RU187579U1 - PLATE FOUNDATION - Google Patents

Abstract

The utility model is aimed at increasing the bearing capacity of the slab foundation on the ground to a level that allows replacing pile foundations. The technical result is achieved by the fact that the slab foundation, including the slab and stiffeners located under the slab, has stiffeners made in the form of longitudinal and transverse ribs located around the perimeter and in the load zones with the formation of a single orthotropic structure, while the height of the stiffener is not less than 1.5 plate thickness. In addition, the choice of the cross section of the stiffener provides a reduction in material consumption while reducing sediment. 4 s.p. f-ly, 6 ill.

Description

The utility model relates to the field of construction, namely to slab foundations.

Known slab foundations with ribs above the slab and under the slab, located along the contour of the slab and under the bearing walls and columns of the building. The main task of the ribs, the height of which, as a rule, does not exceed the thickness of the slab, is to reduce the thickness of the slab and the consumption of concrete and reinforcement in the areas between the ribs. / 1, 2, 3 /

For the closest analogue of the utility model, slab foundations with ribs under the slab, which are widely used in housing construction according to patent RU 2276708, publ. 05/20/2006 / 4 /

The main disadvantages of such slab foundations with ribs is that due to the small deepening of the ribs, the material consumption of the slab decreases and its rigidity increases, but the bearing capacity of the slab foundation on the ground does not change and these ribs do not affect its settlement and the difference in sediment;

Therefore, for high-rise buildings and high-rise buildings that create significant loads on the soil base, where plate foundations do not pass according to permissible precipitation and bearing capacity on the soil, more expensive pile foundations are forcedly used.

- in addition, cracks for the ribs can be arranged only in clay soils in which the walls of the trenches do not crumble, which significantly limits the scope of such plate foundations with ribs.

The technical task of the utility model is to increase the bearing capacity of the slab foundation on the ground in different soil conditions and to reduce precipitation and the difference in precipitation to normalized values.

The technical problem is solved in such a way that in a slab foundation including a slab and stiffeners located under the slab in the longitudinal and transverse directions along the perimeter of the slab and in the load zones with the formation of a single orthotropic structure, according to the utility model, the stiffeners are made of different heights, while each transverse rib is made of the same height in the area between two longitudinal ribs intersecting it, and the longitudinal rib along the entire length is made of different heights, and the height of the stiffener is at least 1, 5 plate thicknesses to ensure optimal bearing capacity on the soil of the slab foundation. The stiffeners along the entire length can be made in the form of walls with a thickness of 0.4 m to 1.2 m and a height of at least 3.0 m. In addition, stiffeners can be made in a trapezoidal section with an angle of inclination of the sides from 25 to 45 degrees and base up. Either a step section, with a decrease in the depth section, in which the overlying step is wider than the underlying width of at least 0.4 m, or a combined section in which the upper part under the slab has a trapezoidal section and the lower part is a rectangular section with a width of at least 0, 4 m

The proposed design of the base plate with stiffeners differs from the known one in that the stiffeners are made of different heights, while each transverse rib is made of the same height in the area between two longitudinal ribs intersecting it, and the longitudinal rib along the entire length is made of a different height, and the height of the stiffener equal to at least 1.5 plate thickness to ensure optimal bearing capacity on the soil of the slab foundation. Such a minimum height of the ribs can already reduce the pressure on the ground and reduce the precipitation of the foundation. In the slab foundation, each transverse rib can be made in the form of ribs of the same height in the area between two longitudinal ribs intersecting it, and the longitudinal rib along the entire length is made in the form of ribs of variable height. The variable rib height, especially for high-rise and interlocked buildings, makes it possible to equalize the difference between the slabs of the slab by its area and thereby reduce the forces in the supporting structures of the building. In the slab foundation for high-rise buildings, stiffeners along the entire length can be made in the form of walls with a thickness of 0.4 m to 1.2 m and a height of at least 3.0 m using the "wall in soil" technology, which is applicable for any soil conditions and the width matches the capabilities of modern equipment. In a slab foundation in disconnected soils and with relatively small loads, the stiffeners have a trapezoidal cross section with an angle of inclination of the sides from 25 to 45 degrees and the base up. The optimal angle of inclination of the side in the specified range is selected according to the calculated angle of repose in order to protect the sides from shedding and collapse. In the slab foundation, in order to increase the bearing capacity over the soil, the stiffening rib is made in steps, with a decrease in the cross section in the depth of the bed, in which the overlying step is wider than the underlying step with a width of at least 0.4 m. With this solution and the width of the rib in sufficiently dense soils operation of the rib is provided both on the lateral surface and on the sole of the rib in two levels, and also corresponds to the running dimensions of excavator buckets. In a slab foundation with heterogeneous soils, the ribs can be made of a combined section, in which the upper part under the slab has a trapezoidal section, and the lower part is a rectangular section with a width of at least 0.4 m.

