A Freezing Method of High Gradient Heterogeneous Freezing Wall

Abstract

The invention discloses a method for freezing a high-gradient heterogeneous freezing wall. The mixed freezing mode of "salt water + liquid nitrogen" is adopted, and a freezing pipe is arranged at the place where the soil around the shaft needs to be frozen, and a brine freezing pipe is arranged inside the freezing wall. , and a liquid nitrogen freezing tube is arranged on the periphery. The liquid nitrogen freezing tubes are arranged in one row, and the brine freezing tubes are arranged in at least one row, and each row is arranged in a circular shape. When there are two or more rows of brine freezing pipes, the diameter of the ring in the innermost row should ensure that the temperature of the well side during excavation is not higher than the ideal value that is conducive to the stability of the well side; the brine temperature setting of the brine freezing pipes should ensure that It can form a temperature field that gradually decreases from the inside to the outside. The temperature field formed by the freezing tube layout method of the present invention has obvious high gradient non-uniformity. Compared with conventional brine freezing, under the same load conditions, the thickness of the frozen wall formed by this pipe layout is small but has a higher bearing capacity, which will reduce the amount of frost heaving and thawing, and reduce the amount of engineering work for freezing holes , The freezing period is shortened.

Description

technical field [0001] The invention belongs to the field of shaft freezing construction, and relates to a freezing method in ultra-deep shaft freezing construction, in particular to a freezing method for heterogeneous frozen walls. Background technique [0002] Sinking by freezing method is the most widely used special wellbore construction method in my country, and nearly 600 wellbores have been completed so far. After decades of development, the problem of mining deep coal resources has become increasingly prominent. After entering the 21st century, the thickness of alluvium in many new mines exceeds 600 meters, and the maximum freezing depth reaches 702 meters. Therefore, it has become a prominent problem in the development of deep wells in my country to study and solve the wellbore construction technology in deep alluvium. [0003] At present, deep well freezing mainly adopts multi-pipe brine freezing system, such as figure 1 , figure 2 As shown, the temperature fi...

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Problems solved by technology

[0006] (3) As the thickness of the excavated topsoil layer increases, the freezing depth increases, the ground pressure increases, and the radial deformation of the frozen wall is too large, which will easily lead to accidents such as fracture of the frozen pipe and water leakage of the well wall

[0007] (4) It takes a long time to freeze brine, especially in deep well freezing, and considering the time for drilling holes in multiple rows of brine freezing, the freezing period is very long

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