RU2413055C1 - Method to measure subsidence of foundations and device for its realisation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to measure subsidence of foundations consists of periodical measurement of position of mark arranged on foundation, relative to practically immovable benchmark. Position of mark at height is measured by sensor of linear displacements with converter of values of these displacements into electric signal relative to practically immovable benchmark, arranged under mark in soil below zone of soil freezing and zone of its deformation from foundation.

EFFECT: increased accuracy of measurement of building or structure foundation subsidence, provision of possibility of efficient monitoring online and for the whole term of operation, reduced material intensity of monitoring.

6 cl, 2 dwg

Description

The group of technical proposals (method and device) relates to geology, construction and can be used for monitoring in automatic mode and in natural conditions, measuring precipitation of the foundations of buildings and other building structures during the entire period of their operation.

The design of the foundations of buildings and structures is regulated by building codes and rules, for example TSN 50-302-96 of St. Petersburg (p.1.8) - [1], TSN 50-302-2004 of St. Petersburg (p.21) - [2], SNIP 2.02.01-83 * “Foundation of buildings and structures” - [3], SNIP 2.02.03-85 “Pile foundations” - [4], which prescribe the organization and conduct of observations on the development of precipitation of the foundations of buildings and facilities, as well as their full monitoring. Carrying out all these regulatory activities requires a considerable investment of time and money for constant measurements.

The well-known "Method for determining the stability of buildings and structures and a system for determining the stability of buildings and structures" according to the patent of the Russian Federation RU 2245531, IPC G01M 7/00, publ. 01/27/2005 - [5], including the excitation of oscillations of the test object at natural frequencies by exposure to a sequence of shock pulses of small amplitude, measuring the vibrations using sensors installed on the object, determining the dynamic characteristics of the object from the measured oscillation parameters and experimentally determining the values of the necessary parameters , including the precipitation of the building.

The well-known "Method for determining the technical condition of building structures and / or their parts and elements" according to the patent of the Russian Federation RU 2341623, IPC Е04В 1/00, G01M 7/00, publ. December 20, 2008 - [6], which includes the selection of measurement points, the installation of vibration sensors at selected points, registration of vibrations, and determination of the frequencies and amplitudes of natural vibrations of the object. The choice of measurement points is made depending on the volumetric configuration of the object. The oscillations are recorded at the coordinates X, Y, Z of the microdynamic background of the natural and technogenic origin of the object, in the conditions of which it is constantly located. To analyze changes in the dynamic characteristics of an object, the frequencies and amplitudes of the natural oscillations of the object are calculated preliminarily using mathematical modeling.

The well-known "Method of monitoring the technical condition of spans" according to the patent of the Russian Federation RU 2194978, IPC G01N 29/04, G01M 7/00, publ. December 20, 2002 - [7], which consists in acting on a building structure with a dynamic load with a wide range of frequencies, measuring mechanical vibration parameters with the help of accelerometers at control points of the building structure, obtaining a diagnostic parameter parameter and determining the position of the zone of abnormal mechanical stress using changing this parameter based on the selected criteria.

However, the application of the known methods [5], [6] and [7] allows only approximately to find the localization of the defect of the building structure, and not the specific values of the foundation settlement.

Currently, precipitation of the foundations of buildings and structures is carried out by carrying out geodetic work, namely leveling sedimentary grades and calculating precipitation, for example, according to the book: Ganshin V.N., Kosykov B.I. and Repalov I.M. Geodetic works during the reconstruction of industrial enterprises. M .: "Nedra", 1990, pp. 135-142 - [8].

The prototype of the claimed technical solution (of the present invention) is a method for measuring the foundation sediment, consisting of periodically measuring the position of the sedimentary mark located on the foundation with respect to a practically immovable benchmark, according to the book: V.T. Grozdov Technical inspection of building structures of buildings and structures. - SPb., 2008, pp. 43-47 - [9]. Fig. 1.12, p. 44 [9] shows the design of the benchmark arranged near the building, in the absence of a geodetic network reference frame near the building. The accuracy of the measurement of foundation sediments using geodetic works (leveling of sedimentary grades) is about 1 mm.

The disadvantage of this method is the need for constant visits by a team of specialists (at least two people) with equipment at the facility for geodetic measurements, which requires labor and financial costs. Especially this circumstance is significant with a large measurement frequency, which happens, for example, with uneven non-standard precipitation. In addition, the accuracy of leveling measurements (up to 1 mm) significantly depends on the weather during the measurements, the qualifications of specialists and their (subjective) state. This, in turn, can introduce significant errors in taking readings.

