DEM-Based Study on the Mechanical Behaviors of Pore-Filling MHBS under Drained True Triaxial Conditions Varying the Intermediate Stress Ratio of Constant Mean Effective Stresses

Data Availability Statement

Notation

b

intermediate principal stress ratio;

C

number of contacts;

c

cohesion;

D

mean diameter of the soil particle;

d

dilatancy index;

dɛ_d

increment on the equivalent deviatoric strain;

dɛ_v

change in volumetric strain;

E_c

Young’s modulus of the soil;

e_a

void ratio in the agglomerate;

e_cr

void ratio in the critical state;

$F_{11}^s$

major principal fabric;

$F_{22}^s$

intermediate principal fabric;

$F_{33}^s$

minor principal fabric;

I_uf

an index to quantify the unbalanced force;

I₁

first stress invariants;

I₂

second stress invariants;

I₃

third stress invariants;

J₂

second invariant of the stress tensor;

k_f

soil characteristic parameter;

k_n

normal contact stiffness;

$k_{n\mathrm{soil}}^p$

soil normal contact stiffness;

$k_{s\mathrm{soil}}^p$

soil tangential contact stiffness;

${\overline{k}}^n$

normal parallel bond stiffness;

${\overline{k}}^s$

shear parallel bond stiffness;

$k_{nmh}^p$

MH normal contact stiffness;

$k_{smh}^p$

MH tangential contact stiffness;

k

laboratory constant;

M_cr

critical stress ratio for different b;

N_br

number of surviving MH bonds in any given state;

N_c

number of contacts;

$N_c^s$

number of the strong contacts;

N_cr

number of MH bonds in the initial state;

N_p

number of particles;

N

number of MH agglomerates required in the pore-filling MHBS;

N₁

number of particles with only one contact;

N₀

number of particles with no contacts;

$n_i^s$

component of the unit vector n^s at the contact between grains i and j;

n_p

number of methane hydrate particles in the MHC;

P

mean effective stress;

p_a

atmospheric pressure;

q

generalized shear stress;

R_a

equivalent radius of the sphere of equal volume;

r

radius of a methane hydrate particle;

S_mh

MH saturation;

V_a

volume of a single MH cluster;

V_mh

MH volume;

V_v

total pore volume;

$\mathrm{△}V$

changes in the volume of the MHBS;

Z_m

mechanical coordination number;

Z

average coordination number;

${\mu }_{\mathrm{soil}}^p$

Soil interparticle coefficient of friction;

${\mu }_{{}^{mh}}^p$

MH interparticle coefficient of friction;

η

stress ratio;

${\overline{\sigma }}_{\mathrm{c}}$

normal parallel bond strengths;

σ₁

major principal stress;

σ₂

intermediate principal stress;

σ₃

minor principal stresses;

ɛ₁

major principal strain;

ɛ₂

intermediate principal strain;

ɛ₃

minor principal strain;

ɛ_d

equivalent deviatoric strain;

ɛ_v

volumetric strain;

V

initial volume of the MHBS;

λ

slope of the CSL;

$\overline{\lambda }$

ratio of the parallel bond radius to the ball radius;

ξ

material constant;

Γ

intercept of the CSL;

θ

Lode angles of the soil;

${\sigma }_{\pi }$

π plane compressive stress;

${\tau }_{\pi }$

π plane shear stress;

${\overline{\tau }}_c$

shear parallel bond strengths; and

φ

internal friction angle.

References