The Calculation Method Of The Main Parameters Of Cutter Shield And Software Development

Shield driving machine is a kind of professional tunneling machinery combining machinery, power, liquid, sensor, and IT technology. Modern shield driving machine is functional in digging and cutting soil body, transporting soil, assembling tunnel lining supports, and correcting guidance error in a survey. Along with the development of modern transportation, undergroud project, mining, hydraulic project, civil engineer and electric communication facilities, Shield driving has become an advanced tunneling technology and has been widely used in large-size constructions such as subway, railway, highway, gas transmission, water transmission, civil engineer and water&power tunnel.Cutting mechanism is the crucial part and its torque is one of the bases on which the machine is designed and produced. Without this crucial technical parameter, there will be no machine at all. Therefore, precision of caculation on moment of torque is the key to design and produce shield driving machine. Quantificational measurment on factors that affect the torque and setting the proper torque equipment has become the frontier subject in designing, producing and using shield driving machines. This treatise makes a summarization of many studying files and documents and contributes several methods in main parameter caculation on shield cutting tools.1. To summarize and evaluate current methods of caculation on the torque of shield cutting tools under earth pressure.At present, resistance torque caculating formula, model test formula, empirical formula and digging test statistic formula are the major methods in caculation on the torque of shield cutting tools under earth pressure. Many theoretical formula derivation are more of establishment on empirical formula than purely theoretical caculating models. As semi-theoretical and semi-empirical formulas, they are unable to take all aspects of the cutting tools and its structue into caculation. And they also have problems in choosing the parameters especilly the geological ones. This treatise propose a caculating model for cutting tool torque by combining the theoretical formulas and empirical formulas. The caculation results of both methods will be considered in torque equipment.2. Caculation on the external applied loadParameters of tunnel structure and geological conditions are desicive factors in caclulating the external applied load from above, below and side of the shield driving machines. These parameters are also the preconditions of caculation of the moment of torque. The external applied load on the cutting head of the shield driving machine when digging in the different level of undergroud are usually considered earth and water pressures from above, below and side. The pressures from earth and water will be added up in caculating load when the machine is operating in soft soil such as silt or cohesive soil.3. Theory of cutting head and mechanical modelDifferent cutting heads are applied on various theories. The cutting of hob break the soil body by rolling and pushing. Forehammer and central convex head push and cut. The friction between hob and soil body is a kind of friction of rolling while the friction between cutting head, forehammer and central convex head and soil body is sliding friction. The hob wears better than other heads in rolling.4. Establishment of mathematic model of caculating torque of different cutting heads Basically, there are two kinds of shield cutting heads——ventral shield and spoke shield. Varied cutting tools can be equipped for various needs by different mechanism.Torque of the cutting head of the ventral shield includes:(1)torque T₁ from the frictional resistance between the head and soil body;(2)torque T₂ from the frictional resistance between the back and soil body in the pressure cabin;(3)torque T₃ from the frictional resistance between soil body and the side of cutting tools;(4)torque T₄ from the resistance of stratum when cutting tools breaking the soil body;(5)torque T₅ when cutting tools rolling;(6)torque T₆ major pressurized frictional resistance;(7)torque T₇ frictional resistance from the main axis;Aperture opening ratio of the spoke cutting head is very big(nearly 100%). The driving torque is also from the 7 forces above. Compared with ventral shield, it's different in caculation on torque because different modulus should be set according to different aperture opening ratios, usually by 75%5. Theory of applied software in caculating the torqueA visualized software computing crucial technical parameters of shield driving machine with geological applicablity can be built under the environment of C++Bulider to transform the mathematical models to caculating and analysis software for direct use. With human-computer interactive interface, this software'll be a dependable and presicive tool to realize the caculation on external applied load, torque of cutting heads, driving force of shield and main power.6. Conclusion and outlookA brief summary of the study and outlook for its further improvement.