When the detailed design has passed the examination, when all the necessary permits and approvals have been received, when the construction site is fenced, geodetic work begins on locating the main and main axes of the future building to begin excavation work.

The erection of building structures begins with the process reverse to design - with the transfer of the design of the structure (its geometric diagram) into nature, i.e. from placing and securing alignment axes on the ground. Therefore, geodetic work on transferring projects of buildings and structures is called geodetic layout of the building (structure).

The alignment axes together represent the geometric diagram of buildings and structures. They are a geodetic (geometric) basis by which elements of building structures and technological equipment are oriented when installing them in their design position. The system of alignment axes plays approximately the same role as the coordinate grid on maps and plans.

The main axes are mutually perpendicular lines, relative to which the building or structure is symmetrical. They are divided for objects that are complex in outline and have significant dimensions. The main axes define the outline of a building or structure in plan.

The axes are divided into longitudinal and transverse (Fig. 3, b).

Figure 3. Schemes of alignment axes

Longitudinal ones are designated by capital letters of the Russian alphabet, transverse ones by numbers. The alignment axes are divided into main ones - axes of symmetry (they are designated for buildings and structures with complex configurations); main or overall (Fig. 5, b) designated A, B and 1, 6. All other axes are intermediate.

The spacing of the alignment axes, i.e., the interaxial intervals, are set in accordance with the module adopted in the design diagram of the building or structure being designed, taking into account its design features. When designing, structural elements are tied with dimensions b and l to the lines - the alignment axes A and 1 (Fig. 5, a).

The process of transferring the dimensions of a building or structure involves the sequential construction of alignment elements on the ground, monitoring the accuracy of the construction and securing the main axes.

So, in accordance with the breakdown data in Fig. 2, at the vertex T8, a polar angle is built with a theodolite and then a polar distance d 8-AI is constructed with a steel compensated tape measure. Dimensional point AI is temporarily secured (with a peg, a piece of reinforcement, etc.). Similarly, from point T9, point AII is taken out and secured.

At points AI and AII, design right angles are constructed, an overall dimension of 12.00 is set aside, and points VI and BII are fixed. By notching the polar distance of points BII from T10, the correct orientation of the building relative to the reference points is checked. For control, the side VI-VII and the angles at the vertices VI and VII are measured. Additionally, the accuracy of constructing dimensions is assessed by measuring the diagonals.

Sometimes, an executive (control) polygonometric or theodolite traverse is laid using the dimensional points, and the accuracy of the constructions is judged by the differences between the executive and calculated coordinates of the points. Requirements for the accuracy of constructions are contained in the relevant regulatory documents, of which the main one is SNiP 3.01.03 - 84.

When transferring the dimensions of buildings and structures from existing permanent structures, the design dimensions determined graphically according to the general plan of the development site serve as the layout data. In Fig. Figure 3 shows one of the layout options for the designed building P with dimensions in axes A, B, 1, 7 and a common facade line with the supporting existing building I.

Let the building being designed be separated from the supporting one at a distance of d 1 , and the outer edges of its walls be separated from the axes by the design dimensions d 2 and d 3 . A theodolite is installed near the end wall of the supporting building at an arbitrary distance L 1 from the longitudinal wall at point b.

Figure 4. Scheme of the breakdown of the main axes of the development object (II) from the existing building (1).

Using a spotting scope, they sight at point a, which is also at a distance of L 1 from the wall, build a right angle, fix point b 1 on the wall with a line and measure the distance l 1 from it to the corner of the building. Using a theodolite, the alignment of the base line ab, parallel to the wall of the supporting building, is continued, and from point b, a design segment equal to l 1 + d 1 + d 2 is built, point b is fixed, and from it, in the same alignment, the overall dimension between axes 1 and 7 is laid down, fixed point d. At point b, a right angle is constructed with a theodolite, a segment of length L 2 =L 1 -d 3 is laid out and point A1 is fixed along axis 1; Along the alignment of this axis, the overall dimension is laid down between axes A and B and point B1 is fixed. Points A7 and B7 are placed in the same way. Then, to assess the accuracy of constructing dimensions, control measurements are made. The process of transferring the dimensions of buildings from the red line or building line differs little from that described.

Figure 5. Methods for securing the main axes

The main alignment work is completed by securing the axes outside the future pit, since during its development all dimensional points will be destroyed. To do this, special axial marks 1 are placed in the alignment of the main axes (Fig. 4, a) and with a theodolite installed at the overall points A1 and G9 or A9 and G1, the main axes are transferred to the signs, where they are fixed on a metal plate with a cross-shaped notch or a cored recess .

One of the sign designs is shown in Fig. 4, b. Signs are laid outside the ground collapse prism when the excavation is open, in places where their safety will be ensured, and in accordance with the construction plan. The axles are secured on both sides of the dimensions of the structure with at least two signs. The signs are tied by measurements to local objects.

If there are permanent buildings, fences, etc. in the alignment of the axes, the axes on their walls are marked with bright indelible paint 2 (Fig. 4, a).

Geodetic alignment is carried out in two stages.