Thus, there is a significant need (task) to improve the accuracy of measuring the settlement of the foundation of a building or structure and the possibility of operational monitoring in real time and throughout the life of the unit. At the same time, it is important to reduce the cost of such monitoring.

The problem is solved in that in the method of measuring the settlement of the foundations, consisting of periodically measuring the position of the mark located on the foundation relative to a practically fixed frame, the position of the brand in height is measured by a linear displacement sensor with a converter of the values of these movements into an electrical signal relative to a practically fixed frame located under brand in the soil below the freezing zone of the soil and the zone of its deformation from the foundation.

The prototype of the claimed device for implementing the method of measuring the foundation sediment is "Reference indication of displacements of the rock mass" according to the patent of the Russian Federation RU 2272134, IPC E21C 39/00, G01B 5/30, publ. March 20, 2006 - [10], containing a brand, which is the end face of the vertical tubular element, as well as a spacer rod located inside the vertical tubular element, fixed on one side in the ground and on the other having a head. The benchmark is a relatively inexpensive technical device and is designed to determine the displacements of the array in the space between the tubing lining and the output circuit filled with concrete.

The use of the device [10] for measuring (and monitoring) the precipitation of the foundations of buildings and structures is not known and impossible in the form known by the patent. This poses the task of adapting the well-known and cheap benchmark [8] for measuring the foundation subsidence with high accuracy (up to a fraction of a millimeter), with the possibility of real-time monitoring of the foundation subsidence in real time and throughout the entire life cycle.

The problem is solved in that the device for implementing the method of measuring the settlement of the foundations contains a brand and a distance rod located inside the vertical tubular element, fixed on one side in the ground and on the other having a head (which is a benchmark), while it is fixedly attached to the mark foundation base with a linear (vertical) displacement transducer installed on it, the spacer rod below is rigidly fixed in the ground below its freezing depth and the def soil formation (compressible stratum) from the foundation, and the head on the remote rod is fixed (with height adjustment) from above and connected to the sensitive element of the linear displacement sensor, the tubular element is made in the form of a casing, the lower end of which does not reach the fixing of the remote rod in soil, and its upper end with the tip of the remote rod, a linear displacement sensor and a support pad firmly attached to the foundation is closed with a thermally insulated casing, the sensor is made with a conversion a linear motion encoder into an electrical signal, and wherein the converter is connected to an information reader. The upper end of the casing with the tip of the remote rod, the linear displacement sensor and the base support platform can be located in the pit near the foundation, while the pit is thermally insulated from above, covered with a hatch and a layer of soil. The converter of linear displacements into an electric signal of the sensor can be performed on piezoresonant structures: on surface active waves (SAWs) or bulk active waves (SAWs), and a transceiver operating at the frequency of these piezoresonant surfactants or SAWs is used as an information reader. A cylindrical insulation made of an inert, porous and pliable material, installed with gaps from the distant rod and from the casing, can be worn on a distance rod along its entire length from the point of fixation in the soil to the upper end of the casing. The remote rod can be made in the form of a steel pipe with an external anti-corrosion and anti-adhesive coating, which has through holes in the bottom at the point of fixation in the ground.

Introduction of signs “as a brand, a support platform is fixedly fixed to the foundation with a linear (vertical) displacement sensor installed on it, the bottom rod is rigidly fixed below from the depth of freezing and the zone of deformation of the soil (compressible thickness) from the foundation, and the head at the remote the rod is fixed (with the possibility of height adjustment) from above and connected to the sensitive element of the linear displacement sensor, the tubular element is made in the form of a casing, the lower end of the cat It doesn’t even come to fix the remote core in the ground, and its upper end with the tip of the remote core ”is necessary for continuous monitoring of the settlement of building foundations and other building structures carried out in automatic mode and under natural conditions. At the same time, at the upper end of the distance rod (with the possibility of height adjustment), a head is firmly installed with which the distance rod interacts in vertical movements with the sensitive element of the linear displacement sensor. The head can be mounted on a remote shaft using a threaded or other adjustable connection.

