RU2763640C1 - Method for increasing the carrying capacity of aerodrome coatings in the conditions of saline permafrost soils - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of construction in permafrost conditions, in particular flat structures of airfields in saline permafrost soils of the Arctic coast. The method of increasing the bearing capacity of airfield pavements in conditions of saline permafrost soils includes excavation, laying on the bottom of the pavement, backfilling of the soil. The excavation is carried out saline soil thawed in summer to the thickness of the design depth, the bottom of the base freed from the soil is covered with a waterproof membrane with a design slope and the possibility of drainage into the water intake, after which the dumped soil is planed, the dumped soil is filtered by sprinkling, the collection of dissolved ground salts followed by desalination by forcing through a filter according to the principle of reverse osmosis, separation into a strong salt solution and a demineralized part, directing the demineralized part to the sprinkler system, and a strong salt solution for disposal.

EFFECT: increasing the bearing capacity of airfield pavements in conditions of saline permafrost soils, ensuring an increase in the freezing temperature of the subgrade, eliminating excessive water consumption and secondary pollution of the underlying soils with saline.

1 cl

Description

The invention relates to the field of construction in the conditions of permafrost soils, in particular, plane structures of airfields in the conditions of saline permafrost soils of the Arctic coast.

A known method of building foundations in winter conditions, including thawing frozen soil, excavation and execution of the foundation block in the excavation (Cherkashin V.A., Development of frozen soils. - L.: Stroyizdat, 1977, p. 51, 79-81).

A known method of building foundations in winter conditions, including the development of a pit by crushing and extracting frozen soil and the implementation of a foundation block in the pit (Cherkashin V.A., Development of frozen soils. - L .: Stroyizdat, 1977, p. 51, 77-79) . The disadvantage of the known methods lies in the insufficient bearing capacity of the foundation.

There is a known method for increasing the bearing capacity of frozen plastic-frozen, saline-frozen soils, including the preparation of a fixing solution based on water, dispersed soil as a filler and small additives of polyvinyl alcohol, injecting it into the space between the foundation and the enclosing soil or ice, introducing the fixing solution into enclosing soils (ice), if necessary, previously loosened or thawed, freezing the fixing solution and holding it for up to five days at the temperature of the surrounding soils (ices) (RF patent No. AND/OR ICE", published 1996.07.27, IPC E02D 27/35).

A known method of building foundations in winter conditions, including the development of a pit by crushing and moving frozen soil and the implementation of a foundation block in the pit, crushing the frozen soil is carried out to the depth of the active layer, and the crushed soil is moved into the thawed soil, first in vertical and then in horizontal directions, moreover, crushing and moving frozen soil can be performed simultaneously. In addition, before crushing the frozen soil, vertical slots are made in it to form blocks, and the slots are made with a depth equal to 0.7-0.8 of the height of the active layer, and/or the slots are filled with a substance of positive temperature, followed by holding in time (RF patent No. 2043461 for inventions "METHOD OF CONSTRUCTION OF FOUNDATIONS IN WINTER CONDITIONS", published on September 10, 1995, IPC E02D 27/26.

There is a known method of strengthening frozen soil in a thawing zone, which includes immersing an injector into the soil, supplying a sealing and penetrating solution under pressure, ensuring the destruction of the soil structure in zones of its weakening with the formation of a zone of compacted soil along the contour of the compaction zone, and subsequent immersions of the injector to form adjacent compaction zones . As a sealing and penetrating solution, a chilled saline solution is used with a filler made of a material whose thermal conductivity is lower than the thermal conductivity of the soil being strengthened. RF patent No. 2275468 for the invention "METHOD FOR STRENGTHENING FROZEN SOIL IN THE THAWING ZONE", IPC E02D 3/12, publ. 27.04. 2006.

A known method of erecting shallow and surface foundations underlain by permafrost or rocky soils, including ramming a pit in a layer of seasonal thawing and freezing with the formation of a compacted zone in thawed soils around the pit and under it, and building a foundation block in a rammed pit, moreover, the broadened base of the foundation block is created by ramming into the lower part of the rammed pit with separate portions of non-porous hard soil material. Initially, tamping is carried out by a rammer, which has needle-shaped elements with a length slightly less than the depth of the thawed layer, then non-porous hard soil material is poured into the voids formed (RF patent No. published on October 27, 2012).

The disadvantage of the known methods is the high labor costs and insufficiently high bearing capacity of the structures and coatings under construction, in particular airfield.

The closest in terms of essential features to the claimed method is a method for increasing the bearing capacity of structures in conditions of saline permafrost soils, including excavation, laying on the bottom of the base of the coating, backfilling the soil into a pit with layer-by-layer compaction, device in the near-surface zone of the soil over the pit of the slab, installation of cooling ventilation ducts; installation of reinforcing meshes, tiered installation of cooling ventilation ducts (RF patent No. 2034955 for the invention "METHOD FOR DEVELOPING THE BASE IN PERMAFROST SOILS", IPC E02D 3/12, publ. 1995.05.10). The known method is characterized by high costs, complexity of work and insufficient bearing capacity of structures, including plane structures of airfields in the conditions of saline permafrost soils of the Arctic coast.

