Composition Design,Hydration Mechanism And Performance Control Of Grouting Material Prepared By Red Mud And Multi-source Solid Waste

With the continuous development of national economy and comprehensive national strength,China's infrastructure construction is booming,and a large number of infrastructure projects,such as highway and railway,water conservancy and hydropower,and urban underground space,have been put into construction.At present,China has become the country with the largest scale and difficulty of tunnel and underground engineering construction in the world.In the construction process of tunnel and underground engineering,unfavorable geology,mainly including fault,broken rock mass,weak strata and karst are often encountered,which can easily induce sudden geological disasters such as surrounding rock collapse,water and mud inrush,water and sand pour,thus causing huge harm to construction personnel and tools,and also seriously threatening the hydrological and ecological environment of the tunnel site area.Grouting material plays an important role in grouting engineering as the object to treat the unfavour geological body.At present,Portland cement-based grouting materials are the most widely used,but with the improvement of the difficulty of underground engineering disaster management,cement-based grouting materials engineering performance defects of long setting time,low early strength growth rate are increasingly prominent,and with the increase of social awareness of environmental protection,the environmental problems caused by cement,such as non-renewable raw materials,high energy consumption and heavy pollution in the preparation process,have become cumulatively apparent.Therefore,the research and development of a new type of grouting material with high performance and low price has become an important topic to ensure the safety of tunnel and underground engineering construction.At the same time,with the rapid development of China's economy,billions of tons of industrial and urban solid wastes are generated every year.At present,most of these solid wastes are stored,and there is no fundamental breakthrough in comprehensive utilization.As a result,the accumulation is increasing,causing huge environmental and social pressure.Although the chemical composition of solid waste is different,its main components are SiO2,CaO,Al2O3,Fe2O3 and so on,which have potential cementitious activity.Using solid waste to prepare grouting materials can not only realize the effective prevention and control of geological disasters in tunnels and underground engineering,but also promote the development of underground engineering construction in China.Moreover,it also meets the development needs of environmental protection industry and green construction industry,and is the inevitable requirement of "ecological civilization" and "green development,circular development and low-carbon development" of society.However,when solid waste is used to prepare grouting materials,there are problems such as large composition fluctuation.poor cementitious activity and environmental pollution.How to use solid waste to prepare green,high quality and low cost grouting materials has become an important direction for the sustainable development of tunnel and underground engineering construction.Performance requirements as the guidance,based on the grouting project in a typical industrial solid waste red mud as the main research object,in view of the preparation of solid waste on the key scientific problems existing in the process of grouting materials research,this paper set up preparation theory of multi-solid waste coordinated utilization of red mud-based grouting material,analyzes the hydration mechanism of red mud-based grouting material,explores its hydration kinetics model,the formation of the red mud-based grouting material performance control method,and the prediction model,and ensure the service safety and environmental characteristics of new grouting material,and implements the red mud-based grouting material consumption capacity analysis,energy saving and emission reduction,which has made a series of research results.(1)For the red mud utilization problem of low cementitious activity and complex and changeable composition,the promoting mechanism of cementitious activity of red mud was revealed,the formation rules of different types of hydration products in the cementitious system of red mud and multiple types of solid wastes was determined,the ratio design method in the preparation process of red mud-based grouting material was put forward,and the preparation theory of red mud-based grouting material based on the cooperative utilization of multiple types of solid waste was established.(2)The rheological and dynamic characteristics,the change law of free water occurrence state,the change characteristics of microscopic morphology and the change law of hydration heat release during the process of hydration hardening of red mud-based grouting material were investigated.The hydration dynamics characteristics of red mud-based grouting materials were determined,and the hydration mechanism of red mud-based grouting materials was revealed.Based on the Krstulovic-Dabic model,the hydration dynamics model of red mud-based grouting materials was established,(3)The complex geotechnical engineering hydrogeological conditions of grouting material presented different performance requirements,the action mechanism of red mud raw material particle size,water cement ratio,admixture and other preparation parameters on the performance of red mud-based grouting materials was revealed,the performance of red mud-based grouting material dynamic control method was introduced,and based on artificial neural network and genetic algorithm,the red mud-based grouting material setting time and mechanical strength of the dynamic prediction model was established.(4)The evolution law of mechanical properties of red mud-based grouting materials under the service environment of ion erosion and stress load was analyzed.According to the Weibull function distribution and the Lemaitre strain equivalent principle,the constitutive model of stone failure of red mud-based grouting materials was proposed.(5)Considering alkaline and heavy metal components in higher pollution factors of red mud may lead to environmental pollution,the alkaline components in red mud based material of the grouting concretion body and the rule of the leaching of heavy metals were revealed,the curing mechanism of the pollution factor was cleared,and the corresponding curing method was proposed,the green environmental protection characteristics of red mud-based grouting material in the process of application in the geotechnical engineering was realized,and based on the eBalance life cycle method to achieve the red mud-based grouting material used in geotechnical engineering analysis of the energy conservation and emissions reduction of consumption capacity.