Study And Application Of Grouting Material To Water Plugging For A Thick Gravel Boulder Formation

ABSTRACT:Grouting has been widely used in transportation, water conservancy, construction and other Engineering field, be used to water plugging and reinforcement. Gravel boulder formation has the characteristics of high porosity, uneven distribution and high hardness, and this is the typical formation in the Beijing area. The exsiting grout is not easy to control, diffusion inhomogeneous in gravel boulder formation. In this paper,through the laboratory test, theoretical derivation, numerical simulation, model experiment and field in-situ test to innovate and improve the grout,adapt to the gravel and boulder strata, and analyses and research the infiltration law, and the main work is as follws:(1)Research and invent the new CD-SCA grout and PC-SCA grout,which is more suitable for gravel boulder strata, and through laboratory test analysis and summarize the initial setting time rule in the case of the different mix ratio.(2) Because the new grout with time-varying fluid viscosity, from the grout in the coefficient of permeability of the soil layer continuously change over time, some improvements were made to the existing osmotic grouting theory.(3) Useing the software PFC2D, studied the diffusion law of permeation grouting in the gravel and boulder strata, and analyzes the effect of grouting parameters toon the grouting effect.(4) Using the combination of model test and field test in situ, tested the improvement of new type of grout in some aspects of the water stop effect. Through the research, obtains the following results:(1) The new CD-SCA grout compared with traditional C-S grout on the diffusion radius, the diffusion uniformity, mixing rate and durability are improved, and water cement ratio on the consolidation time was linear effect; New PC-SCA grout can quickly stop watering, and the sealing effect is good in short-time, its consolidation time with the increase of concentration of phosphoric acid is first decrease and then increase.(2) The permeability coefficient of grout with time-varying fluid viscosity is decreases over time, compared with the Newtonian fluid to reach a certain radius at the same time, we need to increase the grouting pressure, also, while maintaining a certain pressure, on the need to increase the grouting time.(3) Newtonian fluid permeation grouting process in gravel boulder strata can be divided into three stages:the rapid expansion stage, deceleration expansion stage, stable stage.The grout permeability and pore size have great influence on diffusion radius and the soil porosity, grouting pressure only have a greater impact on the soil porosity.