Discrete element method (DEM) contact model building method for reflecting weakening of seepage on rock and soil mass strength

A discrete element method (DEM) contact model building method for reflecting weakening of seepage on rock and soil mass strength, comprising the following steps:

• step 1:
• selecting a filling body in a disaster-causing structure, preparing the filling body into a standard sample of a rock and soil mechanical test, and performing a seepage failure indoor test under a constant water pressure to obtain a change rule of cumulative loss of the filling body along with time under seepage;
• step 2:
• preparing the standard sample again according to a grading of the filling body after the loss in each time period in step 1, respectively performing triaxial compression and shearing mechanical tests, and measuring mechanical parameters of the sample in each time period to further obtain a change rule of mechanical parameters of the filling body along with the loss of the filling body;
• step 3:
• according to the change rules obtained in step 1 and step 2, performing uniaxial tension, triaxial compression, and shearing mechanical test simulation by using DEM software, and finally determining each group of mesoscopic mechanical parameters corresponding to each time period;
• and obtaining a relation function of mesoscopic parameters of the DEM contact model representing a change rule of macroscopical mechanical parameters of the filling body;
• step 4:
• through secondary development of the DEM contact model, embedding each mesoscopic parameter relation function built in step 3 into an existing particle contact model, performing uniaxial compression and triaxial compression test simulation, and updating a fracture failure criterion of the contact model according to a corresponding relation of macro-mesoscopic strength during model failure, so as to realize the simulation of a continuous weakening process of filling body strength;
• and
• step 5:
• based on the seepage failure indoor test, building a seepage failure discrete element calculation model, and simulating a seepage failure process of the rock and soil mass by using the particle contact model and the fracture criterion of the particle contact model obtained in step 4,
• wherein in step 4, a simulation result is compared with a seepage failure indoor test result, and accuracy of the model built is judged by macro-mesoscopic failure mode and mechanical parameter comparison;
• if a matching degree of the simulation result and the indoor test result is low, the method goes to step 3 to obtain the relation function of the mesoscopic parameters of the DEM contact model representing the change rule of the macroscopical mechanical parameters of the filling body again;
• and if the matching degree of the simulation result and the indoor test result is high, the simulation result is able to be better matched with the indoor test result by finely adjusting the mesoscopic parameters, so as to indicate a feasibility and accuracy of the strength weakening simulation of the contact model.