When constructing a structure on sandy soils, all the complexities arise from establishing a solid foundation for the intended structure. The foundation is designed to support the weight of the construction and distribute the load evenly onto the ground. The durability and safety of a building or structure are contingent upon the strength of its structural foundation. Consequently, the foundation of the house plays a leading role. The foundation that is properly designed is the foundation that guarantees the overall reliability of the construction.
When constructing on rock, clay, and similar soils, the selection of foundation type presents no obstacles. Nonetheless, the construction of structures on loose soil necessitates the application of proficient skills in selecting the foundation type, arranging the structural components, and precisely assessing the load-bearing capacity of the supporting components of the foundation on sandy soil.
Sand, which is distinguished by varying grain sizes, is a prevalent form of loose rock. When builders receive the results of geological surveys on the construction site, they often feel dismayed when they encounter mentions of sand in the documents. Nonetheless, it is important to note that not all sand is created equally. It is feasible to construct a solid foundation, even for a multi-story structure, on sandy soil, as coarse-grained sand ranks second in terms of stability, after rock formations. Sand with a coarse grain presents minimal challenges for builders, as its grains with diameters of 1-2.5 mm compact well on their own. Moreover, in the presence of a minimal amount of clay or loam, larger grains can effectively function as compaction agents. The circumstance is distinct with dusty sand, which falls under the category of intricate soils suitable for construction. Sands with dust require a meticulous approach when choosing a foundation type.
Choosing a foundation for sandy soil is important?
Whenever designing a structure on sandy soil, it is important to consider the proximity to groundwater. Dusty sand does not absorb moisture, but it also does not prevent water from infiltrating into the sandy layers. This often leads to subsurface flows in such areas. Furthermore, during soil freezing, there is an upward force exerted on foundation structures, which should be taken into account during foundation design.
What type of foundation is most suitable for sandy soil, thereby ensuring a robust and dependable foundation for a building, thereby guaranteeing a long-term trouble-free operation? There are several options.
- Using coarse-grained sand, any foundation solution can be implemented, as the soil is ideally suited to support even a two-story stone house. The most optimal options for constructing a wooden or brick dwelling, as well as structures associated with small architectural forms, entail constructing pile or column foundations on sandy soil, which necessitate minimal time and investment. When handled by a team of specialists using products of the same factory, foundations made from screwed-in load-bearing elements are easy to install. Columns, like screwed-in rods, are installed at the corners of the perimeter and at the intersections of load-bearing walls. For the purpose of supporting stone or brick:
In the case of asbestos-cement pipes, it is recommended to raise the support during concrete filling at a 30% capacity to thicken the bottom portion. Afterwards, a pre-prepared reinforcement or a welded structure of rebar is inserted into the pipe and filled with concrete mix. It is imperative to take note of the necessity to pour the strip foundation in an even layer simultaneously or in layers, as vertical connecting seams have a significant impact on the foundation's strength and integrity..
- Excavate pits.;
- Fill with gravel for water drainage.
- Lay a layer of waterproofing;
- Construct columns with reinforcement for each row or install asbestos-cement pipes filled with concrete.;
- Place waterproofing on top..
The monolithic slab foundation is a foundation that is constructed by utilizing reinforced concrete slabs. The installation of a foundation beneath a structure facilitates an even distribution of the load, resulting from the weight of the constructed structure, across every square centimeter of soil, which corresponds to the size of the slabs. However, it is not feasible to use slabs on dusty, sandy soils, as it is impossible to achieve stability without the use of pile supports. The requirement for an excavation pit for slab installation only further complicates the process of creating a foundation on loose dusty sands.
- In the case of dusty sand, a shallow strip foundation is used. It is preferable to establish a reinforced concrete strip in the shape of a trapezoid, with the wider base facing downwards. You should also consider utilizing thermal and waterproofing materials to prevent water from affecting the characteristics of the resultant structural element. When determining the foundation depth on sandy soil, it is important to consider the location of a dense layer and the parameters of rock freezing. When constructing a foundation on sandy soil, it is essential to ensure effective thermal insulation. Roll waterproofing prevents the adhesion of frozen soil clumps, which could easily slide off the insulation. Remember that a two-story house with a strip foundation on sandy soil does not imply the presence of a basement.