The introduction of the signs “its upper end with the tip of the remote rod, the linear displacement sensor and the support pad firmly attached to the foundation is closed by a heat-insulated cover” is necessary to prevent unauthorized access to the sensor, and the cover must have locks and locks to them. Thermal insulation of the casing is necessary to minimize the temperature effects of the environment on the sensor readings. At the same time, the casing with the above-described equipment located under it can be located both inside the surveyed task and outside at its foundation.

The introduction of the signs “the upper end of the casing with the tip of the remote rod, the linear displacement sensor and the foundation support platform are located in the pit near the foundation, while the pit is thermally insulated from above, closed by a hatch and a layer of soil” is necessary to further increase safety - to exclude access to the sediment sensors of the subject foundation. When the pit is located below the freezing depth of the soil, the proposed device will work in more favorable temperature conditions and function with minimal temperature errors. Covering the pit hatch, which can be a standard cast-iron sewer hatch, completely maskes the location of the proposed device with a layer of soil and thereby eliminates unauthorized access to it and safe long-term operation.

The introduction of the signs “the sensor is made with a linear displacement transducer into an electric signal, and the converter is connected with an information reader” is necessary for the operative taking of readings from the sensor (there may be several sensors on the foundation under investigation) and transferring them to the reader, which is connected to in turn, through a communication line with a processor (or computer), the collection, processing and display of information in one form or another. Thus, the converter of linear displacements of the sensor into an electric signal is connected to an information reader, which can be installed either directly on a controlled building or structure, or at a distance from it and connected via a telephone line through a modem.

The introduction of the signs “a linear displacement transducer into an electric signal of a sensor is made on piezoelectric structures, and a transceiver operating at a frequency of piezo-resonant structures is used as an information reader” is necessary to significantly simplify the sensor design, exclude the supply of electric wires to it, and increase reliability and durability. It is well known that converters of linear displacements into an electric sensor signal, made on piezoresonant surfactant or OAV structures, can be located in the thickness of soil or concrete up to one meter. Moreover, in the presented method and device for its implementation, it will be necessary to use a casing (or a pit hatch) of radiolucent material in the frequency range of these piezoresonant SAW or OAV structures.

The introduction of the signs “a cylindrical insulation made of an inert porous flexible material installed with gaps from the distant shaft and from the casing” is required on the distance rod along its entire length from the point of fixation in the soil to the upper end of the casing ”is necessary to minimize the temperature effect of the environment on linear expansion remote rod (rapper). It should be noted that the above cylindrical heaters are currently available in a wide range for pipes of cold, hot water and heating of different diameters. The material of these heaters is inert, porous, mechanically malleable and, most importantly, cheap. In addition, a cylindrical insulation made of an inert porous compliant material will fill the cavity (gap) between the spacer rod and the casing and prevent it (cavity or gap) from clogging and effortlessly slide vertically along the spacer rod (without interfering with the main task of the technical proposal - measuring precipitation ), which will increase the durability and reliability of the structure as a whole. In addition, the cylindrical insulation made of an inert porous flexible material filling the annular gap between the casing pipe and the spacer rod will center the latter and thereby will minimize the effects of radial movements of the upper end of the spacer rod with the tip and, therefore, will increase the accuracy of the sensor readings.

The introduction of the signs "the spacer rod is made in the form of a steel pipe with an external anti-corrosion and anti-adhesive coating, which has through side holes at the bottom in the fixing point in the ground" is necessary to significantly simplify and reduce the cost of the design of the proposed device for implementing the method of measuring the foundation settlement. Thus, the use of a steel pipe will make it possible to use finely dispersed concrete mortar, which flows downward through the steel pipe, where it passes through the side through holes into the cavity (gap) between it and the casing, and at the same time (when solidifying, outside the bottom and inside steel pipe) forms a reliable reinforced concrete fastening of the remote rod - a steel pipe. As is known, in a reinforced concrete structure, iron and concrete have the same linear expansion coefficients. The external anticorrosive and anti-adhesive coating of the steel pipe - the spacer is necessary to give it durability and minimize friction on the material filling the cavity (gap) from the concrete fastening (bottom) to the upper end of the casing.

Figure 1 presents a schematic drawing of a device for implementing the method of measuring the precipitation of the foundations. Figure 2 is a schematic drawing of a device for implementing the method of measuring the precipitation of foundations, located in the pit near the foundation, and with the installed tubular sealant of the remote rod from a steel pipe filled with concrete.

