To figure out how to use a level, you don’t need to take any special courses or go to a geological institute. You just need to study all the nuances of the work and become familiar with the technology, after which you can independently carry out measurements no worse than experienced specialists.
The level is used to take the necessary measurements before construction.
The principle of geodesy on a construction site
In the process of putting plans into reality, you will need to determine the difference in heights of several points on the foundation sections and the mark, which is considered a conditional level. Most often, work is done using a level and geodetic slats. In this way, geometric leveling can be determined and carried out.
In this case, the optical axis of the instrument is horizontal. From the conditional level mark, you need to find the difference in the heights of the indicators according to the marks on the slats. During the work, each such point is located at a distance of up to 100 m from the point of installation of the level. The level must be measured at least 3 times, as a result the arithmetic average must be taken. Based on the data obtained, you can prepare a plan of the land plot.
In the process of considering the operating principle of this device, one cannot fail to mention an important component, namely the leveling rod. This is a special bar that is installed vertically at points for measuring heights on the bases. This product is made of wood or metal (in most cases aluminum).
The device has a standard length (3-4 m). For ease of movement, the rail can be folded in half. Modern versions of the slats have a telescopic sliding mechanism.
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List of tools needed for leveling
In most cases, the sides of a standard leveling rod are marked with graduations: on the front side the markings are made in the metric measurement system, and on the back side - in the inch system. First of all, the rail must be installed with a special mark on the bottom metal bracket in the center of the measurement point.
For ease of use, there are special handles for holding the device at a given point. High-quality strips, which are made of iron-nickel alloys, have special bubble levels that are used to control the vertical position of the strip.
In the process of carrying out work on the ground during the initial study of the building being prepared, it is important to perform a comprehensive modeling of the structure being manufactured in dimensional interaction with the natural landscape.
The technology of photographing measuring points with the transfer of real scale values as data for computer software allows for modeling of an object and its interaction with the environment.
You will need the following elements:
- level;
- special software;
- slats.
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Methods of leveling on the ground
Levels are a large group of devices that are used to determine and record the exact location of various elements in height. The elements in this case can be arbitrary marks and sections of the ground, rather than specific landmarks.
The essence of leveling is to determine the height difference between the levels of the structure being manufactured. The total amount of construction work will depend on the magnitude of this excess and proper measurement. For example, from the planned initial level of the first floor of a building, you can calculate the depth of the foundation, groundwater flow, design of the drainage system, type of insulation of the blind area, etc.
The following leveling methods exist:
- Hydrostatic method. It is based on the property of the location of liquid in conforming vessels. It has high accuracy and allows measurements to be taken outside of visual range between specific points. Measurements in this case are associated with the need to lay and fill large lengths of hoses and pipes with liquid, which in some cases is not very convenient.
- Barometric method. Used in the planning process of large architectural structures. To implement this method, you will need to use high-precision barometers and special computer software. This method is not used in the construction of private houses.
- Trigonometric measurements using a rotary theodolite. This method is good because in this case there is no need for assistants with additional strips. Theodolite measurements can be taken at horizontal and vertical angles. However, understanding the operating principle of this device is much more difficult than understanding the functioning of a conventional level. The disadvantage is that theodolite is much more expensive.
- Geometric measurements of elevation angles using conventional levels are carried out exclusively in one plane and require the installation of additional marks (you can use strips) when moving them from one place to another. You will need to make appropriate entries in the journal.
The simplicity and reliability of measurements with a standard level, its compatibility with construction purposes, make this device the most popular in the process of planning many types of work: from pouring the base to checking the accuracy of the roof.
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Design and classification of standard levels
Schemes for the arrangement of axes during level verification: A – c – diagrams for the arrangement of axes during level verification, d – positions of the level during the third verification.
This device has a simple design. The tripod houses the main optical-mechanical unit, into which the lens system is built. This unit must ensure the horizontality of the viewfinder beam, while only minimal deviation is allowed. Lenses can produce a straight or inverted pattern. In the latter case, the measuring rod must also be turned upside down during installation on the ground.
Level sensors must be built into the upper part of the design of all levels. Accurate installation of the device on the ground determines the quality of further measurements. A qualified specialist will regularly check the values of these sensors, adjusting them if necessary using special tilt levers of the optical-mechanical unit. You can promptly detect a random deviation of the device from the exact location on the ground and not take measurements again.