The proposed construction of the foundation differs from the known irregular mutual arrangement of stiffeners and their parameters, providing increased bearing capacity on the soil of the slab foundation. At the same time, the choice of the cross section of the stiffener from among the proposed ones provides a reduction in the material consumption of the slab foundation with a reduction in precipitation required by calculation.

In FIG. 1 shows a plan of a ribbed plate, FIG. 2 - 1-1 of FIG. one; FIG. 3-2-2 of FIG. one; FIG. 4 - trapezoidal section of the stiffener; FIG. 5 - step section of the stiffener; FIG. 6 is a combined section of a stiffener.

The utility model is implemented as follows.

The ribs of plate 1 in the form of walls 2 with a depth of at least 3.0 m (see Fig. 1, 2, 3) are concreted in trenches from 0.4 to 1.2 m wide arranged by excavation of the soil, including on the principle of wall in soil ”under the protection of a bentonite mortar or without it, depending on soil conditions.

The stiffeners of the trapezoidal section of relatively shallow depth up to 1.0-1.5 m (see Figs. 1, 4) are arranged mainly without fixing the walls of the trenches in disconnected or poorly connected soils.

The stiffening ribs of a stepped section, mainly with a depth of 1.5-3.0 m (see Figs. 1, 5), are developed in two stages with or without fastening the walls of the trenches depending on the ground conditions.

Stiffening ribs of a combined section, mainly for dissimilar soils with a depth of 1.5-2.0 m (see Figs. 1, 6), are also developed in two stages, first as a trapezoidal section and then as a section with vertical walls.

The proposed cross-sectional options provide a wide range of possibilities for stiffening ribs under the slab for various soil conditions with protecting the walls of the trenches from collapsing with bentonite mortar, fastening the walls and without it, with partial replacement of weak soils, if necessary with drainage or water reduction, etc.

The use of foundation slabs with developed deepened ribs under the slab allows not only to reduce the thickness of the slab between the ribs, but also to increase the bearing capacity of the foundation on the ground, to reduce precipitation and differences of sediments to normalized values, to simplify the production process, to reduce the lead time and cost of slab foundations compared to pile.

The cost of slab foundations with developed deepened ribs under the slab for buildings of medium and high floors, as well as high-rise buildings will be 1.2-1.5-2.0 times lower than piling foundations.

Information sources:

1. SP 45.13330.2012 “Earthworks, foundations and foundations” (Updated), approved on 02.27.2017

2. SP 22.13330.2011 "The Foundations of Buildings and Structures" was approved on 05.20.2011.

3. Designer guide "Foundations, foundations and underground structures" Moscow, Stroyizdat, 1985

4. Patent RU 2276708 class. E02D 27/01, publ. 05/20/2006. /prototype/.

Claims (5)

1. A slab foundation including a slab and stiffeners located under the slab in the longitudinal and transverse directions along the perimeter of the slab and in the load zones with the formation of a single orthotropic structure, characterized in that the stiffeners are made of different heights, with each transverse rib made of the same height the section between two longitudinal ribs intersecting it, and the longitudinal rib along the entire length is made of different heights to provide increased bearing capacity on the soil of the slab foundation, while the height of the ribs stiffness is not less than 1.5 of the slab thickness. 2. The slab foundation according to claim 1, characterized in that the stiffeners along the entire length are made in the form of walls with a thickness of 0.4 to 1.2 m and a height of more than 3.0 m. 3. The slab foundation according to claim 1, characterized in that the stiffeners have a trapezoidal cross section with an angle of inclination of the sides from 25 to 45 ° and the base up. 4. The slab foundation according to claim 1, characterized in that the stiffener is made of stepwise cross-section, with a decrease in cross-section along the depth, in which the overlying step is wider than the underlying width of at least 0.4 m. 5. The slab foundation according to claim 1, characterized in that the ribs have a combined section, in which the upper part under the slab has a trapezoidal section and the lower part is a rectangular section with a width of at least 0.4 m.

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