Study On The Diffusion Mode And Plugging Law Of Dynamic Grouting In Rough Fracture Under High Temperature Environment

With the implementation of the "Western Development" strategy and the promotion of the"Belt and Road" Initiative,the construction of tunnels and underground engineering is gradually transferred to the southwest of China.A large number of tunnels and underground engineering are faced with complex conditions such as high water temperature,high geotemperature and fracture development.The Yalin section of the Sichuan-Tibet Railway alone crosses multiple hydrothermal active fault zones,which is easy to induce high temperature water inrush disaster.Resulting in casualties and economic losses.At present,grouting is an effective means to control water inrush disaster.However,in the environment of high temperature dynamic water,the characteristics of cement solidification,migration and diffusion mode of grout,and the plugging effect of dynamic water will change significantly.The existing theory of dynamic water grouting is not targeted,so it is difficult to effectively guide the control of the disaster of water inrush in fractures at high temperature.Therefore,it is an important prerequisite for effective control of high temperature water inrush disaster to clarify the diffusion mode and plugging law of dynamic water grouting in fracture under high temperature environment.However,at present,there is a lack of systematic research on the properties of grout and grout consolidation in the environment of high temperature and rich water.The grout diffusion law under the condition of high temperature and dynamic water in rough fracture s is not clear,and the grout plugging criterion has not been established,so it is difficult to provide scientific guidance for engineering practice.Aiming at the above problems,this paper adopts the main research methods such as laboratory test and numerical simulation to study the changing law of grout and grout consolidation properties under high temperature and water-rich environment,proposes three kinds of diffusion modes of dynamic water grouting in rough fractures under high temperature environment,and reveals the changing law of seepage pressure in the process of grout migration and diffusion.The influence of different factors on the plugging effect of dynamic water grouting in rough fractures under high temperature environment is analyzed,and the plugging criterion of high temperature dynamic water grouting is established.The main research contents are as follows:(1)The variation rule of grout and grout consolidation properties in different temperatures and gelling environments was studied.By changing the temperature,the volume ratio of the grout and the gelling environment of the grout,the gelling time and viscosity of the cementsilicate grout,as well as its compressive strength and volume stability of the grout consolidation were tested.The influence rule of the temperature change on the properties of the grout and grout consolidation was analyzed,and the internal mechanism of the evolution of the grout consolidation properties was clarified from the microscopic point of view with the help of the microscopic test means.(2)The diffusion model of dynamic grouting for high temperature rough fractures is proposed.Four factors of dynamic water temperature,dynamic water velocity,fracture roughness and grouting rate were selected to carry out the orthogonal test of dynamic water grouting.Based on the typical grout diffusion morphology and seepage pressure changes,three diffusion modes of dynamic water grouting in rough fractures under high temperature environment were proposed,which revealed the change law of seepage pressure in the process of grout migration and diffusion,and analyzed the influence of different factors on grouting diffusion morphology.Based on the COMSOL numerical simulation software,the effects of temperature,double-hole grouting and different fracture sizes on the diffusion and plugging effect of grouting were further studied.(3)The plugging law of high temperature rough fracture by dynamic grouting is revealed.Using plugging rate as the evaluation index of grouting plugging effect,and the influence of single factors and interactive factors on the water blocking rate was analyzed by using the range method,variance method and cubic spline interpolation method,and the optimal and worst water plugging rate factor levels were proposed.Based on the diffusion mode of hightemperature hydrodynamic grouting and the influence of groundwater,grouting process and grout properties on the grouting plugging effect,the criteria for high-temperature hydrodynamic fracture grouting plugging were established.