What does ground instability or weak ground mean?

The ground beneath us is constantly shifting. Ground instability is the propensity for upward, lateral, or downward movement, which can be caused by natural factors like earthquakes. During construction, ground instability can cause soil slippage which often requires stabilisation prior to conducting additional excavation for building foundations or swimming pools or building retaining walls. Once a building is already in place, ground instability can cause movement of the building or structure, resulting in internal or external wall cracks, inability to open and close windows and doors, sunken floors, and more.

Equally, weak ground cannot adequately support the weight of structures, thereby causing subsidence. Uneven floors, fractured floor tiles and wall cracks are all strong indicators of weak ground beneath the structure.

If a building or structure has subsided due to ground instability or weak ground, it is important to fix it right away, or risk further damage and potential hazards.

What causes ground instability or weak ground?

Ground instability can happen naturally as part of the earth’s constantly shifting crust. It can be exacerbated by issues such as soil compaction, loss of ground moisture, excessive excavation, or erosion. Ground instability causes subsidence and, often, the damage can seem to be reversed as the ground shifts back and forth over time.

However, without soil stabilisation, damage to buildings, such as wall cracks, are prone to reappear. In infrastructure or at large industrial sites, embankment slippage can be an issue, leading to further erosion and damage.

Ground instability should be mitigated where possible.

Furthermore, a number of different things can cause weak ground, whether it’s a natural or man-made occurrence. For example, the ground may already be made up of loosely-packed materials such as soil or sand. Or human activities such as drilling and excavating can loosen previously-dense ground.

Weak ground can happen over a large area or in smaller areas. Ground that is not uniformly weak will still lead to subsidence issues.

Different types of ground are susceptible to different conditions. For example, clay is prone to contracting in drought conditions, gravel can be affected by nearby construction or heavy traffic, and dirt can be softened by excess water.

Regardless of the cause, weak ground is reason to be concerned. Subsidence is the most common issue, which needs to be fixed to protect the building and its inhabitants.

Likely causes:

Water flooding the ground

Drought drying out soil

Washaways from broken pipes (such as water, sewer, stormwater drainage)

Poorly compacted fill

Liquid, gas or mineral resources being removed from the ground

Erosion

Earthquake and seismic activity

Tree roots, which can suck moisture from the ground

Vibrations caused by heavy road traffic or by machinery

Absence of an organised footing system – in very old buildings or in buildings with additions or alterations

Nearby excavation

Heavy loading

Deterioration of retaining walls

How to fix unstable and weak ground?

Mainmark specialises in soil stabilisation and ground compaction, foundation repairing, and strengthening weak ground to improve support for buildings, roads, bridges and other on-ground structures. We treat the ground beneath them to raise, re-level, and re-support these structures.

There are a number of options available to stabilise the ground, such as soil and embankment stabilisation, and void or hole-filling.

For example, Mainmark’s Terefil is the most advanced structural lightweight polymer modified cementitious-based filler. It flows into spaces to fill voids, making it a fast and effective way to stabilise the ground. Compared to typical foams, the patented foam used in Terefil has increased stability, a greater lift thickness, and can be pumped greater distances. It’s a cost-effective and environmentally-inert option that suits a range of applications such as mass fill for large voids, tanks, and abandoned mines.

Permeation grouting can create ground cohesion before excavation. It’s the longest-established and most widely-used technique, which involves filling cracks, joints, and other small defects in non-cohesive soils, sand, or other porous media. It can stabilise the ground at depths of up to 60 metres.

Alternatively, Mainmark can inject our proprietary Teretek engineered resin solution into the foundation ground under a building’s footings. The resins expand together chemically, creating pressure. That pressure lifts the building back to its correct level. Then, if there are weak layers in the ground, continuing injection at deeper levels can resolve this by compacting the ground, densifying and strengthening it to increase its bearing capacity. In some soil conditions, Mainmark can increase the bearing capacity of weak strata by as much as 500 per cent.

In cases of weak ground, Teretek engineered resin also assures sub-grade stability under existing on-ground structures including buildings, concrete floors, driveways, roads, paved airport runways, bridge approach slabs, bridge abutments and more.

Mainmark’s methods are quick, precise, don’t leave a mess, and don’t generally require occupants to vacate a building while work is being done.

Various product warranties and Building Code requirements apply (please contact us to see which apply in your region or country).


Ground instability and weak ground under commercial and industrial structures

Mainmark can stabilise and strengthen the ground under structures of any size, including commercial and industrial structures. The processes are time- and cost-effective, making them sought after around the world.

Ground instability and weak ground under commercial structures can result in damage to plant and machinery, occupational health and safety risks, and reduced efficiency if certain areas can’t be used. By stabilising and strengthening the soil Mainmark can level the structure, resolving damage and bringing the building back to full capacity, so businesses can often regain lost productivity.

From parking areas and loading docks to warehouses and office buildings, Mainmark’s ground stabilisation methods are suitable for foundation repair in any building of any size.

Technologies for strengthening foundation ground include Teretek deep-lift engineered resin solution and Jet Grouting. With both these methods, once in the ground the resins and hardeners mix together, expand to compact the surrounding soils and increase the load-bearing capacity.

To create ground cohesion before excavation, Permeation Grouting can be used, making it a good option for stabilising the ground for retaining walls, for example. It involves filling in small defects, cracks and joints in rock, sandy soils or other porous soils with an injected grout. This option is ideal for commercial and industrial buildings on the coast, as sandy coastal soils are often prone to slippage and can be used to stabilise the ground at depths of up to 60 metres.

Benefits of Mainmark’s ground stabilising methods:

There is minimum disruption to the site

There is little, if any, downtime to the business. In many cases, the site can still operate, with staff able to continue working (this is case-dependent, damage may be such that this is not possible)

Projects are completed in a time-frame significantly less than traditional methods

Non-invasive techniques keep further damage to the building, and the landscaping around it, to an absolute minimum

We don’t tear up floors and excavate ground, so don’t create any mess

Internal and external wall cracks generally close up, leaving only cosmetic treatment (plastering, painting and re-pointing brickwork)

Jammed doors and windows can usually operate properly again

Trip hazards are eliminated. Often, forklifts and trucks can run smoothly just 30 minutes after a floor or driveway is re-levelled

There’s usually no need to move stock or machinery off the floor. No excavation. No mess

Warehouse shelves and conveyor systems usually return to their correct positions as floors are re-levelled

Most large factory and warehouse floor repairs are completed in a day or two. There’s no cutting out of old slabs and no waiting days for new slabs to cure.

Mainmark ground stabilisation methods used for Commercial and Industrial structures: