When assembling prefabricated structures, the geodesic service is entrusted with the task of providing the building being erected with all types of breakdowns necessary for the high-quality installation of structural elements, as well as monitoring the compliance of the geometric parameters of the assembled structures with their design values.
The basis for the transfer in nature and consolidation of the design parameters of the building, the production of detailed center works during the assembly of elements and executive surveys of prefabricated structures is the external center network of the building. Prior to the start of work on the installation of structures of the underground part of the building, the axis of the axis is transferred to the obnojka, the position of the axes and the elevation are transferred from it to the bottom of the excavation.
Upon completion of work on the foundations of the foundations produce a control reconciliation of the planned and altitudinal position of the foundations, make up an executive drawing. When installing the ground part of the building, the following geodetic processes are performed:
■ creating a center geodesic plan with fixing the axes on the building with the possibility of transferring these axes to the floors;
■ vertical transport of the main center axes to the overlap of each floor, i.e., to a new installation horizon;
■ breakdown on the overlap of each installed floor of intermediate and auxiliary axes; ,
■ markings of installation risks necessary for the installation conditions;
■ definition of the installation horizon on the floors;
■ drawing up a floor-by-floor executive scheme.
The necessary geodetic measurements are performed by levels, theodolites, zenith-instruments, using auxiliary equipment.
The level is a geodesic device for determining the relative height of points, transferring marks from geodetic marks to a construction site, determining a floor-by-level mounting horizon, i.e., estimating the relative position of the main points on the floor plan.
A theodolite is a geodetic optical instrument for measuring or fixing horizontal and vertical angles in nature. It is widely used to transfer the main center axes from the ground level to the floors of the building.
The Zenith device is intended only for shifting the axis strictly vertically. When erecting multi-storey buildings and structures, determining the position of the base elements on each floor is found oi crosshairs of the main axes of the building. The Zenit device is intended only for projecting onto a new mounting horizon with the help of an optical beam passing through the main axes.
Laser equipment is used for geodetic works - theodolite lasers, levels, instruments of vertical projection, range finders, tacheometers. The principle of using laser systems to perform the centering work when installing multi-storey buildings is to place a special reflector and a number of such reflectors on the ground floor level along the path of the laser beam, and parallel to the longitudinal axis of the building - a laser theodolite. The laser beam hits the lower reflector, from it at right angles goes to the upper reflector, then goes to the receiving equipment installed on the mounted elements, such as columns. Columns can be equipped with special reflectors, which will allow to control the installation accuracy of the elements by deflecting the beam.
The use of laser technology can significantly simplify the quality control of installation work. The accuracy of the projection by the laser beam does not depend on the distance and allows you to get more accurate results compared to existing geodetic instruments.
To ensure the reliability and high quality of the erected buildings and structures, constant geodetic control of the accuracy of the installation of prefabricated elements in the design position is of great importance. By types of mounted elements, by hooks and floors, an executive survey is carried out - a geodetic check of the actual position of the structures in the plan and in height. According to the geodetic survey, an executive drawing is compiled, according to which the accuracy of the installation is assessed. The correctness of installation of structures is checked with the help of geodetic tools and templates for previously applied axial and other risks and marks.
When installing large-panel buildings for each floor, an executive scheme of deviations from the design position of the installed structures is made. To check the correctness of the installation of structures even when marking the axes and orientation risks, calculate, record and mark the distance at which the structural element from the risks should be located. After installing and fixing the element, measure the distance and calculate deviations from the design dimensions. This distance is recorded on the scheme of the executive survey, judging by its magnitude on the accuracy and quality of installation.
As the building is erected, an executive survey of the alignment of the carrier panels is made. In accordance with these data when installing the next floor make the necessary changes in the position of structures.
When installing frame buildings after the installation of columns of the next tier constitute the executive scheme of the installation of columns. The diagram fixes the marks of the supporting surfaces of the columns of each tier, placed in the center of each column. The displacement of the axes of the columns from the center axes of the building is also calculated, which is checked on all four faces and placed in the diagram on the corresponding faces of the columns.
The verticality of single tall columns is checked after their installation with the help of two theodolites located at right angles along the numerical and letter axes of the building. Cross strings of both theodolites suggest risks noted on the basement glass and the bottom of the column; then smoothly lift the pipe to the risks at the top of the column. The coincidence of the cross threads with the top risk means that the column is installed vertically. After checking the verticality of the row of columns, the upper planes of their consoles and ends, which are supports for the overlying elements, are leveled.
Что бы оставить комментарий войдите
Комментарии (0)