RU2714406C1 - Method of vacuum sealing of base of building structure - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction and is intended for soil compaction during erection of buildings and structures. Method of vacuum sealing of base of building structure includes arrangement of trench in place of installation of support of building structure by excavation of soil; placement in cavity of trench of impermeable geomembrane with formation of sealed container; filling vessel with loose earth; creation of negative pressure in mass of non-coherent soil inside sealed container by its connection to pump station.

EFFECT: technical result consists in provision of building structures having construction bearing capacity required for foundation under construction, erected on non-cohesive soils having finely dispersed structure, including on ice and snow-firn bedded soils, improvement of efficiency of vacuum seal technology of base of building structure with respect to non-coherent soils, reduction of power and labor costs for preparation of the foundation for the construction structure by vacuum sealing.

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Description

The invention relates to the field of construction and is intended for compaction of soils during the construction of buildings and structures.

The invention is used to prepare a foundation having the necessary bearing capacity for the foundation of building structures erected on incoherent soils having a finely dispersed structure, including ice and snow-firn soils.

Definition of terms.

SOIL: Any rocks, soils, sediments and technogenic formations considered as multicomponent dynamic systems and as part of the geological environment and studied in connection with the engineering and human activities (GOST 25100-2011: Soils. Classification, clause 3.8)

DISPERSED SOIL: Soil consisting of a set of solid particles, grains, debris and other elements between which there are physical, physico-chemical or mechanical structural bonds (GOST 25100-2011: Soils. Classification, paragraph 3.9).

SOIL STRUCTURE: The spatial organization, determined by the size, shape, nature of the surface, the quantitative ratio of the structural elements of the soil and the nature of the relationship between them (GOST 25100-2011: Soils. Classification, clause 3.39)

ICE GROUND: Soil containing in its composition more than 90% of ice (GOST 25100-2011: Soils. Classification, paragraph 3.16)

UNCONNECTED SOIL: Dispersed soil with mechanical structural bonds and flowability in the dry state (GOST 25100-2011: Soils. Classification, paragraph 3.23.)

FIRN - ice rock with a density of 450 to 800 kg / m³, consisting of interconnected ice grains. It is a transitional stage between snow and glacial ice, formed in mountainous regions located above the snow line, and in the polar countries where atm. Precipitation falls mainly in the form of snow and does not have time to melt over the summer. Snow turns into firn under the influence of solar radiation, thaws, as a result of recrystallization and sublimation of water vapor. Distinguish firn infiltration, arising from repeated freezing of water in the snow, accompanied by sedimentation and recrystallization; reels, formed as a result of rounding, collective recrystallization and subsidence of snow; recrystallization, formed as a result of snow metamorphism without the participation of liquid water. The first is commonly found in firn bass. mountain glaciers (to a depth of 20-30 m), the second and third in the upper horizons of the ice sheets (in Antarctica, the firn thickness reaches 100 m). The largest grains emit fine-grained (less than 1 mm), medium-grained (1-3 mm) and coarse-grained (more than 3 mm) firn (Geography. Modern Illustrated Encyclopedia. - M.: Rosmen. Edited by Prof. A. P. Gorkin. 2006 )

SNOW — a type of precipitation consisting of frozen water vapor forming ice crystals (Scientific and Technical Encyclopedic Dictionary https://dic.academic.ru/dic.)

ICE (a. Ice; n. Eis; f. Glace; and. Hielo) - solid water. Ice is found in nature in the form of ice itself (mainland, floating, underground, etc.), as well as in the form of snow, hoarfrost, etc. ICE is a low-temperature monomineral rock composed of the lightest mineral. Under Earth's conditions, it is in a state close to its phase transition into water (Mountain Encyclopedia. Http://mining-enc.ru/l/led/).

There are various methods of strengthening the foundation of buildings under construction by compaction of the soil.

