Comprehensive stage construction method for super-large-span underground cavern of fractured rock mass

Abstract

The invention relates to a comprehensive stage construction method for a super-large-span underground cavern of fractured rock mass. The comprehensive stage construction method comprises the followingsteps that 1, construction condition data of the super-large-span underground cavern are collected and analyzed before construction; 2, the overall initial design stage in the initial construction stage comprises initial ground stress evaluation, section initial supporting structure design and pilot tunnel design; 3, pilot tunnel and supporting construction is conducted, and actual geological parameters of the cavern are obtained; 4, the design stage is analyzed in detail in the construction process; 5, the construction monitoring feedback stage is conducted; and 6, secondary lining construction is conducted, construction is completed, and construction summary is conducted. According to the comprehensive stage construction method, the comprehensive stability analysis method of the three stages of initial supporting structure design and pilot tunnel design, pilot tunnel construction actual measurement detailed design and construction monitoring feedback is adopted, safety and reasonability of the super-large-span cavern construction scheme are ensured, and a solid foundation is provided for construction safety and smooth service of the cavern.

Description

technical field [0001] The invention belongs to the technical field of tunnel and underground engineering design and construction, and in particular relates to a stage comprehensive design and construction method for constructing a super-long-span underground cavern in a rock mass with developed cracks. Background technique [0002] The development and utilization of underground space is an inevitable requirement of China's economic development and urbanization, and there will be more and more projects to build underground super-span underground spaces such as stations and tunnels. At the same time, there is also a strong demand for ultra-large span caverns such as underground oil storage depots, hydropower plant buildings, and underground defense facilities. The span of these caverns can reach the order of 50-80m. Typical super-long-span caverns built at home and abroad include underground stadiums, subway stations, high-speed rail stations and long-span tunnels. The main ...

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Problems solved by technology

For ultra-large-span caverns, the standard design method is obviously not suitable, and there is no suitable standard to apply; the principle of the new Austrian design method combined with engineering experience and measurement results is suitable, but what parameter support is used in the design stage? The belt is very random and risky, which also brings great hidden dangers to the engineering construction process; using the analytical calculation method, the load structure calculation method commonly used in the engineering field cannot determine the definite load for super long-span structures. The force mode does not conform to the theoretical assumptions of the load structure method

[0004] Generally, tunnel engineering does not pay much attention to calculation, but for giant caverns with a span of more than 50m or even greater, it is not enough to rely solely on experience and on-site measurement. A scheme with a sufficient safety factor must be designed before the construction starts, because collapse The consequences of risk accidents such as instability are unacceptable

Since the width of the ultra-long-span cavern increases, but the height does not change much, it has to be made into a flat arched structure, and the following mechanical characteristics are formed: the stress redistribution after excavation becomes unfavorable; The stress concentration at the foot is too large, requiring a large foundation bearing capacity; the vault is unstable, and the loose ground pressure is large; the buried depth is relatively small, and the arching effect cannot be well exerted; the bearing capacity of the supporting structure is relatively small

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