Before using the level and the bar, you will need to familiarize yourself with the main types of devices for geometric measurements of excess height.
The simplest and most accessible is a level with a cylindrical level, which is located on the sighting tube.
A meter with automatic compensation for installation errors is more accurate, but it costs much more. It is convenient to use when taking measurements on problematic soils: crushed stone, sand, etc. Devices with an electronic measurement system are used in the design of large-scale objects. This design is difficult to set up and operate.
According to the class of measurement accuracy, leveling structures can be divided into the following main groups:
- technical devices (marking N-10, N-12, etc.);
- precision devices (designations from N-3 to N-9);
- ultra-precise devices (designations from N-05 to N-2.5).
The numbers in the marking indicate the average measurement error in mm/km. It should be understood that even a technical device will give a deviation of about 1 cm per 1 km of distance to the object. This is enough to carry out accurate design and proper planning of a large number of construction works.
Installing the level into the working position involves bringing the sighting axis to a horizontal position. To do this, a tripod with a level attached to it is placed so that the upper plane of the head is horizontal and the legs are firmly driven into the ground. Then, using lifting screws, the round level bubble is brought to the zero point. The telescope is placed parallel to two lifting screws and, by rotating them in opposite directions (inward or outward), the bubble is brought to the middle in a direction parallel to these screws. Then, without turning the telescope, they operate with one third screw.
The final adjustment of the sighting axis to a horizontal position is performed immediately before taking a reading on the staff by bringing the cylindrical (contact) level bubble to the zero point with an elevation screw. The image of the ends of the cylindrical level bubble is transmitted to the field of view of the telescope using a system of prisms. When the bubble of the cylindrical level is at the zero point, the images of the ends of the bubble are combined (Fig. 2.2) and the sighting axis of the telescope is in a horizontal position. When the level bubble deviates from the zero point, the ends of the cylindrical level diverge.
The telescope is prepared for observation by rotating the eyepiece ring (sharpness of the reticle) and rotating the focusing screw (sharpness of the observed object).
The level is never precisely centered over a plumb point. Each time before taking a reading on the staff, the images of the ends of the contact level bubble are combined using an elevation screw.
2.4 Level checking
Before starting to work with the level, you must make sure that the relative position of the axes of the device (Fig. 2.3) corresponds to its basic design diagram. To do this, check the level.
Checking the round level
Condition. The axis of the circular level (КК 1) must be parallel to the vertical axis of rotation of the level (ВВ 1), (Fig. 2.3).
Performance. Verification is performed by rotating the level around the vertical axis by 180° after installing it in its working position.
Tolerance Bubble level can deviate from the center by no more than one division.
Correction. Since after turning the level by 180°, a double angle of deviation is fixed, then using the correction screws (which are located under the round level) the bubble should be returned to half the deviation from the center, after which the bubble is again set to the middle using the lifting screws and the verification is repeated.
Rice. 2.3 Diagram of the main axes of the level
2.4.2 Checking the thread mesh
Condition. The horizontal thread of the mesh should be perpendicular to the vertical axis of rotation of the level (BB 1), and the vertical thread should be parallel to it (Fig. 2.3).
Performance. Verification in the first way is carried out by moving the pipe in azimuth with a micrometer screw while simultaneously observing the observed point (A) or reference on a staff mounted on a solid base 25+30 meters from the level.
The second method of verification is carried out by hanging a plumb line in a place protected from the wind and combine the vertical thread with the plumb line.
Tolerance When deviations are noticeable to the observer's eye, or when the reading on the staff changes by more than 1 mm, a correction is made.
Correction. Correction is made by turning the reticle ring, after first removing the eyepiece cover and loosening the screws securing the ring. With the second verification method, correction is made easier, since we see the location of the entire plumb line.
N
ivelir at a construction site, the second most important tool after a measuring tape. Having no idea how to work as a leveler, there is no point in even thinking about starting any more or less serious construction. At the same time, the operating principle of the level and the basic techniques for working with it are so simple that even a primary school student can master them.
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Video version of the article
Level device
Let's look at what a regular optical level consists of and how it works. The main part of the device is an optical tube with a lens system capable of zooming in on observed objects with a magnification of twenty times or more.