At the first stage, called “main alignment work”, relying on a geodetic basis or existing capital structures, the main and main axes are transferred into nature. As a result, only the general position of the structure is determined relative to the points of the geodetic basis or existing buildings.

The accuracy of transferring the dimensions of structures must be no less than the accuracy of the plan on which it is designed.

The accuracy of transferring the dimensions of structures can be increased if this is determined by the design, such as in the case when the structures are technologically connected to each other and increased demands are placed on the accuracy of their relative positions.

The second stage - “detailed breakdown of axes” consists of identifying and fixing in nature intermediate axes or lines parallel to them. Detailed layout is carried out with an accuracy higher than the main layout work. This is due to the fact that structural elements installed along the axes are required to be almost completely mated without additional adjustment in place. The accuracy of the detailed breakdown is determined by special calculations, taking into account the accuracy of manufacturing and installation of the elements. Detailed work ensures the fixation of the configuration, dimensions and elevations of building elements.

The pit is laid out before digging it out along a plumb line with stretched wires, marking its boundaries with pegs.

For a detailed breakdown of the axes of buildings, marking the contour of the pits and securing them on the ground, a construction cast-off is used. It can be continuous around the entire perimeter of the building or discontinuous. Intermittent wear is more convenient, as it does not impede the movement of construction vehicles and vehicles on site. During the construction process, the positions of castings and alignment marks on the ground are periodically monitored. Dressing device, securing axes (Fig. 6, 7).

On slopes, cast-offs are arranged with ledges.

Figure 6. Layout device and fastening of axes: a - diagram of the pit layout; b - cast-off elements; 1 -- cast-off made of wooden elements; 2 -- pin - a control sign for fixing the axle on the ground; 3 -- edged board; 4 -- a nail for securing the axle to the cast-off; 5 -- cast-off rack

The cast-off is installed using geodetic tools parallel to the main axes that form the external contour of the building at a distance that ensures that its position remains unchanged during the construction process.

The cast-off is a frame of pillars driven into the ground at a distance of 3 m from each other. From the outside, edged boards with a thickness of 40...50 mm are nailed to the pillars with the wide side, each of which rests on at least three posts. The top edge of all boards is placed horizontally, which is controlled using a level. The optimal height of the cast-off is 0.5...1.2 m. Structurally, the cast-off can be made of wood or metal. Advantages of metal cast-off: it is convenient to use, easy to dismantle and has multiple turnover.

The distance from the edge of the pit to the cast-off must be at least 3...4 m. This distance is checked by calculation based on the condition that when the pit is pulled out, the stability of the cast-off is not disturbed. The cast-off borders the future building parallel to its sides; gaps are created in it for the passage of people and the passage of vehicles.

To mark the axes on the cast-off, the theodolite is installed and oriented along it. Then, they transfer it with a pipe and secure the axles with nails on the edges of the cast-off boards. All constructions with a theodolite are made at two positions of the circle, each time a point is marked and, if there is an acceptable discrepancy in their position, the average one is accepted and finally fixed. The final position of the axes on the cast-off is fixed with nails, outlined with oil paint and their numbers are signed.

Figure 7. Construction of an intermittent cast-off (bench cast-off)

Regardless of the type of cast-off, it must meet the following requirements: its sides must be parallel to the longitudinal and transverse axes of the structure, and the boards must be straight and horizontal. The degree of compliance with these requirements depends on the accuracy of the axes on the cast-off.

All data from the alignment drawing is taken out for cast-off, in particular, the main axes of the building are taken out and secured with nails; the axes themselves, longitudinal and transverse, are made using a tightly stretched wire or cord, which is secured to these nails. The edges of the future pit are taken out from the axes of the walls and marked with nails on the same cast-offs. The edges themselves are also carried out using wire “in nature”.

The intersection of the wires of the longitudinal and transverse directions of the axes determines the intersection points of the main axes of the building, which are checked with a plumb line and which must coincide with points previously fixed on the ground, determined using geodetic instruments.

At some distance from the cast-offs on which the main axes of the building are fixed, in case of their damage and in order to easily find the sign of fixing the axis during work, pins are usually installed - control signs of fixing the axial lines. Usually these are reinforcing bars driven into the ground at a distance of 5...10 m from the cast-off and protruding 2...6 cm above the ground surface.

The cast-offs are preserved only for the period of construction of the underground part, after which the alignment axes are transferred directly to the building under construction. In modern conditions, with the presence of laser geodetic instruments, cast-offs can be installed much less frequently, and the axes can be depicted (fixed) on temporary buildings and structures of the construction site (inventory rooms, fences, etc.).

Also at the construction site, the mutual perpendicularity of the axes is checked. Deviation from a right angle is allowed no more than 60”. For large deviations, it is necessary to move the nearest point slightly. It should be borne in mind that the mutual perpendicularity of the main axes is one of the main requirements for their layout, since the misalignment of these axes will subsequently lead to the misalignment of all other axes of the structure.

The axes of the structure must be laid out relative to each other with an error of the order of ±5 mm. The accuracy of geodetic work should be ±1-2 mm.

Errors that depend on the method of constructing design lines and angles in nature are called alignment errors.

