Raymond pile characteristics in foundation engineering: which of the following statements about typical dimensions and shell thickness are correct?

Introduction / Context:
Raymond piles are a type of cast-in-situ concrete pile formed inside a corrugated thin steel shell that is expanded or shaped. Recognizing their common dimensional ranges helps with selection and estimation.

Given Data / Assumptions:

• Typical length range, head (top) and toe (bottom) diameters, and shell thickness trends are provided.
• We assess whether these are consistent with standard practice.

Concept / Approach:
In Raymond piles, the steel shell is often tapered; the top is wider to receive the pile cap, and the bottom smaller at the toe. The shell thickness correlates with pile size and driving conditions to prevent buckling and maintain shape during concreting.

Step-by-Step Solution:
Length 6–12 m: within common practice for medium-depth foundations.Top diameter 40–60 cm and bottom 20–28 cm: matches a tapered shell profile.Shell thickness depending on diameter: larger diameters and driving stresses require thicker shells.Thus, all listed statements align with typical Raymond pile specifications.

Verification / Alternative check:
Foundation handbooks document taper and dimensional ranges for Raymond and similar shell piles, validating the given figures.

Why Other Options Are Wrong:

• Choosing any single statement would omit other equally correct traits; all are valid together.

Common Pitfalls:

• Confusing Raymond piles with straight, uniform-diameter cast-in-situ piles that use removable liners.

Final Answer:
all the above