--- title: "Sheet pile and deflected shapes" subject: "Foundation Engineering" chapter: 5 key: "semester_5/foundation_engineering:sheet-pile-deflected-shapes" source: https://www.bctengineer.com/q/semester_5/foundation_engineering/sheet-pile-deflected-shapes site: BCT Engineering --- # Sheet pile and deflected shapes Foundation Engineering · Chapter 5: Flexible Retaining Structures and Coffer Dams - Asked in: 2080 Baisakh, 1+3 marks - Video: [What is Sheet Piling? | Installation Process of Sheet Piles at Site](https://www.youtube.com/watch?v=T2yp28REpMU) — Bridge Construction Training Institute - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/foundation_engineering/sheet-pile-deflected-shapes - Whole chapter: https://www.bctengineer.com/md/semester_5/foundation_engineering/chapter-5 ## Question What is a sheet pile? Draw the clear deflected shapes for the following: (i) cantilever sheet pile, (ii) anchored bulkhead driven to shallow depth and (iii) anchored bulkhead driven to deeper depth. ## Short answer A sheet pile is a slender interlocking section driven to form a continuous retaining wall. Cantilever piles deflect toward the excavation, rotating about a point and moving the toe backward. An anchored bulkhead with shallow embedment (free earth) curves without contraflexure; with deeper fixed-earth embedment, the toe is fixed, producing a point of contraflexure and reverse curvature. ## Answer A **sheet pile** is a slender, interlocking section of steel, timber or concrete driven into the ground to form a continuous wall that retains soil or water (for example in excavations, cofferdams and waterfronts). #### Deflected shapes (schematic, retained soil on the left) ```text (i) Cantilever (ii) Anchored, shallow (iii) Anchored, deeper (free earth support) (fixed earth support) | T o------->| T o------->| | | | | | | ------+\----- dredge line ---------+\----- dredge line -----+\----- dredge line | \ | \ | \ | \ | \ | ) point of | o pivot point | \ tip rotates | ( contraflexure | / toe moves back | \ \ | / (into the soil) | \| tip fixed (vertical) ``` - **(i) Cantilever:** the wall deflects toward the excavation and rotates about a point near the lower part of the embedded length, so the toe moves backward (into the retained soil). - **(ii) Anchored bulkhead, shallow depth (free earth support):** the pile is held at the anchor and its tip rotates freely; there is a single curvature and no fixity at the bottom. - **(iii) Anchored bulkhead, deeper depth (fixed earth support):** the toe is fixed in the soil, so the deflected curve has a point of contraflexure, with reverse curvature near the bottom. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is a sheet pile? A. A thick mass concrete wall B. A slender interlocking section driven to form a continuous wall retaining soil or water C. A pile used only for bearing loads D. A ground anchor Answer: B. Sheet piles are slender interlocking steel, timber or concrete sections forming a continuous wall. (Key point: Sheet pile definition) 2. How does a cantilever sheet pile deflect? A. Toward the soil side only B. With zero deflection C. Toward the excavation, pivoting near the lower part of the embedment with the toe moving back D. Only at the top, none at the toe Answer: C. It rotates about a pivot point and the toe moves backward. (Key point: Cantilever deflection) 3. What characterises an anchored bulkhead driven to shallow depth? A. Fixed toe with contraflexure B. Tip free to rotate, single curvature, no fixity (free earth support) C. Cantilever action only D. No anchor Answer: B. Shallow embedment gives free earth support: held at the anchor, tip free to rotate. (Key point: Shallow anchored bulkhead) 4. What is special about the deflected shape of a bulkhead driven deeper? A. It has no curvature B. It is straight C. Tip is free D. The toe is fixed, giving a point of contraflexure and reverse curvature Answer: D. Fixed earth support has a fixed toe and reverse curvature near the bottom. (Key point: Deeper anchored bulkhead) ## Related in Foundation Engineering - [Anchor reduces cantilever sheet pile depth](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aanchor-reduces-embedment) — Foundation Engineering, chapter 5 - [Anchored sheet pile, free earth, with anchor pull](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aanchored-sheet-pile-embedment) — Foundation Engineering, chapter 5 - [Anchored sheet pile, free earth procedure](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aanchored-sheet-pile-free-earth-procedure) — Foundation Engineering, chapter 5 - [Cantilever sheet pile, 5 m excavation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Acantilever-sheet-pile-5m-sand) — Foundation Engineering, chapter 5 - [Cantilever sheet pile, simplified method](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Acantilever-sheet-pile-backfill-3m) — Foundation Engineering, chapter 5 - [Cantilever sheet pile, 8 m excavation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Acantilever-sheet-pile-8m-excavation) — Foundation Engineering, chapter 5 ## Related in other subjects - [Sheet pile seepage quantity numerical](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Asheet-pile-seepage-quantity-numerical) — Soil Mechanics, chapter 7 - [Sheet pile flow net; graded filter](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Asheet-pile-flow-net-graded-filter) — Soil Mechanics, chapter 7 - [Flow net under sheet pile, discharge](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Asheet-pile-flow-net-steps-discharge) — Soil Mechanics, chapter 7