The Study Of Bentonite-based Grouting Formulation In Water-rich Sand And Gravel Stratum

In the construction of urban rail transit,the complexity of the construction environment and the protection of the groundwater make the precipitation conditions more and more harsh.Therefore,most of the underground tunnels should be reinforced by grouting to the rock mass during the construction.As an effective method of stratum reinforce treatment,grouting technology is the main technical means for excavation and reinforcement in water rich condition.According to the previous engineering experience,the water plugging effect of cement-water glass double slurry under the condition of rich water is poor and its strength is instable.In order to solve the problem of water sealing and strengthening in the construction of water rich stratum tunnel,a new type of slurry with controllable gel time,good seepage resistance and small environmental pollution is needed to replace the traditional cement-water glass double slurry.Based on the field grouting experiment in the subway line eight,the general cement-water glass slurry system is improved through laboratory experiments and field experiments.The specific research contents includes:(1)Add bentonite to the ordinary cement-water glass double liquid slurry,and taste the gel time,compressive strength,viscosity and anti dynamic water properties of the formula by laboratory experiments and field experiments.(2)The effect of the addition of sulphoaluminate cement on the performance parameters of the ordinary slurry system was studied and the factors affecting the hydration of sulphoaluminate cement in the slurry system were studied by parallel experiments.(3)The performance parameters of accelerator-ordinary cement-sulphoaluminate cement-bentonite slurry were tested by using accelerated coagulant instead of water glass.(4)The effect of early strong agent on the slurry performance was tested by adding aluminium chloride,sodium sulfate,lithium carbonate,triethanolamine,and the compound of early strong agent.(5)The hydration process and hydration products of different slurry components were tested by XRD and SEM experiment,and the reasons for improving the early strength of the slurry were analyzed from the microscopic view.