Study On Grouting Material For Flowing Sand Reinforcement

It's often passes through special geological sections in the construction process of underground engineering,such as the geological section of the flowing sand layer.The stability of the section is extremely poor and it is very likely to occur collapse accident during the construction process,which seriously affects the progress,safety and quality of the construction.In order to ensure the construction of the project safely and smoothly,the grouting reinforcement of the convective sand layer becomes an indispensable part of the underground construction.With the continuous development of grouting technology,grouting materials with good construction performance,low cost,excellent performance and environmental friendliness have emerged.In this paper,three different grouting reinforcement materials were studied for fine sand and medium coarse sand strata.Through the single factor test and orthogonal test design method,combining with viscosity analysis,fluidity analysis,mechanical analysis,infrared analysis,particle size analysis and microscopic analysis,the influence of different factors on the performance of grouting slurry was discussed.The developed grouting material was applied to the construction site and the groutability of the grouting material was verified,in addition,we testing the diffusion radius of the grouting slurry.The results showed that:?1?For the water glass grouting material,ethyl acetate is used as the water glass curing agent,and Tween 20 is used as the emulsifier instead of peregal.The optimum ratio of the curing agent emulsion is m?ethyl acetate?:m?Tween 20?:m?water?=10:0.3:10,the producted curing agent emulsion has small viscosity,small droplet diameter,uniform distribution and good storage stability of the emulsion.The optimal ratio of water glass grouting slurry is m?curing agent emulsion?:m?water glass?=0.5:1,the viscosity of the slurry is low?12 mPa·s?and it has good injectability.It has small change in viscosity before gelation and it will have sudden change in viscosity when gel time is reached.The laboratory simulated grouting solid sand block has high strength,uniform diffusion and good reinforcement effect.The mechanism of the curing agent is confirmed by infrared analysis.?2?For cement grouting materials,the water reduction rate is the highest when the Sika water reducing agent is added,and the saturated incorporation is 0.4%.The blending of bentonite can effectively improve the stability of the cement slurry and incorporate sodium metaaluminate not only can adjust the setting time,but also improve the stability.When the incorporation of Sika water reducing agent is 0.5%,the incorporation of bentonite is 3.5%,and the incorporation of sodium metasilicate is1.5%,cement grouting slurry has the best performance.?3?For the slag powder grouting material,when the incorporation of water reducing agent is 0.7%,the incorporation of NaOH is 4%,the incorporation of Na₂CO₃ is 3%,and the incorporation of Ca?OH?₂ is 0.5%,slag micro-powder grouting slurry has the best performance.Combining with the SEM micro-test,with the increase of time,the alkali-excited-slag powder hydration product is more and more dense and the strength is getting higher.The slag powder has been completely hydrated after 7 days and the strength of test block tended to be stable.?4?Comprehensive comparative analysis of cement and slag micro-powder grouting materials shows,the raw material particle size of slag powder grouting material is smaller,the setting time is shorter,the early strength is higher,the stability is better,and the comprehensive performance is better than cement grouting material.?5?Through the on-site grouting application test,the water glass grouting material developed by this subject and it's diffusion radius will reach 320 mm in the fine sand layer,and the diffusion radius will reach 440 mm in the medium coarse sand layer at a water binder ratio of 0.6.The diffusion radius will reach 800 mm in the medium coarse sand layer at a water binder ratio of 0.8.