> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/technical-background/soil-structure-interaction/axial-soil-models/axial-qz-soil-models/drilled-shaft-igm-non-cohesive-qz-mayne-and-harris-1993.md).

# Drilled Shaft IGM Non-Cohesive QZ (Mayne and Harris) \[Mayne and Harris, 1993]

The base resistance of a socket in a Category 3 intermediate geomaterial follows the same socket load-settlement solution as the [side resistance](/technical-background/soil-structure-interaction/axial-soil-models/axial-tz-soil-models/drilled-shaft-igm-non-cohesive-tz-mayne-and-harris-1993.md) (Model 2 of \[O'Neill et al., 1996], Eqs. 41–54).

### Ultimate End Bearing

Undrained failure is assumed beneath the base, with the operational undrained strength correlated to the effective vertical stress at the base and the overconsolidation ratio:

$$
\tag{1}
s\_u = 0.23\sigma'*{v0}OCR^{0.8}, \qquad OCR = \frac{0.2N*{60}p\_a}{\sigma'\_{v0}}
$$

$$
\tag{2}
q\_{max} = 9.33s\_u
$$

### q-z Curve

The socket load-settlement relation is three-branched: elastic up to $$Q\_{t1}$$ at settlement $$w\_{t1}$$ (Eqs. 4–6 of the side-resistance page), then linear to the plunging load $$Q\_{t,max}$$, then vertical. The base share of it is:

$$
\tag{3}
Q\_{b1} = Q\_{t1}-Q\_{s,max}
$$

$$
\tag{4}
Q\_{t,max} = Q\_{s,max}+q\_{max}\frac{\pi D^2}{4}
$$

$$
\tag{5}
\Delta w\_b = (Q\_{t,max}-Q\_{t1})\frac{(1-\nu)(1+\nu)}{E\_bD}
$$

giving the *q-z* curve through (0, 0), ($$w\_{t1}$$, $$Q\_{b1}$$) and ($$w\_{t1}+Δw\_b$$, $$q\_{max}πD²/4$$), constant beyond, where $$E\_b = E\_{sL}/ξ$$ is the modulus of the geomaterial beneath the base ($$ξ$$ = 2.5 for Piedmont residuum).

{% hint style="info" %}
The Georgia Tech report of Mayne and Harris is not on file; the method is implemented from the FHWA report of O'Neill et al. (1996), which reproduces and revises it.
{% endhint %}

***

\[Mayne and Harris, 1993] Mayne, P. W. and Harris, D. E. (1993). *Axial Load-Displacement Behavior of Drilled Shaft Foundations in Piedmont Residuum.* FHWA Reference No. 41-30-2175, Georgia Tech Research Corporation, Atlanta. (Report not on file.)

\[O'Neill et al., 1996] O'Neill, M. W., Townsend, F. C., Hassan, K. M., Buller, A., and Chan, P. S. (1996). *Load Transfer for Drilled Shafts in Intermediate Geomaterials.* Report FHWA-RD-95-172, Federal Highway Administration, McLean, VA.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.openbrim.org/technical-background/soil-structure-interaction/axial-soil-models/axial-qz-soil-models/drilled-shaft-igm-non-cohesive-qz-mayne-and-harris-1993.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.