Research On Numerical Simulation And Stability Analysis Of Grouting Engineering Based On Three-dimensional Refined Geological Model In Hydraulic Project

Grouting is the most common repair/ strengthening action undertaken to reduce the hydraulic conductivity of dam and the subsidence of goaf in inter-basin long-distance water transfer project,which is a major part of the construction process and must be given great attention in the planning and execution phases in order to obtain a satisfactory result.The invisibility of grouting engineering remains a significant difficulty for the evaluation of grout filling effect,grouting effectiveness and the stability of hydraulic engineering.Due to the prioritized exploitation of project sites with good geological conditions,complex geological structures are increasingly involved in the construction of hydraulic projects,i.e.,high dam engineering,inter-basin long-distance water transfer project.As the geological structures of rock mass can be regarded as fractured medium or porous medium,the grout flow characteristics in different mediums are quite different,and the involving geological modeling theory and numerical simulation method are also quite different.Invisible geological condition,complex grout spread behaviors,comprehensive evaluation of grouting effect and stability analysis of grouting engineering are the issues of crucial importance for the numerical simulation of grouting engineering.Based on a grouting engineering of dam foundation with fractured rock mass and a goaf grouting engineering underlying an inter-basin long-distance water transfer project,numerical simulation and stability analysis of grouting engineering based on three-dimensional refined geological model in hydraulic project is performed,in-depth research and analysis on the problems mentioned above are shown in this thesis and the achievements are listed as follows:1?Considering the problems that stochastic fractures in current grouting simulation researches are simplified and the grout spread mechanism in complex fracture network has not been accurately revealed by the CFD(Computational Fluid Dynamics)method,the theory and method of Bingham fluid grouting simulation based on 3D geological model of fractured rock mass are proposed.Researches on grouting simulation simplify the stochastic fracture as one planar fracture or regular fracture network,only few of them have established a three-dimensional geological model to reveal the actual stochastic and complex features of fractures,and the grout spread mechanism in complex fracture network cannot be simulated effectively.Aiming at the above problems,a model ofBingham fluid grouting simulation based on three-dimensional fractured rock mass model is proposed and established.Secondly,based on the theory of probability and statistic,Monte Carlo stochastic simulation method is used to simulate the geometrical parameters of fractures,and a three-dimensional random fracture network model is established.Furthermore,based on the established three-dimensional random fracture network model,three-dimensional N-S(Navier-Stokes)equation and Bingham fluid model are used,and a mathematical model of Bingham fluid grouting simulation based on three-dimensional fractured rock mass model is proposed.And the polygonal mesh generation technique is used to establish the fine grid model of grouting for three-dimensional fractured rock mass.Finally,the VOF method is used to study the flow pattern of Bingham grout in complex fractured network.2?Considering the problems that previous studies of grouting simulation in porous medium mainly focused on the grouting simulation in a single borehole and the different grout concentrations distributions has not been revealed detailedly,research on multi-hole sequential grouting simulation in porous medium is carried out based on the three-dimensional refined geological model.The flow characteristics of grout in different stratifications are revealed,which provides an important theoretical basis for the stability analysis of grouting engineering in hydro-mechanical coupling theory.In the current researches of porous medium grouting simulation,most of them focus on single grouting hole,and the study of the diffusion law of the grout in the actual grouting engineering is ignored.Aiming at the above problems,the porous media grouting simulation is carried out under the condition of multi-hole grouting.A mathematical analysis model of three-dimensional porous media grouting simulation based on the three-dimensional refined geological model is proposed.Secondly,the three-dimensional refined geological model including geological structure model and hydraulic building model is established by effectively integrating the data sources of different scales and types.Then,based on the three-dimensional N-S equation and Bingham fluid model,a mathematical model of porous media grouting based on the three-dimensional refined geological model is established.Finally,through the coupling between the refined geological model data and the CFD model data,a three-dimensional porous grouting calculation grid model is established to simulate the multi-hole infiltration process of the Bingham grout