Construction processes are often influenced by external factors that cause accidents. For their control, special forecasting and integrated analysis systems are being developed, which helps to prevent such threats by taking appropriate measures or changing the tactics of working activities. One of the central areas of such control is geotechnical monitoring (geotechnical monitoring), through which it is possible to predict and even control the state of the target object from the point of view of its interaction with factors of negative influence of a natural nature.
GTM concept
Under the geological and technical measures is understood a complex of measures related to monitoring the state of structures of a constructed or reconstructed object. Particular attention in the control is given to the base of the supporting massif and the surrounding structures. Technologically, these works are organized on the basis of observation points located both in the construction production zone and outside it in laboratory conditions. At the same time, geotechnical monitoring of buildings and structures is not limited only to monitoring the state of the target object during its construction. Even at the stage of project development, it may be possible to integrate the fuel and gas system in the range of maintenance activities during the operation of the facility.
GTM goals
The main objectives of geotechnical observation should include ensuring safety during the construction and operation of the controlled facility, as well as the formation of a database of indicators by which it is possible to assess the degree of its reliability. This applies not only to the facilities being built and put into operation, but also to the works carried out as part of the repair and reconstruction. The goals of geotechnical monitoring are achieved by timely detection of processes of change in the studied parameters. It takes into account both the characteristics of the structure and the properties of the soil base.
GTM tasks
In the process of geotechnical control, the following tasks are solved:
- Regular recording of changes in the parameters of the geological massif and the structures located on it.
- Timely detection of deviations of parameters, as well as any changes that may violate expected trends in the course of work.
- Assessment of risks that entail identified deviations of controlled parameters.
- Establishment of the reasons for the recorded changes.
- Based on the results of geotechnical monitoring of buildings and structures, a set of measures is being developed that will help prevent and eliminate further negative processes.
Application of geological and technical measures in construction
The geological and technical measures are connected to the construction processes at the zero-cycle stage during geodetic surveys and land works. In particular, this applies to the soil base, foundation and basic load-bearing structures. In relation to foundation pits for construction, monitoring is carried out in relation to enclosing structures that exclude the risk of collapse. Surveys and underground facilities - communications, engineering structures and tunnels are also affected. In the framework of geotechnical monitoring in construction, factors that influence the object being constructed or being reconstructed are taken into account. Potentially hazardous geological processes (subsidence, landslides, suffosion) and dynamic impacts, the sources of which are directly construction works, are taken into account.
Geological and technical measures for soil control
During the implementation of the geological and technical measures, the state of the soil mass, its behavior and possible changes associated with the exerted loads during construction are evaluated. In relation to organic soils, the following characteristics are analyzed:
- Deformation of the foundation under the foundation of the structure under construction.
- The horizontal displacement of the soil formation in depth.
- Groundwater level.
- Hydrodynamic pressure that can occur in water-saturated organic-mineral and organic soils due to the impact of the additional load.
- The nature of the change in the physical and mechanical properties of the array.
In relation to bulk soils, geotechnical monitoring provides for the following measurements of controlled parameters:
- The degree of sediment that occurs due to self-compaction of newly dumped and existing soils.
- The load from the foundation platform of the structure under construction.
- Loads from massive building materials and equipment located on the site.
- Basic characteristics of bulk soils.
Scope of work on geological and technical measures
According to the regulations, geotechnical monitoring includes the following activities:
- Development of a program and project for monitoring the target. The list, volumes and methods of operations are determined on the basis of the performed geological surveys at the construction site.
- Determining the timing and frequency of monitoring operations. The schedule is set depending on the planned duration of the construction, taking into account the land work and operations associated with the elimination of the identified negative impact factors.
- Determination of controlled parameters. In this case, both local geological conditions and the characteristics of the facility under construction, including its level of responsibility, are taken into account.
- Processing the received data and drawing up a report on the basis of which measures are taken to reduce the recorded risks.
