RU2482243C1 - Stay-in-place form for erection of walls in soil - Google Patents

Abstract

FIELD: construction.SUBSTANCE: stay-in-place form for erection of walls in soil in a prepared trench. Comprises a pile used as a pipeline for supply of concrete mix into the pile base for fixation of the pile on the bottom of the trench, made of a pipe, along which symmetrically relative to the longitudinal axis of the pipe at the outer side there are two rectangular blocks of stay-in-place form fixed, made of elastically deformable material, for instance, thin-sheet steel, glass plastic, coal plastic. The height of form blocks is equal to height of or is slightly higher than the erected wall, the distance between vertical walls is determined by trench width, between each other the vertical walls are additionally connected by flexible joints, which are distributed with a certain pitch along the entire surface of the form, so that when a filler fills under certain pressure compartments of form joints, the size of the form in cross direction increases, and side walls of the form provide active pressure at trench walls, providing for resistance of not only the trench walls, but also soil base and foundation of existing buildings and structures located in close proximity. Along height forms are separated into several separate compartments with flexible partitions.EFFECT: increased reliability of both a structure and a soil base, in which a wall is erected, increased stability of foundations and bases of buildings and structures located in close proximity.

Description

The invention relates to the field of construction - to foundation engineering, can be used in the construction of walls in the ground, fencing pits, landslide barriers, etc. in conditions of weak, quicksand soils and dense existing buildings.

The construction of the foundation pit enclosure in the form of a “wall in the ground” of adjoining bored piles is known (Mangushev R.A., Osokin A.I. Geotechnics of St. Petersburg, Monograph. M: Publishing house ASV, 2010, p. 146, Fig. 6.2). This design is one or two rows located close to each other in terms of piles made with excavation.

The disadvantage of this design is the possibility of excessive sampling of soil from under the tip of the piles, which leads to excessive deformation of the surrounding buildings. Also disadvantages include the difficulty of controlling the continuity of the wall, that is, the presence of gaps between piles, which can lead to flooding of the pit.

There is also known the construction of a foundation pit enclosure in the form of a “wall in soil” made of contiguous cement and soil piles made using SMW technology (Soil Mixing Wall System - “soil mixing system”), designed to create enclosing structures and anti-filter curtains. Work is carried out by captures 1 meter wide. The working tool is made in the form of three simultaneously working short screws, which allows uniform mixing of the soil with the working solution to a depth of 14 meters (Mangushev R.A., Osokin A.I. Geotechnics of St. Petersburg, Monograph. M: Publishing House DIA, 2010, p. 146, Fig. 6.3).

The technology for constructing structures of this type of fencing is well-established, and all technological processes are mechanized, however, the use of structures of this type in the conditions of existing dense development causes undesirable deformation of the soil base of nearby buildings and structures. The disadvantage is that in thixotropic soils, the use of structures of this type is often impossible under the conditions of reliability and safety.

Known development of the company "Bauer" - CSM (Cutter Soil Mixing - "mechanical mixing of the soil") (Mangushev RA, Osokin AI Geotechnics of St. Petersburg, Monograph. M: Publishing house ASV, 2010, p. 147).

The CSM system is used to construct load-bearing and enclosing walls by mechanical mixing during drilling of soil trenches and cement slurries and form walls from the resulting mixture.

The disadvantage of the CSM system is the increased consumption of cement, since the granulometric composition of the concrete mixture - soil-cement slurry - cannot be optimized to create concrete of sufficient strength.

When installing walls in water-saturated quicksanding soil, collapse of the walls of the trench is possible and, accordingly, the movement of the soil base due to the dynamic effect of vibration of the equipment used.

There is also a method of constructing a trench "wall in the ground" (Mangushev R.A., Osokin A.I. Geotechnics of St. Petersburg, Monograph. M: Publishing house ASV, 2010, pp. 146-147, Fig. 6.4), which consists in the construction of enclosing and supporting walls of underground structures as anti-filtration curtains by extracting deep narrow trenches under the protection of clay mud, followed by the installation of reinforcing frames and laying concrete or precast concrete elements in the trench. When installing a monolithic concrete or reinforced concrete wall, the concrete mixture is placed in a trench by the method of a vertically moving pipe (VPT), the clay solution is squeezed out, cleaned of sludge and can be used on the following grips.

The disadvantages of this method of the device "wall in the ground" are as follows:

- “passive” effect of the “wall” on the soil base, which in some conditions can reduce the reliability of the structure as a whole;

- the presence of technological processes below the groundwater level, which degrades the quality of work performed and increases labor costs;

- the use of the walls of the trench as a formwork in soft soils significantly reduces the quality and, as a result, the reliability of the wall structure, in addition, deformations of the soil base due to the collapse of the walls of the trench become possible;

- reinforcing frames installed in the trench, reduce the quality of laying concrete mixture.

The closest in technical essence is the design of fixed formwork (TsNIIOMTP Gosstroy of the USSR, Guidelines for the design of formwork and the production of formwork. M: Stroyizdat, 1983, pp. 152-171).

The permanent formwork for the construction of "walls in the ground" according to this manual is recommended to be assembled from reinforced concrete reinforced cement, glass-cement plates, steel sheets or a woven steel mesh.

This type of formwork after concreting the main structure is not removed, but remains in its body and works with it, being an external reinforcing and waterproofing element of the structure.

