Analysis of regulatory documents required and recommended for use in Russia during the examination of the foundations and basements of buildings



The main document regulating the conduct of the survey of basements and foundations is GOST 31937–2011 «Buildings and structures. Rules of examination and monitoring of technical condition» [1]. This document introduced with effect from 1 December 2014 to replace the outdated GOST 53778–2010 [2] for voluntary application. One of the distinguishing features of the new document is a separate section in the Foundation. In section 5.2. «A examination of technical condition of bases and foundations» and determined the composition, volumes, methods and sequence of works on inspection of technical condition of foundations and basements in accordance with the technical specifications. The scope of work listed in this regulatory document can be divided into three parts: a survey of Foundation soils, the Foundation of the sampling and laboratory testing and calculations. The scope of works for the survey of soil bases and foundations of buildings (structures) include:

‒ Desk study on geological engineering research carried out in this or in neighboring areas;

‒ study plan and site improvement;

‒ study of materials relevant to laying the foundations of the investigated buildings and constructions;

‒ the excavation of test pits, mainly near foundations;

‒ drilling wells with the selection of soil samples, groundwater samples and the determination of their level;

‒ test of soil;

‒ soil testing static load;

‒ soil testing by geophysical methods;

‒ laboratory tests soils and groundwater;

‒ condition survey pile artificial bases and foundations.

During the examination of bases and foundations is recommended to perform the following work:

‒ clarify the geotechnical structure of site development;

‒ take ground water samples to evaluate their composition and aggression (if necessary);

‒ determine the types of foundations, their shape, size, depth, reveal a previously completed underpinning and anchoring grounds;

‒ set damage to the foundations and determine the strength of materials to their structures;

‒ take samples for laboratory testing of materials foundations;

‒ establish the presence and condition of waterproofing.

The location and total number of workings, sounding points, the necessity of application of geophysical methods, volume and composition of physico-mechanical characteristics of soils determined by the SP-11–105–97 [3] and depends on the size of the building or structure and the complexity of engineering-geological structure of the site. The survey of soils associate the new data with archive data (if available).

Test pits dug depending on local conditions with an external or internal side of foundations. As a rule the examination of the basement there is no possibility of adopci sounding with the outside of the building. The pits have on the basis of the following requirements:

‒ in each section of the Foundation of one pit in each kind of design in most on loaded and non-loaded areas;

‒ if you have mirrored or repeated (and contours) sections one section off all the pits, and the rest have one or two pits in the most loaded areas;

‒ in places where you intend to install additional intermediate supports, each section off one pit;

‒ optional tear off for each building two to three test pits in the most loaded areas on the opposite side of the wall, where there is development. In the presence of deformations of the walls and foundations of the pits in these places digging is required, whereas in the process appoint an additional test pits to determine the boundaries of weak Foundation soils, or borders of foundations that are in poor condition.

The depth of the pits near the Foundation should exceed the depth of the bottom 0.5–1 m. This is necessary, for example, to determine the presence of wooden beams. The length of the exposing section of the Foundation must be sufficient to determine the type of Foundation and assessment of the state of its structures.

Equipment, ways of penetration and fastening openings (wells) engineering geological purpose is selected depending on the geological conditions and terms of the entrance transport, the availability of communications, the compressed sites, the soil properties, the transverse dimensions of the test pits and depth of excavation. For studies of soil below the bottom of Foundation well is being drilled from the bottom of the pit. The results of the geotechnical survey in accordance with SNiP 2.02.01–83 [4] and SNiP 2.02.03–85 [5] must contain the data required for:

‒ determine the properties of the Foundation soils for the ability to add additional floors, the device of cellars, their penetration, etc.;

‒ identify the causes of defects and damages and identify measures on strengthening of the bases, foundations, advancement structures;

‒ choosing the type of waterproofing underground structures, basements;

‒ establish the type and amount of dewatering activities at the site.

The width of the base of the Foundation and the depth of laying should be determined by field measurements. In the most loaded areas of the sole determine the width of the bilateral pits, in less loaded — allowed to take a symmetrical development of the Foundation according to the sizes defined in a one-sided pit. The depth of the foundations is determined using suitable measuring instruments.

