The Making of the Shoring Walls as the Pit Decends, Tier by Tier, 42 Feet Below Grade *Completed*

The first tier of the projects shoring wall nears completion. The iron rod protrudes from the shotcrete wall are the anchors or tendons that must be maneuvered into long predrilled holes into the side walls. The length of the holes (for this project) ranges from approximately 25 feet in length to 97 feet. The rods are inserted into the predrilled holes at a prescribed angle as specked by the engineers.  The second tier excavation can begin once all of the rods pass a stress test. Each row is approximately six feet high. Due to the slope of the project grade, roughly fifteen feet of the south wall needs to be excavated before digging begins on the north wall. The south wall will be approximately 45 feet below grade, while the south wall will be about 30 feet below grade.

The perimeter (from Prospect Street, north; Barton Road, south; Anderson Street, east; and Campus Steet, west) for the new hospitals, which will tower east and adjacent to the existing Loma Linda University Medical Center, was fenced off in the late Spring of 2016. Until the steel structure begins to rise above the chain link fence, the visitor can only imagine what is going on behind the fence. Hopefully, this website will satisfy the curiosity of the visitors to this site. Questions concerning the construction are welcome. All questions should be sent to: ttletc@gmail.com

Before the pit can be dug 75-foot H-beam iron pilings (also known as soldier piles) must be sunk. The shoring walls will be attached
to the H-beams after the soil is cut back or excavated parallel to the beams at six-foot vertical intervals. Because of the north-south elevation slope
of approximately 12-feet, the building pad will level out at about 30-feet below grade at the northern shoring wall while the south shoring wall
will level out at approximately 42-feet below grade.

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The First Tier Exposed:
While the piling holes continue to be drilled and the H-beams lowered and cemented in the 75-foot holes, the first vertical cutback of approximately
six-feet is made along the southern bank. With the H-beams exposed, the shoring wall process begins. Four-and-a-half months later (mid-October 2016),
excavators reached pad level at the south wall at 42-feet below grade.

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After the initial bench cutback, a small bucket attached to the hydraulic elbow boom of a Bobcat mini excavator cuts away the
compacted soil from around the H-beam pilings. A mini Bobcat skip loader removes the excess dirt from the bottom of the cutback.

Small rock wheel attached to the end of a hydraulic boom allows for a mini excavator to grind away cement, rocks, and compacted soil from
between the H-beam pilings.

With handheld jackhammers, laborers cut away soil and concrete from around the H-beams.

When the concrete is too thick, an excavator-mounted hydraulic jackhammer is used to break up the concrete from around the H-beams.

Once the wall has been  cleared and cleaned to the width of the H-beam appropriately spaced rebar spikes are driven into the vertical wall.

After measuring the width and height of the section, the rebar is cut with a portable rebar cutter to the measured lengths.

The first rung of rebar placed between H-beams on previously hammered rebar spikes previously hammered into the wall.

With the skill and speed of a surgeon suturing a wound, these laborers tie the rebar together with wire.

The Last Tier Exposed:
After the last vertical section of H-beams are exposed and the rebar mesh is completed, the last tier of the south wall will be sprayed with
shotcrete at the final pad level of 42-feet below grade. The south shoring wall incorporates seven six foot tiers, which creates a wall 42-feet below grade.
Each H-beam (soldier piling) column on the south shoring wall is anchored by four anchor rods vertically spaced from about four feet below grade, 16 feet
below grade, 24 feet below grade, and 30 feet below grade.

With a high-pressure hose, shot create is sprayed on the wall covering the rebar. The rebar serves three purposes: reinforcement, strength, and stabilization.

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A nozzleman applies shot create from a snorkel crane.

After the shotcrete is applied over the rebar mesh, a concrete laborer carefully screeds (trowels) the section to smooth out the material. 

After the screeding process, a laborer sprays a chemical on the surface to assure proper hydration and proper curing.

Beginning with the top tier a black dimpled membrane, sometimes referred to as a drainboard, is nailed to the compacted soil between each H-beam. The membrane, which is placed between the soil and shotcrete will extend to about 36 feet below grade where it will terminate into and drain out of a PVC pipe.

 The first tier skeleton on the north shoring wall, which is ready for the shotcrete application. Notice the black drainboard centered in each section.

The above photo illustrates how the dimpled weep pads terminate into PVC pipes. One drain is angled down toward the floor while the other drain is angled up, which allows for a more even displacement of moisture. To reach permanent grade, one more horizontal six-foot cutback must be completed. The writing in yellow chalk on the center piling at midline tell the laborer the following (from top to bottom): ok=the anchor rod is ready to be grouted, 11-c=the piling number, 30’=the anchor rod is 30 feet in length, and 25=the rod is angled at 25 degrees. This section is also ready to be sprayed with shotcrete.

The second tier excavation can begin once all of the rods pass a stress test. Each row is approximately six feet high. Due to the slope of the project grade, roughly fifteen feet of the south wall needs to be excavated before digging begins on the north wall. The south wall will be approximately 45 feet below grade, while the south wall will be about 30 feet below grade.

The photo above, which was taken on October 21, 2016, illustrates the full height of the shoring wall along the southern perimeter of
the project. The last tier on the south side is being prepared for the last six feet of shotcrete. Once the final tier is completed around the
whole perimeter of the project, work will begin on the underground ducting which will be encased in cement under the four-inch thick
concrete mat. Reinforcement rebar will be laid on top of the mat to support and strengthen the four-foot thick concrete foundation pad.

As the final tier is being prepared for shotcrete, iron workers lower one of the many 45-foot rebar skeletons called caissons (pilings)
into the ground. According to the specs three caissons will be strategically placed parallel the south shoring wall and five caissons will be placed
parallel to the north shoring wall . Once lowered to the proper depth and stabilized, concrete will be poured into the hole. Caissons are used to
distribute the structural load of the building and will be integrated into the four-foot thick concrete building pad.

The south shoring wall looms tall above the construction pit floor. The structure at the top of the photo (at grade) is parking structure P4. This
multi-story facility is under construction across Barton Road, which is a four-lane thoroughfare with a median.