How deep are ground screws installed?

Standard Product Specifications and Non-standard Custom Services

Our ground screws vary in both length and diameter, with our “everyday” range starting at 76mm diameter and fixed lengths of 1050mm, 1250mm, 1550mm and 2050mm.We can also customize the production according to your requirements. The 76mm standard model is the most versatile basic model in the market. It can be widely used in small wooden houses, garden fences, small photovoltaic support structures and other lightweight infrastructure projects. Besides the existing standard dimensions, the manufacturer supports adjusting the screw diameter, total length, pitch and thickness of the spiral blades as per individual requirements. Moreover, we can produce molds specifically for special terrains and special load-bearing needs. It can flexibly adapt to various niche projects and effectively solve the problem of standard specifications not being applicable.

Introduction to Fixed Multi-Diameter and Retractable Ground Screw Products

We also have 89mm and 114mm diameter screws in fixed lengths, and we have a range of extendable ground screws available in 76mm, 89mm and 114mm diameters, allowing installation to any depth required to reach a load-bearing ground. The 89mm and 114mm large-diameter products have greater bearing capacity and are mainly used in large and medium-sized photovoltaic power stations and steel structure platforms. The telescopic and spliced screws are composed of multiple sections of rods and are not limited by the length of a single finished product. During construction, it can continuously extend the screws and continuously drill until it reaches the stable bearing soil layer. It is the preferred product for projects involving backfill soil, soft soil, and mountainous areas.

Selection Principles Based on Soil Type, Bearing Capacity, and Elevation Difference

To determine what length of ground screws are needed for a project, ground conditions and the load-bearing capacity need to be considered. Ground levels also need to be taken into account, where we will often use a variety of lengths in an installation to bring up ground that is uneven or sloping, ensuring each screw has an equal or greater load-bearing capacity than required. For land with soft soil and low bearing capacity, longer-sized ground screws should be selected and driven through the weak soil layer. When encountering slopes or sites with large height differences, screws of different lengths need to be used at the same construction point. Uniformly set the top elevation of the screws to ensure that the upper components are installed horizontally and that all the bottom ends of the ground screws fall within the qualified bearing layer. This can meet the design load-bearing requirements.

Constraints on the Selection Process due to the Surrounding Environment of the Project

The surrounding area may also come into consideration when selecting the right ground screw for your project. For example, if the site is subject to potential flooding or if there are trees with underlying roots nearby. In areas prone to flooding, the groundwater level is high and the soil has been soaked in water for a long time, becoming soft. Therefore, the burial depth needs to be increased and coarse-diameter screws should be selected. In areas with dense tree roots, the main growth zone of the roots should be avoided. Moreover, the screw positions and the depth of insertion need to be adjusted to prevent the tree roots from squeezing and damaging the foundation. At the same time, avoid damaging the original tree roots during the drilling process.

Preventing Soil Bulging and Properly Controlling the Pre-buried Depth

Finally, it is essential to install ground screw foundations to a depth that will not be subject to ground heave – the upward movement of the ground usually associated with the expansion and contraction of soils when wet and drying out. Clay and silt soils expand when wet and contract when dry, which is highly likely to cause soil bulging. In extremely cold permafrost regions, there is also the problem of frost heave uplift. The construction depth must be lower than the soil layer affected by expansion and contraction, so as to fundamentally prevent the foundation from being lifted by the soil and the supports from deforming and cracking. This will significantly increase the service life of the foundation.

Pre-sale On-site Survey and Supporting Technical Services

When required, we can complete a pre-installation site survey, checking the ground conditions for suitability and ensuring the correct size of ground screws are specified for your project. The on-site survey includes soil layer sampling, bearing capacity testing, and groundwater level measurement, among other things. By precisely matching the screw specifications based on the measured data, it ensures that no safety hazards are caused by using specifications that are too small. At the same time, it also avoids the waste of materials due to the blind selection of overly long products, thereby reducing costs and increasing efficiency for the project.