SU1728391A1 - Arrangement for protecting foundation against effects of underlying mine workings - Google Patents

Abstract

This invention relates to the protection of foundations against the influence of mine workings. The purpose of the invention is to increase the effectiveness of protection of the foundation in winter. The device to protect the foundation from the effects of mining is a rigid structure 4, which is placed in trench 2. The trench is located close to foundation 1. In the supporting structure, the upper part of the face facing away from the basement is made obliquely angled a arcsinfH y / (2 Rh ) where a is the bevel angle of a rigid structure facing away from the foundation, H is the depth of the trench, у is the bulk density of the soil, R is the calculated resistance of the soil to compression, h is the depth of soil freezing. The top of the bevel is located below the ground freezing zone. The rigid structure is placed in a trench with a gap relative to the foundation. After installing the rigid structure, the trench is filled with dry, pliable material. 1 il. sl C

Description

The invention relates to the construction and relates to the construction of foundations in the undermined territories using special devices to protect them from the harmful effects of mining operations associated with the compression of the base in the horizontal plane.

The purpose of the invention is to increase the effectiveness of protection in winter.

The drawing shows the described device, a cross-section.

The foundation protection device 1 is a rigid structure 4 housed in trench 2 with waterproofing 3. Trench 2 opens against the outer edge of the foundation.

The width of the trench is chosen so as to ensure that a rigid structure 4 is erected therein. In addition, the width of the trench can be determined by a excavation mechanism designed to dig the trench. The rigid structure 4 is arranged with a beveled outer face in its upper part, for example of a triangular shape. The top of the bevel angle of the structure is directed in the opposite direction from the foundation, arranged below the freezing zone of the soil. It is desirable to place the top of the angle below the maximum depth of frost penetration by 0.2-0.5 m.

The bevel angle of the upper part of the face of a rigid structure facing away from the foundation is equal to

and arcsin (n yy),

where H is the depth of the trench;

y is the bulk weight of the soil;

R is the calculated compressive strength of the soil;

h - depth of soil freezing.

Trench 2 is filled with dry, well compressible material, such as boiler slag or dry river sand. On the top of the trench, a blind area is restored, which simultaneously serves as a waterproofing of the trench.

The described solution is based on the results of a study of the relationship of the stress-strain state of structures and the deformative state of the base during the underworking. It has been established that the surrounding soil has greater deformations than the foundation. This is due to the relative movement of the foundation and base.

Relative movement of soil and foundation in a vertical plane (time 5

ten

15

20 25 0

five

P

to

Q f

knowledge) depends on the magnitude of the load on the base, which can be represented as

a- |.

where is the base load;

P is the weight of the structure;

S b - the footing area of the foundations;

b - the width of the base of the foundations:

I - the length of the foundations.

When the surface layer of soil freezes and freezes over to the outer edges of the foundations, the area of the building’s structure increases.

S l (b + a)

where a is the broadening of the base of the foundations due to the freezing of the hardened soil layer to it.

The load on the base decreases, the relative movement of the foundations and the base stops and the structures are distorted by the same amount as the base. During this period, in the winter time an increase in additional efforts was recorded by 4-6 times. After thawing and separation of the priming base from the basement in the springtime, the additional forces are sharply reduced. However, in winter, the structures have time to get damaged.

With the passage of trench 2 directly near the foundation 1, the waterproofing of its cavity from moistening prevents the freezing of the near-surface layer to the foundation. In order to increase the reliability of the method in the case of a waterproofing impulse, the rigid structure is made with an inclined plane. In this case, when the subsurface layer slides on the inclined edge of the rigid structure, the pressure on the foundation is not fully transferred, since the load from the horizontally moving soil is divided into components by the inclined plane. Having taken the value of the horizontal component equal to the domestic pressure of the soil, which existed in it before fragments of the trench, we find the angle of inclination of the plane of the rigid structure

a arcsin (Hl2-j).

In the solution being described, waterproofing 3 prevents the freezing of the surface layer of the soil. Moreover, since

there is no wet soil directly near the outer face of the foundation, i.e., the face of the trench is aligned with the base of the basement, the foot of the base of the foundation does not wrinkle and when working, such a platform cuts more intensively, straightening the curvature of the deforming base. At the same time, the load on the lateral edge of the foundation 1 from the horizontal displacements of the soil is quenched with a compliant trench cavity 2.

In the event of a breakthrough of waterproofing 3 of the trench 2, in the local zone, the pliable backfill of the trench will become moistened, and in winter this place adjacent to the surface will freeze. The frozen near-surface layer of the soil during horizontal movement slides along the inclined face of the rigid structure 4 and the load on the lateral face of the foundation 1 does not exceed the domestic pressure of the soil, which was before the trench fragments.

The invention allows to reduce the harmful effects of mining in the winter, and also increases the reliability of the protective action of a rigid structure in the event of a failure of waterproofing at any point in the trench.

Claims (1)

Apparatus of the Invention A device for protecting a foundation from the effects of mine workings, including a rigid structure placed in a trench and at a distance from the outer edge of the foundation, and backfilling of a trench made of dry ductile material, so as to increase the effectiveness of protection in winter the time facing from the basement of the rigid structure is made oblique to its upper face, the top of the bevel is located below the zone of freezing of the soil, and the bevel angle is determined by the formula where a is the angle of the bevel of a rigid structure facing away from the foundation; H - trench depth; y is the bulk weight of the soil; R is the calculated compressive strength of the soil; h is the depth of soil freezing, with rigid structures placed in a trench adjacent to the outer face of the foundation.