Alignment axes, installation (indicative) marks should be applied from the signs of the external or internal alignment networks of the building (structure). The number of alignment axes, installation marks, beacons, their locations, and method of fastening should be indicated in the work project or in the geodetic work project.

The internal alignment network of a building (structure) is created in the form of a network of geodetic points on the initial and installation horizons of the building (structure). The type, layout, accuracy, and method of fixing the points of the internal alignment network of a building (structure) should be given in the work project or in the geodetic work project.

The creation of an internal alignment network of a building (structure) on the initial horizon should be carried out with reference to the points of the external alignment network, and on the installation horizon - to the points of the internal alignment network of the initial horizon.

The correctness of the marking work must be checked by laying control geodetic passages (in directions that do not coincide with those accepted during the laying out) with an accuracy no lower than during the laying out.

The results of measurements and constructions when creating an internal alignment network on the original and installation horizons should be recorded by drawing up diagrams of the location of signs that fix axes, marks and landmarks.

When transferring individual parts of a building (structure) from one construction and installation organization to another, the signs necessary for subsequent geodetic work, securing the axes, marks, landmarks and materials of as-built surveys must be transferred according to the act.

A detailed breakdown is made on the basis of the removed main axes of the structure in accordance with the stages of construction and installation work: for excavation work, construction of foundations and communications, construction of the above-ground part of buildings and structures and installation of technological equipment.

Immediately before the start of alignment work, the contractor checks with control measurements the inviolability of geodetic signs that secure the basis of alignment work - points for securing the main axes, construction grid, etc.

The accuracy of the detailed breakdown depends on the type and purpose of the structure, the material used to make the parts, the technology of their construction or assembly, etc. It is usually required that the maximum errors of geodetic measurements when laying out and monitoring the accuracy of the position of structural elements do not exceed 33% of the tolerance for construction and installation work. Errors in the horizontal position are considered relative to the alignment axes, and in the high-altitude position - relative to the nearest working reference points. At the same time, they try to maintain the relative position of the axes and structural elements of the structures specified in the project, both in terms of plan and height.

To control the inviolability of the cast-off during the construction process, the main axes are additionally secured with ground marks placed under the cast-off. Control is carried out using a plumb line. To preserve cast-offs, they are sometimes built after preparing the foundation pit.

Having completed the work on laying out and securing the main axes, an as-built drawing is drawn up, on which the following is applied:

a) points of the construction grid from which the main axes are divided according to coordinates, indicating the order in which the latter are divided;

b) cast-off with the location of the axes and indicating the distances between them according to the results of control measurements;

c) axle mounting marks.

The breakdown is drawn up in an act, to which is attached a diagram of the location and fastening of the axes, including the starting points of the geodetic basis, indicating the results of control measurements.

The angular notching method is used to lay out inaccessible points located at a considerable distance from the starting points.

There are direct and reverse corner serifs. In the direct angular intersection method, the location of the design point on the ground WITH (Fig. 1) are found deposited at the starting points A And IN design angles 1 and 2. The basis of the notch is either the specially measured side or the side of the alignment network. Design angles 1 and

2 is calculated as the difference between the directional angles of the sides. Directional angles are found from solving the inverse geodetic problem using the design coordinates of the point being determined and the known coordinates of the starting points.

Figure 1 - Layout scheme using straight and linear notches Reverse corner cutting method. Approximate position is found on the ground ABOUT" point to be staked ABOUT (Fig. 2). At this point, a theodolite is installed and angles are measured with the required accuracy to at least three starting points with known coordinates. Using resection formulas

calculate the coordinates of an approximately certain point and compare them with the design values. From the difference in coordinates, the reduction values ​​(angular and linear elements) are calculated and the point is shifted to the design position.

To control the angles at this point, calculate its coordinates again and compare them with the design ones. In case of unacceptable discrepancies, all actions are repeated.

1. Figure 2 - Scheme of the reverse corner cutting method

Linear notching method In the direct angular intersection method, the location of the design point on the ground

In the linear intersection method, the position of the point to be staked out (see Fig. 1) are determined at the intersection of design distances 1 S (see Fig. 1) are determined at the intersection of design distances 2 And (Fig. 1) are found deposited at the starting points, plotted from the original points And IN.

This method is usually used to lay out the axes of building structures in cases where the design distances do not exceed the length of the measuring device. (Fig. 1) are found deposited at the starting points It is most convenient to carry out the breakdown using two tape measures. From point (see Fig. 1) are determined at the intersection of design distances 1 measure the distance using a tape measure And, and from the point (see Fig. 1) are determined at the intersection of design distances 2 on the second roulette − (Fig. 1) are found deposited at the starting points, plotted from the original points And, . Moving both roulettes with the zeros aligned with the centers of the points (see Fig. 1) are determined at the intersection of design distances 1 at the intersection of the ends of the segments 2 and S find the position of the point to be determined

WITH.

