SU927901A1 - Method of thermal consolidation of soil - Google Patents

Description

{5) METHOD OF THERMAL SOIL STRENGTHENING

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 The invention relates to the construction of buildings and structures on weak soils, in particular to their strengthening by thermal action.

There is a method of thermally strengthening the soil, including drilling a well, sealing it, feeding combustible mixtures of fuel and compressed air into the well, burning them and pressing hot gases into the soil t.

The closest to the present invention is a method of thermally strengthening the soil, including drilling a well, its thermal insulation and sealing, supplying combustible mixtures to the well, burning them and injecting hot gases into the soil 2.

The disadvantages of these methods consist in a relatively long process of strengthening the soil in the order of 0.6-0.9 days / m with a high consumption of fuel and compressed air.

The purpose of the invention is to reduce energy costs.

The goal is achieved in that according to the method, including drilling a well, its thermal insulation and sealing, supplying combustible mixtures to the well, burning them and introducing dormant gases into the soil, thermal insulation is carried out by placing a perforated pipe in the well with an annular gap and then filling gap porous

10 with heat-conducting heat-resistant material, and in the process of introducing hot gases into the soil, injection is made into the annular gap of compressed air.

The value of the annular gap is determined from the dependence

(ET1SHR1

TO

where DO is the diameter of the well, m, H is the depth of the well, m, 39 GL heat capacity of the well, kJ / m, i is the heat transfer coefficient of the heat-resistant material, kJ / (h.m ° C), 620 is the experimental coefficient, (nm. С) / мД «, tc - temperature of the borehole wall is acceptable, С, t) - air content in the combustible mixture,. The drawing shows the well, longitudinal section, reinforced soil mass and location of the pipeline, heat-resistant material and measuring devices. The process technology is as follows. First, the well 1 is drilled, then the perforated pipeline with a gap 3, determined from relation (1), is installed coaxially with it to its entire height. On the outer side of the pipeline 2, perforated pipes k are arranged symmetrically around its circumference for supplying compressed air into the gap 3. After that, the gap 3 is filled with graphitic sand sand mixture and the well 1. is sealed with a gate 6 with a nozzle 7 and a hot mixture is fed into it; equal to 1/620, the allowable heating temperature of the pipeline 2 is taken, and clearance 3 through pipe 4 as air of combustible mixtures is compressed air is injected from compressor 8. Combustion of combustible mixtures is carried out until the design temperature, for example, ZOO-BOO C, does not reach the outer boundary 9 of the reinforced soil mass 10, which is determined by the reading of thermocouples 11 installed along circuit 3 and caMoriMiuyuHf M devices 12. After the burning is completed well 1 is depressurized, the pipe and heat resistant material 5 are removed, and well 1 is filled with local soil or bacon. The use of heat-resistant material 5 makes it possible to create a large temperature difference between the gases inside the pipeline 2 and the borehole wall}, which reduces the air flow in the combustible 1. mixture, uniformly heats the entire surface of the borehole 1, which reduces the duration of the process and increases the multiplicity of use of the pipeline 2, which is made of heat-resistant steel, thereby reducing the cost of reinforcing the soil. The injection of compressed air into the gap 3 contributes to an increase in the thermal power of the well 1 and to a reduction in the consumption of heat and air, as well as a reduction in the duration of the thermal strengthening of the soil. PRI me R. At the site of work, thermal strengthening of the soil with a capacity of 6 m in individual pillars with a diameter of 2 m is carried out with a heating temperature along the outer contour. Boreholes 1 with a diameter of 0.2 m are drilled with a PVVS-15 machine and then a perforated cylindrical tube 2 with a diameter of 0 m, 1 m is installed coaxially along the entire height, with four pipes C with a diameter of 12 mm placed on its outer side. Pipes 2 and 4 are made of heat-resistant steel OH23YU5AS with a temperature of long-term heating of 1800 C. After that, the gap 3 is filled with graphite-sand mixture 5 of 1:10 composition with a temperature-start of sintering 1800 ° C, wells 1 are sealed with valves 6 with nozzles 7 B wells 1 are supplied with combustible mixtures with air content k, 5 nm / kg, which corresponds to the content of fuel in mixtures x 2.9 mJ / nm, and burn them at an excess air pressure of 0.0–0.2 MPa. As the combustible mixtures are burned, the gap 3 through the pipes 4 is supplied to compress the air. Thermal soil reinforcement lasts 72 hours and ends when the design temperature of 300 ° C reaches the outer boundary 9 of the soil array to be strengthened 10, which is recorded by reading thermocouples 11 of type TXA-USH and recording instruments 13 accuracy class 0.5. Simultaneously, for comparison, thermal strengthening is carried out in a known manner . The test results are shown in the table.

The volume of soil reinforced around each well, m

The duration of strengthening the soil, h

Consumption

The application of the proposed method in practice will allow to increase productivity by 1.53 times, to reduce the consumption of fuel and air, respectively, by 1.22 and 1.64 times and to reduce the cost of thermal strengthening of the soil by 30.

Claims (2)

Invention Formula J. A method of thermally strengthening the soil, including drilling a well, its thermoisolation and sealing, feeding combustible mixtures into the well, burning them and introducing hot gases into the soil, characterized in that, in order to reduce energy costs, thermal insulation is carried out by a well with an annular gap of the perforated pipe and the subsequent filling of the gap with porous heat-conducting heat-resistant material; and in the process of introducing hot gases into the soil, compressed air is injected into the annular gap. 25L 25, 109 72 2. The method according to claim 1, of which is the fact that the size of the annular gap is determined from the dependence 2fHA. () - tc . but . where DO is the diameter of the well, m, H is the depth of the well, m, 0-- the heat capacity of the well, kJ / h D.- coefficient of thermal conductivity of heat-resistant material, kJ / (h-mS). U- air content in combustible mixtures, nm / mJ, in; 620-experimental coefficient (nm-Su / mJ tc permissible temperature of the heating of the borehole wall, C. Sources of information taken into account in the examination 1. USSR Author's Certificate No. 613005, cl. E 02 D 3/10, 1976. 2. USSR author's certificate for H 297189V29-33, cl. E 02 D 3/11, 11 .08.80. .