Chemical Intervention Study On Disintegration Process Of Strongly Weathered Purple-red Mudstone In Badong Formation Of Three Gorges Reservoir Area

During the operation of the reservoir,mudstone on the slope surface in drawdown area will disintegrate under cyclic wetting-drying condition,which has an adverse effect on the stability of the bank slope.Disintegration test under the combined action of wetting-drying cycle and slope stress was carried out on the strongly weathered purple-red mudstone of the Badong formation in the Three Gorges reservoir area,it was found that the disintegration of the mudstone sample was caused by the development of micro-pores and micro-cracks inside the mudstone sample,and it is due to the hydration reaction of clay minerals and water.Aiming at the disintegration mechanism of mudstone samples,waterborne polyurethane resin was selected to interpose the disintegration process of mudstone samples.The proportioning of chemistry intervention material was determined by durability test,and the proportioning of chemistry intervention material is waterborne polyurethane resin: silane coupling agent: cross-linking agent(Waterborne sealed isocyanate curing agent): water repellent = 88: 1.5: 10: 0.5.After chemical intervention on mudstone samples,the disintegration test under combined action of wetting-drying cycle and slope stress was carried out on the mudstone sample.The disintegration characteristics and disintegration mechanism of the mudstone samples after chemical intervention were obtained by the material composition test and the macroscopic and microscopic test of the mudstone samples after chemical intervention,and analyzing the effectiveness of chemical intervention materials.The specific research content and the research results are summarized as follows:(1)The numerical simulation calculation determines that the two-way stress of the mudstone on the slope surface is 0.0-1.0MPa.Three representative stresses of 0.0MPa,0.5MPa and 1.0MPa are selected for test,and the stress loading simulation during the test is carried out.The results show that the stress applied by the disintegration apparatus can be loaded onto the mudstone sample.(2)When the slope stress is 0.0MPa,0.5MPa and 1.0MPa,environmental simulation tests show that the wetting time is 4days and the drying time is 1 day during one wetting-drying cycle.(3)The chemical intervention materials interposed the disintegration of mudstone samples effectively,and the mudstone samples,intervened by chemical material,did not disintegrate during 21 th wetting-drying cycles.(4)Ion concentration test,XRD test,SEM test and water absorption test reveal the intervention mechanism of chemical intervention materials.The sample is separated from the distilled water to inhibit the hydration reaction of the clay mineral,thereby the disintegration process of the mudstone sample are interposed.