tMohrCoulombPointwise.cc - pism - [fork] customized build of PISM, the parallel ice sheet model (tillflux branch)
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tMohrCoulombPointwise.cc (2854B)
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1 /* Copyright (C) 2019 PISM Authors
2 *
3 * This file is part of PISM.
4 *
5 * PISM is free software; you can redistribute it and/or modify it under the
6 * terms of the GNU General Public License as published by the Free Software
7 * Foundation; either version 3 of the License, or (at your option) any later
8 * version.
9 *
10 * PISM is distributed in the hope that it will be useful, but WITHOUT ANY
11 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
12 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 * details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with PISM; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19 #include <cmath> // pow, tan, atan
20
21 #include "MohrCoulombPointwise.hh"
22
23 namespace pism {
24
25 MohrCoulombPointwise::MohrCoulombPointwise(Config::ConstPtr config) {
26 m_W_till_max = config->get_number("hydrology.tillwat_max");
27 m_till_cohesion = config->get_number("basal_yield_stress.mohr_coulomb.till_cohesion");
28 m_reference_effective_pressure = config->get_number("basal_yield_stress.mohr_coulomb.till_reference_effective_pressure");
29 m_reference_void_ratio = config->get_number("basal_yield_stress.mohr_coulomb.till_reference_void_ratio");
30 m_compressibility_coefficient = config->get_number("basal_yield_stress.mohr_coulomb.till_compressibility_coefficient");
31 }
32
33 double MohrCoulombPointwise::effective_pressure(double delta,
34 double P_overburden,
35 double water_thickness) const {
36
37 double
38 s = water_thickness / m_W_till_max,
39 N0 = m_reference_effective_pressure,
40 N_till = (N0 * pow(delta * P_overburden / N0, s) *
41 pow(10.0, (m_reference_void_ratio / m_compressibility_coefficient) * (1.0 - s)));
42
43 return std::min(P_overburden, N_till);
44 }
45
46 double MohrCoulombPointwise::yield_stress(double delta,
47 double P_overburden,
48 double water_thickness,
49 double phi) const {
50
51 double N_till = effective_pressure(delta, P_overburden, water_thickness);
52
53 return m_till_cohesion + N_till * tan((M_PI / 180.0) * phi);
54 }
55
56 double MohrCoulombPointwise::till_friction_angle(double delta,
57 double P_overburden,
58 double water_thickness,
59 double yield_stress) const {
60
61 double N_till = effective_pressure(delta, P_overburden, water_thickness);
62
63 return 180.0 / M_PI * atan((yield_stress - m_till_cohesion) / N_till);
64
65 }
66
67 } // end of namespace pism