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

Patent metadata

Field	Value
Publication number	US-11977825-B2
Application number	US-202017299100-A
Country	US
Kind code	B2
Filing date	Oct 23, 2020
Priority date	Dec 31, 2019
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

A discrete element method contact model building method includes: selecting a filling body in a disaster-causing structure to obtain a change rule of cumulative loss of the filling body; performing test simulation, and determining a relation function of each group of corresponding mesoscopic mechanical parameters in each time period and mesoscopic parameters of a DEM contact model representing a change rule of macroscopical parameters of the filling body; embedding each mesoscopic parameter relation function into an existing particle contact model, performing test simulation, and updating a fracture failure criterion of the contact model according to a corresponding relation of macro-mesoscopic strength during model failure; and based on a seepage failure indoor test, building a seepage failure discrete element calculation model, and simulating the seepage failure process of a rock and soil mass by using the obtained particle contact model and the fracture criterion of the particle contact model.

First claim

What is claimed is:

1. 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.

2. The DEM contact model building method for reflecting weakening of seepage on rock and soil mass strength according to claim 1 , wherein in step 1, at time intervals Δt i , the filling body flowing out in the test process is collected, dried and weighed, the mass of the filling body flowing out in each time period is separately weighed, and then, the mass of the filling body flowing out in the test process is added to obtain the total mass of the filling body flowing out.

3. The DEM contact model building method for reflecting weakening of seepage on rock and soil mass strength according to claim 1 , wherein in step 2, the filling body flowing out in each time period in step 1 is subjected to a screening test to measure the grading of the filling body flowing out and further obtain each grading specific weight of the rest filling body.

4. The DEM contact model building method for reflecting weakening of seepage on rock and soil mass strength according to claim 1 , wherein the mechanical parameters in step 2 comprise a shear strength τ, a compression strength σ, an elastic modulus E, cohesive force c and an internal friction angle φ.

5. The DEM contact model building method for reflecting weakening of seepage on rock and soil mass strength according to claim 1 , wherein in step 3, based on macroscopical mechanical parameters of the filling body in each time period, macro-mesoscopic parameter calibration is performed, and finally, each group of mesoscopic mechanical parameters corresponding to each time period is determined.

6. The DEM contact model building method for reflecting weakening of seepage on rock and soil mass strength according to claim 1 , wherein in step 3, the value of each mesoscopic mechanical parameter in each time period is separately subjected to function fitting, to reveal the relation between the macroscopic mechanical parameters of the filling body and the mesoscopic parameters of a discrete element contact model, and further obtain the relation function of the mesoscopic parameters of the DEM contact model representing the change rule of the macroscopic mechanical parameters of the filling body.

Assignees

• Univ Shandong

Inventors

• Li Shucai
• Zhou Zongqing
• Li Liping
• Yang Weimin
• Lin Chunjin
• Shi Shaoshuai
• Gao Chenglu
• Shang Chengshun
• Geng Yang
• Bai Songsong

Classifications

• G06F30/25 Primary

  using particle-based methods · CPC title

• G01N15/08 Primary

  Investigating permeability, pore-volume, or surface area of porous materials · CPC title

• E02D1/027 Primary

  by investigating properties relating to fluids in the soil, e.g. pore-water pressure, permeability (sampling of groundwater E02D1/06) · CPC title

• G01N3/08

  by applying steady tensile or compressive forces (G01N3/28 takes precedence) · CPC title

• G01N3/24

  by applying steady shearing forces (G01N3/26, G01N3/28 take precedence) · CPC title