2.3 Polar coordinate method

The method of polar coordinates is widely used when laying out the axes of buildings, structures and structures from points of theodolite or polygonometric traverses, when these points are located relatively close to the points taken out into nature. In the direct angular intersection method, the location of the design point on the ground(Fig. 3) are found on the ground by deposition from the direction AB design angle and distancesS. The design angle is found as the difference between the directional angles α AB and α AC, calculated as well as the distance S from solving inverse problems using the coordinates of points A, B A find the position of the point to be determined To control the position of a fixed point In the direct angular intersection method, the location of the design point on the ground can be checked by measuring at the point And angle β" and comparing it with the value obtained as the difference between the directional angles α BA and α BC.

Figure 3 - Layout scheme using the polar coordinate method

If the point to be laid out is located at a considerable distance from the starting point, then it is necessary to postpone the design angles and distances several times using the polar method, laying out the design course (Fig. 4). If there is direct visibility from the Sleep point, the point And for control, adjacent angles are measured And , forming a closed corner polygon, which is why this method is called using the design site method. During precise alignment work, the corners of the polygon are equalized, the coordinates of point C are calculated from them and the design distances, they are compared with the design ones and, if necessary, reduced to the design position.

With a sparse alignment, the design polygon method can be used to lay out all intersection points of the main axes of a structure from one starting point. In this case, the design path with the design angles and distances is laid completely.

Figure 4 - Scheme of laying out the design polygon using the method

Basic methods and methods of marking work

The layout of individual elements of a structure is carried out from well-fixed points and lines of the support network on the ground or from the points of the main alignment axes of the structure.

In the breakdown, the methods of rectangular coordinates (perpendiculars), polar coordinates, bipolar coordinates (angular, linear, combined and cross-sections), alignments and measurements can be used.

Breakdown and transfer of construction projects into nature according to their actions inverse to geodetic survey work.

The angular notching method is used to lay out inaccessible points located at a considerable distance from the starting points.

There are direct and reverse corner serifs.

In the direct angular notching method the location on the ground of the design point C (Figure 6) is found by deposition at the starting points (Fig. 1) are found deposited at the starting points, plotted from the original points And design angles β 1 and β 2. The basis of the notch is either the specially measured side or the side of the alignment network. The design angles β 1 and β 2 are calculated as the difference between the directional angles of the sides. Directional angles are found from solving the inverse geodetic problem using the design coordinates of the point being determined and the known coordinates of the starting points.

Figure 6 - Layout scheme using straight angular and linear serifs

The accuracy of the stakeout using the direct angular intersection method is influenced by the errors of the straight intersection itself, the initial data, the centering of the theodolite and sighting targets, and the fixation of the stakeout point, i.e.

The mean square error of the notch itself is equal to

(15)

, (16)

where m β - root mean square error of deposition of angles β 1 and β 2.

For approximate calculations, take S 1 = S 2 = S. Then formula (16) will look like:

. (17)

During alignment work, centering the theodolite and sighting targets using optical plummets and fixing the set-out point can be performed relatively accurately. Therefore, the main errors that determine the accuracy of the direct angular intersection method are the errors of the intersection itself and the source data. The total value of these errors will be:

. (18)

The use of the reverse corner intersection method for staking is also based on the principle of reduction. . Approximate position is found on the ground Reverse corner cutting method. Approximate position is found on the ground split design point point to be staked(Figure 7). At this point, a theodolite is installed and angles are measured with the required accuracy to at least three starting points with known coordinates. Using resection formulas, the coordinates of an approximately certain point are calculated and compared with the design values. From the difference in coordinates, the reduction values ​​(angular and linear elements) are calculated and the point is shifted to the design position. To control the angles at this point, calculate its coordinates again and compare them with the design one. In case of unacceptable discrepancies, all actions are repeated.

To calculate the coordinates of a point Reverse corner cutting method. Approximate position is found on the ground you can use the formulas of Delambert and Gauss. In relation to (Figure 7), they will look like:

The accuracy of the stakeout using the reverse angular intersection method is influenced by the errors of the intersection itself, the initial data, the centering of the theodolite and sighting targets, fixing the stakeout point and reduction. Obviously, at relatively large distances from the target to the reference points, the influence of the first two sources will be the most significant; other errors can be neglected.

Figure 7 - Scheme of the reverse corner cutting method

The error of the resection itself can be calculated using the approximate formula:

(21)

Where (see Fig. 1) are determined at the intersection of design distances - distance from the identified one to the corresponding support points;

b - the distance between the corresponding support points;

ω bac- the angle between the original sides.

Source data errors are taken into account using the formula:

(22)

Where t A = t in = t c = t ABC – error in the position of the starting point;

τ = β 1 + β 2 + ω VAC – 180 0.

In the linear intersection method, the position of the point C to be set out into nature (Figure 6) is determined at the intersection of the design distances (see Fig. 1) are determined at the intersection of design distances 1 and S 2 plotted from the original points (Fig. 1) are found deposited at the starting points, plotted from the original points And This method is usually used to lay out the axes of building structures in cases where the design distances do not exceed the length of the measuring device.