A device for implementing the method of measuring the foundation sediment contains a support pad 2 fixed to the foundation 1 of the building with a linear (vertical) displacement sensor 3 installed thereon, a distance rod 4 (diameter d), which is rigidly fixed from below to the ground 5 below its freezing depth and zone deformation of the soil (compressible thickness) from the foundation 1, for example, using concrete 6. On top of the remote rod 4 is fixed (with the ability to adjust it in height) head 7 connected to the sensing element 3, the linear displacement sensor. The remote rod 4 is located in the casing 8 (diameter D), the lower end of which does not reach the fastening of the remote rod in the ground (concrete 6) at a distance l = 5 ÷ 15D. The ratio of the diameters of the casing 8 and the remote rod 4 are correlated as D = 10 ÷ 20 d. The upper end of the casing 8 with the measuring tip 7 of the remote rod 4, the linear displacement sensor 3 and the support pad 2 fixed to the foundation is closed by a casing 9 with a layer of thermal insulation 10. The sensor 3 is made with a linear displacement transducer into an electrical signal, and the transducer is connected with an information reader (not shown in FIGS. 1 and 2), wired or wirelessly. The upper end of the casing 8 with the tip 7 of the remote rod 4, the linear displacement sensor 3 and the supporting platform 2 of the foundation 1 can be located in the pit 11 near the foundation 1, while the pit is closed from above with a thermal insulation layer 10, a hatch 12 and a soil layer 5. The linear displacement transducer the electrical signal of the sensor 3 can be performed on piezoelectric resonance structures on surface active waves or bulk active waves, and a transceiver operating at the frequency of these zorezonasnyh (BAW or SAW) structures. On the remote rod 4 along its entire length from the point of fixation in the soil 5 (concrete 6) to the upper end of the casing 8, a cylindrical heater 13 of inert, porous and pliable material can be dressed, installed with gaps from the remote rod 4 and from the casing 8 The remote rod 4 can be made in the form of a steel pipe with an external anti-corrosion and anti-adhesive coating, which has bottom through holes 14 at the bottom in the place of fixing in the ground.

A device for implementing the method of measuring the settlement of foundations as follows. Initially, on a support platform 2 fixed to the foundation 1 with a linear (vertical) displacement sensor 3 mounted on it, the value of sensor 3 is set to zero. For this, on (located coaxially in the casing 8 and fixed below in the ground 5, for example, using concrete 6) the upper end of the remote rod 4 weaken the tip 7 and its smooth adjustment in height reach the required zero reading of the sensor 3. After adjustment, the tip 7 is fixed to the remote rod 4. Remote The rod 4 can additionally be located in a cylindrical insulation 13 made of inert, porous and ductile material, which will additionally center it (distance rod 4) and thereby increase the accuracy of the sensor 3 by minimizing the effect of radial movements of the head 7. When moving the foundation 1 ( up and down) the head 7 of the remote rod 4 interacts with the sensor element of the sensor 3, which converts these movements into electrical signals transmitted to the reader by wire am If a piezoresonant SAW or OAB structure is used as a transducer of linear displacements in an electric signal in a sensor 3, the individual (zero) readings of the sensor 3 are additionally stored by an information reader (a transceiver operating at the frequency of these piezoresonant structures). After adjustment, the value is set to zero the sensor 3 is closed by a casing 9 with a layer of thermal insulation. When the sensor 3 is in the pit 11, the latter is first closed with a layer of thermal insulation 10, then with a hatch 12, over which a layer of soil 5, after which the sensor 3 is ready for operation.

In case of precipitation of the examined foundation 1 (or raising it by heaving of soil 5 under the foundation 1), together with the foundation 1, the support platform 2 fixed on it with the sensor 3 rises or falls, the sensitive element of which interacts with the practically stationary head 7 of the distance rod 4, fixed below the depth of its freezing of the soil and the zone of its deformation (compressible thickness) from the foundation 1. From the sensor 3, a signal is transmitted that is transmitted to the reader, after which it is processed by a processor or computer with the subsequent issuance of information necessary for analysis. In the case of using piezoresonant surfactant or OAV structures in the sensor 3, information from the sensor 3 is taken directly by the transceiver operating at the frequency of these piezoresonant structures.

