| 主权项 |
1. A bridge system for providing a surrounded water flow pathway tunnel adapted to produce an environmentally friendly tunnel bottom, the system comprising:
a plurality of four-sided precast concrete bridge units in abutting relationship to create the surrounded water flow pathway tunnel, one end of the pathway tunnel located upstream along a natural water path and an opposite end of the pathway tunnel located downstream along the natural water path, wherein each of the four-sided precast concrete bridge units includes: spaced apart side walls interconnected by a top wall, and a bottom configuration formed by a plurality of precast concrete beams extending from one side wall to the other sidewall and that are spaced apart along a depth of the bridge unit to define a plurality of elongated through openings for interacting with flowing water and earthen material in flowing water to enhance capture and settling of earthen material along the pathway tunnel, wherein each of the plurality of elongated through openings extends from one side wall to the other side wall to provide full span connectivity between the pathway tunnel and the underlying ground along each elongated through opening, each elongated precast concrete beam having a bottom side that is in a common plane with a bottom surface of each of the side walls so as to aid in transferring load to ground below the bridge unit, wherein at least one elongated precast concrete beam has a configuration that is different than a configuration of another one of the elongated precast concrete beams; wherein at least forty percent of the bottom configuration of each of the four-sided precast concrete bridge units is open; wherein, in the case of each of the four-sided precast concrete bridge units, at least one elongated precast concrete beam has a depth that is greater than a depth of another one of the elongated precast concrete beams; wherein, in the case of each of the four-sided precast concrete bridge units, at least one elongated precast concrete beam includes a plurality of upwardly projecting sedimentation members spaced apart in a spanwise direction to define gaps between the sedimentation members, at least one sedimentation member having a height that is different than a height of another sedimentation member, each sedimentation member having a height that is between about ten percent and about twenty-seven percent of a clear height of the pathway tunnel at top dead center, each gap between the sedimentation members is between about six percent and about twelve percent of the span of the pathway tunnel, a center-to-center spacing between adjacent sedimentation members is between about twelve percent and about seventeen percent of the span of the pathway tunnel, and sedimentation members located toward the side walls have heights that are greater than heights of sedimentation members located centrally along the span of the pathway tunnel; wherein, in the case of each of the four-sided precast concrete bridge units, at least one of the elongated precast concrete beams lacks any sedimentation members, such that a depthwise center to center spacing along the pathway tunnel between elongated precast concrete beams having sedimentation members is between about thirty percent and about seventy percent of the span of the pathway tunnel; and wherein, in the case of each of the four-sided precast concrete bridge units, a first one of the elongated precast concrete beams at one end of the bridge unit lacks any sedimentation members and a second one of the elongated precast beams at an opposite end of the bridge unit includes sedimentation members, and the plurality of four-sided precast concrete bridge units are arranged such that, in the case of adjacent bridge units, the first elongated precast concrete beam of one bridge unit abuts the second elongated precast concrete beam of the other bridge unit. |