The pipe is mounted on a special rotating frame, necessary for the following functions:
- tripod mounts;
- setting the optical axis of the level to a strictly horizontal position, for which the frame has three height-adjustable “legs” and one or two (in models without automatic adjustment) bubble levels;
- precise horizontal aiming, which is carried out with paired or single handwheels.
In some models, the bed has a special dial, a scale that allows you to measure or construct horizontal angles.
On the right side of the pipe there is a handwheel designed to adjust image sharpness.
Adjustment to the operator's vision is made by rotating the adjustment ring on the eyepiece.
When looking through the eyepiece of a level telescope, we will see that in addition to bringing the object observed through the device closer, the level superimposes a system of thin lines on its image, called a reticle or reticle. It forms a cross-shaped pattern of vertical and horizontal lines (see Figure 1).
Additional devices and equipment
In addition to the device itself, for work we will need the already mentioned tripod, as well as a special measuring rod with divisions and numbers printed on it. The divisions are stripes of alternating black or red stripes 10 mm wide.
The numbers on the rod are marked in increments of ten cm, and the value from zero to the end of the rod is in decimeters, with the numbers expressed in two digits. So, 50 cm is designated as 05, the number 09 indicates 90 cm, the number 12 indicates 120 cm, etc.
For convenience, the five centimeter marks of each decimeter are also united by a vertical strip, so that the entire strip is marked with signs in the form of the letter “E”, straight and mirrored.
To work with a level, you must have certain skills and knowledge. This device is indispensable during the construction of objects of varying degrees of complexity. It ensures the accuracy of the placement of all objects in space and prevents irreparable errors.
Level - device features, scope of application
A level at a construction site is an indispensable device. With its help, you can find the level of location of certain points relative to a specific base. Before any construction begins, site planning is carried out, which involves eliminating unevenness. The easiest way to do this is to use a level. You cannot do without this device when performing many other works - when arranging a foundation, pouring floors, installing formwork.
Design features
The main structural element of the level is called the telescope. It is equipped with a lens system that can magnify the image twenty times or more. This element is mounted on a special stand – a tribrach. It has three lifting screws, with which the device can be adjusted exactly to the level. To facilitate this process, there is a bubble level on the stand.
The design of the unit also includes a tripod. It is better to choose aluminum options, which are lightweight and durable. Some devices have a dial with which you can measure or construct angles.
The telescope contains a flywheel. With it you can adjust the sharpness of the image. To adjust the device to the visual acuity of a particular person, a regulator is used on the eyepiece.
Additional equipment and inventory
To work with a level, you need to purchase not only the device itself with a tripod, but also some additional equipment. You need to have a special ruler with divisions and numbers printed on its surface, which will make it easier to take the appropriate measurements. The scale is presented in the form of red and black stripes, 1 cm wide.
On the bar there are numbers in increments of 10 cm. The measured value is decimeters, and all numbers are written in two-digit form. 60 cm is designated as 06, 120 cm - 12, etc. For ease of use, each of the five stripes is united by a vertical line. Therefore, the entire bar is covered with peculiar letters E - in the usual and mirror form.
Some old models of levels reverse the image, so all the numbers on the staff are in the same unusual form. Each level must be accompanied by a passport and instructions for use. The documentation for the device indicates the date of the last verification, which guarantees its operating efficiency.
Other equipment included as standard for each model:
- protective case for storing the telescope;
- maintenance key;
- a plumb line for installing the device strictly at the specified point;
- soft cloth for cleaning lenses.
Step-by-step instructions for working with the level
How to use a level without the necessary experience? Beginners should follow simple instructions while working.
Step 1 – Tripod Installation
- the fastening screws on the legs are relaxed as much as possible;
- the supports of the device extend to the required length;
- the tripod is set in the desired position, taking into account the horizontal level;
- screws on the tripod are secured on all sides.
Step 2 - installation of the level
The leveling tube is secured to a mounted tripod using several mounting screws. Using level sensors (by rotating them) a strictly horizontal position of the device is achieved. It is necessary that the bubbles on the scale be in the area of the indicated marks.
First, it is advisable to accurately set the first of them. Only after this do they proceed to adjusting the second screw, focusing on the previous one. Only such a step-by-step adjustment of the level will help achieve good results in your work. The optical axis of the device must be strictly horizontal.