It is most convenient to carry out the breakdown using two tape measures. From point (Fig. 1) are found deposited at the starting points measure the distance using a tape measure (see Fig. 1) are determined at the intersection of design distances 1 , and from the point And on the second roulette - (see Fig. 1) are determined at the intersection of design distances 2 . Moving both roulettes with the zeros aligned with the centers of the points (Fig. 1) are found deposited at the starting points, plotted from the original points IN, at the intersection of the ends of the segments (see Fig. 1) are determined at the intersection of design distances 1 , plotted from the original points (see Fig. 1) are determined at the intersection of design distances 2 find the position of the determined point C.

The error of the actual linear intersection with the same accuracy m s deposits of distances S 1 and (see Fig. 1) are determined at the intersection of design distances 2 can be calculated using the formula:

The minimum error of the actual linear notching will be at the angle γ = 90°. In this case

The influence of source data errors in a linear intersection is expressed by the formula:

. (25)

When m A = m B = m AB

For serif at γ = 90° m out = m AB.

When using measuring instruments, there are no centering errors. Then the total error in determining the position of the staked point C will mainly depend on the total error of the intersection itself and the initial data and is expressed by the formula:

. (27)

For approximate calculations, taking γ = 90°, we will have

. (28)

If rangefinder kits are used for linear notching, which are centered using tripods, then the effect of centering errors can be determined by the formula:

The method of polar coordinates is widely used when laying out the axes of buildings, structures and structures from points of theodolite or polygonometric traverses, when these points are located relatively close to the points taken out into nature.

In this method, the position of the determined point In the direct angular intersection method, the location of the design point on the ground(Figure 8) are found on the ground by deposition from the direction AB design angle β and distance (see Fig. 1) are determined at the intersection of design distances. The design angle β is found as the difference between the directional angles α AB, plotted from the original points α AC, calculated as the distance (see Fig. 1) are determined at the intersection of design distances from solving inverse problems using point coordinates A, B And WITH. To control the position of the fixed point C, you can check it by measuring at the point And angle β" and comparing it with the value obtained as the difference in directional angles α VA, plotted from the original points α sun.

The mean square error of setting out point C is determined by the formula

Figure 8 - Layout scheme using the polar coordinate method

The error of the polar splitting itself depends on the error t β construction of angle β and errors m s deposits of design distance S

. (31)

The influence of source data errors when t A = t b = t AB expressed by the formula:

, (32)

and centering errors

. (33)

Formulas (32) and (33) are similar. It follows from them that to reduce the influence of errors in the source data and centering it is necessary that the angle β and the S/b ratio were minimal, the polar angle would be less than a right angle, and the design distance would be less than the layout basis, i.e. β 90°, (see Fig. 1) are determined at the intersection of design distances b.

For approximate calculations, taking β = 90° and (see Fig. 1) are determined at the intersection of design distances = b, we get

(34)

and for the total error in the position of a point divided by the polar coordinate method,

(35)

If the point to be laid out is located at a considerable distance from the starting point, then it is necessary to postpone the design angles and distances several times using the polar method, laying out the design course (Figure 9). If there is direct visibility from the point In the direct angular intersection method, the location of the design point on the ground per point And for control, the adjacent angles γ 1 and γ 2 , forming a closed corner polygon. Therefore, this method is called the design polygon method . During precise alignment work, the corners of the polygon are equalized, and the coordinates of the point are calculated from them and the design distances WITH, compare them with the design ones and, if necessary, reduce them to the design position.

Figure 9 - Scheme for laying out the design polygon using the method

With a sparse alignment, the design polygon method can be used to lay out all intersection points of the main axes of a structure from one starting point. In this case, the design path with the design angles and distances is laid completely.

The methods of alignment and alignment-linear notches are widely used for setting out the alignment axes of buildings and structures, as well as the installation axes of structures and technological equipment.

Design point position In the direct angular intersection method, the location of the design point on the ground in the step serif method determined at the intersection of two alignments defined between the starting points 1-1" , plotted from the original points 2-2" (Figure 10). The alignment is usually set with a theodolite, which is centered above the starting point (for example, 1), and the telescope is oriented towards the sighting target, centered on another starting point (in this case - 1"). Point position In the direct angular intersection method, the location of the design point on the ground fixed in a given alignment.

The root mean square error of the alignment depends on the errors in the construction of the first m c1 and the second m c 2 alignments, as well as fixation errors

Figure 10 - Schemes of laying out using the alignment (a) and

folding-linear (b) serifs

The main errors when constructing each of the alignments are errors in the position of the starting points, errors in the centering of the theodolite and sighting targets, sighting errors and changes in the focusing of the telescope when pointing at the sighting target and at the determined point, i.e.

Errors in the position of the starting points for setting a target have meaning only in the direction perpendicular to the target, i.e., for each target along one of the coordinates X or u. Their influence is determined by the formula:

, (38)

Where d- distance from the theodolite installation point to the determined point;

(see Fig. 1) are determined at the intersection of design distances - the distance between the starting points (alignment length).

The combined influence of errors in the centering of the theodolite and the sighting target is expressed by the formula:

. (39)

Analyzing formulas (38) and (39), we can conclude that errors in the initial data and centering have the least impact on the position of the determined point in the middle of the alignment. As it approaches its starting points, these errors increase.

