mechanics_functions.bearing_capacity_funcs.calc_air_drop_dyn_bearing(pffp_accel, pffp_velocity, pffp_mass, pffp_frontal_area, soil_contact_area, drag_coeff, gravity, rho_air)

Calculate the soil dynamic bearing capacity for air drops.

This function computes the dynamic bearing capacity of the soil when subjected to air drops, following the equations provided below. Units are assumed to be standard SI (m/s^2, Newtons, kg). The reference frame convention assumes the direction towards the sky is positive.

Note: DO NOT pass raw accelerometer data to this function. The acceleration passed should be the sensor offset by 1g down (i.e., pffp_accel = raw_sensor_accel - 1g).

Parameters:

  • pffp_accel (float) – Acceleration of the portable free fall penetrometer (pffp) during impact.

  • pffp_velocity (float) – Velocity of the pffp.

  • pffp_mass (float) – Mass of the pffp.

  • pffp_frontal_area (float) – Frontal area of the pffp.

  • soil_contact_area (float) – Contact area between the soil and the pffp.

  • drag_coeff (float) – Drag coefficient.

  • gravity (float) – Gravity constant.

  • rho_air (float) – Density of the air.

Returns:

Net dynamic bearing capacity.

Return type:

float

Notes

Equations:

  1. \[F_{Br} = m_{p} a_{p} + m_{p} g - \frac{1}{2} \rho_{fluid} v_{p}^{2} C_{D} A\]
  2. \[q_{Dyn} = \frac{F_{Br}}{A}\]
where:

  • \(F_{Br}\) : Force of soil bearing resistance.

  • \(m_{p}\) : Mass of the portable free fall penetrometer (pffp).

  • \(a_{p}\) : Acceleration of the pffp during impact.

  • \(g\) : Gravity constant.

  • \(\rho_{fluid}\) : Density of the fluid.

  • \(v_{p}\) : Velocity of the pffp.

  • \(C_{D}\) : Drag coefficient.

  • \(A\) : Frontal area (single value).

mechanics_functions.bearing_capacity_funcs.calc_dyn_bearing_capacity(pffp_accel, pffp_velocity, pffp_mass, pffp_frontal_area, soil_contact_area, pffp_volume, water_drop, drag_coeff=0.0, gravity=9.80665, rho_water=1020, rho_air=1.293)

Calculate the dynamic bearing capacity of the soil for both water and air drops.

This function acts as a wrapper for calculating the dynamic bearing capacity for both water and air drops. It uses the acceleration of the portable free fall penetrometer (pffp) and other parameters to compute the dynamic bearing capacity. Note that the acceleration should not be the raw sensor acceleration but should be adjusted to the pffp acceleration.

Parameters:

  • pffp_accel (float) – Deceleration of the pffp.

  • pffp_velocity (float) – Velocity of the pffp, used to calculate the drag force.

  • pffp_mass (float) – Mass of the Free Fall Penetrometer (FFP).

  • pffp_frontal_area (float) – Frontal area of the pffp. This is a single number.

  • soil_contact_area (float) – Contact area between the FFP and the soil.

  • pffp_volume (float) – Volume of the FFP.

  • water_drop (bool) – True for water drops, False for air drops.

  • drag_coeff (float, optional) – Drag coefficient of the pffp. Default is 1.0.

  • gravity (float, optional) – Gravity constant. Default is GRAVITY_CONST.

  • rho_water (float, optional) – Density of water. Default is 1020 kg/m^3, a good estimate for ocean water.

  • rho_air (float, optional) – Density of the air. Default is 1.293 kg/m^3.

Returns:

Dynamic bearing capacity of the soil.

Return type:

float

Notes

This function selects the appropriate calculation method based on the water_drop flag. If water_drop is True, it uses the water drop calculation. If False, it uses the air drop calculation.

mechanics_functions.bearing_capacity_funcs.calc_qs_bearing_capacity(velocity, strainrateCorrectionType, qDyn, k_factor=0.1, ref_velocity=0.02)

Calculate the quasi-static bearing capacity value.

This function computes the quasi-static bearing capacity value based on the given velocity, strain rate correction type, dynamic bearing capacity, and other parameters.

Parameters:

  • velocity (array-like) – Array of FFP velocity values [m/s].

  • strainrateCorrectionType (str) – Type of strain rate correction to use. Must be one of “log”, “Brilli”, or “invHyperSin”.

  • qDyn (float) – Dynamic bearing capacity value.

  • k_factor (float, optional) – K factor to be used. Default is 0.1.

  • ref_velocity (float, optional) – Reference velocity for strain rate correction. Default is 0.02 m/s.

Returns:

Quasi-static bearing capacity value.

Return type:

float

Raises:

ValueError – If strainrateCorrectionType is not one of the following: “log”, “Brilli”, “invHyperSin”.

Notes

This function calculates the strain rate correction factor (f_SR) based on the specified strainrateCorrectionType and then uses it to compute the quasi-static bearing capacity value (qsbc).

The strain rate correction types are as follows:

  • “log”: Logarithmic strain rate correction.

  • “Brilli”: Strain rate correction following Brilli et al. (20??). Commonly used for air drops.

  • “invHyperSin”: Inverse hyperbolic sine correction factor following Stephan (2015) and Randolph (2004).

Warning

A warning is printed if a non-standard k_factor is used for the Brilli type strain rate correction.

mechanics_functions.bearing_capacity_funcs.calc_water_drop_dyn_bearing(pffp_accel, pffp_velocity, pffp_mass, pffp_frontal_area, soil_contact_area, pffp_volume, drag_coeff, gravity, rho_water)

Calculate the soil dynamic bearing capacity for water drops.

This function computes the dynamic bearing capacity of the soil when subjected to water drops, following the equations provided below. Units are assumed to be standard SI (m/s^2, Newtons, kg). The reference frame convention assumes the direction towards the sky is positive.

Note: DO NOT pass raw accelerometer data to this function. The acceleration passed should be the sensor offset by 1g down (i.e., pffp_accel = raw_sensor_accel - 1g).

Parameters:

  • pffp_accel (float) – Acceleration of the portable free fall penetrometer (pffp) during impact.

  • pffp_velocity (float) – Velocity of the pffp.

  • pffp_mass (float) – Mass of the pffp.

  • pffp_frontal_area (float) – Frontal area of the pffp.

  • soil_contact_area (float) – Contact area between the soil and the pffp.

  • pffp_volume (float) – Volume of the pffp.

  • drag_coeff (float) – Drag coefficient.

  • gravity (float) – Gravity constant.

  • rho_water (float) – Density of the water.

Returns:

Net dynamic bearing capacity.

Return type:

float

Notes

Equations:

  1. \[F_{Br} = m_{p} a_{p} + m_{p} g - \rho_{f} V_{p} g - \frac{1}{2} \rho_{f} v_{p}^{2} C_{D} A\]
  2. \[q_{Dyn} = \frac{F_{Br}}{A}\]
where:

  • \(F_{Br}\) : Force of soil bearing resistance.

  • \(m_{p}\) : Mass of the portable free fall penetrometer (pffp).

  • \(a_{p}\) : Acceleration of the pffp during impact.

  • \(g\) : Gravity constant.

  • \(\rho_{fluid}\) : Density of the fluid.

  • \(V_{p}\) : Volume of the pffp.

  • \(v_{p}\) : Velocity of the pffp.

  • \(C_{D}\) : Drag coefficient.

  • \(A\) : Frontal area (single value).