An efficient remedy for the false volume expansion of DDA when simulating large rotation

Num Anal Meth Geomechanics

Zheng

2019

Summary Orienting the circular and rigid particle medium, the variational inequality‐based discontinuous deformation analysis (DDA) is established. In the proposed DDA, the global stiffness matrix, the penalty parameters, and the open‐close iteration are successfully avoided. The contact constraint is transferred into the problem of variational or quasi‐variational inequalities. And explicit variational expression on the contact force is firstly established. To speed up the rate of solving contact force, on the basis of the two‐stage prediction‐correction method, we design a compatibility iteration algorithm (PPC‐CI). The C++ code is developed in multicore environment through the open multi‐processing (OpenMP) in order to take advantage of the parallelizable features of the new DDA. Numerical tests suggest that the presented DDA is effective and promising.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variational inequality‐based particle discontinuous deformation analysis

Fan

Num Anal Meth Geomechanics

Zheng

2019

“…Beyabanaki [20] presented existing blocks in discontinuity failure analysis as deformable disks. Jiang and Zheng [21] proposed an effective method to correct the error in the increase in volume caused by a large rotation. Morgan and Aral [22] proposed a hydrogeological model to model hydraulic breaks using deformed breakdown analysis.…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis of Slope with Multiple Sliding Surfaces Based on Dynamic Strength‐Reduction DDA Method

Zhu

Advances in Civil Engineering

et al. 2019

The present study aims to elucidate the problem of a rock mass structural plane with a range of damage degrees and the numerical model selection for analysis of a slope with multiple sliding surfaces. Based on the relative displacement between blocks, the dynamic strength reduction-discontinuous deformation analysis (hereinafter referred to as DSR-DDA) method is proposed for studying slopes with multiple sliding surfaces. The slope-slider classic case was used to test the displacement threshold. The model was applied to the stability analysis of multiple sliding surfaces of a high rock slope in the Fushun West Open-Pit Mine. The results show that when the displacement threshold is set to 1 mm, the error between the DSR-DDA results and the theoretical solution is within 0.5%, which satisfies the calculation requirements. The most dangerous slip surface in the Fushun West Open-Pit Mine slope was identified. Based on the numerical slope model after the first landslide, the position of the secondary slip surface was then identified. The failure mode is traction sliding failure, and the middle and lower oil shales play a key role in the slope stability. This study recommends that mining of the remaining oil shale should stop to avoid causing large-scale landslides in the upper part of the slope and landslides at the pit-city boundary.

Numerical Meth Engineering

“…To improve its capacity in coping with deformation, the nodal‐based DDA and the coupled FEM‐DDA approach have been proposed. In dealing with geometrical nonlinearity, various forms of extension on DDA have been proposed, including those based on the postadjustment method, the Taylor series method, the trigonometric method, the displacement‐strain modification method, and the strain‐rotation (SR)–DDA based on the SR decomposition theorem –. In particular, the SR‐DDA formulation helps to void the small deformation assumption.…”

Section: Introductionmentioning

confidence: 99%

Variational inequality‐based framework of discontinuous deformation analysis

Fan

Zhao

Zheng

2018

Summary For modeling discrete particle‐block systems, a new framework of discontinuous deformation analysis is established on the basis of finite‐dimensional variational inequality. The presented method takes into account the contacts, the rolling resistance, and the tensile resistance of cemented interface among particles and blocks using the corresponding variational or quasivariational inequalities. The new formulation avoids using the artificial springs that are usually indispensable in many conventional methods dealing with similar discrete problems and conveniently integrates the rigid circle particles, the nonrigid ring particles, and the arbitrary shape blocks into a uniform framework. The proposed discontinuous deformation analysis approach is further coupled with the finite element method using a node‐based composite contact matrix and several simple transformation matrices to solve practical problems. A particle/block‐based composite contact matrix is constructed to further broaden the application of the proposed method. The accuracy, robustness, and capability of the presented method are demonstrated with examples.