Liquid nitrogen freezing system of high water pressure super-long-distance large-sectional tunnel and method of quickly changing shield tail brushes

Abstract

Disclosed are a liquid nitrogen freezing system of a high water pressure super-long-distance large-sectional tunnel and a method of quickly changing shield tail brushes. The system comprises a liquid nitrogen storage tank, a main gate valve, a liquid supply pipe, distributors, liquid distributing pipes, freezing pipes, gas colleting pipes, exhaust pipes, a temperature measuring hole and cold discharge pipes. The liquid nitrogen storage tank is connected with the liquid supply pipe provided with the main gate valve. Two branches of the liquid supply pipe are connected with the distributors respectively; each distributor includes 8 to 10 branches, each branch is connected with a group of series freezing pipes through one liquid distributing pipe, each group of last freezing pipes is connected with one gas collecting pipe and is connected with one exhaust pipe through the gas collecting pipe; the exhaust pipes discharge vaporized nitrogen into air; the front ends of the cold discharge pipes are connected with the liquid distributing pipes, and the their tail ends are connected with the gas collecting pipes. The method of quickly changing the shield tail brushes is further provided. The system and the method are suitable for the projects of quickly changing the shield tail brushes for the high water pressure super-long-distance large-sectional tunnels; the system and the method have the advantages such as high forming speed of a frozen wall, high strength, no toxicity or pollution, safety and reliability in use, and convenience in construction.

Description

technical field [0001] The invention relates to a high water pressure ultra-long-distance cross-river (sea) large-section liquid nitrogen freezing system and a rapid replacement method for a shield tail brush of a shield tunnel, belonging to the technical field of shield tunnel reinforcement. Background technique [0002] With the widespread application of shield construction methods in subways and cross-river and sea-crossing tunnels, under the conditions of soft ground and highly confined aquifers with a water pressure of 0.4MPa~0.7MPa, the ultra-long distance of more than 1000m, with a diameter of 14 The engineering problems encountered in the construction of ~16m large-section shields are becoming more and more prominent. Among them, the prevention and control of shield tail leakage and the replacement of shield tail brushes are construction difficulties in cross-river and sea-crossing traffic tunnel projects. If the shield tail leakage is serious, It will cause the wate...

AI Technical Summary

Problems solved by technology

[0011] ②Even if the freezing station is placed inside the tunnel, the brine freezing period will be longer, which will seriously affect the construction period (the large shield machine will stop for one day and the economic loss will be huge, and it is urgent to save time);

[0012] ③ It is difficult to adapt to the emergency needs of large-scale high-risk shield tunneling projects such as high water pressure and long-distance cross-river tunnels

[0015] The long-distance liquid nitrogen freezing system for ground construction is suitable for projects where the distance between the tunnel freezing working face and the tunnel working well is not more than 800m, the soil conditions of the liquid nitrogen freezing working face are relatively good, and the tunnel diameter is small. Adapt to projects with high water pressure, ultra-long distance, and complex soil conditions, especially large-scale high-risk emergency projects

[0016] Usually, the shield tail brush is replaced by welding, which takes a long time, and the frozen working surface returns to temperature quickly, which is easy to cause leakage on the frozen working surface. Therefore, how to choose a reliable construction method can better solve the problem of high water pressure and long The rapid replacement of shield tail brushes in long-distance shield tunnels is a key issue that needs to be solved urgently

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