5. Example of use#

The stability analysis of a dam or dyke takes place in 5 steps:

  1. Definition of the model and the material field.

  2. Calculation of the interstitial pressure field using the D_ PLAN_H (static) or D_ PLAN_HH (transient) model.

  3. Definition of mechanical loads (hydrostatic pressure and gravity in general).

  4. Introduction of hydraulic pressure in a new material field via the keyword factor AFFE_VARC.

  5. Calculation of the stability factor using the macro command CALC_STAB_PENTE.

5.1. Example of calculation using method SRM#

An example of use for static calculation with method SRM is shown below. In the test case [V1.01.135] there are more details.

CMPTOT = AFFE_MATERIAU (AFFE =( _F (GROUP_MA =( 'foundation',),
                              MATER =( FOND,)),
                            _F (GROUP_MA =( 'background_fill',),
                               MATER =( ROCK,)),
                            _F (GROUP_MA =( 'rockfill_down', 'rockfill_up'),
                               MATER =( Backfill,)),
                            _F (GROUP_MA =( 'core',),
                               MATER =( CLAY,)))),
                        AFFE_VARC =_F (EVOL = REPTOT,
                                    NOM_VARC =' PTOT ',
                                    TOUT =' OUI '),
                        MAILLAGE = MAILME
                        )

TABFOS = CALC_STAB_PENTE (MODELE = ModMe,
                         CHAM_MATER = CMPTOT,
                         GROUP_MA = ('ZONE_SRM',),
                         EXCIT =( _F (CHARGE = DIRI),
                                _F (CHARGE =Gravity,
                                    FONC_MULT =multi),
                                _F (CHARGE =Presrep,
                                    FONC_MULT =multi)),

                         INCREMENT =_F (LIST_INST =LT),
                         CONVERGENCE =_F (ITER_GLOB_MAXI =50),
                         COMPORTEMENT =_F (RELATION =' MOHR_COULOMB '),
                         FS=_F (FS_INIT =1.2,
                                 INCR_INIT = 0.4,
                                 RESI_MAXI = 0.02,),
                         CHAM_DEFO = CL ('field'),
                        )

IMPR_TABLE (TABLE = TABFOS, UNITE =8)

IMPR_RESU (RESU = _F (RESULTAT = chamdef), UNITE = 2)

Transient hydraulic calculation makes it possible to evaluate the stability of a hydraulic structure in embankment under transient loads, such as flooding for dikes and emptying quick from the tank. However, macro command CALC_STAB_PENTE is not not capable of handling transient loads directly, except for quasistatic loads with a multiplier function that is used to improve the convergence of the calculation.

However, the evaluation of the stability of the structure under temporary hydraulic load can possibly be done with CALC_STAB_PENTE by checking, at each transitory calculation step, the static stability of the structure. With this method we will get the tables as a result of which the total number is equal to the number of physical moments. It is therefore possible to trace the variation of the safety factor as a function of time.

5.2. Example of calculation using method LEM#

An example of use for stability analysis using the simplified Bishop method is shown below.

TABFS = CALC_STAB_PENTE (CHAM_MATER = CHMAT1,
                        METHODE_STAB = 'LEM',
                        METHODE_LEM = 'BISHOP',
                        CRITERE = 'DRUCK_PRAGER',
                        GROUP_MA = ('range_slope',),
                        NB_TRANCHE = 5,
                        RAFF_MAIL = _F (NB_RAFF_MAXI = 1),
                        X1_ MINI = 3. ,
                        X1_ MAXI = 3. ,
                        X2_ MINI = 13.2,
                        X2_ MAXI = 13.2,
                        NB_POINT_1 = 1,
                        NB_POINT_2 = 1,
                        Y_ MINI = 1.2,
                        Y_ MAXI = 1.6,
                        CHAM_DEFO = CL ('field'),
                        )

An example of use for stability analysis using the Morgenstern-Price method is shown below.

TABFS = CALC_STAB_PENTE (CHAM_MATER = CHMAT1,
                        METHODE_STAB = 'LEM',
                        METHODE_LEM = 'MORGENSTERN_PRICE',
                        CRITERE = 'MOHR_COULOMB',
                        GROUP_MA = ('range_slope',),
                        NB_TRANCHE = 5,
                        RAFF_MAIL = _F (NB_RAFF_MAXI = 1),
                        X1_ MINI = 3. ,
                        X1_ MAXI = 3. ,
                        X2_ MINI = 13.2,
                        X2_ MAXI = 13.2,
                        ALGO_EFWA = _F (ETAT_INIT = TAB_INIT, MARGE_PENTE = 0.8),
                        CHAM_DEFO = CL ('field'),
                        )

More details can be found in test case [V1.01.146].