Stress-Strain State Assessment of Building Subfoundations Having Flexible Constructive Scheme in Irregular Soil Stratification

Introduction. One of the main problems in the operation of buildings and structures is possibility of their damage due to non-uniform deformation of subfoundation soil caused by the various natural and technogenic factors. To establish the possible character and degree of damage of the above-surface structures, it is necessary to calculate the value of subfoun- dation relative differential settlement at the level beneath the foundation bottom. The subfoundation settlement is calculated within the compressible soil thickness using the specific gravity values and soil deformation modulus. The increment of settlement is induced by the increase of vertical stresses in the massif and increase of soil deformability upon growth of moisture. The purpose of the study is to establish the dependence of the magnitude of the relative difference in settlement on the deformation properties of soils with uneven occurrence of layers in order to predict the nature of damage to above-ground structures.

Materials and Methods. An example of subfoundation deformation calculations at the bottom level of the free-standing foundations of a building having flexible constructive scheme has been studied. A model of stratification of two heterogeneous geotechnical elements with a 1:4 boundary slope and differing physical and mechanical properties has been used. It has been assumed that one of the geotechnical elements has natural properties enabling the building foundations to rest on it without prior site preparation. Another geotechnical element has significantly worse properties. The calculations on determining the settlement have been made in accordance with the layer-wise summation methodology.

Results. The regularity in alteration of the predicted settlement value depending on the ratio of firm and soft soils thickness in the irregular stratification has been established. It has been proven that the difference between the specific gravity values of the heterogeneous beds within 10 % does not affect the depth of compressible soil thickness if the calculation of settlement is made using the layer-wise summation methodology.

Discussion and conclusions. The calculation results analysis of the subfoundation settlement of the equidistant column foundations was carried out, the engineering solution was proposed to ensure reliability per limit state groups.

1. Dalmatov BI. Mekhanika Gruntov, Osnovaniya i Fundamenty (Vklyuchaya Spetsial'nyi Kurs Inzhenernoi Ge- ologii): 7-th edition. Saint Petersburg: Lan' Publ.; 2022. 416 p. (In Russ.). URL: https://e.lanbook.com/book/254639 (ac- cessed: 14.07.2023).

2. Shereshevskii IA. Konstruirovanie Promyshlennykh Zdanii i Sooruzhenii. Manual for Students of Civil Engineering Majors. Moscow: Arkhitektura-S Publ.; 2005. 168 p. (In Russ.).

3. Il'icheva VA, Mangusheva RA (eds). Spravochnik Geotekhnika. Osnovaniya, Fundamenty i Podzemnye Sooruzheniya. Moscow: ASV Publ.; 2014. 728 p. (In Russ.).

4. Zhur VN. Study of the Influence of the Parameters of Engineering-Geological Elements of Foundation Soils on the Scale of Foundations Settling. Nauchnoe Obozrenie. 2014; (9):859–863. (In Russ.).

5. Prokopov AYu, Tkacheva KEh, Zhur VN. Analiz Prichin Neravnomernykh Deformatsii Osnovaniya Metallicheskogo Rezervuara. In: Sotsial'no-Ehkonomicheskie i Ehkologicheskie Problemy Gornoi Promyshlennosti, Stroitel'stva i Ehnergetiki. Procedings of the 11th International Conference on the Problems of Mining, Construction and Energy. Kovalev RA (ed); 2015. P. 203. (In Russ.).

6. Prokopov A, Zhur V, Medvedev A. Application of The Cartographic Method of Research for the Detection of the Dangerous Zones of Mining Industrial Territories. In: MATEC Web Conf. XXVII R-S-P Seminar, Theoretical Foundation of Civil Engineering (27RSP) (TFoCE 2018); 2018. 196 р.

7. Gridnevskii AV. Complex Assessment of Geological Hazards of the Territories of Rostov Region. Engineering Journal of Don. 2013(3(26)). (In Russ.). URL: http://www.ivdon.ru/ru/magazine/archive/n3y2013/1946 (accessed: 22.07.2023).

8. Konovalov PA, Konovalov VP. Soil Bases and Foundations of Buildings under Reconstruction: Monograph. Moscow: Assotsiatsiya Stroitel'nykh Vuzov Publ.; 2011. 384 p. (In Russ.).

9. Prokopova MV, Luk'yanova GV. O Vozmozhnykh Izmeneniyakh Svoistv Gruntov pri Uvelichenii Urovnya Podzemnykh Vod. In: “Stroitel'stvo-2011”: Proceedings of the Internatioanl Sience and Practical Conference. Rostov-on-Don: Rostov State Civil Engineering University Publ; 2011. P. 144–145. (In Russ.).

10. Semenenko AI, Timoshenko MS. The problem of assessment of the geological risk of urbanized territories. Engineering Journal of Don. 2013(4(27)). (In Russ.). URL: http://www.ivdon.ru/ru/magazine/archive/n4y2013/2204 (accessed: 04.07.2023).

11. Prokopov AYu, Prokopova MV, Zhur VN. Issledovanie Svoistv Lessovykh Prosadochnykh Gruntov Vostochnogo Donbassa. In: Transport, Science, Education, Production: Collected Papers. Vol.2. Technical Sciences. Rostov-on-Don: Rostov State Transport University Publ.; 2017. P. 354 – 358. (In Russ.).