编号 9 (2024)

Comprehensive hardening soil models are widely used in geotechnical design. Some of the stiffness parameters of such models, characterizing the behavior under very small and small strains, should be determined by wave (dynamic) methods. These techniques can be implemented both in the laboratory and in the field scale. Each of the methods has its advantages and disadvantages, which directly affect the quality of the initial data obtained for calculations and the results of geotechnical forecasts and the reliability of construction facilities. The article provides an overview of wave methods applicable for stiffness parameters of complex soil models estimation. The scope of application of test methods is given depending on the geotechnical task, the defined parameters and engineering-geological conditions. The comparison of the test results by field and laboratory methods at the experimental site is given. It is shown that the results obtained by field methods require additional reference to the initial stress state in the soil mass before their application as input parameters of comprehensive soil models. Recommendations are given for correcting the initial soil shear modulus based on the integration of laboratory and field wave methods.

In the process of construction and operation of buildings and structures located on weak water-saturated clay foundations, there is often a need to change their physical and mechanical properties. Currently, various methods of surface and deep compaction are used to improve the characteristics of weak soils. It is known that in the process of deep compaction, the soil is compressed under the action of radial stress on the wall of the leading well using an auger (in reverse motion), pile foundation technology, a rotor, etc. In this paper, the main attention will be paid to solving the axisymmetric problem of consolidation of a soil cylinder under the influence of radial pressure. The diameter of the well in this case increases by 2–3 times and is filled with working material – sand and gravel mixture. The purpose of this study is to carry out a theoretical analysis based on a different approach to solving the problem of the stress-strain state of weak soil during compaction of weak foundations and determining the required characteristics of the compacted composite massif transformed by a bored crushed stone pile. The results of the study convincingly prove that the technology under consideration, based on the expansion of the diameter of the leading borehole in water-saturated soil using crushed stone pile drains, is one of the most cost-effective and efficient solutions. It can compete with traditional compaction methods and the more expensive use of deep foundations.

When installing underground structures in soil layers with high groundwater filtration rates, special requirements are imposed on the material of anti-filtration curtains. The conditions of application of jet cementation technology for modification of watered fractured rocky soils of low strength in order to form a composite material with the required mechanical and filtration characteristics are considered.The technological parameters of the cementation process have been experimentally and theoretically determined to ensure the necessary radius of propagation of the bonding mixture, and methods of laboratory and field control of the modified zone have been developed. The maximum permissible values of the controlled parameters have been determined.

The construction of buildings and structures in cramped conditions requires a special approach from hydraulic engineers and builders, requiring the preservation of the surrounding development in a working condition. This circumstance requires a geotechnical forecast of deformations of objects falling into the zone of geotechnical influence of the construction of a building under construction at the design stage and then the organization and implementation of geotechnical monitoring of deformations as a result of construction and installation work. It should be noted that the objects of the surrounding development can be in different categories of technical condition. According this circumstance the permissible deformations may be different. In any geotechnical case, there is an urgent need to install excavation fences that perform a dual task: both ensuring the stability of the soil walls, and reducing the impact of the new construction object on existing buildings. The determination of the bearing capacity of the enclosing structures of the excavation, especially the retaining soil anchors themselves, is of great importance in modern geotechnical construction. The engineering method used in this article to determine the bearing capacity of drilling-injection anchors with sufficient accuracy for technical calculations showed the convergence of calculated and real values based on the results of static tests.

The article presents the main provisions that it is advisable to follow when organizing and conducting monitoring during the operation of cultural heritage sites. It is noted that the existing regulatory documents do not take into account the specifics of monitoring during operation, but are mainly aimed at protecting the monument from neighboring construction.Criteria are proposed to control the technical condition of historical buildings. Among them is the rate of development of long-term precipitation, which is considered as an indicator of the intensity of natural and man-made impacts on the building.Among them is the rate of development of long-term precipitation, which is considered as an indicator of the intensity of natural and man-made impacts on the building. It is noted that for stone structures, critical masonry stretching deformations serve as an effective criterion for the preservation of historical buildings, since in calculating the interaction of structures and foundations they are the primary criterion for calculating the second group of limiting states. In relation to it, the criterion of absolute precipitation and relative difference of precipitation is secondary. It is shown that over time, for buildings built on weak water-saturated clay soils, an increase in the unevenness of precipitation occurs. Special attention is paid to taking into account the accumulated uneven precipitation of buildings of historical development. The article presents the most characteristic types of deformations of buildings, among which in St. Petersburg the bend is most common, which is due to the regularity of building and rebuilding sections of urban neighborhoods.Monitoring is also considered as a reliable means of diagnosing the technical condition of the monument. The monitoring function is considered as a means of controlling the limitations of the monument’s operability, which continues to be operated in conditions of limited operational technical condition.

This paper provides a review of the regulatory framework of the permissible value of the vibration level depending on the accuracy of the equipment, a review of the problem of the influence of vibration on the operation of high-precision equipment. Based on the results of the analysis of the identified problem, a lack of initial data from manufacturers of vibration sources in terms of vibration characteristics was identified, and a solution was proposed to obtain the necessary parameters for frequency analysis.