When a retaining wall itself does not provide sufficient stability, horizontal or angled holes are drilled into solid earth or rock. By setting and tensioning anchors, the stability of the wall is increased and this increases the allowable depth of the excavation. A full-length hole is drilled through the soil and into the bond zone in soil or rock using casing if necessary. A threadbar or strand tendon anchor is inserted into the hole and the hole is filled with high-strength grout.
The anchor head is then connected to the structure requiring the support and tensioned to the designated load.
Secant pile walls are formed by creating a row of intersecting concrete piles. Primary piles are poured along the line of the wall leaving gaps between the piles.
Next, secondary piles are installed in the gaps before the concrete on the first set of piles has reached full strength. These walls require precision both in placement and in installation.
Secant walls transfer lateral, vertical or a combination of both loads through weak soil layers to a suitable bearing layer.
They create an effective water control barrier for building structural walls where the water table is an issue.
Tangent pile walls are a variation of secant pile walls that are constructed with no overlap, in which one pile touches the other.
Compared to secant pile walls, tangent pile walls offer the advantage of increased construction alignment flexibility and easier and quicker construction. The main disadvantage of tangent pile walls is that they cannot be used in high groundwater tables without dewatering.
Perhaps more than any drilled shaft application, building secant and tangent walls requires precision.
There is no room for computational imprecision or operator error. Drilling Service Company has been designing and building secant and tangent walls for decades. We deliver both precise planning and steady, experienced execution.
Soil nailing drives or drills steel rods at precise angles and depths, which are then overlaid by wire mesh and shotcrete. This strategy can be part of a stabilization system or a stand-alone tool.
The walls are generally constructed from the top down. Soil is excavated from the top of the planned excavation. Near-horizontal holes are drilled into the exposed face.
Steel bars are inserted into the holes and grouted. A drainage system is installed on the exposed face, followed by the application of reinforced shotcrete facing.
Soldier Beams & Lagging
After drilling shafts and setting steel H-beams in concrete, we connect those beams with timber or concrete lagging to build a retaining wall.
The lagging resists the load of the retained soil and transfers it to the piles. Depending on the situation, we may also install tiebacks beyond the failure point for added strength.
Beam & Plate
In certain applications steel H-beams are set in drilled shafts and backfilled with pea gravel. We then bridge the area between the vertically-set beams with steel plates set in the flanges
of the beams to build a retaining wall. After providing the necessary working space to put a structure’s foundations in place, the beams and plates can be removed and the gap is then backfilled.