A foundation is a fundamental part of a building or structure. It is from him that the durability and quality of absolutely any building will depend. It is necessary to correctly calculate the volume of earthwork so that no problems arise in the future. Usually this is done by people who have received the necessary knowledge in colleges or universities, with a specialized diploma and experience. But anyone who wonders how to calculate the volume of earthwork can figure it out.
What you need to count
To correctly calculate the volume of earthwork, you need to have:
- Foundation drawing.
- Formulas
What type of earthwork is needed for different types of foundation
If you plan a monolithic strip or prefabricated foundation in a building with a large number of load-bearing walls, it is necessary to plan digging a pit.
If the bearing walls are few or far between, a trench is suitable.
If the foundation is columnar, digging of special notches is provided.
Foundation pit
Only having the project drawing at hand can you make all the calculations for digging pits.
This is due to the fact that there are many technological nuances of the final design. List of formulas that you need to know to determine the volume of earthwork:
- if the shape of the pit is rectangular with slopes:
Ok = N / 6 * {Ak * Bk + Akv * Bkv + (Ak + Akv) * (Bk + Bkv}};
where, Ok - the indicator of the volume of the pit, in meters;
Ak - an indicator of the width along the bottom, in meters;
Bq - an indicator of length along the bottom, in meters;
Aqu - the indicator of the width on top, in meters;
Bqv - an indicator of the length on top, in meters;
N - an indicator of depth, in meters.
- if the shape is polygonal with slopes:
Ok = N / 6 * (F1 + F2 + 4 * Fsr);
where, F1 - an indicator of the bottom area, in square meters;
F2 - an indicator of the area of the top, in square meters;
Fsr - an indicator of the cross-sectional area in the middle of the height, in square meters.
Ok = N / 38 (F1 + 2 + √ 12).
Trench
To calculate the volume of earthwork when digging a trench, you need to use the following formulas:
- if the trench has vertical walls:
OTR = Atr * (H1 + H2) * B / 2;
where, Atr - width, in meters; H1 and H2 are the depths of the sections.
or
Negr = (F1 + F2) * L / 2;
where, F1 and F2 are cross-sectional areas; B is the distance between them.
F1.2 = (Atr + M8H1.2) * H1.2;
where M is the slope coefficient.
Parameters of various soils
For the development of pits and trenches, it is important to consider what soil is being developed.
Soil can be rocky and non-rocky.
Rocky rocks are rocks that occur as a continuous massif. This type of soil is difficult to develop. It can only be developed by blasting, jack hammers and wedges.
Neskalnye are developed easier, but among them there are difficult species, for example, scrap clay. Soil, consisting of sand and dust particles, is easiest to develop.
What properties dictating the complexity of the work are soils:
During work with soil, its volume becomes larger. This is called "initial loosening." This happens because the compaction of the soil occurs due to the influence of the weight of the layers of the earth that lie above, as well as due to wetting with precipitation and the weight of vehicles moving around the territory of the future development.
Counting volumes, it is necessary to compile a list of volumes of earth masses, which includes:
- soil of the planned territory;
- displaced soil;
- excess during loosening;
- soil to be removed;
- fertile soil.
Having calculated all these parameters, it is necessary to accept the correction for compaction 0.02 and calculate the total amount of soil. With these data, it is already possible to calculate the volume of earthwork.
What else needs to be provided
Before starting excavation work, it is necessary to prepare the territory on which construction will be carried out. Preparation includes:
- fencing of the area of future development;
- site clearance;
- demolition of unnecessary buildings;
- redirecting interfering engineering networks;
- site protection against erosion by surface waters;
- laying of communications;
- the installation of temporary structures: cabins, warehouses, administrative buildings (if this is the construction of some large facility);
- installation of castoff;
- carrying out geodetic works.
If you plan to buy a land plot and build a manor house on it, you should take a soil analysis to find out the type of soil. This procedure should be done before the purchase of the site, to make sure that during excavation there will be no problems.
Before calculating the volume of excavation, the width of the foundation sole and the depth of freezing of the soil should be calculated. Such calculations are done after the architectural part of the project is ready.
The sole of the foundation is laid 30 centimeters below the depth of freezing of the soil.
In addition, it is worth strengthening the soil, in order to avoid the collapse of the upper part of the slopes.
The best time for excavation is early autumn and summer. In these seasons, the soil is soft and easy to dig.
When removing the surface layer, in addition to the area of the future foundation pit, it is necessary to take into account the area of the blind area of the building under construction. To do this, you can simply add a meter to the width of the borders of the trench or foundation pit.
The height of the layer of fertile soil is approximately 30 centimeters. This parameter will vary individually depending on each plot allocated for development.
Waste soil should be removed immediately, in the process of work, otherwise this land will take up a lot of space.
Special digging
If the basement or the ground floor is provided for in the building for which earthwork is being carried out, then special digging machines will not work.
What types of development exist:
- mechanical - the soil is separated from the main array by machines;
- hydromechanical - soil is washed away or absorbed by the dredger;
- explosive - on the construction site, wells are drilled into which special explosives are laid; this method of excavation is practiced away from the city or in rocky soils.
The mechanisms:
- loosen the soil;
- develop;
- sprinkle;
- transported;
- level the soil;
- condense;
- plan slopes and squares.
What machines are used during earthwork:
- bulldozers;
- shovel excavators;
- continuous excavators;
- loaders;
- bulldozer-loosening machines;
- trailed scrapers;
- self-propelled scrapers;
- trailed rollers.
Earth-moving mechanisms are needed to remove soil in layers, transport and unload in an embankment / dump.
Scrapers are used in hydraulic construction.
Excavators with a straight shovel are needed then to develop the soil and engage in the loading of waste soil into the car body. The face should be located above the excavator's parking lot, and the machine that is used to transport waste soil should be higher.
Backhoe excavators must be at the same level with the machine, and the bottom should be lower than their parking.
When connecting to the work of mechanisms, it is necessary to check whether there are any power line equipment, underground utilities or groundwater in the work area.
The choice of transport for such work depends on the parameters of the soil and work.
Manual work
You can dig the soil manually when the volume is small - the foundation is small in area and height. But, even if the work with the soil is carried out in a mechanized way, you have to manually clear the bottom. When working with an excavator, it is necessary to leave a small amount of land so as not to “suffice too much”, because if you scoop deeper than it should, it will be wrong to put the soil back, because it has the peculiarity of loosening.
How are earthworks
The sequence of earthworks includes:
- Removal of the surface layer.
- Soil removal.
- Installation of the foundation.
- Backfill soil.
Do you have difficulty calculating the volume of earthwork?