An intense time schedule compelled us to work with two bore and grout units simultaneously. As work space and access to heavy-lift cranes were limited, we conducted our job almost exclusively in night shifts, such that concreting and steel tying works nearby were not obstructed by our pres-ence. The enclosed nature of our working area required extensive planning and coordination on our part.
For quality assurance, we insisted on the use of a digital drill data measuring system. As depicted in Image 4, our system captures drill progress, con-tact pressure, torque, grout pressure, and grout quantity during bore and grout works. These data enabled us a precise and transparent analysis of our works. For instance, in combination with a suspension scale we were able to accurately monitor cement consumption, and adapt material usage for optimal pile production. Such predic-tions enabled us to keep material cost low and satisfy our client’s demands.
The GEWI- bars were inserted recessed by 8,50 m into the bore hole. As simply letting the heavy steels bars fall to the bottom may have caused damage to the double corrosion protection, we provided for a controlled placement of the load bearing element. The bridging of the 8,50 m gap took place via a system consisting of fold-out nut and a special coupling device that was connected to the GEWI- bar and lifted to the upper entry into the bore hole. A two-piece muffle was attached, as shown in Image 2, in order to hold the steel bar in place and then lower it slowly to the bottom of the drill hole, where it was released. We routinely verified the correct by checking the protrusion of our coupling device from the bore hole.
Thanks to our flexibility and competence we man-aged to complete our job timely and to the satis-faction of our client despite the challenges posed to us. We especially owe a great deal of respect to our work crews, who persistently delivered top performance in night shifts for more than eleven weeks.
