Boring through rock is not as hard as you think
Purchase or hire one of Robbins' small diameter boring machines and experience the most time and cost effective way to bore through hard rock. If you have a utility installation project that requires rock bores, or if you are a contractor that wants to extend your capabilities, then read about the high quality, durable, proven solutions that Robbins has to offer. Robbins employs a highly qualified, knowledgeable team that can help you tackle your next project with confidence.
No other company knows more about boring through hard rock.
Click on the links below to learn more about each machine type:
Robbins Small Boring Units (SBU-As)
The SBU-A is a small diameter rock cutting head (from 24"/600 mm to 72"/1.8 m) that can be used with any Auger Boring Machine (ABM) to excavate hard rock on drives less than 500 ft (150 m). The Robbins SBU-A has been proven on hundreds of jobs across the U.S. Over one hundred contractors in locations around the world have proven the SBU-A works better than any other method of excavating small diameter, hard rock bores.
Robbins Motorized Small Boring Units (SBU-Ms)
If you need to bore a small diameter tunnel in hard rock where line and grade are critical, Robbins offers Motorized Small Boring Units (SBU-Ms). These machines have been specifically designed for long bores (over 500 ft/150 m) with difficult ground conditions. They are offered in cutterhead diameters from 48"/1.2 m to 78"/2.0 m. If you are not familiar with SBU-As, we suggest you read about them before researching SBU-Ms.
Robbins Rockhead (SBU-RHSS or SBU-RHDS)
If line and grade are critical and you have a longer bore (over 1000 ft/300 m in length) for your next project, you should consider the Robbins Rockhead. The diameter range is available between 54" (1.35 m) and 78" (2.0 m). The Robbins Rockhead is a powerful mid-sized tunneling machine available in both Single Shield and Double Shield models.
SBU A
The Small Boring Unit (SBU-A) is a proven solution for medium to hard rock utility installations up to 150 m in length. The SBU-A can be used with any conventional auger boring machine (ABM) from 0.6 to 1.8 m in diameter and utilizes a full-face auger for spoils removal. For excavation,the SBU-A is welded to the lead casing. An ABM provides both torque and forward thrust to the cutting head. In hard rock, the circular cutterhead is fitted with disc cutters, while in mixed ground a combination of ripper teeth, drag, bits, and disc cutters are used.
MACHINE DIAMETERS 0.6 to 1.8 m
ROCK STRENGTHS 25 to over 175 MPa UCS
GROUND CONDITIONS Medium to hard rock, or mixed ground
SBU M
The Motorized SBU is the optimal choice for longer utility installations (over 150 m) or for crossings with specific line and grade requirements. The SBU-M is a manned-entry, hard rock boring machine for use with a standard Auger Boring Machine (ABM) or pipe jacking unit. The SBU-M uses disc cutters to excavate rock, while a small invert auger removes spoils from the face. Like the SBU-A, the SBU-M is welded to the lead casing prior to excavation. An in-shield motor provides torque to the drive train, while forward thrust is derived through the casing.
MACHINE DIAMETERS 1.2 to 2.0 m
ROCK STRENGTHS 25 to over 175 MPa UCS
GROUND CONDITIONS Medium to hard rock, or mixed ground
CUTTERHEADS Both hard rock and mixed ground cutterheads are available
CUTTERS All machines can be equipped with 165, 241, or 292 mm (6.5, 9.5, or 11.5") discs
Rockheads
The Robbins Rockhead is a powerful mid-sized tunneling machine modeled after larger TBMs that generates torque from a drive unit mounted at the cutterhead thrust bearing assembly. Each Rockhead is custom designed to fit your project's specifications, and is available in both Single Shield (SBU-RHSS) and Double Shield (SBU-RHDS) models.
Rockheads employ a different excavation method from the Robbins SBU-A, which is dependent on the auger for torque and a standard boring machine for thrust. . Double Shield Rockheads are self-propelled using a gripper system, while Single Shield Rockheads must be used with a pipe-jacking system or primary liner erected in the tail shield. Torque is achieved through an in-shield drive motor
The Robbins Company has the right machine for your job. Let us help you select the right machine from our proven designs.
Bore Diameter:
The diameter range for the Robbins Rockhead is available between 54 inch (1.35 m) and 78 inch (2.00 m).
Bore Length:
For bores that are over 1,000 ft (300 m) in length. The maximum bore length is dependent on ground conditions and other specifications on your project.
Carrier Pipe:
The Robbins Rockhead can be used in conjunction with:
- Steel casing
- Reinforced concrete pipe
- Ring beam and board
- Four flange liner plate
Spoil Removal Options
There are several methods to consider, and most are dependent on the length of the bore and what equipment you already own.
- Machine belt conveyor to invert auger: For short to mid-sized bores (<500 ft or <150 m).
- Machine belt conveyor to small