Study On Simulation Grouting Experiment In Gravel & Mechanism Of Permeating Grouting

Gravel strata, which is very abroad distribution in our country, is familiar bad ground for civil engineering. It is difficult for civil engineering experts to improve capability of gravel all through. Grouting is put forward to improve capability of gravel by author. But grout permeation in gravel is affected by many factors, the theoretical formula now available can't exactly predict cost and effect of grouting. In this situation, the author has aimed at the experiment study of grouting in gravel. Being need of experiment study, indoor large scale multifunction test bench was developed , which is a new way for study grouting.Permeating law of grout in gravel and Strength of reinforced body consolidated fill by grout has something to do with geometric shape, space distribution and character of porosity gravel. Fractal character of gravel is studied with fractal theory, fractal theoretical model and statistical model of gravel fractal number are established. Relationship between gravel fractal number, porosity fractal number and porosity degree are studied. Theoretical formula of gravel fractal number, porosity fractal number and porosity degree are established, which has great theoretical significance to reinforcement engineering design and simulation grouting experiment of gravel. Theoretical fractal value of gravel was attained by fractal theoretical model.Being complexity of internal structure of strata and qualitative diversity of grouting liquid, it is very difficult to make the study of grouting theory. At present, all the study simplifies the grouting material as Newtonian time-independent fluid, however, most of the grout is Bingham, a kind of Non-Newtonian time-dependent fluid. This simplification makes the calculation results significantly different from the fact. In order to make the calculation results agree with the practice, the author treats the grout as Bingham time-dependent fluid. Based on constitutive equations of Bingham and permeating law of Darcy, permeating law of time-dependent Bingham in gravel, distribution pattern of pressure, pressure grads and velocity of grouting fluid, the relationshipbetween the grout amount, grouting permeating distance and grouting time are studied. Relevant calculation formulae are provided. These theoretical formulas reveals permeating process of grout in strata, it is great importance to study the permeating law of grout in porous strata.Indoor simulation grouting experiment was directed by permeating model of Bingham fluid. Experiment result proves that capability of gravel was improved greatly. Analysis of regression experiment result proved that the remarkable factor which affect grout amount and the key factor which affect grouting permeating distance is grouting pressure, the key factor which affect strength of reinforced body is water cement ratio. Influence relationship between porosity degree, coefficient of permeability, water cement ratio, grouting pressure and grout amount, grouting permeating distance, strength of reinforced body are analyzed. Relevant calculation formulae are provided, which has great theoretical significance to predict effect of grouting and direct grouting.Base on educed theoretical model, computer program was programmed and computer simulation grouting was done. Simulation grouting result is according with experiment result, which proves that computer simulation grouting is feasible.Base on established grouting theoretical formula, grouting experiment and technical application are carried out in Jacking Engineering of Bridge Beneath Railway at right main streets in Peking. The result proves that grouting is an effective method to reinforce gravel strata.