Study On Mechanism And Influential Factors Of Water-Mud-Inrush Under Hydraulic Tunnel Construction

The hydropower cascade development promote a new round high tide of building hydropower engineering in my country,then a large number of hydropower stations were born at the right momen.Hydraulic tunnel is extremely important to hydraulic construction. However.it my encounter a variety of complex and unfavorable geological conditions in the process of building the hydraulic tunnel.The wate-mud-inrush is especially more serious in the fractured zone and bring great threat for tunnel construction and surrounding environment.In this thesis,different types of water-mud-inrush’s macroscopic and mesoscopic mechanism are researched through information Investigate, theoretical study and numerical simulation which are based on the hydraulic tunnels of Muli river.The major factors that influence mud-water-inrush in the process of tunnel excavation are discussed.Based on geological structure, karst, hydro geological condition and rock property, the macro phenomenon of water-mud-inrush are classified and the research objects is established.For providing the basis for the numerical simulation.it need phenomenon explain,mechanics analysis and theoretical calculation in foundation of classifications to get the macroscopic rule of water-mud-inrush.According to the type of water-mud-inrush in the process of tunnel construction, illustrate the theoretical basis and implementation method for different numerical model of fluid-structure coupling after combining methods on particle flow simulation of fluid-structure interactionxonsidering the applicable scope of numerical method.matching suitable numerical models for different types of water-mud-inrushTo simulate and mechanism research different types of the water-mud-inrush process:Firstly calibrate mechanical parameters and hydraulics parameters of surrounding rock by PFC built-in system to established mesoscopic and macroscopic connection while change micro-structure to modelling different structural types of rock mass characteristics;According to different types of water-mud-inrush,established two dimensional erosive and split particle flow model separately.Different types of water-mud-inrush process are respectively calculated according to the surrounding environment which is loose structure mass (grade V),single joint fractured rock mass(grade IV) and complete rock mass (grade III).Study mechanism and find that the type of water-mud-inrush in the progress of tunnel construction is closely related to the surrounding rock;the different way seepage and stress fields coupled affect water-mud-inrush process which indicate that there is big difference on porosity change,fracture distribution,water-mud-inrush scale,displacement,spatial orientation of water inrush channel and failure mode between erosive and split water-mud-inrush.Considering different human and environmental factors influence on water-mud-inrushucompare the change on macroscopic phenomenon and mesoscopic mechanism caused by factor varied.Then determine the critical damage condition and critical value.It provide the reference for tunnel construction.