Study On Acidic Water Glass And Grouting Reinforcement In Silty And Fine Sand

As a reinforcement method of foundation,the grouting method has unique advantages such as simple and flexible construction,short time-consuming,small footprint,small impact on the urban environment,and wide application range,but it is theoretically applied to some grouting methods.At the engineering level,it is still inexperienced,especially in special formations such as fine sand,which are more difficult to inject,and to ensure that the grouting reinforcement works as expected,it is necessary to consider how to choose the grouting material and a reasonable grouting process,and how Controlling and verifying the quality of grouting construction operations and how to ensure the reinforcement or impervious effect of grouting.These problems have been the main problems and directions for grouting engineering research.Only by ensuring the effective solution of the above problems can we reduce or avoid the source.Due to the failure of the grouting project,different degrees or even serious engineering accidents are caused.In China,there are a considerable number of projects in which fine silt and sand formations exist.The study of grouting reinforcement mechanisms in fine sand formations is conducive to the scientific and efficient guidance of grouting in grouting of special formations such as silty sand,as well as The application of grouting method in other strata provides some reference.In this paper,theoretical research,laboratory experiments and numerical simulation methods are used to summarize and summarize the relevant fine sand formation engineering examples.Fault tree analysis is used to analyze the fine sand formation accidents,and the grouting theory and grouting for the fine sand formation are studied.The materials were elaborated and compared with the material properties of different pulp materials and the properties of the fine sand layer were used to screen the suitable pulp for the fine sand,and the comparative experiment method was adopted for the water glass-sulfuric acid and water glasssulfuric acid.The gel pH and gelling time of the calcium carbonate reaction system were studied.The grouting parameters were designed based on the shield tunneling project of the station between Zhangjie Street and Tongda Street,and FLAC3 D was used to predict the grouting under different excavation methods.The effect of prediction of formation deformation.The main research results of this paper are as follows:(1)The main type of damage of fine sand stratum is mainly liquefaction,especially when the loading rate is large,deformation will occur very quickly,and shear liquefaction,sandstorm,and other unfavorable geological disasters will occur easily.(2)Based on the risk sources of foundation pit accidents in fine sand formations,the following risk prevention measures are proposed: to ensure the foundation and the depth of the envelope structure,the support strength meets the design requirements,and to control the load on the slope to ensure its stability,Well point precipitation was performed as required to prevent soil seepage and pipeline rupture.(3)Derive the cylindrical diffusion radius formula considering the timedependent viscosity.(4)The more suitable type of slurry for screening fine sand is acid water glass,which has better permeability and safety.(5)The main influencing factors for water glass and sulfuric acid gel time are pH value,and the pH of the mixture can be adjusted to between 2 and 5,so that the gel time is suitable for the actual project.(6)Adding calcium carbonate in water glass-sulfuric acid slurry with a gelation time of more than ten hours,and adjusting the p H of the mixture to between 3 and 5,can make the gelling time of the liquid and liquid within 1 h.(7)In the water glass-sulfuric acid-calcium carbonate slurry,as the mass of calcium carbonate increases,the compressive strength of the solid sand body at different ages continuously increases,but the degree of increase is reduced to determine the compressive strength.The optimum ratio of water glass-sulfuric acid-calcium carbonate to the maximum intensity is 0.946 : 1 : 0.062.For the shield tunnel construction in formation of silty and fine sand formation,the rule of displacement variation rule is basically the same under the operating conditions of single-line excavation method and the double-line excavation method.However,under the single-line excavation method,the vault settlement change ratio is excavated.double-line excavation is smaller.