Regina's expansion through the mid-20th century pushed construction southward across Wascana Creek into areas where the glacial Lake Regina sediments dominate the subsurface profile. The city sits on up to 18 meters of high-plasticity lacustrine clay overlying glacial till, a sequence that makes lateral earth support systems far more demanding than a simple cantilever wall can handle. When a developer breaks ground for a parkade near Victoria Avenue or a utility vault in the Warehouse District, the shoring solution almost always requires active/passive anchor design to manage the sustained creep pressure these clays exert over time. Our team has worked extensively with the local stratigraphy, including the stiff upper till at roughly 9 to 12 meters depth that serves as a reliable bond zone for strand anchors. We pair this understanding with the slope stability analysis methods described by Spencer and Morgenstern-Price to verify global stability, and we routinely specify deep excavations monitoring protocols when adjacent structures require settlement thresholds below 10 millimeters.
Saskatchewan's high-plasticity clays exert long-term lateral pressures that a simple Rankine analysis cannot capture—anchored systems must account for undrained stability during construction and drained creep over the structure's service life.
Applicable standards
CSA A23.3: Design of Concrete Structures – Annex D (Anchoring to Concrete and Rock), NBCC 2020 – Division B, Part 4 (Structural Design) – Seismic provisions for Regina, PTI DC35.1-14: Recommendations for Prestressed Rock and Soil Anchors, ASTM A416/A416M: Standard Specification for Low-Relaxation Seven-Wire Steel Strand, CAN/CSA-G40.20/G40.21: General Requirements for Rolled or Welded Structural Quality Steel
Common questions
How much does an active/passive anchor design service cost for a project in Regina?
Our anchor design fees for a typical Regina excavation project range from CA$1,500 to CA$4,730 depending on the number of anchor rows, the complexity of the soil profile, and whether proof testing supervision is included. A single-family lot retaining wall with 2–3 anchors sits at the lower end; a multi-level parkade excavation with four rows of strand anchors and a full testing program falls at the upper end of that range.
What is the difference between active and passive anchors in Regina's clay soils?
Active anchors are post-tensioned to a lock-off load (typically 65–70% of the tendon's ultimate strength) immediately after the grout reaches sufficient strength, actively compressing the retained soil mass and reducing lateral movement. Passive anchors are not prestressed; they develop resistance only when the wall moves enough to engage the tendon, making them suitable for temporary cuts in the stiff upper till where some deformation is acceptable. In Regina's soft lacustrine clay, we almost always specify active anchors for permanent structures because the creep rate under sustained load is lower than the deformation required to mobilize a passive system.
How do you determine the bond length in Regina's glacial till?
We calculate bond length using the effective stress approach, multiplying the average overburden pressure at the bond zone by a friction factor derived from drained triaxial testing on undisturbed till samples. In the till underlying Regina, we typically use a grout-to-ground bond stress of 80–120 kPa for low-pressure gravity-grouted anchors, increasing to 200–350 kPa when post-grouting techniques are employed. Every design is verified by on-site proof testing; we require a minimum of three sacrificial test anchors when the bond zone is within 2 meters of the clay-till interface.
Are there any special corrosion protection requirements for anchors in Saskatchewan soils?
Yes. The sulfate-rich nature of the glacial lake sediments in the Regina area—often exceeding 1,500 ppm in the upper 5 meters—requires Class I double-corrosion protection per PTI recommendations for all permanent anchors. This means a corrugated plastic sheathing over the full free length, epoxy coating on the strand in the bond zone, and a watertight encapsulation at the anchor head. We also specify electrical isolation testing between the strand and the surrounding steel reinforcement before lock-off to verify the integrity of the protection system.