When constructing a target, you have to sight twice: first at the sighting target installed at the starting point, then at the target that fixes the position of the point being set on the target. In both cases, the linear value of the sighting error for the determined point will be proportional to the distance d from the theodolite to this point. Therefore, for alignment structures, the sighting error (in mm) will be equal to

. (40)

When constructing a alignment, you have to sight at points located from the theodolite at different distances, which leads to the need to change the focusing of the pipe. Changing the stroke of the focusing lens causes a displacement of the sighting axis of the pipe and leads to an error that must be taken into account during precision work.

In modern high-precision theodolites, the error due to tube refocusing is approximately equal to the sighting error. Therefore, for approximate calculations one can take t fork = t visas Taking this into account, the combined influence of sighting and focusing errors during alignment formations can be expressed by the formula:

. (41)

Sliding-linear method allows you to determine the design position of point C to be set out in nature (Figure 10) by plotting the design distance d along the target AB.

The method of rectangular coordinates is used mainly when there is a construction grid on the site or in the workshop of an industrial enterprise, in the coordinate system of which the position of all the main points and axes of the project is specified.

The breakdown of the design point C (Figure 11) is carried out according to the calculated increments of its coordinates ∆х, plotted from the original points ∆у from the nearest grid point. Larger increment (in the figure - ∆у) laid down along the alignment of grid points AB. At the resulting point D install a theodolite and build a right angle from the side of the grid. A smaller increment is laid along the perpendicular and the resulting point is fixed find the position of the point to be determined To control the position of the point In the direct angular intersection method, the location of the design point on the ground can be determined from another point on the construction grid.

The scheme of the rectangular coordinates method essentially combines the scheme of the linear and polar methods.

Figure 11 - Layout scheme using the rectangular coordinate method

Mean square error in point position WITH, determined by the method of rectangular coordinates, can be expressed by the formula:

, (42)

where m ∆ x, and T∆у - errors in deposition of coordinate increments.

If the ordinate is plotted along the perpendicular, then in formula (42) the quantity ∆х is replaced by ∆у.

The influence of errors in the position of the starting points provided TA = TB = m AB expressed by the formula:

, (43)

and centering errors

, (44)

Where b - side length of the construction mesh.

The construction of a house begins with laying it out in kind. Laying out the foundations begins after clearing the right-of-way from trees, stumps, shrubs and removing the vegetation layer. Laying out a house, or transferring the project to nature, is geodetic work performed on the ground to determine the actual position of the main points of the house under construction (in plan and height).

The house on the site is tied to known points or an existing building and to the red line. The breakdown work is carried out in two stages.

First stage:

• detailed breakdown of the subgrade of the house construction site
• transferring to the terrain the projection of the edges and boundaries of earthen slopes of embankments, excavations and drainage structures
• At the obtained points of the planned layout, sighting towers are installed, to which the high-altitude elements of the broken canvas are transferred by geometric leveling

Second phase:

• securing a detailed layout with alignment extensions beyond the border of the right-of-way in order to be able to subsequently restore detailed layout points if they are lost on the ground
• the most important alignment line is the axis of the structure (I-I and II-II), which is hung across the terrain using poles and fixed on the ground with benchmarks

The following elements of alignment work are most often repeated:

• construction of design angles (performed using a theodolite)
• deposition of design distances (measuring tools)
• placing design marks into reality (level, theodolite)

Transferring the house plan to the area

The transfer of individual points and lines of house corners to the terrain is carried out depending on local conditions in one of three ways:

For flat areas of house construction

1. The method of rectangular coordinates is used when there is a construction coordinate grid (on a site with its boundaries marked in kind).
2. One of the sides of the house, for example AB, is taken out at its extreme points by laying out segments at right angles from the nearest axes of the coordinate grid.
3. The remaining sides are laid off from segment AB using a surveying tool and a measuring steel tape.

For areas with complex, mountainous terrain

The angular notching method is used when measuring lines is impossible due to obstacles on the ground or when the points to be determined are located in different planes and are separated from the main points by a space difficult to measure.

In this case, to transfer points A and B (whose coordinates are known) to the terrain, calculate the values ​​of angles a, b, c, d, and transfer them to reality using a polygonometer.

Points A and B are obtained at the intersection of two straight lines:

• for point A - lines a1b1
• for point B - lines c1d1

For objects with complex configurations

The polar method is used for structures that have round or other complex shapes, as well as when the measurement of corners and rectangular segments can be carried out from one geodetic reference point.

In this case, the removal of points A, B and C to the area is carried out:

• constructing angles a, b, c and marking off the corresponding segments with a measuring tape - a1, b1, c1.

Laying out the axes of a house on level ground

The breakdown begins:

• from demolishing one axis of the house
• then use a theodolite to construct a right angle
• determine the second axis and also transfer it to the cast-off
• measure the length of the house along this axis on a cast-off piece
• determine the location of the second angle
• build it using a theodolite, etc.

The axes of the house are transferred to cast-offs from the axial markers (marks) fixed on the ground. All marks of the alignment drawing are also transferred to the cast-off around the house.

A plate with the axle number is attached under the clamps and nails.

The axes of the house can also be laid out along the edge or directly along the bottom of the pit.