in the porous medium.Through the study of the flow diffusion law of the grout in the three-dimensional refined geological condition,the distribution of the grout concentration field and the distribution of the grouting pressure in the study area can be obtained.The results can provide the theory and foundation for the stability analysis of grouting engineering based on hydro-mechanical coupling theory.3?Previous studies of grouting effect evaluation only take single factor into account and cannot assess the permeability and tightness for rock mass simultaneously.Only a few efforts have been devoted to the comprehensive evaluation of grouting effect,which fail to consider the uncertain problems thoroughly.A fuzzy comprehensive evaluation of grouting effect based on cloud model is proposed with consideration of fuzziness and randomness.Current evaluation of grouting effect research mainly focus on single factor evaluation.It is difficult to describe the relationship between different test results and the overall effect of grouting engineering.And there is a lack of evaluation from the perspective of permeability and compactness.In addition,because of the fuzziness of relationship among evaluation indexes and relationships between evaluation indexes and evaluation results,and the uncertainty of relationships between index and final evaluation results,grouting effect evaluation is a multi-index comprehensive evaluation problem with multiple uncertainties.Currently,there is also a lack of consideration of the uncertainty in the evaluation of grouting effect by using fuzzy comprehensive evaluation method.Therefore,the fuzzy comprehensive evaluation theory and method of grouting effect based on cloud model are proposed.Firstly,research framework and mathematical model for comprehensive evaluation of grouting effect are established.Secondly,the groutability is introduced as the evaluation index and the evaluation criteria including permeability and compactness of rock mass are constructed on the basis of the evaluation indexes of conventional grouting effect,such as permeability,sound wave velocity and filling rate.Thirdly,a fuzzy comprehensive evaluation method based on cloud model is proposed,by which the fuzziness,randomness and discretization in grouting effect evaluation are organically combined.The model is established to solve these problem:(1)the relationship between the evaluation index and the result was fuzzy,(2)a large number of field data could not be revealed,(3)and the determination of the importance scale and membership are easy to be influenced by subjective factors.Lastly,it is difficult to fully and truly reflect the grouting effect because it is basis of a single evaluation grade,fuzzy entropy is introduced as an auxiliary evaluation of grouting effect.The results of two-dimensional evaluation are built from the two levels of grade and complexity,and the grouting effect was evaluated synthetically.4?Aiming at the problems that researches on the stability analysis of grouted engineering in hydraulic project simplify the grouted rock mass as a homogeneous material and ignore the influence of grouting pressure,the theory and method of stability analysis in grouting engineering are performed based on the hydro-mechanical coupling theory.In the current stability analysis of grouting project,the difference of grout concentration in different regions and the influence of grouting pressure are ignored.Selection of grouting filling parameters is mostly relied on engineering experience,which affects the accuracy of grouting stability analysis.In order to solve the above problem,the coupling model of grout and rock mass is established based on the mechanical mechanism of hydro-mechanical coupling.The stability analysis of inter-basin long-distance water transfer project is taken as an example.Firstly,based on the hydro-mechanical coupling analysis model,the grout concentration field data are applied to the grouting stability analysis.The physical and mechanical parameters of filling body after grouting reinforcement are determined reasonably,and the grouting pressure is loaded.Secondly,the finite element method was adopted to analyze the deformation mechanism and deformation characteristics influenced by multi-factors.And the stress and deformation in the whole process of the construction and operation of the overlying structure are discussed in detail.The above work provides technical support for the stability design and construction of hydraulic engineering.By applying the grouting simulation theory in fractured medium and porous medium,the fuzzy comprehensive evaluation method of grouting effect and the stability analysis method based on the hydro-mechanical coupling theory,theoretical analysis and applied research are carried out,taking a grouting engineering of dam foundation with fractured rock mass and a goaf grouting engineering underlying an inter-basin long-distance water transfer project as the research cases.It is shown that the theory and method proposed in this thesis are able to provide a reasonable theoretical basis and technical support for the grouting simulation,grouting effect evaluation and stability analysis of hydraulic engineering.