When introducing the proposed method for measuring the foundation sediment and the device for its implementation, the cost of such monitoring is significantly reduced and the accuracy of measuring the foundation precipitation increases from 1 mm to a fraction of a millimeter. The depth of the compressible thickness, or zone of deformation of the soil from the upstream foundation, depending on the type of soil and the height of the building or structure located above the foundation, is from 4 to 10 meters. There can be several such wells of small diameter (up to 200 mm) with remote rods installed in them, connected with sensors on the same foundation of the building (or a whole series), depending on its length, soil condition and work performed. The location of the proposed devices for implementing the claimed method of measuring the settlement of the foundation can be carried out both outside the foundation of the building and inside it in the basement.

We believe that the proposed device has all the criteria of the invention, since:

the method of measuring the precipitation of the foundations and the device for its implementation, together with the restrictive and distinctive features of the claims, are new for well-known methods and devices for measuring the precipitation of the foundations and, therefore, meet the criterion of "novelty";

the totality of the features of the claims of the device is unknown at this level of development of technology and does not follow well-known rules for measuring precipitation of foundations, which proves compliance with the criterion of "inventive step";

the introduction of the method of measuring the precipitation of the foundations and the device for its implementation does not present any structural, technical and technological difficulties, whence the compliance with the criterion of "industrial applicability" follows.

Information sources

1. TSN 50-302-96, St. Petersburg.

2. TSN 50-302-2004, St. Petersburg.

3. SPIL 2.02.01-83 *, the Foundation of buildings and structures.

4. SNIP 2.02.03-85, Pile foundations.

5. RF patent RU 2245531, IPC G01M 7/00, publ. January 27, 2005, “A method for determining the stability of buildings and structures and a system for determining the stability of buildings and structures”.

6. RF patent RU 2341623, IPC Е04В 1/00, G01M 7/00, publ. December 20, 2008. "A method for determining the technical condition of building structures and / or their parts and elements."

7. RF patent RU 2194978, IPC G01N 29/04, G01M 7/00, publ. 12.20.2002, "Method of monitoring the technical condition of spans."

8. Ganshin V.N., Kosykov B.I. and Repalov I.M. Geodetic works during the reconstruction of industrial enterprises. M .: "Nedra", 1990

9. Grozdov V.T. Technical inspection of building structures of buildings and structures. - St. Petersburg., 2008 - the prototype of the proposed method.

10. RF patent RU 2272134, IPC E21C 39/00, G01B 5/30, publ. 03/20/2006, "Reference indication of displacements of the rock mass" - a prototype device for implementing the claimed method.

Claims (6)

1. A method of measuring the settlement of foundations, consisting of periodically measuring the position of the mark located on the foundation, with respect to a practically immovable reference point, characterized in that the position of the mark in height is measured by a linear displacement transducer with a converter of the values of these displacements into an electrical signal, relative to a practically immovable reference point brand in the soil below the freezing zone of the soil and the zone of its deformation from the foundation. 2. A device for implementing the method of measuring the settlement of the foundations according to claim 1, containing marks and a spacer rod located inside the vertical tubular element, fixed on one side in the ground and on the other having a head, characterized in that the mark is fixedly fixed to the foundation a support platform with a linear displacement sensor installed on it, the distance rod from below is rigidly fixed in the soil below the depth of freezing and the zone of soil deformation from the foundation, and the head is at a distance The rod is fixed on top and connected to the sensitive element of the linear displacement sensor, the tubular element is made in the form of a casing pipe, the lower end of which does not reach the fastening of the distance rod in the ground, and its upper end with the tip of the distance rod, linear displacement sensor and fixedly attached to the foundation the reference platform is closed by a thermally insulated casing, the sensor is made with a linear displacement transducer into an electrical signal, while the converter is connected to the reader I have information. 3. The device according to claim 2, characterized in that the upper end of the casing with the tip of the remote rod, the linear displacement sensor and the support platform of the foundation are located in the pit near the foundation, while the pit is thermally insulated from above, closed with a hatch and a layer of soil. 4. The device according to claim 2 or 3, characterized in that the transducer of linear displacements into an electric signal of the sensor is made on piezoresonant structures, and a transceiver operating at a frequency of piezoresonant structures is used as an information reader. 5. The device according to claim 2 or 3, characterized in that a cylindrical heater made of an inert porous ductile material, installed with gaps from the distant rod and from the casing, is dressed on a distance rod along its entire length from the point of fixation in the soil to the upper end of the casing . 6. The device according to claim 2 or 3, characterized in that the spacer rod is made in the form of a steel pipe with an external anti-corrosion and anti-adhesive coating, which has through lateral openings at the bottom in the place of fixing in the ground.

Images