Skip to main content

Installation Considerations for Piles on Alluvial Land

 

Piling on alluvial land requires a special approach. Alluvial soil typically consists of water-saturated sand with a very loose structure, obtained by hydraulic flushing from quarries or dredging.

Specifics of Working with Alluvial Soil

Alluvial soil differs from conventional backfill in the way it is formed. With hydraulic filling, sand is added with a large amount of water, settles in a designated area, and gradually dehydrates. This type of soil has certain characteristics.

Characteristics of alluvial soil:

•        High initial moisture content (30–40% or more)

•        Very loose structure—porosity coefficient of 0.7–0.9

•        Unevenness across the surface—in some areas, more large particles have settled, while in others, more small ones have settled.

•        Continued shrinkage under its own weight for 1–3 years.

•        Uneven density across depth.

The main problem with alluvial areas is that they continue to compact for years after filling. If construction begins too early, the foundation will settle along with the soil.

Technical Solutions for Alluvial Areas

When working with alluvial soil, one must either wait for it to compact naturally (1.5–3 years), employ special accelerated consolidation technologies, or use long piles that will penetrate the entire alluvial layer.

Solution options:

1.       Use longer piles to reach dense layers beneath the alluvial layer.

2.       Install additional piles to reduce the load on each pile (increments of 1.5–2 m instead of 2.5–3 m).

3.       Use piles with a larger blade area (diameter 300–350 mm instead of 250 mm).

4.       Mandatory grillage for uniform load distribution.

5.       Install a drainage system to remove excess moisture.

6.       Monitor settlement during the first 2–3 years of operation using benchmarks.

Comments

Post a Comment

Popular posts from this blog

How to screw in helical piles?

  A helical pile (screw anchor) is a pipe with a pointed end and a spiral blade that can be screwed into the ground, similar to screwing a screw into wood. While this may seem simple, this type of work is very difficult and demanding. Screwing Methods Pile foundation elements can be screwed into the ground in two ways: ·        Using construction equipment. For this purpose, special excavator-mounted or self-propelled drilling rigs are used, which drive anchors even into frozen ground as if they were butter. This technique is also used to test the load-bearing capacity of pile structures. ·         Manual Method. This technology is used when it is impossible to bring equipment to the site. Manually installing helical anchors is very difficult and labor-intensive. Online and in print publications, this type of work is sometimes portrayed as simple and quick, but in reality, this is far from the case. Self-tappi...
Post a Comment
Read more

Common mistakes when working with backfill

Experience shows that most foundation problems on fill soils arise from common mistakes that can be easily avoided with the right approach. Common mistakes developers make •         Forgoing engineering surveys to save money is the most common and costly mistake. Without soil data, it's impossible to accurately calculate pile length and their bearing capacity. •         Using short piles that don't reach dense soil is the second most common mistake. Developers choose standard 2.5-3 meter piles without considering the thickness of the backfill. As a result, the piles rest on soft soil and settle. •         Installing piles immediately after backfilling, without allowing time for settling, causes the fresh backfill to compact under the piles, causing them to settle. The minimum curing period for backfill is 3-6 months with good compaction. •      ...
Post a Comment
Read more