Study On Mechanism Of Slurry Diffusion And Sealing At The Process Of Underground Engineering Moving Water Grouting And Its Application

With the growth of national economy, the current underground works in China has entered a new stage. Strong demand for coal and steel promotes the extension of construction and exploitation of mines. It is estimated that in the next 15 years many coal mines in our country will reach to the depth of 1500-2000 m. At the same time, some metal mines turn to deep mining, with the depth about 1000m. With the deep exploration of mines, the greatly hazard, namely, the gushing water pressure are more likely to occur, which results in dire threats on the safety production. In respect of the tunnel construction, due to the westward expansion, China will be shifting the center of highway and railway construction to the western region. The west is in the geological transition zone of China. In the transition zone, the Karst landform is very common and the geological structure is very complex, which leads to the great challenges in the tunnel construction, one of which is the water fathering.The underground water disasters, with diverse forms, are harmful for the underground constructions. The control of underground water disaster can be approached in many ways, i.e., detections of the water structure in the water fathering region and the water source, analysis on the grouting theory, mechanics of slurry diffusion and seal under hydrodynamic conditions, developing the sealing techniques, etc. At present series of achievements on the slurry diffusion under hydrostatic or anhydrous conditions has been obtained by scholars both at home and abroad, which greatly promotes the fracture grouting theory. While, theory falls far behind experience, with no mathematical model being in line with realistic and the diffusion effect on the slurry being not taken into consideration. As the underground water disaster becoming increasingly serious, analysis on the theory of slurry diffusion and seal need to be carried out urgently.In this work, diverse research tools are utilized, such as the geological classification, detection of water source and water channel, model test on hydrodynamic grouting, mechanics of slurry diffusion and seal for different types of grouts, new techniques for hydrodynamic conditions and its application, etc. Some useful conclusions have been obtained. (1) Grounded in the analysis of slurry diffusion and seal in fracture, from the geological perspective, the underground water fathering is divided and the most common practical plane of cracks and water gushing is analyzed. According to the types of water channel, the underground water disaster is divided into three major classes, namely, structural water fathering, exposing water fathering and contacting water fathering. Further, it is divided into ten subclass and their own characteristics are discussed in detail.(2) Based on the theory and techniques of geophysical detection, multi-purpose use of seismic wave, radar and transient electromagnetic exploration, the occurrence of water source and water channel are detected accurately. By the field test and the Seismic wave bi-phase medium reflection theory, the methods to detect and locate seismic large body of underground water ways are proposed. Besides, the Electromagnetic wave reflection rule is analyzed, radar signal response characteristics of the aquifer and the fracture criteria for sub-consciousness are proposed. Combining with the field test, the detection of water fractures are realized. Based on the achievements, detection and locate seismic large body of underground water are realized, which provides conditions for controlling the water fathering.(3) Develop a visual large-proportion quasi-three-dimensional test system for the physical model of fracture-grouting in flowing water; this system is the first set of its kind both at home and abroad. Develop the flow sensor which based on Fiber-Bragg-Grating. In addition to its high accuracy, the test system is also able to adapt to the complex environment, achieves the real-time monitoring and recording of the parameters of micro-fractures in dynamic flow field. The system can be used in the research of model of fracture-grouting in flowing water; it also lays the theoretical foundation for the research of grouting in flowing water.(4) Research the diffusion patterns of different slurries on the quasi-three-dimensional plane fracture in flowing water. Propose the U-shape diffusion pattern of grouting in flowing water for the first time; conclude the diffusion equation of flowing-water grouting. Propose the method of describing the extent of slurry spread with the diffusion degree of slurry (L) and the diffusion distance against the current (N). (5) The diffusion and sealing of cement grout are studied deeply through model test method. Partition layered diffusion mechanism of cement grout are first proposed, and the relationship between different grouting parameters and grout diffusion opening and diffusion radius against the current of the grout are studied. Fast water separating and deposition phenomenon of cement grout are detected in dynamic grouting. The transport capture function mechanisms of fissure dynamic water to slurry water are analyzed. Fast water separating layered principle and sedimentary retained mechanism are revealed. The concept of sediments core are put forward, by which effective containment area are represented, and the relationship between ediments core diffusion parameter LO, NO and grout-water ratio C are obtained. When cement grout form an effective sedimentary diffusion, the range of corresponding grout-water ratioξis [0.15,1.5]. Combined with diffusion and retained sealing mechanism of cement grout, dynamic sealing grouting construction technology is proposed, and it is verified by laboratory experiments and field tests.(6) Through grouting model tests and theoretical analysis, choosing the chemical slurry and the anti-dispersion slurry as representatives, the different types of diffusing and blocking mechanism of two kinds of slurry have been researched respectively. The tests propose the anti-proliferation mechanism and dispersion-displacement-block-retention mechanism of the anti-dispersion slurry. Introducing the determining value of the displacement-diffusion state, and find the critical range of Dp values, that is, when Dp≥36, the diffusion-displacement of slurry occurs. The main factor which affects the retention of the slurry has been found. A new kind of cement-based anti-dispersion slurry has been developed. Achieving the displacement-diffusion and effective retention of slurry; developing the corresponding sealing technology for the flowing water environment. At the same time, the peculiar assimilation-transport-diffusion mechanism of chemical slurry has been found; and proposes the fracture sealing mechanism which applies to the flowing water condition. This fracture sealing mechanism is based on the ant-group effect and time-varying retention property of the slurry. In the course of sealing fracture gush with slurry, five principles of significant importance have been proposed. The control method of chemical grouting has also been presented. (7) In the Longgu coal mine field test. with the help of key hole injection grouting technology, we adjusted the design of drill hole by geological analyzing and water source detecting. By using multi-level analysis of factors method, we evaluated the quality of drilling and selected optimized key hole. Choose the slurry-water ratioξas the key control factor in the design of injection grouting, seal the water inflow successfully through the informationization construction. This test made economic effectiveness.verified the research conclusions, and also has some theoretical significance of the project spread value.