An assessment of the strength of materials foundations performed by nondestructive methods or laboratory tests. In our time, unfortunately, often have to deal with the failure of technology application methods, reduced volume control, not the implementation of the preparatory works and other disturbances [6]. Samples of materials foundations for laboratory testing in cases where their durability is crucial in determining the ability of additional the load of or upon detection of deterioration of the material of the Foundation.

During the inspection of the foundations record:

‒ cracks in the structures (transverse, longitudinal, oblique, etc.);

‒ the exposed rebar;

‒ fall of concrete and masonry, cavity, sink, damage to the protective layer, revealed areas of concrete to change its color;

‒ damage to the reinforcement, embedded parts, welds (including corrosion);

‒ schemes bearing structures, the mismatch sites of intersection prefabricated structures design requirements and the deviation of the actual geometric dimensions of the design;

‒ the most corrupted and damaged sections of the structures of foundations;

‒ the results of determining the moisture content of the Foundation material and the presence of waterproofing.

For foundations of historical buildings of St. Petersburg focuses on the identification of cracks, the destruction of the brickwork. The presence of metallic elements in such structures are extremely rare.

According to the results of the visual survey on extent of damage and the characteristic when the signs of the defects provide a preliminary evaluation of the technical condition of the foundations. If the results of the visual inspection is insufficient to assess the technical condition of the foundations, carried out a detailed (instrumental) examination, which can be continuous or selective. Sure, the cost of the visual inspection are much lower detailed. You must try as much as possible to use visual inspection where it will not affect the quality of the results. Reducing the cost of operations in this case are «at the forefront» in the competition for a particular object [7]. Continuous survey carried out in the absence of project documentation, the reconstruction of a building with increase in load (including when the depth of the basement), defects of the structures, reducing their carrying capacity, in some other cases.

A sample survey is carried out if necessary, examination of individual structures, and in potentially dangerous places, where due to the unavailability of structures, it is impossible to conduct complete surveys.

Another important regulatory instrument for the inspection of buildings is BCH 57–88(r) [8]«Regulations on technical inspection of residential buildings». However, it should be noted that the provisions in this document is obsolete and should be used with caution and in cases of impossibility of use of the basic GOST described above.

You can not just ignore the building rules SP 13–102–2003 [9]«Rules of examination of bearing building structures of buildings and constructions», which are really not relevant in this work due to the lack of a separate part of the foundations in addition, there are a significant number of normative documents in the form of a SNiP, SanPiN, SP, GOST, VSN, TSN, RD, which contain the requirements for building constructions, engineering systems, the parameters of the microclimate, surrounding area and etc. Moreover, the current documentation has a narrow specificity, the effective use of it in practice is complicated due to the large amount of information and the need for its analysis to apply when examining a particular object.

In accordance with the objectives of the study the analysis of the organization of the survey of residential buildings in the normative acts and documents.

In accordance with SP 13–102–2003 inspection of buildings is generally carried out in three related phases:

1) preparation for conducting the survey;

2) preliminary (visual) examination;

3) detailed (instrumental) examination.

Preparations for the survey includes familiarization with the object, project, Executive and operational documentation. Most of the work on the survey performed in immediate proximity to the structure, therefore in the preparatory phase and address the issues of access. The existing building is difficult enough to get permission from the owners of adjacent premises, for example during the examination of the overlaps [10].

Visual inspection is carried out for preliminary assessment of technical condition of building structures by their appearance and the need to conduct detailed instrumental examination. Unfortunately, it is difficult to find a universal algorithm for visual inspection, in the modern normative documents is virtually no guidance on the procedure of examination about the sequence of actions [11]. The basis of the preliminary inspection is the inspection of buildings and separate constructions with application of simple measuring tools and instruments (binoculars, photographic equipment, tape measures, calipers, feeler gauges, etc.).

