The new rotary tool designed by Baronissi brand is perfect for drilling in the hardest rock conditions. It is highly appreciated by drillers who want to push rigs performance beyond the limit.
Compared to conventional methods, the new Tri Roller designed by Sip&T allows a high coefficient of penetration, a longer duration and a greater number of cored meters per day . In this way, thanks to an efficient and relevant reliability, it is able to maximize customers drill’s return on investment . Here in details, we explain how it produce s its advantages .
Development as motivation Since the production started in 1996 with the first conical auger, Sip&T has built thousands of rotary drilling tools and many of these are still in operation worldwide . The reason for the high reliability is that our engineers firmly control the whole process, from design and development to production and testing before delivery. The perfect match between drill characteristics, drilling tools and soil conditions is a key factor for SIP&T tools achievement. All single processes are constantly monitored and supported by certified internal quality control department, from the raw material choice to the permitted tolerance. Many ideas, requirements and wishes of our customers often merge into our continuous improvement processes. The technology of rotary drilling tools represents a world apart: for instance, the chance to transfer a torque through a kelly bar up to a depth of 100 meters or the skills of flight auger cutting edge to destroy and pick rock debris are complex topics rich of difficult situations. Giving a right science interpretation, knowledge of materials, application of mechanical principle s and the introduction of special technologies for soil treatment, are the only way to face and solve matters concerning the drilling of extremely hard rock layers with compressive strength > 100 MPa. Chart A stands for the scheme of drilling tools chosen according to the Rock Compressive Strength. An important notice is that not only the Rock Compressive Strength (RCS) influences the drillability and rock tool life, but also the degree of fracture and the number of joints in the rock mass as well as the resistance of the material to traction, friction, cutting and scraping forces. One of the most frequent question of SIP&T team is: what type of drilling tool could be applied when the RCS is greater than 100 MPa?
Future has come We know that perforation becomes difficult as the compressive rock strength increases and so as the diameter of the hole. Techniques like FFC (Full Face Cutter), DTH (DownThe Hole) and MHD (Multi Hammer Drill) expect the use of expensive tools due to the customized mechanical components made in agreement with pile diameter, type of rock to drill and drill characteristics. Furthermore, it is necessary to analyze the environmental impact: dust is one of the worst enemies made by the mentioned technologies.
In remote areas, dust emission could be more tolerable than suburban areas. However, it poses a threat for health and workplace safety and should be minimized. For all these reasons, in particular for the workplace safety, important subject for SIP&T, the company has recently designed the PRA-S LINE auger and created a new tool, the Tri Roller Bits Core Barrel. It can be used in rock with high compressive strength and along with PRA-S LINE auger and the Roller Bits Core Barrel, it avoids equipping the drilling rig with very expensive parts and significantly reduces the environmental impact.
and, on the bottom side, by three concentric rings. On these rings, there are kind of particular rotating heads got in staggered position having a hard cutting edge insert with ballistic shaping to scratch the rock. The rotating cutters can be also interchangeable. Moreover, available on request, it is possible to wrap up a spiral along the barrel to help the extraction of crashed rock from the bottom of the hole. What is the main advantage of this solution? Core Barrels that use rollers can crack rock with a width approximately equal to the diameter of the tri roller. Therefore, when the drill progresses, a rock core is created and it grows inside the cylindrical body. However, if the diameter of the hole is large, the crack weakens the rock core but not enough to allow its breaking point and extraction. TriRoller is made of three concentric crowns and achieves a groove in the rock three times higher than the previous situation described. More than that, it makes the rock layer weak with two easier possibility to have its extraction. It is clear that with a penetration rate three times higher, a significant reduction of drilling times is a big plus. Job site as case study As part of the program to develop the Romanian railway line, Trivel Sud Company of Vibonati, in Salerno, won a contract for the realization of a pile foundation batch. The Campania-based company has more than 30 years of experience in this field: it collaborates alongside giants companies to realize great civil engineering works.
Trivel Sud is specialized in drilling, piling and special foundations, with a certificate for the execution of public works (SOA OS 21 V classification and quality certification in accordance with UNI ENI ISO 9001: 2015). The company has modern and specific equipment as well as technical expertise gained during the realization of job sites both in Italy and abroad. It carries out foundation works from small to large diameter, both in the public and private industry, using different drilling techniques such as micro piles, borehole, cased piles or with the use of polymers, displaced and secant piles, CFA, diaphragms walls.The Romanian ongoing project expects the adjustment of the railway network to EU-15 standards able to guarantee top speeds of 200 km/h for passenger trains and 120 km/h for freight trains (high capacity). Trivel Sud is building partially cased piles up to a total depth of 35 meters with a diameter of 1.800mm by using a piling rig of about 80 tons, set up on a crawler truck of 4,5meters wide.The rig has a 443 HP engine, main winch of 220 kN, rotary head with max torque of 217 kNm and a piston stroke of 180 kN. The morphology of the subsoil within the project area mainly consists of igneous, metamorphic and sedimentary rocks. The geological report shows the massive presence of Granites with an RCS value between 130 and 250 MPa, quartzite with RCS between 150 and 300 and limestones with RCS between 55 and 220. The area is also subjected to the Andesitic rock substrate, which was found in some layers during the drill. Results In a first phase, drilling takes place with the use of standard core barrels, although in the strengthened version, reaching a penetration rate between 40 e 70 cm/h that allows a 35 m drilling pile in one working week. All with a maximum torque applied to the rotary head of 217 kNm at a pressure of 300 bar and a rotation speed of 11 per minute. By replacing the classic core barrel with the Tri Roller, the piston stroke increases of about 57% with the consequent completion of the pile in approximately three days. Max torque applied to the rotary head remains unchanged, and equal to 217 kNm, but the pressure of the same is reduced to 180 bar. The rotation speed increases from 11 to 18 with a 64% percentage increase. Another benefit is the fuel consumption, which goes from 55 to 37 l/h with about 33% percentage reduction.
According to these notes, the rig shows a much more stable behavior with less vibration during drilling operations and in general less wearing. Conclusion It can be said that drilling to make foundation piles using conventional rotary tools is generally limited to rocks with compressive strengths less than or equal to 100 MPa. Tri Roller is an alternative method to penetrate hard rocks when conventional drilling tools become ineffective and the overheads nose up. Many end users have caught the opportunity to use this innovative tool in extreme conditions of rock hardness by reporting positive comments on the increase in productivity, fuel saving, reputation on job site and return on investment.
