Investigation On Performance Of Capillary Crystalline Slurry On Seepage Control And Its Underlying Mechanisms

Grouting is the most commonly used technique to control the tunnel seepage and other flood diseases.Reasonable selection of grouting materials with good waterproof performance is a key factor to effectively control diseases and ensure the grouting effect.There are many kinds of grouting materials which are often used in engineering and their characteristics are different.Therefore,it is still a key research direction how to design a kind of slurry with outstanding waterproof ability,comprehensive performance,economy and convenience used in the treatment of leakage water in tunnel and underground engineering.In this paper,a new grouting material,the capillary crystalline slurry,is created by mixing capillary crystalline material,cement and various additives.Through the research methods of performance test,mechanism,composition analysis,microstructure observation,model test and discrete element numerical simulation,the performance,anti-seepage mechanism,microstructure and grouting effect of the capillary crystalline slurry are systematically studied.The main research contents and results are as follows:(1)The the capillary crystalline slurry was designed with the summary of various grouting materials characteristics commonly used in engineering,and with the use of the PENETRON Admix(referred to as PA).Through a series of tests on the basic performance of slurry,the change rules were obtained that slurry performance,such as density,setting time,viscosity,water separation rate,concretion rate,permeability coefficient and compressive strength,changed with different amount of PA added.The causes of various changes were analyzed in detail from perspective of material mechanism.Finally,the reasonable addition amount of PA in the slurry was determined to be 4.0% of the total mass of cement,and the performance parameters of the slurry were given.(2)Aim to further improve the performance and application range of slurry,the performance of the modified capillary crystalline slurry was researched.Various cement additives were used in the slurry,and the normal working of additives in the slurry was screened and studied.The reasons for mutual effects between various additives and PA were explained from perspective of action mechanism.The types and amounts of additives for the slurry were given.The performance number of the modified slurry and the reasonable proportion scheme of the slurry were determined.(3)On basis study of the capillary crystalline slurry,the mechanism of the capillary crystalline slurry was analyzed and summarized.The reason for the permanent waterproof effect of the material and the micro repairing ability of structure were reasonably explained.Through chemical test,X-ray fluorescence spectrum and X-ray diffraction analysis technology,the material of capillary crystalline slurry were researched.The material composition and content information contained were determined,which provides basic reference for optimization of proportion scheme and the simplification of the preparation method of the osmotic crystalline slurry.(4)Through CT scanning method,the internal structure characteristics of the capillary crystalline slurry indurations were studied,and the effects of different PA content on internal structure,porosity and pore volume of the consolidated body were observed and analyzed.Through SEM scanning method,the micro structure of the slurry induration was analyzed,and it was determined that materials generated water-insoluble strip and grid in the induration.From the point of view of microstructure,it was confirmed that the reason why PA changed the performance of the capillary crystalline slurry was that the insoluble crystalline material generated by PA blocks the micro cracks in the consolidated structure,reduces the porosity of the structure,and improves the density of the structure.(5)Using the self-designed large-scale geotechnical model test platform,the study of capillary crystalline slurry grouting in crash rock with different stone content was carried out.The indoor pumping test method was used to evaluate the grouting effect of slurry.The diffusion radius,diffusion range and diffusion form of slurry in crash rock with different stone content were determined.(6)A numerical simulation model was established by using the discrete element software Mat DEM,to analyze the diffusion characteristics of the capillary crystalline slurry under different engineering conditions.The diffusion progress of the capillary crystalline slurry under conditions of different grouting pressures grouting time,friction coefficient and slurry viscosity of rock mass were simulated.The variation of diffusion radius and influence range of slurry was analyzed.The grouting effect of slurry was researched,which provided technical reference for practical engineering application of slurry.