Step 3 – focusing the optical assembly
After installing the level in the desired position, they proceed to adjusting its telescope, focusing on the operator’s visual acuity. To do this, you need to move the device to a well-lit object, and turn the regulator until the marking grid is displayed as clearly as possible.
The same work must be done on other objects that are illuminated less well. Focus adjustments are carried out as long as necessary.
How to determine the excess of points?
Working with an optical level involves determining the difference in height of several points on the surface. To do this, you need to have a special measuring rod and an assistant who will transfer it from one place to another.
To perform the work, you must adhere to the following instructions:
- Select the first point at which the rail is installed in a vertical position.
- In order for the bar to stand as level as possible, it is necessary to adjust its location, focusing on the reticle on the device.
- The level is pointed at the staff. By rotating the eyepiece, maximum image clarity is achieved.
- The values of the measuring rod where the horizontal line of the reticle is located are written down in a notebook.
- The bar is moved to another point and all the work is carried out first according to a similar scheme.
- The level is positioned motionless. Therefore, the higher the measured value on the staff, the lower the specific point is.
Rules for transferring marks to the surface
A level at a construction site is an indispensable thing, since it can be used to determine the depth of digging a pit in each specific case. Let's consider a situation where it is necessary to obtain a recess with the bottom at a level of -2.000 relative to the floor of the building. To do this, the excavator operator must indicate his mark.
To perform this work correctly, set the rail at a point that corresponds to the floor of the building - at the design zero. At a construction site, such benchmarks are usually set up by a surveyor.
Let us assume that at this point it was possible to measure the value of 153. At the location of the future pit, a peg is installed and a rod is attached to it. Take the value that came out, for example, 168. A difference of 15 cm is set aside from the bottom of the peg upward. Next to it you can hammer another column. Its top should correspond to the mark made, which will provide the excavator with a more reliable reference point.
Instrument maintenance rules
It is necessary to work with the level carefully, which is explained by the sensitivity of this device to any damage.
After each work performed, it is recommended to wipe the eyepiece and lenses with soft flannel, which is usually provided by the manufacturer as part of the standard package for each model. The slightest contamination on the surface of the optical system leads to inaccurate measurements, which negatively affects the results of the work performed.
To ensure high accuracy of the equipment, it is regularly calibrated. It is done once every three years, about which a corresponding note is made in the passport for the device.
This should be left to professionals, but in some cases you can do it yourself. A regular sheet of paper is used, which is placed at a known distance from the marking strip. The optical system of the level is adjusted until the measured values coincide with the actual ones.
For any type of construction, setting marks according to design data is mandatory. For this purpose, a geodetic instrument such as a level is used. There are two types of this tool: optical and laser.
The optical level is a horizontal circle, adjusted with special lifting screws and a telescope fixed at the top of the device. Before starting to work with it, the surveyor secures it on a tripod, centers it over a reference point and brings it to an absolutely horizontal position.
The device is ready for use when the bubble of the round level is in the center and does not move when the device is turned in different directions.
When performing a survey, you can rely on the Baltic coordinate system if there is a reference point nearby (a point with a known elevation above sea level), otherwise, a relative system is set and any one is taken as a reference point.
To determine the horizon of the instrument, a geodetic rod is installed on the reference point, on which a scale is printed graphically and in the form of numbers. The geodesic engineer takes a mark from the crosshairs of the filament grids in the telescope and adds it to the mark of the reference point. This is where the horizon of the device is located.
To determine the elevations of other desired and unknown points, a geodetic rod is installed sequentially on each of them. The readings obtained are subtracted from the horizon of the instrument, the results obtained are the marks of the required points.
In order not to do unnecessary work, a height gauge is installed in place of each point. The actual height obtained is either recorded on it, or the crossbar is installed at a height equal to the design one.
Based on these elevation marks, it is possible to carry out further work, be it filling the site with inert material to the design elevations or pouring the formwork with a concrete mixture.
It is not allowed to remove the level from its working position until all necessary geodetic work is completed. Otherwise, installation and reinstallation of the device into the working position is repeated according to the above algorithm and will take some additional time.
There are situations when one of the required points is inaccessible for visual reading on the staff. In this case, it is necessary to make a transition and reinstall the device to another location, thereby changing the horizon of the device.
The operating principle of a laser level is almost identical to an optical instrument. The only difference is that the laser beam is focused on the geodetic staff and there is no need to look at the reading through the eyepiece.
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