The first and one of the most important stages of building a house is the development of a foundation pit. The reliability and durability of the entire supporting structure of the building will depend on the characteristics of its foundation. It remains only to choose an acceptable method for solving this problem. Manual excavation methods, with all the advantages, are less and less in demand, and mechanized technologies come to the fore. The most optimal solution today is the development of a pit with an excavator according to a previously prepared project.
What should be considered at the initial stage?
Even before ordering a project, it is recommended to determine in general terms the parameters of the future excavation and the scope of work, which will directly affect the development cost. At the same time, the larger the structure, the lower the cost per 1 m2. And not every project with a minimum volume, in principle, provides for mechanized digging - this nuance should also be taken into account.
Further definedthe configuration of the pit - for example, whether there will be a basement in it. Some types of foundation require the creation of a trench without continuous development of the area under the house. However, the presence of a basement or cellar in terms of means that you will have to remove the soil around the entire perimeter. Today, it is increasingly practiced to develop a pit with an excavator for a foundation of complex shape with steps, kinks and ledges. These structural elements should also be calculated in advance so that they can be completed by professional equipment.
Development of design solution
Organization of work on the excavation involves the initial preparation of two documents:
- Project of work (PPR).
- Technological map for the development of the pit.
As for the first document, it contains explanatory notes, plans and drawings with detailed information on earthmoving in specific conditions. When creating a project, individual preferences of the customer and regulatory technical and architectural requirements are taken into account. A typical WEP for the development of a pit with an excavator, in particular, contains a set of initial data, a phased description of the work, characteristics of the construction of fences, a schedule, etc.
The technological map defines the sequence of work operations. Separately, a list of geodetic and planning activities, the process of developing soil with loading and unloading operations and subsequent refinement with cleaning the base of the arranged pit are described.
Preparation of the construction site
Before the immediate start of earthmoving activities at the work site, it is advisable to organize a travel path if it is not available. Responsible approach should also be taken to the problem of removing trees on the site. Barren trunks over 5-6 years old can be uprooted only with the permission of the local administration. After planting the tree, it is necessary to fill the resulting pit with coarse sand to the level of the foundation.
In the process of arranging the construction site, it will be useful to fix the zones where the fertile layer is removed. In the future, this information will be useful for agricultural work near the house. Before excavating the pit with an excavator, it is also recommended to organize platforms or containers for collecting the excavated fertile soil. Since it may come in handy in the future, it should be laid in places where there is no construction debris or other household waste. For the duration of the work, a temporary fence is installed in front of the house from the entrance side with an opening only for working equipment.
Features of using different excavators
Technically, excavation can be carried out in different ways, depending on the type of excavator. The following machines are used for pits:
- Dragline excavator. Suitable for soils that are below the state of the art. This option is optimal if you need to dig deep and wide pits, as well as develop from under water. The dragline is distinguished by its digging depth (up to 12 m) and largecapture radius (up to 10 m).
- Backhoe excavator. Also used when the dig level is below the parking surface of the machine. However, excavation with a backhoe excavator focuses on small amounts of work without performing layer-by-layer excavation. And yet, due to its moderate dimensions, high maneuverability and low resource costs, this type of earth-moving equipment is most often used in excavation.
- Excavator-grab. It is usually used to create engineering and utility structures like wells, trenches and ditches. In the creation of pits, this technique is used in cases where it is necessary to provide a greater depth below the groundwater level.
Most excavators realize precise excavation even in tight spaces. The workflow may be accompanied by the storage of land and removal, but with the connection of other equipment like a dump truck. The head of the work process controls the coordinated interaction of different functional groups, achieving efficiency and clarity in the execution of operations. At the final stage, the technology for excavating the pit with an excavator provides for cleaning the bottom. If the capabilities of a particular model of equipment allow, the operator can prepare a strong and reliable sole for the foundation. At least after the main soil sampling, loose areas and embankments are eliminated, which can further shrink.
Fixing the walls of the pit
According to the rules of SNiP, the walls of weakly weathered and loose pits, the depth of which exceeds 5 m, are to be strengthened. Such walls withstand hydrostatic pressure and prevent subsidence of the rock. But this strengthening option is not suitable if the work was carried out on floating and bulk soils. The excavation of a pit by an excavator in conditions of unstable soils with an elevated level of groundwater is one of the most important operations that should be completed with sheet pile strengthening of the walls. This is a kind of variation of metal reinforcement, but instead of a concrete base, a corrugated or corrugated steel fence is used. In some cases, bored rigs are also used when it is necessary to create a high-strength solid fence.
Features of the development of a pit with an excavator in the sand
On sandy soils, excavation is quite problematic, so more often in such conditions, manual force is used. But, if we are talking about a large site, then mechanized equipment is indispensable. In this case, a universal single-bucket machine will help, which allows you to perform several diverse operations. Thanks to the change of attachments, the operator will be able to clean the bottom, remove oversize, finish slopes, compact and loosen.With regard to sandy soils, the development of pits with single-bucket excavators is advantageous for the ability to perform soaking and compacting operations. Proper development of such a foundation will eliminate the risk of foundation shrinkage even with seismic movements. After work, it will be necessary to quickly create excavation slopes with a safe slope.
From the point of view of organization, the use of an excavator is, in principle, a rather troublesome solution for earthworks. And this is not to mention financial costs, since on average, with this approach, maintenance of 1 m3 costs 300-500 rubles. What justifies the development of a pit with an excavator with such shortcomings? This method allows you to quickly and efficiently cope with hard work, minimizing the risks of leaving technical and structural defects in the structure. It also matters plus in the form of a general mechanization of the process of moving the soil, if it is not planned to be used on the site. An excavator in conjunction with the same dump truck or truck will rid the site of the selected land in the shortest possible time.