A known method of dynamic soil compaction, including the use of large loads, usually from 10 to 100 tons, falling from a height of mainly 10-40 meters. The location of impact points on the ground and other processing parameters (energy, phase, periods of no exposure) depends on the characteristics of the soil being cultivated and, possibly, on the measurement results obtained in the test area. These parameters are determined in advance based on the required soil characteristics (RF patent No. 2344 228 for the invention “METHOD AND DEVICE FOR DYNAMIC SOIL SEALING”, IPC E02D 3/02, published on 02.20.2008). The known method is characterized by laboriousness and requires heavy equipment. Using the known method is difficult for compaction of frozen soils and ice soils, including snow-firn in remote and inaccessible places.

A known method of compaction of the soil, including immersion in the ground of a vibrating device, holding the specified device at a given depth and periodically, as it rises, re-lowering it during continuous operation of the vibrator. (V.M. Zubkov et al. “Method for deep vibration compaction of sandy bases.” Foundations, foundations and soil mechanics. No. 2, 1983, M .: Stroyizdat, RF patent No. 2236503 for the invention “METHOD FOR SEALING SANDY OR SOIL LAYING IN WINTER TIME ", IPC E02D 3/02, E02D 3/046, publ. 09/20/2004). The disadvantages of this method is the uneven density of the soil in depth after compaction. The application of this method is also difficult for ice soils, including snow-firn.

A known method of increasing the strength of the soil by compaction, including immersing injectors in the soil, supplying fluid cement material under pressure through the injector, measuring and registering the solution pressure, forming a zone of hardened soil and subsequent immersion of the injector with the formation of adjacent zones of hardened soil; during the immersion of the injector, the strength of the soil is determined and, when the strength is less than acceptable, flowing cement material is supplied under pressure exceeding the acceptable strength of the soil (USSR patent No. 1114348, MKP E02D3 / 12, publ. 15.09.84). The known method is characterized by complexity and high labor and energy costs and is practically not applicable for snow-firn soils.

Common disadvantages inherent in the above methods of compaction of the soil are: the long duration of compaction of the soil, the need for an inert material unloading embankment and the risk of loss of stability of the base in the process of pre-compaction. In addition, the use of known methods has limited capabilities in high mountain or high latitude regions with stably low air temperatures at which snow does not reach or close to melting temperature.

Known closest to the claimed invention in terms of essential features and selected as a prototype is a technology for vacuum compaction of the base of a building structure (Menard Vacuum TM), developed by Menard (France). The technology of vacuum compaction of the foundation of a building structure (soil evacuation) consists of the following steps:

- device of vertical and horizontal drains;

- placement of an impermeable geomembrane over the vacuum section;

- tight fastening of the membrane in the perimeter trenches. For the same purpose, a soil-bentonite wall can be made if excavation is required to a considerable depth;

- creation of negative pressure in the soil mass under a sealed membrane by connecting to a pumping station ;.

- monitoring the compaction of the base.

Vacuum compaction technology can significantly reduce or eliminate the need for a loading embankment and ensure good controllability of the consolidation process is observed, and, accordingly, more accurate predictability of sediment values. The main advantages of vacuum compaction technology are: reduction in the period of foundation consolidation (compared to classical vertical drainage); a significant reduction in the need for inert material of the unloading embankment; elimination of the risk of loss of stability of the foundation in the process of pre-construction consolidation. Vacuum compaction provides acceleration and triggering of filtration consolidation (primary filtration sediment) before the start of operation of structures, stability of the base and limitation of secondary consolidation (creep of the skeleton) to acceptable values. (N.V. Romanov, J. Rasine, “A Survey of Modern Methods for Strengthening and Stabilizing Weak Bases,” Vestnik MGSU Volume 13 Issue 4 (115) pp. 499–513); http://www.menard-russia.ru/technology/vacuum-seal/). The known method can be used for finely dispersed soils, including snow-firn soils in regions with stably low air temperatures. However, the known technology requires significant energy and labor costs associated with the installation of vertical and horizontal drains; perimeter trenches and ensuring tight tightening of the geomembrane along the perimeter of the evacuated area. The most significant energy costs are associated with the absence of a lower airtight geomembrane.

The task to which the claimed technical solution is directed is to increase the efficiency of the vacuum compaction technology of the foundation of a building structure in relation to incoherent soils, in particular, fine and snow-firn.

 The technical result achieved by solving the task is to reduce the energy and labor costs for preparing the foundation for the foundation of a building structure using the vacuum compaction method.