According to the results of the visual inspection is a preliminary assessment of the technical condition of building structures, which is determined by the characteristic signs of defects and damages. If the results of the visual inspection will be insufficient to achieve the objectives, and conduct detailed instrumental examination. In this case, if necessary, a program of works for detailed examination.

Detailed instrumental examination includes work on the measurement of the required geometric parameters of buildings, structures and their elements, including the use of special instruments, instrumental determination of parameters of defects and damages, determining the actual strength characteristics of materials of the basic bearing structures and their elements, measurement of parameters of the internal operational environment, the definition of actual operating loads at the expense of opening individual sections of the designs and the actual design scheme. On the basis of the obtained data of instrumental examinations are conducted check calculations, analysis of the causes of defects and damages in structures. Further components of the final document with conclusions on the survey results and recommendations for further operation or special events. The conclusions contain the category of the technical condition of the object of examination in accordance with SP 13–102–2003:

1) proper technical condition;

2) serviceable condition;

3) limited-a serviceable condition;

4) unacceptable technical condition;

5) emergency technical condition.

The article analyzes the current normative documents regulating the activities on the survey of the bases and foundations of buildings. The documents contain a detailed description of works on tool survey. At the same time, the visual survey method is given insufficient attention. It is necessary to develop more detailed recommendations for the visual inspection of bases and foundations, and building as a whole.

References:

1. GOST 31937–2011 «Zdanija i sooruzhenija. Pravila obsledovanija i monitoringa tehnicheskogo sostojanija» [Buildings and constructions. Rules of inspection and monitoring of the technical condition] 2012.
2. GOST 53778–2010 «Zdanija i sooruzhenija. Pravila obsledovanija i monitoringa tehnicheskogo sostojanija» [Buildings and constructions. Rules of inspection and monitoring of the technical condition] 2010
3. SP-11–105–97 «Inzhenerno-geologicheskie izyskanija dlja stroitel'stva» [Engineering-geological surveys for construction] 2012.
4. SNiP 2.02.01–83 «Osnovanija zdanij i sooruzhenij» [The grounds of buildings] 1983.
5. SNiP 2.02.03–85 «Svajnye fundamenty» [Pile foundations] 1985.
6. Ulybin A. V. O kachestve instrumental'nogo obsledovanija zdanij [About the quality of the instrumental examination of buildings] /Integracija, partnerstvo i innovacii v stroitel'noj nauke i obrazovanii: Sbornik materialov Mezhdunarodnoj nauch. konf. [Integration, partnership and innovations in construction science and education: materials of the International scientific conference].-M.: Izd-vo MGSU, 2015. Pp. 222–228
7. V. Ulybin, S. V. Zubkov. Problemy cenoobrazovania na rinke obsledovaniy zdaniy i sooryjeniy [Problems of pricing in the market of inspection of buildings and structures] Magazine of civil ingineering, 2010 No.(17) pp. 53–56
8. VSN 57–88(r). Polozhenie po tehnicheskomu obsledovaniju zhilyh zdanij [Technical inspection of residential buildings]. — M.: Gosstroj Rossii, GUP CPP, 2003.- 92 p.
9. SP 13–102–2003 Pravila obsledovanija nesushhih stroitel'nyh konstrukcij zdanij i sooruzhenij [Rules of examination of bearing building structures of buildings and constructions] -M.: Gosstroj Rossii, GUP CPP, 2003
10. Lanko, A. V. Ulybin, A.Je. Radchenko. Metodika predvaritel'noj ocenki celesoobraznosti pokupki i rekonstrukcii podval'nyh pomeshhenij nebol'shoj ploshhadi [Methodology for a Preliminary Assessment of the Feasibility of Investing in the Small Basements]. Construction of Unique Buildings and Structures No. 3 (30). 2015. Pp. 188–208
11. V. Ulybin, N. I. Vatin. Kachestvo vizualnogo obsledovania zdaniy i soorujeniy i metodika ego vipolnenia [The quality of the visual inspection of buildings and constructions and the method of its implementation] Construction of Unique Buildings and Structures No. 10 (25), 2014, p.p.134–146.