RU2496943C1 - Combined frame-raft foundation for low height construction on soft soil - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: combined frame-raft foundation for low height construction on soft soil includes a girder reinforced concrete foundation under all bearing walls of the building from factory-built slabs joined to each other and combined into a system of cross bands laid onto a levelled base on the hydraulic insulation layer in the form of a film under the entire building, each of the slabs is made with a section of closed shape with an insulant arranged inside, and the space between the slabs of the frame is filled with earth mass and a layer of the insulant on top, forming the bearing structure of the first floor slab. Slabs of the girder reinforced concrete foundation under all bearing walls are made in the form of a shell of trapezoid rigid shape of section of spatial and closed type, formed from upper and lower slabs of the spatial type, connected to each other. The lower slab is arranged as wider than the upper one and is equipped with boards along the length. The upper slab is made with inclined ribs. In the boards and in the lower part of inclined ribs there are slots, where bushing keys are embedded, with the help of which the upper and lower slabs are connected to each other, and in the places of joints the slabs are equipped with reinforcement protrusions for joining with reinforcement of adjacent elements with node embedding.

EFFECT: increased efficiency of a frame raft foundation due to increased rigidity, improved thermal protection properties, reduced material intensity and labour costs in manufacturing, provision of operation reliability.

2 cl, 3 dwg

Description

The invention relates to the construction of foundations of low-rise buildings on soft soils, which are characterized, on the one hand, by the low weight of the low-rise building, and on the other hand, by the weak bearing properties of the base (less than 1 kg / m ² ).

In traditional solutions, according to the construction rules SP-50-101-2004 of clause 8.3, it is indicated that “in difficult engineering and geological conditions (specific soils, high groundwater levels, etc.), the types of foundations specified in clause 10 can be used. 8.2 b and c ”, i.e. "Foundations on locally sealed bases (in rammed or stamped pits, driven blocks, etc.), short piles." Clause 8.9 of the same joint venture states: “prefabricated monolithic and monolithic foundations of all walls must be rigidly interconnected and combined into a system of cross tapes”. Specific soils also include bulk, waterlogged, peat, etc.

Known columnar-ribbon foundation, including columns laid to the depth of freezing, and a ribbon grillage connecting the upper ends of the posts in a single structure. A distinctive feature of such a foundation is the presence of an air gap of 10 ... 15 cm under the tape. Outside, the gap is closed by a blind area not connected to the grillage tape. When installing the foundation on heaving soils, the air gap compensates for the expansion of the heaving soil, and on non-heaving soils it provides a “soft” support of the house on the base. (Yakovlev R.N. Universal foundation. TISE technology, 2006).

Known shallow foundation laid on a locally compacted base, made in the form of a reinforced concrete or concrete element placed on a cushion of non-porous material - sand of large and medium size, small gravel, etc. This material is filled (with a layer-by-layer seal, as with a pillow device) and the sinuses of the trench. The foundation elements are interconnected by welding or twisting through the outlets of reinforcement, filled with concrete and form a prefabricated-monolithic horizontal frame redistributing uneven soil deformations (Bodanov Yu.F. Foundation from A to Y. Moscow, 2005, Fig. 39, p. 75 )

Known shallow foundation, which is a concrete or reinforced concrete element, usually laid on a pillow or bed of non-porous material, which reduce the movement of the foundation both during freezing and thawing. As the material of the filling for the device of the cushion, sand of gravel, coarse or medium size, fine gravel, boiler slag, and non-porous soils can be used (BCH 29-85. Design of shallow foundations of low-rise rural buildings on heaving soils. Moscow 1985, paragraph 3.2 -3.4, fig. 2).

The disadvantages of the above known analogues of the foundations are: insufficient reliability for construction on weak, subsidence, heaving soils and in seismic zones due to sensitivity to uneven soil deformations; significant heat loss through the foundation; increased material consumption and high labor costs associated with hardening the foundation and the use of specialized equipment.

