> 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-tz-soil-models/driven-pile-sand-tz-mosher-mosher-1984.md).

# Driven Pile Sand TZ (Mosher) \[Mosher, 1984]

\[Mosher, 1984] developed load-transfer criteria for axially loaded piles in sand from instrumented pile tests at the US Army Waterways Experiment Station and proposed a hyperbolic side-resistance curve defined by the ultimate unit side resistance and an initial modulus:

$$
\tag{1}
t = \frac{z}{\frac{1}{K\_t}+\frac{z}{t\_u}}
$$

where,

$$t$$ = unit side resistance (skin friction)\
$$z$$ = vertical displacement of the pile\
$$t\_u$$ = ultimate (nominal) unit side resistance\
$$K\_t$$ = initial modulus of side resistance

Initial estimates of $$K\_t$$ by relative density:

| Description  | $$ϕ$$ (°) | $$K\_t$$ (lb/ft²/in) |
| ------------ | --------- | -------------------- |
| Loose        | 28–31     | 6000–10000           |
| Medium dense | 32–34     | 10000–14000          |
| Dense        | 35–38     | 14000–18000          |

$$t\_u$$ is entered directly as the ultimate shear stress of the layer; where it is not known, Figure 76 of \[Mosher, 1984] relates it to relative depth and friction angle.

{% hint style="info" %}
The WES report is on the DTIC server but could not be retrieved at the time of writing, so the model is implemented as it is reported in the secondary literature. It will be checked against \[Mosher, 1984] once the report is obtained.
{% endhint %}

***

\[Mosher, 1984] Mosher, R. L. (1984). *Load Transfer Criteria for Numerical Analysis of Axially Loaded Piles in Sand. Part 1: Load-Transfer Criteria.* Technical Report K-84-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg. (Report not on file.)


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