Case Study 1: Passive Reinforcement of a Cut Slope

A contractor is widening a highway through a hilly region, requiring a near-vertical $6\text{-meter}$ excavation in stiff clay. The engineer designs a top-down soil nail wall to stabilize the excavation face.

Case Study 2: The "Gravity Wall" Concept

During a design review for a $10\text{-meter}$ high soil nail wall, a junior engineer questions why the nails are relatively closely spaced and relatively short compared to ground anchors.

Case Study 3: Active Restraint for Deep Excavations

A $15\text{-meter}$ deep excavation is required for a skyscraper foundation in a dense downtown area. The excavation is adjacent to a historic masonry building that cannot tolerate any lateral movement. The engineer specifies a soldier pile and lagging wall supported by pre-tensioned ground anchors (tiebacks).

Case Study 4: The Function of the Unbonded Length

During the construction of a tieback wall, a contractor suggests saving money by grouting the entire length of the ground anchor tendon, rather than leaving a designated "unbonded" length near the wall. The engineer immediately rejects this proposal.

Case Study 5: Pullout Failure in Ground Anchors

During the proof testing phase of a tieback installation in stiff clay, a ground anchor fails to hold its design test load. As the hydraulic jack pressure increases, the anchor continuously displaces outward without a corresponding increase in load resistance.

Case Study 6: Global Stability Failure of a Nailed Wall

A $8\text{-meter}$ high soil nail wall is constructed perfectly according to internal stability specifications (adequate nail tensile strength and pullout resistance). However, after a heavy rainfall event, the entire wall, including the soil mass it retains, slides downward and outward into the excavation.