Patent Publication Number: US-6908262-B1

Title: Systems and methods for driving large diameter caissons

Description:
RELATED APPLICATIONS 
   This application is a continuation-in-part of Ser. No. 10/260,116 which was filed on Sep. 27, 2002, now U.S. Pat. No. 6,672,805, which claimed priority of U.S. Provisional Application Ser. No. 60/325,881, which was filed on Sep. 27, 2001. 

   FIELD 
   The present invention relates to systems and methods for driving elongate members into the earth and, more particularly, to systems and methods adapted to drive large diameter caissons into the earth using vibration. 
   BACKGROUND OF THE INVENTION 
   In building, road, bridge, and other construction projects, the need often exists for driving elongate members into the ground. The elongate members may be solid, as in the case of wood or concrete piles, or they may be hollow. Hollow piles are typically made of plastic or metal. 
   The present invention relates to a specific type of hollow metal pile referred to as a caisson. More specifically, the present invention relates to systems and methods for driving large diameter caissons into the ground. 
   U.S. Pat. Nos. 6,427,402, 6,431,795, and 6,447,036 to White disclose systems and methods for driving caissons into the earth. The systems and methods disclosed in these patents typically employ one or more vibratory devices, a clamp system for clamping the vibratory device(s) to the caisson, and a suppression system for inhibiting transmission of vibratory forces to a crane, spotter, or other system for holding the vibratory device in place. The caissons to be driven by the systems disclosed by these patents are typically less than 20 feet in diameter. 
   In some situations, the need exists to drive caissons of even larger diameter. For example, certain construction projects require that caissons with diameters exceeding 40 feet be driven into the ground. Although known caisson driving systems could be scaled up in size to drive such large diameter caissons, simply increasing the size of the driving system increases the costs and complexity of transporting and operating the driving system. The need thus exists for systems and methods for driving large diameter caissons that may use conventional vibratory systems and methods. 
   SUMMARY OF THE INVENTION 
   These and other objects may be obtained the systems and methods of the present invention. In particular, the present invention may be embodied as a system for driving a large diameter caisson into the ground comprising a crane assembly, a plurality of vibratory devices, a clamp assembly, a suspension assembly, and a timing system. Each vibratory device generates a vibratory force. The clamp assembly rigidly secures each of the vibratory devices to one of a plurality of predetermined angularly spaced locations about the caisson. The suspension assembly connects the vibratory devices to the crane assembly such that transmission of vibratory forces from the vibratory devices to the crane assembly is inhibited. The timing system operatively connects the plurality of vibratory devices to synchronize the vibratory forces generated thereby. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view depicting a caisson driving system of the present invention; and 
       FIG. 2  is a perspective view depicting a vibratory system employed by the caisson driving system of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , depicted at  20  therein is a caisson driving system  20  constructed in accordance with, and embodying, the principles of the present invention. The exemplary caisson driving system  20  comprises a crane assembly  22  and a vibratory assembly  24  and is adapted to drive caissons  26  one at a time at a desired location  28 . 
   The crane assembly  22  is or may be conventional and comprises a rigid support structure  30  from which is suspended a crane line  32 . The vibratory assembly  24  is suspended from the crane line  32  above the desired location  28 . 
   The exemplary crane assembly  22  is barge mounted and thus adapted to drive the caissons  26  at a desired location under or near water; however, other crane assemblies may be used to implement the present invention. For example, the crane may be platform or track mounted for support and/or movement on land, and a plurality of smaller cranes may be used in place of one large crane. 
   Referring now to  FIG. 2 , the vibratory assembly  24  will now be described in further detail. The vibratory assembly  24  comprises a plurality of vibratory devices  40 , a clamp assembly  42 , a suspension assembly  44 , and a timing system  46 . 