- When conducting a geodetic assessment of water-saturated, easily erodable soil conditions, it is recommended to consider not a simple strip foundation, but a reinforced one with screw-in supports. A pile-strip foundation enables the construction of houses or other structures using heavier materials. Smaller architectural forms like garages, gazebos, saunas, and the like can be built on this foundation using cost-effective construction materials. Screw-in supports offer an optimal choice for foundational columns. A screw-type pile, overcoming unstable layers of dusty sand, penetrates into a solid layer, providing stability to the structure. However, it is imperative to have accurate knowledge that there are no loose soils beneath the solid layer. This necessitates a geodetic survey of the soil structure.
Advantages of constructing a pile foundation on sandy soil
Another type of foundation for load-bearing structures is the helical screw pile foundation, which is preferable for less stable sandy soils. Why choose this construction? The explanation is straightforward. The helical pile is an impeccable support that effectively transfers the weight of the building to deeply seated stable soils.
Constructing a foundation on sandy soil using helical piles is a swift process that requires minimal earthwork compared to other foundation types. The screw-type pile is installed in open spaces as well as densely built areas. Foundation installation can be done manually, and for complex configurations, substantial weight, and larger dimensions of piles, specialized equipment such as a hydraulic drill or pile driver is employed.
Piles for Sandy Soil The "Egoza" plant's helical pile can meet any requirements for length and configuration of the supporting element. Even in the case of dusty sands, a double-bladed pile will induce some compaction of the powdery soil. Fastening using self-drilling parts in dense, deep-seated rock formations will establish a stable base for a house or other structure on flat or sloping terrains.
If the objective is to establish a stable foundation on a site closely adjacent to a hill, the challenge lies in the uneven height of supports and the heterogeneity of rock formations. The utilization of self-drilling piles with varying configurations and equal load-bearing capacity solves both problems simultaneously. Additionally, the use of screw-in rods proves to be an effective method for creating a reliable foundation in coastal areas near rivers and seas, where sandy soils are more prevalent than rocky or clayey ones.
Key Aspects of Pile Foundation Construction
When the installation of a pile foundation is carried out by the skilled professionals of "Egoza" company, there is no need to worry about the correctness of constructing the structural framework. However, when independently forming the base for a building using helical piles, it is important to follow a specific sequence of actions.
- After the design phase, where a foundation is planned on self-drilling supports, it is imperative to clear the designated construction site of vegetation and remove topsoil.
- A string line (nylon cord) is used to mark the site. The result should resemble a blueprint for the future structure.
- When using concrete supports, holes are drilled until solid ground is reached. In the case of a screw-in support, the process is much simpler – it is simply screwed into the planned mark on the product's stem..
A pile-screw foundation is a viable option when confronted with a loose soil condition. Regardless of the site's continuous instability, a screw pile that reaches a solid layer ensures the reliability and stability of the structure.
When utilizing helical supports on sandy soils, it is imperative to adhere to the following guidelines:
- It is recommended that leading drilling be conducted with a drill diameter of at least 200 mm. This diameter is significantly larger than on denser rock formations, but it compensates for sand settling.
- Using water to simplify and expedite the drilling process on sandy soils is not recommended, as water contributes to sand erosion and settling.
Helical screw piles can provide a certain degree of cost savings in foundation work, especially when using coarse-grained sand. What is the economic impact of this?
- The significance of the depth of sand freezing is negligible owing to its slackness, enabling the helical pile to swiftly attain the intended depth..
- The aggregate length of the pile does not exceed two meters. Reducing the minimum length of the support allows for cost savings on the price of rod elements with bladed tips.
- The extent of earthworks is less extensive compared to other foundation types. This results in significant savings during the preparatory phase.
When choosing a foundation with "self-tapping" load-bearing elements, consult with the experts at "Egoza" plant - they can recommend the optimal configuration of the support rod, taking into account the specific characteristics of sandy soils in your area.