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GROUND COMPACTION - URETEK Deep-Injection

THE WORK PROCEDURE

EVALUATION CRITERIA BEFORE SITE WORKS

Before repair by any means, it is important that the cause of the problem be determined and, if necessary - and possible, addressed.

Thus, before correction by URETEK Deep-Injection, either:- The causes of subsidence should no longer exist. e.g. an adjacent excavation, now permanently retained.

A decision may have been made to accept future maintenance. e.g. tree roots or decaying vegetable matter in the ground.

and/or
A geotechnical investigation will have determined the likely suitability of the ground for compaction by URETEK Deep-Injection. The nature of the ground and problem is known with enough certainty for the work to proceed.

Based on building design and client needs, plan locations for the Deep-Injection points are proposed. Then, based on available geotechnical information, (often multiple) depths are proposed for each location.

RESPONSIBILITIES AND HOURS OF WORK

A statement in relation to the above, together with a definition of the URETEK scope-of-works, plus any responsibilities of the client or others, is set out in a prior written submission to the client.

The works are programmed to meet client requirements. In commercial situations or on highways, work can be carried out overnight but this is generally unnecessary, as the intrusion of URETEK operations is minimal.

ESTABLISHMENT ON SITE

All work is carried out by specialist URETEK technicians, operating from a fully equipped mobile workshop.

Upon arrival, the work area and scope of works are reconfirmed with the client and responsibilities are checked.

Pedestrians and vehicles are excluded from the immediate work area and any necessary action is taken to protect finishes and fittings.

SITE SURVEY & SET-OUT

The affected area is surveyed with laser or computer level and the current degree of settlement is noted.

Checking site conditions, injection locations are confirmed.

At one or more locations, a hand or hydraulically operated penetrometer may be used to establish or confirm variation in bearing capacity of ground layers, down to several metres (20 to 30 feet). If relevant, this can allow the technicians to concentrate on specific soft layers. Further, or alternatively, it allows for comparison with penetrometer testing immediately after injection.

Using very long drill bits, exclusive to URETEK, a series of holes 16 mm to 25 mm (1") in diameter are drilled to required depths, at spacings of 1 to 2 metres and long, multiple injection tubes installed. The holes may be at an incline, or vertical, right through the footings of the structure.

Laser receivers, capable of detecting minute movement, are fixed to the structure to allow continuous monitoring.

COMPACTION PROCESS

Within a very short period, injection can begin.

A plural component, delivery hose is run out from the mobile URETEK workshop. URETEK material, stored in the workshop, is injected down through the injection tubes. The hose is very long, allowing the workshop vehicle to be conveniently parked a long way from the point of application.

Each injection is halted as soon as the smallest movement of the structure is detected and compaction thus confirmed.

LIFTING PROCESS

If required, injection may be later repeated, in order to lift the structure towards the required level.

SEQUENTIAL WORK

These processes are then sequentially repeated, at multiple depths and across the affected area.

If determined necessary, The URETEK Method for lifting may be used in combination with URETEK Deep-Injection to complete the treatment.

QUALITY CONTROL TESTING

From time to time, 'before and after' Dynamic Cone Penetrometer testing may be carried out and the results passed to the supervising engineer.

FAST CLEANUP

Cleanup is simple and usually consists of a broom, dustpan and perhaps a light vacuum.

RETURN TO USE

Each completed work area can be returned to use, or is ready for following trades, immediately.

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