The marking of the bottom of the pit (trenches) must be marked on the alignment drawing. The stripping is carried out at a distance of 3-5 m from the external walls of the house and at least 1-1.5 m from the edge of the future pit. For passage and passage, gaps 3-4 m wide are left in the cast-offs.

The cast-off consists of pillars firmly buried in the ground to a depth of 1-1.2 m, and nailed to them on the outside with boards 40-50 mm thick (on edge) or scraps of metal pipes.

The distance between the cast-off posts is 2.1-3.2 m, and the height above ground level is 1.0-1.2 m. In the places where the alignment axes are attached, shallow cuts are made in the cast-off boards for better fixation.

The wire or fishing line is usually attached 20-30 cm above the waterproofing layer of the future wall in such a way that it is convenient to use a plumb line when constructing foundations and plinths.

The layout of trenches and pits is laid out taking into account the permissible steepness of earthen slopes. Cast-off posts are installed on a theodolite parallel to the axes of the future house along the entire perimeter. For large house sizes, additional internal demolition is done every 40-60 m.

If there are few alignment axes, you can get by by tying them with separate posts, preferably from scraps of metal pipes. To better fix the axes, the top of the pipes should be sawn to a depth of 3-5 mm, and the pipe itself should be firmly fixed in the ground.

To break down the rounded parts of the building, a wooden sparrow rail is used, movably fixed in the center. The sparrow is moved along special cast-off boards installed along the contour of the round part at a distance of 1-1.5 m from the wall. When building a small house, the axes can be laid out without using a theodolite, by constructing a right triangle with an aspect ratio of 3:4:5.

The axes of trenches and pits, as well as their edges, are determined by pulling the wire. Markings of the bottom of the trench and pits are indicated on cast-offs, benchmark posts or vertically placed boards. The axles are transferred to shallow pits (up to 2 m) as follows:

• according to the marks on the cast-off, a thin wire is pulled, fixing the center axes of the house
• at the intersection point, a plumb line is suspended, projecting the position of the axes onto the bottom of the pit
• the intersection of the axes is secured with a steel pin driven into the ground
• markings determine the outline of the location of the foundation block

The axles are transferred into deep pits using a theodolite.

Layout of the axes of a house on a slope

The height of the house is divided from a reference point. Using a level, determine and fix on the ground near the house the absolute mark of the finished floor of the 1st floor, indicated in the drawings.

This mark is conventionally taken as zero and the marks of all elements of the house (window and door openings, interfloor ceilings, etc.) are counted from it. To do this, use two levels, a staff and a tape measure with a suspended load.

With one level, a reading is taken along the staff on the crossbar and by turning the telescope in the horizontal plane, this reading is transferred to the tape measure, the zero division of which is at the top.

Deviations of the length and width of the house from the design values ​​should not exceed:

• 10 mm - for sizes up to 10 m
• 30 mm - for sizes 100 m and more

Act on the breakdown of the axes of the house

During the construction process, constant monitoring must be carried out to ensure horizontal and vertical compliance with the design parameters of parts of the building and utilities. After completing the installation of the house, an executive geodetic survey of the actual position of the house structures in plan and height must be carried out.

The layout of the axes of the house is drawn up in an act with the attachment of an executive layout diagram. The diagram indicates:

• design and actual distances between alignment axes
• distances from home to benchmarks
• the absolute elevation of the base of the foundation of each corner of the house, the differences in the base of the foundation and the base of the foundation at the intersection of the alignment axes

All this is necessary to have for laying future underground communications of the house and for restoring the layout in case of its violation during the construction of the foundation and basement of the house. After laying the walls, the alignment axes are removed. Of course, a house with a complex configuration and in an area with complex terrain should only be carried out by a surveyor.

But you will already have an idea of ​​how a house is laid out, and what material needs to be prepared to carry out the work of breaking down a house at the construction site. Well, now you can do the layout of the axes of a small building on a flat area yourself.

To perform marking work, the following methods are used: polar and rectangular coordinates, angular, linear and alignment serifs.

Angular notching method used to mark inaccessible points located at a considerable distance from the starting points.

There are direct and reverse corner serifs.

In the direct angular intersection method, the location of the design point on the ground WITH(Fig. 10) are found deposited at the starting points (Fig. 1) are found deposited at the starting points, plotted from the original points And design angles at 1 and at 2. The basis of the notch is either the specially measured side or the side of the alignment network. Design angles at 1 and at 2 are calculated as the difference between the directional angles of the sides. Directional angles are found from solving the inverse geodetic problem using the design coordinates of the point being determined and the known coordinates of the starting points.

Rice. 10.

The accuracy of the layout using the direct angular intersection method is influenced by errors: the direct intersection itself, the initial data, theodolite centering and sighting targets , fixing the alignment point. During alignment work, centering the theodolite and sighting targets using optical plummets, as well as fixing the set-out point can be performed relatively accurately. Therefore, the main errors that determine the accuracy of the direct angular notching method are the errors of the notching itself and the source data. The total value of these errors can be significant, which will require angular notching with increased accuracy.