   The vibratory devices  40  comprise a vibration unit  50  and a suppression unit  52 . The vibratory devices  40  are connected between the clamp assembly  42  and the suspension assembly  44  such that vibratory forces are transmitted along a vibratory axis A to the clamp assembly  42  but not to the suspension assembly  44 . In the exemplary vibratory assembly  24 , four vibratory devices  40  are used as will be described in further detail below. 
   In particular, the vibration units  50  may incorporate conventional counter-rotating eccentric weights  54  to translate rotational movement of the eccentric weights  54  into vibratory forces along the vibratory axis A. The suppression units  52  also are or may be conventional and employ a housing  56  rigidly connected to each vibration unit  50  and a plate  58  rigidly connected to the suspension assembly  44 . Resilient shock absorbing members (not shown) are connected between the housing  56  and the plate  58  such that only a portion of the vibration of the vibration unit  50  is transmitted to the plate  58  through the housing  56 . Suitable vibratory devices are sold by American Piledriving Equipment as Model Number 400. 
   The clamp assembly  42  comprises a clamp frame  60  and a plurality of clamping devices  62 . The clamping devices  62  are mounted to a lower surface of the clamp frame  60  and extend downwardly to clamp onto one of the caissons  26  and thereby secure the frame  60  relative to the caisson  26 . The clamp frame  60  is large enough to extend across the diameter of the caissons  26  such that the clamping devices  62  engage predetermined angularly spaced locations about an upper perimeter edge  64  of the caisson  26 . 
   In the exemplary vibratory assembly  24 , the clamp frame  60  is generally cruciform in shape and defines eight corner locations, with one clamping device  62  located at each corner location such that the clamping devices  62  spaced at forty-five degree increments about the caisson  26 . Other numbers and angular arrangements of clamping devices  62  are possible, and the exact details of the frame  60  are not critical as long as the frame  60  is capable of transmitting the vibratory forces of the vibratory devices  40  to the caisson  26 . 
   The suspension assembly  44  comprises a plurality of suspension cables  70  attached to the crane cable  32  and a suspension frame  72  that spaces the suspension cables above the vibratory devices  40 . 
   The timing system  46  comprises a plurality of timing shafts  80  and gear boxes  82 . In the exemplary vibratory assembly  24  having four vibratory devices  40 , six timing shafts  80  and three gear boxes  82  are employed. Two of the shafts  80  extend into each of the three gear boxes  82 . The gear boxes  82  translate axial rotation of one of the shafts  80  extending therein into axial rotation of the other of the shafts extending therein. Each of the shafts  80  further extends into one of the vibratory devices  40 , with two of the vibratory devices  40  receiving two shafts  80  and two receiving one shaft  80 . 
   The shafts  80  and gear boxes  82  mechanically interconnect the vibratory devices  40  such that the rotation of the eccentric weights  54  within the vibratory devices  40  is synchronized in both revolution speed and phase (as determined by angular location of the eccentric weights). 
   In particular, the vibratory devices  40  are connected in a daisy chain manner with one of the devices  40  being the master and the other of the devices being slaves. The revolution speed and phase of the master device  40   a  is transmitted through a first shaft  80   a  to a first gear box  82   a , from the first gear box  82   a  through a second shaft  80   b  to first slave device  40   b , from the first slave device  40   b  through a third shaft  80   c  to a second gear box  82   b , from the second gear box  82   b  through a fourth shaft  80   d  to a second slave device  40   c , from the second slave device  40   c  through a fifth shaft  80   e  to a third gear box  82   c , and from the third gear box  82   c  through a sixth shaft  80   f  to a third slave device  40   d.    
   The master/slave relationship among the various vibratory devices  40   a-d  ensures that the eccentric weights  54  therein counter-rotate in synchrony such that the vibratory forces created by the vibratory devices  40   a-d  are all in phase. The in-phase vibratory forces ensure that all four quadrants of the cruciform clamp frame  60  move up and down at the same time such that the effect of the vibratory forces is cumulative and not subtractive. The cumulative driving forces of the clamping devices  40   a-d  greatly increases the ability of the system  20  to drive the caissons  26  into the ground.