A well-known foundation for low-rise construction on soft soils, adopted as a prototype, includes a strip reinforced concrete foundation under all the bearing walls of the building, interconnected and combined into a system of cross tapes, while the foundation for low-rise construction in monolithic or precast-monolithic design is made in a plate-frame foundation under all the bearing walls of the building, laid on a leveled base without reinforcing it by special means on a waterproofing layer in the form of a film However, the entire building, including the blind area, the cross-section of the elements of the slab-frame foundation has a closed box-like shape, consisting of upper and lower reinforced concrete slabs, combined with extreme lateral and middle thickened ribs, between which a plate insulation is laid, the protruding part of the slab-frame foundation beyond the plane the outer walls acts as a basement and is joined with the blind areas laid on the insulated base in the case of heaving soils, the space between the frame elements is laid by the earthen mass and a layer of insulation spruce on top forming the supporting structure of the floor of the first floor, and in the monolithic version, the elements of the slab-frame foundation are made in the factory version as prefabricated with releases of reinforcement for joining neighboring elements with reinforcement with patent assembly (patent No. 105637 U1, priority date 01/11/2011 , publication date 06/20/2011, authors Abovsky N.P. et al., RU, prototype).

The disadvantages of the prototype are: insufficient rigidity of the frame to ensure low sensitivity to uneven deformation of the soil due to the rectangular cross section of the element of the slab-frame foundation; low heat-shielding properties due to the presence of a partition in the said section of the element, made in the form of a thickened rib; increased consumption of concrete for the implementation of a rectangular element with a thickened middle rib with increasing height to ensure sufficient rigidity.

The objective of the invention is to increase the efficiency of the slab-frame foundation for low-rise construction on soft soils by increasing rigidity, improving heat-shielding properties, reducing the consumption of concrete and reinforced concrete, as well as labor costs in manufacturing, and ensuring reliable operation.

To solve this problem, in a slab-frame foundation for low-rise construction on soft soils, including a strip reinforced concrete foundation under all the bearing walls of the building from factory-made plates, interconnected and combined into a system of cross tapes laid on a leveled base on a waterproofing layer in the form of a film under the entire building, each of the plates is made with a closed-shape cross-section with a heater located inside, and the space between the frame plates is laid by the ground mass and the insulation layer casting on top, forming the supporting structure of the floor of the first floor, according to the invention, the slabs of the strip reinforced concrete foundation under all the bearing walls are made in the form of a rigid trapezoidal shell of a cross-section of a spatial and closed type, formed from the upper and lower plates of the spatial type, interconnected, while the lower the plate is wider than the top and provided with sides along the length, and the top plate is made with inclined ribs, and grooves are made in the sides and at the bottom of the inclined ribs, ryh hardwired key by which the upper and lower plates joined together, and in the ground slab joints are provided with valves releases for docking with the armature assembly with adjacent elements embedment.

According to the invention, the space inside the shell of a trapezoidal rigid form is filled with any type of insulation.

The effectiveness of the inventive slab-frame foundation for low-rise construction on soft soils is based on all the advantages inherent in the prototype compared to well-known analogues, and the increase in its effectiveness is due to a change in the cross-sectional shape of the foundation plates in the form of a rigid and trapezoidal shell of a spatial and closed type. Due to the change in the cross-sectional shape of the slab, the issue of material consumption was resolved, since as a result of the removal of inefficient zones, the cross-sectional area was reduced, and, consequently, the material consumption itself. The proposed cross-sectional shape is also more advantageous in terms of heat-shielding functions and constructive transfer of effort.

The implementation of the slabs of the claimed slab-frame foundation for low-rise construction on soft soils in the form of a hard-shaped trapezoidal shell of a section of a spatial and closed type, formed from the upper and lower plates, bonded to each other by concreting the keyways of the keys and the space between the grooves, is a simpler convenient design in the manufacture. This foundation design allows the use of plate insulation and other types of insulation that do not have strength properties. Thus, this design helps to increase the efficiency of the slab-frame foundation for low-rise construction on soft soils by reducing labor costs when building the foundation on soft and heaving soils, increasing rigidity, reliable operation, improving heat-shielding properties and reducing the consumption of concrete and reinforced concrete.

The invention is illustrated by drawings, where figure 1 shows a fragment of a section of the foundation; figure 2 - Assembly of the foundation plate, figure 3 is a General view of the foundation, a perspective view.

