Bored piles are the most versatile piles and, consequently, are largely used in the field of deep foundations.
The pile diameters that can be achieved have no limitation, but generally vary progressively between 400 and 2500 mm. The depths that can be reached exceed 60 m.
In this field, TREVl's technological development has been aimed at reducing the static bentonite mud commonly used to support the excavation in presence of cohesion less or soft cohesive soils by using polymeric mixtures. The goal of this elimination is a reduction in the job site overall dimensions, and the solution to the problem of debris polluted by drilling muds.

Trelicon piles, the continuous auger bored piles, belong to the category of bored piles with partial soil removal. Drilling is performed by means of a hollow, continuous auger.
During the auger extraction, the cavity left by the auger is filled with concrete which is pumped through the central hollow bar. Once the auger has been extracted, the steel cage is inserted into the fresh concrete. This technique is optimal for the execution of piles in confined areas, since it does not require bentonite mud, or when working next to pre-existing buildings, since no vibration or soil decompression is caused and little noise is produced.
This technique allows the production of piles with diameters varying from 300 to 1000 mm, for a maximum depth of 30 meters.

Diaphragm walls are used to form vertical shields with minimal thickness in comparison with their length.
Diaphragm walls are used for the following applications:

Micropiles enable the solution of all those foundation problems which could not be faced by means of other techniques, thanks to the possibility of using equipment with reduced overall dimensions, hence causing the minimum disturbance to the soil and pre-existing buildings.

Modern equipment used to check the quality of concrete in the foundations are utilized by TREVI, the equipment is regularly updated.

Ground anchors are structural elements, traction-operated and capable of transmitting loads to depths. Ground anchors can be classified as having an "active" part, the real anchoring, and a "passive" part, the transfer of stresses from the anchoring head of the item to the "active" part.

With reference to the method of execution, ground anchors can be divided into:

Soil mix & jet grouting: Improvement of soil mechanical caracteristics can be obtained by mixing soil & cement, using high or low pressures which are generally called Jet grouting and Soilmixing.

The jet grouting technique consists in disintegrating the soil and mixing it with cement mixtures by means of high pressure jets. Such techniques, which involve different treatments, allow to operate in an extremely wide range of soils and offer a remarkable flexibility of applications.

TREVI started its activity in this field in 1979, by signing an agreement of cooperation and sole agency with the renowned KAJIMA company which developed and patented this system, among many others. In the following years, TREVI developed and improved the application system called TREVIJET.

The diameters of consolidated soil columns, obtained with the above methods, vary according to the adopted treatment parameters and the type and mechanical characteristics of the soil from 0.35 meter to 2.2 meters. It is possible to reach dephts exceeding 60m.

Soilmix is a mechanical method mixing the low pressure grouting with the soil in situ, aiming at obtaining consolidated columns.

Drains: The time required for soft soil consolidation can be drastically reduced with the application of vertical drains. Prefabricated vertical drains consisting of corrugated plastic sheets with geotextile filters are pushed into the soil by means of a steel mandrin and left in place while the mandrin is extracted.

Interstitial water contained in the soil is filtered by the geotextile and brought to the surface by the corrugated sheet where it can be easily collected and canalised.

The equipment is able to reach more than 30 m depth with the option to use vibrators to facilitate the introduction of the drains and overcome possible obstructions.

Vibrotrevi is a special driven cased pile where a temporary steel casing is driven into the soil and retrieved by means of powerful hydraulic vibrator alter the concrete pouring. The system allows the total reutilization of the casing, giving, costwise, great advantages with its application. Vibrotrevi has been experimented in many sites, with diameters ranging from 400 to 600 mm and depth up to 25 m.

Precast Pile Precast square elements are driven by means of diesel or hydraulic hammers and joint together with special keys designed by Trevi technical department. The elements are prepared in Trevi's precast yards which are able to produce up to 300 linear meter per day with dimensions of 27.5 x 27.5 cm. and 36x36 cm. Precast piles are especially utilised for their low cost advantages, for sites in remote areas and for foundations with contained vertical loads applied.

Drilling & Grouting: Especially used for the hydraulic sealing treatments of dams' foundations, the drilling and grouting technique is also reccomended for civil work applications like bottom plugs or the reconditioning of old building foundations. The drilling and grouting techniques are mainly used in rocks and consist in executing small diameter drillings through which grout is injected, in order to seal any possible fissures or cracks. Modern drilling and grouting equipment is normally used by our Trevi teams for the different grouting methods required by the technical specifications. Mixtures to be used are selected depending on the size and locations of the works to be performed.

Cased piles are executed in situ without the necessity for soil removal. Driving is carried out by means of a diesel or hydraulic hammer. Maximum depth of 96 meters, with diameters varying from 355 to 760 mm.

Every civil project requires a proper understanding of the soil characteristics of the whole construction area as well as the detailed knowledge of the underground conditions. TFN has been constantly involved in the soil investigation surveys of all the major projects executed in the country for more than 20 years with its fleet of 20 equipment and the knowledge of a vast experience in the field,also supported by a logistic net of offices and yards.

Onshore or offshore bore holes with sample recovery, standard penetration tests, electrical and mechanical static penetration tests, pressumeter tests and a wide range of in situ tests are performed by Trevi geotechnical department.

Moreover, a modern, fully computerised geotechnical laboratory equipped with the most advanced devices is able to assist, with its output, an already competent capacity in the field.