Geotechnical Monitoring Project
During the development of the project of the geological and technical measures, a set of constructive solutions is formed that could provide a minimum degree of influence on the object from negative impact factors. This takes into account not only the effectiveness of the methods, but also the economic feasibility of their application. A technological map of the production of analytical measures is drawn up, and optimal methods for examining the territory are selected taking into account the climatic and geophysical parameters of a particular region. The project for geotechnical monitoring of the construction of the building also prescribes environmental safety requirements, which may manifest itself in the form of restrictions on the use of certain methods of influencing the natural landscape, in particular. Ultimately, developers present a comprehensive set of measures with a timetable for their implementation and the possibility of adjustment depending on the influence of external factors.
Geotechnical Forecasting
An important role in the GTM complex is played by forecasting. This toolkit is used in the design processes of foundations, underground parts of buildings and foundations. A forecast of this kind is understood as an assessment of the possible impact of the construction process on the condition and characteristics of the soil mass. Similar events are also a necessity when developing projects for laying engineering communications located on a built-up territory. As the initial data for geotechnical monitoring with forecasting, the parameters of the movements of the enclosing structures are used, and the nature of the stress-strain impact on the soil from the side of the structure being built is taken into account. In the calculations, numerical and analytical methods are used to assess possible changes. In predicting additional deformations that may be caused by vertical loads from the constructed object, it is allowed to use a design scheme in the form of a linearly deformable half-space.
GTM methods
Various technological approaches are used for monitoring, among which are geodetic, visual, vibrometric, parametric, etc. The simplest and most common group of methods involves visual-instrumental control, in which an object is inspected with subsequent taking necessary measurements. In particular, geotechnical monitoring of buildings with visual inspection records the processes of development of cracks in structures, deviations in the position of ceilings and walls, damage characteristics, etc. Geophysical monitoring methods offer a different approach to monitoring. In this case, a complex of engineering-geological and hydrogeological research activities is carried out, which may not affect the parameters of the construction object, however, they fully study the properties of local soil and its physical characteristics, taking into account the levels of groundwater occurrence.
GTM data capture tools
Almost all methods of modern geotechnical control involve the use of technical means and devices for the precise determination of controlled indicators. It can be the simplest measuring tool like a level or a roulette wheel, and electronic devices that automatically fix the target parameters - not only physical and geometric, but also microclimatic. For example, to measure the draft and roll of a building or its individual structures, complex geotechnical monitoring systems are used that record parametric data thanks to pre-installed sensors and markers. Over a period of time, readings are taken from them, allowing you to track the dynamics of roll progression or crack opening. But for forecasting, such indicators as the temperature regime with the dynamics of differences, humidity coefficients, pressure level, etc. are also significant. For these and other measurement operations, piezometers, inclinometers, mass dosages, dynamometers, tensometers and other devices are used.
Geotechnical Monitoring Programs
After fixing the controlled values of geotechnics, they enter specific data into the logbook to generate a report. Next, a comprehensive analysis of the information obtained is made in order to develop protective measures, if necessary. To solve such problems, special geotechnical monitoring programs are used, among which the following solutions can be noted:
- TUN2 system. A simple and easy-to-use software tool designed to perform the static calculation of underground structures.
- POLUPROM program. The algorithm of this system allows the calculation of core structures and structures, offering the possibility of modeling lines of influence. Also, this program is used as a universal engineering calculator.
- Midas complex. Korean multi-functional product, with the help of which they perform basic geotechnical data processing operations, as well as specialized calculations in the field of tunneling.
Conclusion
Geotechnics in construction in a primitive form has been used since ancient times, when when arranging housing, people tried to provide for the risks of impacts from natural phenomena. Today, we can talk about multilateral and high-tech geotechnical monitoring, which allows you to identify, record, analyze and develop tools to eliminate both existing and possible threats during the construction or operation of various objects. However, you should not consider the methods of such control only as a means of unilateral reporting of problems. Modern methods of geological and technical measures become more interactive, which gives reason to consider them both as a means of ensuring security and as a tool for finding optimal economic solutions for the implementation of a project.