The slab-frame foundation for low-rise construction on soft soils is made under all the load-bearing walls of building 1 and consists of plates made in the form of a rigid trapezoidal shell of a spatial section and a closed type, formed from the top plate 2 and the bottom plate 3 of a spatial type, interconnected . In this case, the lower plate 3 is made wider than the upper plate 2 and provided with the lengths of the sides 4. The upper plate 2 is made with inclined ribs 5. In the sides 4 and in the lower part of the inclined ribs 5 grooves 6 are made in which the keys 7 are monochromatic, with which the upper 2 and lower 3 plates are interconnected. Moreover, the space between the upper 2 and lower 3 plates is filled with insulation 8 of any type. At the joints of the plates are equipped with releases of reinforcement 9 for docking with the reinforcement of adjacent elements with monolithic site.

Slab-frame foundation for low-rise construction on soft soils, laid on a leveled base 10 on a waterproofing layer 11 in the form of a film for the entire building. The space between the foundation slabs is laid with an earthen mass 12 and a layer of insulation 13 on top, forming the supporting structure of the floor 14 of the first floor.

All elements of the tape reinforced concrete foundation are made in the factory version with the installation of mounting loops 15 in the bottom plate 3.

The construction of the slab-frame foundation for low-rise construction on soft soils is carried out as follows.

Several layers of waterproofing film 11 with a low coefficient of friction for the entire area of a low-rise building are laid on a leveled base 10. On the waterproofing film 11 under the supporting walls of a low-rise building, the elements of the lower plate 3 of a spatial type are laid, for example, a plate heater 8 is installed on them, then the upper plate 2 is laid on the lower plate 3 and they are joined by monoling the keys 7 in the grooves 6 made in on the sides 4 and in the lower part of the inclined ribs 5. At the joints of the plates, the outlets of the reinforcement 9 of the adjacent elements are connected and the nodes are monolithic.

The space between the foundation plates from the inside is laid with earth mass 12 and a layer of insulation 13 on top, forming the supporting structure of the floor 14 of the first floor.

If necessary, for household and operational needs in the interval between the frame elements, an underground room (technical cavity) can be arranged, which has independent structural solutions from the slab-frame foundation. This is very important for soft soils, since the room is actually in favorable insulated conditions and is used for household needs.

Technical and economic advantage of the slab-frame foundation for low-rise construction on soft soils

The use of the foundation for low-rise construction on soft soils allows you to build in difficult soil conditions (on very weak, subsidence, heaving soils, etc.) without preliminary hardening of the soil, using the natural properties of soils, combining structural and functional properties and providing strength, rigidity, allows you to use any insulation. Due to the spatial rational shaping, bending stiffness is increased, due to this the design becomes insensitive to uneven deformations of the base, thereby increasing the reliability of operation without preliminary significant excavation and cushioning.

This design helps to reduce labor costs and reduce the cost of construction by reducing the volume of earthworks, which are minimized, since the device does not require an earthen pillow and the use of specialized equipment.

This design helps to improve heat-shielding properties by reducing heat loss through the floor and foundation by 10-15%. The insulation is protected from moisture and destruction, i.e. its durability is provided, and, therefore, reliable protection of the soil from frost heaving. In addition, the insulated soil mass forms the supporting structure of the floor foundation.

A sliding layer in the form of several layers of film under the foundation system performs waterproofing functions, creates the possibility of slipping a powerful seismic wave under the foundation.

Thus, this construction of the foundation of plates in the form of a shell of a trapezoidal rigid shape of a section of a spatial and closed type for low-rise construction on soft soils is effective and has reliability, durability, and cost-effectiveness.

Claims (2)

1. A slab-frame foundation for low-rise construction on soft soils, including a strip reinforced concrete foundation under all the bearing walls of the building from prefabricated plates interconnected and combined into a system of cross tapes laid on a leveled base on a waterproofing layer in the form of a film under the entire building , each of the plates is made with a closed-shape cross-section with a heater located inside, and the space between the frame plates is laid by the earthen mass and a layer of insulation on top, forming a carrier the first floor floor structure, characterized in that the slabs of the strip reinforced concrete foundation under all the bearing walls are made in the form of a rigid trapezoidal shell of the spatial section and closed type, formed from the upper and lower spatial plates connected to each other, while the lower plate is made wider the upper and is provided with the lengths of the sides, and the upper plate is made with inclined ribs, and in the sides and at the bottom of the inclined ribs grooves are made in which the keys are monolithic, with the help of which upper and lower plates joined together, and in the ground slab joints are provided with valves releases for docking with the armature assembly with adjacent elements embedment. 2. The plate-frame foundation according to claim 1, characterized in that the space inside the shell of a trapezoidal rigid form is filled with any type of insulation.

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