The first and one of the most critical 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 methods of excavation with all the advantages are less and less in demand, and mechanized technologies come to the fore. The most optimal solution to date is the development of an excavation pit by 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 foundation pit and the amount of work that will directly affect the cost of development. 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 digging in a mechanized way - this nuance should also be taken into account.
Next, the configuration of the pit is determined - for example, whether there will be a basement in it. Some types of foundations require the creation of trenches without the continuous development of the area under the house. However, the presence in the plan of the basement or cellar means that you have to remove the soil around the perimeter. Today, it is increasingly practiced to develop an excavation pit under an excavator for a complex shape foundation with steps, kinks and ledges. These structural elements should also be calculated in advance so that they are performed by professional equipment.
Design solution development
The organization of work on the excavation device involves the initial preparation of two documents:
- Project Production 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 PPR for the development of an excavation pit by an excavator, in particular, contains a set of initial data, a phased description of the work, the design characteristics of the fencing, a schedule, etc.
The routing determines the sequence of work operations. The list of geodetic and planning measures, the process of soil development with loading and unloading operations and subsequent refinement with the cleaning of the foundation of the pit are described separately.
Site preparation
Prior to the immediate start of excavation at the work site, it is advisable to arrange a driveway if it is not there. You should also responsibly approach the problem of removing trees on the site. Non-fruiting trunks older than 5-6 years old can be uprooted only with the permission of the local administration. After tree planting, it is necessary to fill the formed hole with sand of a large fraction 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 a pit with an excavator, it is also recommended to organize sites or containers for collecting excavated fertile soil. Since it can come in handy in the future, it should be placed in places where there is no construction waste or other household waste. For the period of work in front of the house, a temporary fence with an opening only for working equipment is installed on the entrance side.
Features of the use of different excavators
Technically, excavation can be carried out in different ways, depending on the type of excavator. For pits use the following machines:
- Excavator dragline. Suitable for soils that are below the prior art. This option is optimal if you need to dig deep and wide pits, as well as conduct development from under the water. The dragline has a digging depth (up to 12 m) and a large capture radius (up to 10 m).
- Backhoe excavator. It is also used in cases where the digging level is below the surface of the parking lot. However, the development of the excavation pit by a backhoe with an excavator focuses on small amounts of work without performing layer-by-layer excavation. And yet, due to moderate dimensions, high maneuverability and low resource costs, this type of earthmoving equipment is most often used in the construction of foundation pits.
- Excavator grapple. 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 greater depth below the groundwater level.
Manufacturing jobs
Most excavators realize accurate excavation even in tight conditions. The work process may be accompanied by land storage 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 speed and clarity of operations. At the final stage, the excavation technology for the excavation of the excavation involves cleaning the bottom. If the capabilities of a particular model of technology allow, the operator can prepare a solid and reliable sole for the foundation. At least after the main sampling of the soil, loose areas and embankments are eliminated, which can subsequently shrink.
Mounting the walls of the pit
According to the SNiP rules, walls of weakly weathered and loose pits, the depth of which exceeds 5 m, are subject to strengthening. The most effective method of such strengthening is considered to be a “wall in soil”, which forms a stable vertical surface from a concrete slurry. Such walls withstand hydrostatic pressure and prevent subsidence of the rock. But this option of strengthening will not work if the work was carried out on floating and bulk soils. Excavation of a foundation pit in unstable soils with elevated groundwater levels is one of the most critical operations that should be completed with sheet pile wall strengthening. This is a kind of variation of reinforcing with metal elements, but instead of a concrete base, a wavy or corrugated steel fence is used. In some cases, bored installations are also used when it is necessary to create a high-strength continuous fence.
Features of the excavation pit excavator in the sand
On sandy soils, soil development is quite problematic, therefore, manual force is often used in such conditions. But, if we are talking about a large platform, then without mechanized technology can not do. In this case, a universal single-bucket machine will help, allowing you to perform several diverse operations. Thanks to the change of attachments, the operator will be able to clean the bottom, remove oversized materials, finish slopes, seal and loosen. With regard to sandy soils, the development of pits with single-bucket excavators is advantageous for the ability to perform soaking and tamping operations. Proper study of such a framework will eliminate the risks of shrinkage of the foundation, even with seismic movements. After work, you will need to quickly create slopes of the excavation with a safe slope.
Conclusion
From the point of view of the 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, servicing 1 m3 costs 300-500 rubles. What justifies the development of the excavation pit with such an excavator? This method allows you to quickly and efficiently cope with hard work, minimizing the risks of leaving technical and structural defects of the structure. Plus also matters in the form of 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 as soon as possible will relieve the site of the selected land.