The Hampton Roads Connector Partners JV (HRCP) consisting of Dragados USA, VINCI Construction, and Flatiron, has been selected to construct the $3.3BN Design Build project; the largest civil construction contract ever awarded by the Virginia Department of Transportation (VDOT).
The project scope across a9 milesection of the I-64 will include: a new 3.5-mile bridge-tunnel crossing that will accommodate a total of 8 lanes of capacity across the water, replacement of the existing marine approach bridges and the addition of a third lane on I-64 in each direction. The twin 45' diameter 1.5-mile tunnels will be bored by TBM, creating the second largest TBM tunnel opening for a TBM in North America. The project is expected to continue to the end of 2025.
The HRBT tunnel boring machine is a mobile plant 425 feet long and 45 feet in diameter, equipped with recent technology (variable density) allowing it to excavate in difficult geologies. The operator carries out a permanent control of the progress of the machine, from the cockpit he regulates the pressure parameters in the excavation chamber, the pressure of the thrust cylinders, the speed of rotation of the cutting wheel and its step, the injection of 27,5 cubic yards every 6,5 feet of a two-component mortar into the annular void and follows the planned route in a 3D environment. The use of the Variable density adds to all this, the management of additional parameters which are, adjustment of the flow rates in the drilling fluid network (up to 13,200 USgpm) 3000 m3 / h, the distribution of this flow between the excavation chamber and fluidization box, and the speed and pressure in the extraction screw of the excavated materials.
The TBM Operator will work jointly with a team of electricians, automation engineers, specialized mechanics, hydraulic engineers and topographers. it is also in contact with the surface and the operator of the drilling fluid treatment plant with which it determines the rheological adjustments required per the geologies crossed.
The candidate must know how to appreciate many parameters in mechanics, electricity, automation, but also in civil engineering, they must also consider the geological nature of the ground.
This position is a key position on tunnel sites, which is why the operator must know how to manage a certain stress, identify incidents and breakdowns. He is at the center of the tunnel boring machine's communication, he must know how to receive and transmit the right information to the right person, in short, it is his responsibility to find the ideal understanding between the machine, the people and the ground to bedigged.
The complexity of operating a machine of this diameter (45 feet), as example pressure difference between the top of the excavation chamber and the bottom is 1.4 bar (20.3 psi, and this under the ocean, in difficult geology, and in the immediate vicinity of two other tunnels open to traffic, it is in its ability to have the right reflex if an unexpected situation arises, or to be able to give the right diagnosis if there is a technical problem, that the experience of the operators can here really make the difference and ensure the safety of the employees who work on the construction, as well as the good completion of the work.
Because we are going to use a variable density tunnel boring machine, the operators must necessarily have extensive experience on large diameter Mix Shield and Earth Pressure Balance machines, with high pressures.
As a TBM Operator on the $3.3BN Hampton Roads Bridge Tunnel Expansion Project (HRBT) in Virginia, you will assist the TBM Superintendent with the tunnel excavation.
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