The use of GIS technologies for geodetic monitoring

Using GIS technologies, the article analyzes, systematizes, and processes, the data obtained in the process of geodetic monitoring of man-made territories and objects, which will make it possible to analyze the existing state of the object and provide an opportunity to determine critical spatial deviations that can lead to irreversible processes of destruction of buildings and structures. This provides an opportunity to prevent processes that can lead to large-scale disasters, as well as determines the adoption of timely measures to prevent the destruction of structures and predict emergencies.


Introduction
On the territory of Ukraine, there are many potentially dangerous objects of the fuel and energy complex, hydraulic structures, industrial facilities, mineral extraction enterprises, and others, of which operational resource is almost exhausted.Therefore, any dangerous phenomena of an endogenous and exogenous nature (earthquakes, landslides, and floods), or man-made factors caused by human activity can lead to large-scale disasters.We must not forget about the energy issue of state security, which is currently gaining great importance.Therefore, a necessary factor in preventing the destruction of objects and predicting deformations of engineering structures is the use of GIS technologies for geodetic monitoring of man-made territories and objects.

Methodology
On April 26, 1986, the largest man-made disaster in the history of mankind occurred -the explosion at the Chornobyl nuclear power plant.In a short time -from July to November 1986 -a protective structure was erected over the destroyed fourth power unit of the Chornobyl NPP (a little later it received the unofficial name "Shelter") to protect the environment from further pollution [1].
Since the "Shelter" facility was built within a short period and under extreme conditions, it does not comply with the rules and regulations for the design, construction, commissioning, and operation of either nuclear installations or radioactive waste management facilities, or regular industrial buildings.Therefore, after its construction, constant engineering, and geodetic monitoring of the state of the entire complex of buildings and structures of the "Shelter" facility became the key task.

2
The volume of engineering and geodetic observations of the "Shelter" facility includes the regular determination of the height position of the settlement control marks on the foundations and the spatial position of the deformation marks located, respectively, in the plinth (lower tier) and on the upper tiers of the "Shelter" facility (figure 1).The signs installed on the foundations of buildings are placed on the transverse and longitudinal axes of at least four signs around the perimeter.They are installed on the end walls of the "Shelter" facility according to the assembly diagram.In the places of temperature seams on both sides of them, control marks are installed.
When laying sedimentary marks, the conditions of access to them and the possibility of attaching a leveling rail to them should be considered, as a rule, at 0.4-0.8m from the level of the intersection or the level of the clean floor.Sediment deformation marks should be painted with indelible masking paint, numbered, and tied to the corners of the walls or protrusions according to the scheme [2].
3 Observations at the points are performed in groups of 4-5 directions to eliminate errors of focus change during one reception of observations due to different distances and errors of closing the horizon.Angular measurements are carried out by high-precision tacheometers [3].Angles and lines are measured by the method of tunnel triangulation of the 1-T discharge and tunnel trilateration of the 1-T discharge, respectively.The scheme of determining the spatial position of control marks from the points of the plan-altitude network is shown in figures 2 and 3.