The specified technical result is achieved by the fact that the method of vacuum compaction of the base of the building structure includes: equipping the pit at the installation site of the support of the building structure by excavation; placement of an impermeable geomembrane in the cavity of the pit with the formation of a sealed container; filling the tank with incoherent soil; creation of negative pressure in the mass of incoherent soil inside the sealed container by connecting it to the pumping station.

It is preferable that the pit be equipped with an area 10–20% larger than the area of the pylon of the building structure.

Preferably, a vacuum pump is used as the pumping station.

Preferably, the compaction process monitors soil compaction parameters.

It is preferable that finely dispersed soil or ice ground or snow-firn soil be used as an incoherent soil.

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

- arrangement of the pit at the installation site of the support of the building structure by excavation;

- placement of an impermeable geomembrane in the cavity of the pit with the formation of a sealed container;

- filling the tank with incoherent soil;

- connecting a sealed container to the pumping station.

In preferred cases, the invention differs from the well-known, closest technical solution:

- arrangement of a pit with an area 10 - 20% higher than the area of the pylon of a building structure;

- using a vacuum pump as a pumping station;

- using finely dispersed soil, or ice ground, or snow-firn soil as incoherent soil.

Arrangement of the pit in the place of installation of the support of the building structure by excavation; placement of an impermeable geomembrane in the cavity of the pit with the formation of a sealed container; filling the tank with incoherent soil; the creation of negative pressure in an array of incoherent soil inside a sealed container by connecting it to a pumping station allows you to compact incoherent, including fine and snow-firn soil to the required size. At the same time, there is no need to place geomembrane over large areas, install drains and perimeter trenches, which significantly reduces material and labor costs, allowing the use of the inventive method for the construction of buildings and structures in remote high-altitude regions and areas with low temperatures.

The method of vacuum compaction of the base of a building structure includes arranging a foundation pit at the installation site of a building structure support by excavating incoherent soil (finely dispersed, snow-firn, etc.). The area of the excavated foundation pit should be 10-20% greater than the area of the pylon of the building structure. An impermeable geomembrane, for example, geotextile fabric, is placed in the cavity of the excavation, with the formation of a sealed container, for example, in the form of a bag of geotextile fabric. The tank is filled with incoherent soil, a pipe with a valve sealed with clamps is mounted on the tank. Then a negative pressure is created in the mass of incoherent soil inside the sealed tank by connecting the tank to the pumping station, which can be used as a vacuum pump. A hose may be used as a means of connecting a vacuum pump to a sealed container.

The invention works as follows.

When you connect a sealed container with incoherent soil to the pumping station, a negative pressure is created equivalent to a load of 70 ... 80 kPa, which corresponds to the pressure from an embankment with a height of 3 ... 4 m. Between the granular structural soil treated inside the sealed container, moisture is removed using a vacuum pump and air, which leads to compaction of the soil. The number of connection points of the vacuum pump to the sealed tank is determined by the dimensions of the sealed tank. During the evacuation process, monitoring of soil compaction parameters is carried out, including using vacuum gauges, tensometers, inclinometers, surface and deep sedimentary grades and other measuring and control tools, providing control of the compaction process.

The invention can be used in high-altitude or high-latitude regions with increased solar radiation, high reflectivity of the surrounding snow cover and stably low air temperatures at which the snow does not reach or close to the melting temperature.

Claims (5)

1. A method of vacuum compaction of the base of a building structure, including: arranging a foundation pit at the installation site of a building structure support by excavating; placement of an impermeable geomembrane in the cavity of the pit with the formation of a sealed container; filling the tank with incoherent soil; creation of negative pressure in the mass of incoherent soil inside the sealed container by connecting it to the pumping station. 2. The method of vacuum sealing according to claim 1, characterized in that the pit is equipped with an area 10-20% greater than the area of the support of the building structure. 3. The method of vacuum sealing according to claim 1, characterized in that a vacuum pump is used as a pumping station. 4. The vacuum compaction method according to claim 1, characterized in that the soil compaction parameters are monitored. 5. The vacuum compaction method according to claim 1, characterized in that finely dispersed soil, or ice ground, or snow-firn soil, is used as an incoherent soil.