The required layout accuracy in this case can be achieved as follows. Having set aside the angles in l and in 2 as accurately as possible, the position of the point is determined in nature In the direct angular intersection method, the location of the design point on the ground. Then, at the reference points, the exact value of the delayed angles is measured using the appropriate number of techniques. For the example given, when using a 2T30 theodolite, at least four steps must be performed. The angle r at the point is also measured In the direct angular intersection method, the location of the design point on the ground. Having distributed the discrepancy in the triangle equally across all three angles, determine the coordinates of the point In the direct angular intersection method, the location of the design point on the ground. By comparing them with the design values, corrections (reductions) are found, according to which in nature they shift (reduce) the approximately offset point In the direct angular intersection method, the location of the design point on the ground. This method is called closed triangle method.

The use of the reverse corner cutting method for staking is also based on the principle of reduction. Approximate position is found on the ground Reverse corner cutting method. Approximate position is found on the ground split design point point to be staked(Fig. 11). At this point, a theodolite is installed and angles are measured with the required accuracy to at least three starting points with known coordinates. Using resection formulas, the coordinates of an approximately certain point are calculated and compared with the design values. From the difference in coordinates, the reduction values ​​(angular and linear elements) are calculated and the point is shifted to the design position.

Rice. eleven.

To control the angles at this point, calculate its coordinates again and compare them with the design ones. In case of unacceptable discrepancies, all actions are repeated.

In the linear intersection method, the position of the point to be staked out In the direct angular intersection method, the location of the design point on the ground(see Fig. 10) are determined at the intersection of the design distances S 1 and S 2, plotted from the starting points (Fig. 1) are found deposited at the starting points, plotted from the original points And This method is usually used to lay out the axes of building structures in cases where the design distances do not exceed the length of the measuring device.

It is most convenient to carry out the breakdown using two tape measures. From point (Fig. 1) are found deposited at the starting points on a tape measure the distance S 1 is plotted, and from the point And on the second roulette - S 2. Moving both roulettes with the zeros aligned with the centers of the points (Fig. 1) are found deposited at the starting points, plotted from the original points IN, at the intersection of the ends of the segments S 1 and S 2, find the position of the point to be determined In the direct angular intersection method, the location of the design point on the ground. geodetic alignment road construction site

Polar coordinate method widely used when laying out the axes of buildings, structures and structures from points of theodolite or polygonometric traverses, when these points are located relatively close to the points taken out into nature.

In this method, the position of the determined point In the direct angular intersection method, the location of the design point on the ground(Fig. 12) are found on the ground by deposition from the direction AB design angle b and distance S. Design angle b is found as the difference in directional angles b AB , plotted from the original points b AC , calculated as well as the distance S from solving inverse problems using the coordinates of points A, B and C. To control the position of a fixed point In the direct angular intersection method, the location of the design point on the ground can be checked by measuring at the point And angle in" and comparing it with the value obtained as the difference in directional angles b VA , plotted from the original points b Sun " .

Rice. 12.

The error of the actual layout using the polar method depends on the error in constructing the angle b and the error in deposition of the design distance S. The calculation shows that for these conditions, reducing the error in the position of the point set out in nature is possible only with a significant reduction in the error in deposition of the design distance - at least by half.

If the point to be laid out is located at a considerable distance from the starting point, then it is necessary to postpone the design angles and distances several times using the polar method, laying out the design course.

Methods of leading and leading-linear serifs are widely used for setting out the alignment axes of buildings and structures, as well as the installation axes of structures and technological equipment.

Design point position In the direct angular intersection method, the location of the design point on the ground in the alignment notch method, it is determined at the intersection of two alignments specified between the starting points 1-1" and 2-2" (Fig. 13). The target is usually set with a theodolite, which is centered over the reference point (for example, 1), and the telescope is oriented towards the sighting target, centered on another reference point (in this case 1"). Position of the point In the direct angular intersection method, the location of the design point on the ground fixed in a given alignment.

The mean square error of the alignment intersection depends on the errors in constructing the first and second alignments, as well as the error in fixing the reference points.

Rice. 13. A- alignment serif; b- leading-linear serif

Sliding-linear method allows you to determine the design position of the point to be plotted In the direct angular intersection method, the location of the design point on the ground(see Fig. 13) by plotting the design distance d along the target AB.

Rectangular coordinate method They are used mainly when there is a construction grid on the site or in the workshop of an industrial enterprise, in the coordinate system of which the position of all the main points and axes of the project is specified.

Design point breakdown In the direct angular intersection method, the location of the design point on the ground(Fig. 14) are produced according to the calculated values ​​of the increments of its coordinates D X and D Y from the nearest grid point. Larger increment (in Figure D Y) laid down along the alignment of grid points AB. At the resulting point D install a theodolite and build a right angle from the side of the grid. A smaller increment is laid along the perpendicular and the resulting point is fixed In the direct angular intersection method, the location of the design point on the ground. To control the position of the point In the direct angular intersection method, the location of the design point on the ground can be determined from another point on the construction grid. The scheme of the rectangular coordinates method essentially combines the scheme of the section-linear and polar methods.

Rice. 14. Layout scheme using rectangular coordinates