However, the assembly of fixed formwork for the erection of "walls in the ground" in the trench is very difficult.

The design under consideration has the following disadvantages:

- the installation of volumetric blocks of the formwork of this type in the trench is not possible, because in a weak soil base the walls of the trench can be damaged;

- among other things, at the surface of the formwork slabs facing concrete (active surface), good adhesion to concrete must be ensured to ensure the joint work of concrete and formwork, which cannot be guaranteed when working in a trench;

- the orientation and fixation of the formwork elements is also difficult in cramped conditions.

Thus, the currently used structures and equipment do not fully provide reliability when installing walls in the ground under the conditions of the existing dense buildings and weak water-saturated soil bases.

In addition, the physico-mechanical properties of the materials from which the wall is being built should have certain and stable characteristics, which will ultimately determine the bearing capacity of the structure.

The main tasks in developing a new design of a device for erecting walls in the ground is to increase the reliability of both the structure itself and the soil foundation in which the wall is being erected, as well as the stability of foundations and foundations located in the immediate vicinity of buildings and structures.

These tasks are solved as follows.

The fixed formwork for erecting a wall in the ground in the prepared trench is formed by a pile used as a pipeline for supplying concrete mixture to the base of the pile to fix the pile on the bottom of the trench made of a pipe along which two rectangular blocks of fixed formwork are fixed symmetrically relative to the longitudinal axis of the pipe from the outside made of an elastically deformable material, for example sheet steel, fiberglass, carbon fiber. The height of the formwork blocks is equal to or slightly greater than the wall being erected. The distance between the vertical walls is determined by the width of the trench. Between themselves, the vertical walls are additionally connected by flexible bonds that are distributed with a certain pitch over the entire surface of the formwork, so that when the filler fills the compartments of the formwork joints under a certain pressure, the size of the formwork in the transverse direction increases and the side walls of the formwork exert active pressure on the walls of the trench, providing the stability of not only the walls of the trench, but also the stability of the soil base and foundations of existing buildings and structures located in close proximity awns. The height of the formwork is divided into several separate compartments by flexible partitions.

The fixed formwork for erecting walls in the ground is illustrated by the drawing, where Fig. 1 shows a general view of the device, which is formed by a pile 1 made of a pipe and two rectangular blocks of formwork 2, which are attached to the pile 1 and are located symmetrically relative to the longitudinal axis of the pile 1; formwork blocks 2 are provided with internal partitions 3, which divide the blocks 2 in height into a number of compartments; the side walls of the container 2 are interconnected by flexible ties 3, which are located at a certain distance from each other and which determine the maximum transverse size of the formwork, while the ties 3 can be adjusted along their length depending on the given width of the trench.

Figure 2 presents a vertical transverse section bB. Figure 3 shows a horizontal longitudinal section aa.

The internal space of the pile 1 is additionally equipped with a piping system, which is designed to supply concrete mixture under the edge of the pile 1 and into the internal compartments of the formwork 2.

The work of erecting a wall in the soil is carried out as follows: a trench of the required depth and width is cut in the soil base, the device is lowered into the trench, pile 1 is fixed in a pre-prepared well and, if necessary, is fixed with concrete mortar, which can be pumped under a certain pressure around the pile edge. After installing the device and fixing the piles 1, the formwork 2 is filled with concrete mortar so that the thickness of the filled containers 2 is not more than half the width of the trench, after which the trench is designed to install the next device, and the device is installed so that the formwork 2 of the next device is would be oriented and in contact with one plane with the plane of the formwork 2 of the previously installed device, after which the pile 1 will be fixed and concrete formwork 2 will be filled with as a result, in the area formed by the formwork 2 of the first device and the formwork 2, the trench is filled to its entire width, while it is possible to exert an active and controlled pressure on the walls of the trench, which can vary, if necessary, along the height of the wall.

By developing a trench along the grips and installing sequentially proposed devices, it is possible to erect a wall in the soil of large extent of sufficient bearing capacity.

Thus, when developing a new design, the tasks set have been solved and the proposed device will allow the construction of walls in the ground, fully providing a "gentle" construction technology, under the conditions of existing dense buildings in weak soft soils, since concrete with predetermined physical and mechanical properties in in combination with the walls of the fixed formwork and internal connections, it forms a reinforced concrete structure with external reinforcement, while when filling the formwork it is possible to carry out the active and necessary pouring on the walls of the trench for guaranteed stability of the soil base.

Claims (1)

Fixed formwork for erecting walls in the soil in a prepared trench, characterized in that it consists of a pile used as a pipeline for supplying concrete mixture to the base of the pile for fixing the pile on the bottom of the trench made of a pipe along which it is symmetrical with respect to the longitudinal axis of the pipe from the outside fixed two rectangular blocks of fixed formwork made of elastically deformable material, for example sheet steel, fiberglass, carbon fiber, while the height of the formwork blocks is equal to the height or several more than the wall being erected, the distance between the vertical walls is determined by the width of the trench, the vertical walls are additionally interconnected by flexible bonds, which are distributed with a certain step along the entire surface of the formwork, so that when the filler fills the compartments of the joints of the formwork under a certain pressure, the size of the formwork in the transverse direction increases and the side walls of the formwork exert active pressure on the walls of the trench, providing stability not only to the walls of the trench, but also to the stability of the ground the foundations and foundations of existing buildings and structures located in close proximity, the height of the formwork is divided into several separate compartments by flexible partitions.

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