Table 1.

Mechanical properties used in the DEM model. An asterisk (*) indicates those properties that were varied within the ranges indicated in square brackets

DEM mechanical property
Poisson's ratio${\nu }_{\mathit{particle}}$	0.3
WL restitution coefficient$e_u^{\mathit{wl}}$	0.1
Slab restitution coefficient$e_u^{\mathit{slab}}$	1
Friction coefficient${\mu }_u$	0.5
Mean weak layer particle density (kg m−3)	550
* Mean slab layer particle density (kg m−3)	455, [363 – 545]
* Slab particle elastic modulus$E_{\mathit{slab}}^{\mathit{particle}}$(MPa)	7, [1.35 – 33.6]
* Weak layer particle elastic modulus$E_{\mathit{wl}}^{\mathit{particle}}$(MPa)	47.5, [14.25 – 109.25]
Slab bond strength (kPa)	infinite
* Weak layer bond strength${\sigma }_c^{\mathit{wl}}$(kPa)	144, [70 – 208]
PST mechanical property
Mean weak layer density (kg m−3)	110
* Mean slab layer density (kg m−3)	250, [200 – 300]
* Slab elastic modulus$E_{\mathit{slab}}$(MPa)	5.2, [1–25]
* Weak layer elastic modulus$E_{\mathit{wl}}$(MPa)	1.0, [0.3 – 2.3]
* Weak layer tensile strength (kPa)	2, [0.98 – 2.9]
* Weak layer shear strength (kPa)	1.2, [0.59 – 1.73]
* Weak layer compressive strength${\sigma }_{\text{wl}}^{\text{th}}$(kPa)	4.3, [2.1 – 6.2]
System geometry
Slab porosity	45%
Weak layer porosity	80%
Weak layer height (m)	0.02
Slab height (m)	0.4
* Slope angle$\psi$(°)	0 – 45