The task to be solved by the claimed technical solution is the development of a highly efficient method for increasing the bearing capacity of airfield pavements in saline permafrost soils.

The technical results of the proposed invention are: an increase in the freezing temperature of the soil base, the elimination of water overruns and secondary contamination of the underlying soils with saline.

These technical results are achieved by the fact that the method of increasing the bearing capacity of airfield pavements in the conditions of saline permafrost soils includes excavation, laying the base of the pavement on the bottom, backfilling the soil. The excavation is carried out on saline soil thawed in summer to the thickness of the design depth. The bottom of the base freed from the soil is covered with a waterproof membrane with a design slope and the possibility of flow into the water intake. After that, the layout of the dumped soil is carried out; filtering the dumped soil by sprinkling; collection of dissolved ground salts with subsequent desalination by forcing through a filter according to the reverse osmosis principle; separation into a strong saline solution and a desalted part; the direction of the desalinated part to the sprinkling system, and the strong saline solution - for disposal.

Preferably, the end of the desalination process is controlled by a solution density sensor at the inlet to the desalination system.

A comparative analysis of the claimed invention with the prototype showed that in all cases of execution, it differs from the known, closest technical solution:

- excavation of saline soil thawed in summer to the thickness of the design depth;

- covering the bottom of the base freed from soil with a waterproof membrane with a design slope and the possibility of flow into the water intake;

- implementation of the layout of the dumped soil;

- filtration of the poured soil by sprinkling;

- collection of dissolved ground salts;

- desalination of the collected solution of ground salts by forcing through the filter according to the principle of reverse osmosis;

- separation of a solution of ground salts into a strong saline solution and a desalinated part;

- direction of the desalinated part to the sprinkling system;

- sending a strong saline solution for disposal.

In the preferred embodiment, the invention differs from the known, closest technical solution by controlling the end of the desalination process with a solution density sensor at the inlet to the desalination system.

The excavation of thawed saline soil in the summer period reduces the cost of work due to the absence of the need for expenses for thawing the soil. Covering the bottom of the base freed from soil with a waterproof membrane with a design slope and the possibility of flow into the water intake; filtering the dumped soil by sprinkling; collection of dissolved ground salts with subsequent desalination by forcing through a filter according to the principle of reverse osmosis, separation into a strong saline solution and a desalinated part; the direction of the desalted part into the sprinkling system ensures a high degree of desalination, reduces the consumption of water used for sprinkling, and prevents its overspending. The direction of a strong salt solution for disposal eliminates the secondary contamination of the underlying soil with saline. Soil desalination improves the physical and mechanical properties of the soil of a natural base, since it provides an increase in the freezing temperature of the soil base, which in turn contributes to an increase in the bearing capacity of the soil on permafrost soils (PMG).

The way to increase the bearing capacity of airfield pavements in the conditions of saline permafrost soils of permafrost desalination consists in the fact that the saline soil thawed in the summer period is removed to the thickness of the design depth. Further, the substrate - the bottom of the “trough”, the foundation freed from the soil, is covered with a design slope, which ensures the flow of water into a special catchment tray, with a waterproof membrane. The excavated soil is then backfilled. After the leveling of the dumped soil, a sprinkling system (artificial irrigation) is mounted on it. During subsequent sprinkling, water filtering through the soil mass dissolves soil salts and flows down the waterproofing membrane into the tray. Through the tray, the brine enters the desalination system, in which the brine is forced through the filter according to the reverse osmosis principle and it is separated into a strong brine and the desalted part. The desalinated water flow is sent back to the sprinkler system. Strong salt composition is disposed of in a separate container. The end of the desalination process is controlled by a solution density sensor at the inlet to the desalination system.

Claims (2)

1. A method for increasing the bearing capacity of airfield pavements in the conditions of saline permafrost soils, including excavation, laying the pavement base on the bottom, backfilling the soil, characterized in that the excavation is carried out by saline soil thawed in summer to the thickness of the design depth, the bottom of the base freed from soil cover with a waterproof membrane with a design slope and the possibility of flow into the water intake, after which the dumped soil is leveled, the dumped soil is filtered by sprinkling, the dissolved soil salts are collected, followed by desalination by forcing through the filter according to the reverse osmosis principle, separation into a strong saline solution and the desalinated part, the direction of the desalinated part to the sprinkling system, and the strong saline solution - for disposal. 2. The method according to claim 1, characterized in that the end of the desalination process is controlled by a solution density sensor at the inlet to the desalination system.