Result
Processing of the results is carried out using the CREDO software complex, which allows performing in-camera processing of traditional geodetic measurements and post-processing results of satellite measurements of various accuracy classes in the selected coordinate system with the possibility of considering the geoid model and a complex of reduction corrections.Moreover, various geodetic constructions are performed in the system [4].The CREDO software product allows importing data from field measurements obtained from electronic tacheometers within accepted formats.After entering the initial data and importing the measurements, the CREDO system automatically recognizes and separates the data by types of measurements and forms the network connections.
The system pre-processes the measurements, calculates, considers the necessary corrections and reductions, and calculates the preliminary coordinates of the points.If necessary, the system allows you to detect, localize and neutralize gross errors in the coordinates and heights of the starting points, linear and angular measurements, and leveling using several methods, including the analysis of the MSE (mean square error) of a unit of weight, automatically in dialog and automatic (tracing) modes by the method of sequential exclusion [5].
The CREDO program analyzes and interprets the results of repeated geodetic measurements during the observation of deformation and sedimentary processes.The program can be used to monitor the condition of buildings and structures, monitor deformation and sedimentary processes, control dangerous areas and solve other local tasks, such as the executive survey of crane tracks, calculation of the deformation of tower-type structures, etc.It is possible to work with graphical data on a plane (2D) and view the deformation surface in a 3D format, both in a static mode and in the dynamics of changes according to the observation cycles [6].
The export of digital models of the terrain, situation, and project solutions made in CREDO systems is implemented in DXF (AutoCAD), MIF / MID (MapInfo), and TXF / SXF (Panorama) format files.At the same time, information about point marks, as well as point, linear, and planar thematic objects is transmitted [7].
After the obtained results of the sediment marks survey, the exported file is uploaded to the CREDO program.As a result, an array of directed vectors to the corresponding points with starting points and names of observation points is obtained (figure 4).Next, the file is exported to the AutoCAD software package, where a vector display of the directions of the monitoring points is obtained (figure 5).
Vector directions intersect to form a triangle of measurement error from different survey points (minimum three) under the same observation conditions.At the intersection point of the medians is the center of the observation point (figure 6), where the coordinates of the X and Y point are determined (figure 8).Then the obtained results are entered into the table of observations according to the cycle the geodetic monitoring was carried out.
Since the beginning of the observations, the horizontal movements of 10 control marks of the northern wall of the "Shelter" facility amount to 28 mm on average with the northern direction of the vector.The mark M-18 (figure 8) has the maximum horizontal movements -34 mm from the beginning of observations.
The average horizontal movements of the control marks (M-16, M-20) of the northwest corner from the beginning of observations are 31 mm with the northern direction of the vector.At the same time, the maximum values of horizontal movements are 33 mm (the M-16 mark).
The average horizontal movements of control marks M-4 and the "Pin" of the roof of the central hall from the beginning of observations is 19 mm with the northern direction of the vector.The maximum values of horizontal movements are 24 mm (for the M-4 mark).The control marks of the MKU tower along the Z row received average horizontal movements from the beginning of observations -8 mm with the north-west direction of the vector, and the marks of the P row got respectively 9 mm with the west direction of the vector.The control Control marks M-50Z and M-50P on the wall axis 50 have received horizontal displacements of 5 mm and 13 mm from the initial observation.The horizontal displacement of the new control marks on the southern wall of the machine hall in row A, from mark M-302 to M-312, during the observation period ranges from 2 mm to 10 mm.The horizontal displacement of the control mark on the western wall of the machine hall on axis 68, mark M-301, has become 6mm since the beginning of the observation.
Analysis of the magnitudes of horizontal and vertical displacements of control marks indicates that the process of deformation is taking place in the object and adjacent buildings and structures.

Conclusion
The analysis of the horizontal and vertical movements of the control marks shows that the deformation process of the "Shelter" object and its adjacent buildings and structures continues.
For the analysis of movements of control marks "over a year", operational limits of safe operation are established, since geodetic measurements are equalized between observation same seasons "over a year" with minor fluctuations in measurement temperatures.The obtained results will be used as input data for tracking the dynamics of movements, the stability of building structures and taking timely measures to prevent the destruction of structures, and forecasting emergencies of the "Shelter" facility, as well as its adjacent buildings and structures.The values of movements of the control marks of the structures of the northern cascade wall for the annual period, between the seasonal observations of the same name, do not exceed the permissible parameters of movements established by regulatory documents.
The use of GIS technologies allows for fast data processing, reduces the workload on the employee, and makes it impossible to make mistakes during data processing and analysis.With the help of the CREDO software complex, the processing of the results of geodetic surveying of monitoring points reduces the time burden, which allows for a more in-depth analysis of deformation processes, which, in turn, makes it possible to timely identify critical indicators, if any, during data analysis.

Figure 1 .
Figure 1.The scheme of the location of control marks at the "Shelter" facility.

Figure 2 .
Figure 2. The scheme for determining the spatial position of control marks of the northern cascade wall from the points of the plan-elevation geodetic network at the "Shelter" facility.

Figure 3 .
Figure 3.The scheme for determining the coordinates of control marks.

Figure 4 .
Figure 4. Data processing in the CREDO program.

6 Figure 5 .
Figure 5.A vector display of directions of monitoring points.

Figure 6 .
Figure 6.An error triangle, the center of the observation point.

Figure 8 .
Figure 8.The values of horizontal and vertical movements of control marks of the "Shelter" object.