M2 group found that the degree of damage and the total amount of sediment loss on the slope of the dispersive soil were larger than that of the S2 modified soil.The test results showed that the S2 modified soil did not have dispersibility and was resistant to rain washability than dispersion.Strong soil.The results show that the dispersive earth embankment slope treated by the two modification schemes has long-term anti-scour stability.The results of this study show that the two modification schemes can effectively reduce the erosion damage of the dispersed earth embankment slope in cold regions,and effectively reduce the potential safety hazards of the long-term operation of the dispersed soil embankment.The research results and methods can provide reference for the erosion and erosion control of dispersed earth embankments.