Piling terminology: Additional piles driven adjacent to existing vertical piles to increase the overall load-carrying capacity of the foundation are called…

Introduction / Context:
Foundations supported on piles sometimes require augmentation when loading increases or when lateral forces become significant. Understanding the function and naming of auxiliary piles ensures correct specification and design checks for combined vertical and horizontal actions.

Given Data / Assumptions:

• An existing arrangement includes vertical piles carrying gravity loads.
• Additional piles are proposed to enhance capacity/stability.
• Terminology options include construction, raking (batter), eccentric, and sinking piles.

Concept / Approach:
Raking (batter) piles are driven at an angle to the vertical. Their inclined geometry allows them to mobilize axial capacity to resist both vertical and significant horizontal components, effectively increasing overall system capacity under combined actions (e.g., due to wind, wave, or crane surge). Though vertical capacity can be improved by adding more vertical piles, raking piles are commonly added where lateral stability or uplift is also of concern. Other terms listed are either generic (construction piles), process-related (sinking piles), or geometric misplacements (eccentric piles), and do not specifically denote the load-augmentation function in typical practice.

Step-by-Step Solution:
Identify the objective: increase foundation capacity of a vertical-pile group.Recognize that batter piles add both vertical and lateral resistance due to axial action along the inclined axis.Map alternatives and eliminate those that are process/generic labels.Select “Raking (batter) piles.”

Verification / Alternative check:
Marine and bridge substructure designs commonly introduce raking piles to supplement vertical groups where lateral loads dominate; group analysis shows reduced pile-head shears and improved overall stiffness.

Why Other Options Are Wrong:
Construction piles: Not a functional category; refers to piles installed as part of construction.Eccentric piles: Nonstandard naming; eccentricity refers to loading, not a pile type.Sinking piles: Describes the driving/boring operation, not capacity augmentation.Relief piles: Term used in some contexts for drainage or unloading; not a standard capacity descriptor.

Common Pitfalls:
Assuming only vertical piles improve vertical capacity; in practice, batter piles efficiently share both vertical and horizontal components in demanding conditions.

Final Answer:
Raking (batter) piles.