# liquefaction.crr_15()

In-situ cyclic resistance ratio at the 15-cycle reference.

Usage

[Source](https://github.com/lornearnold/driven-pile/blob/main/src/driven_pile/liquefaction.py#L94-L112)

``` python
liquefaction.crr_15(
    n160,
    fines,
    sigma_v0,
)
```

## Parameters

`n160: array_like`  
Corrected blow count N1,60.

`fines: array_like`  
Fines content, percent.

`sigma_v0: array_like`  
Vertical effective stress, ksf.

## Returns

`ndarray`  
`CRR_M7.5(N1,60cs) * K_sigma`.