Multiscale problems and analysis of soil mechanics

Fang, Yingguang; Li, Bo

doi:10.1016/j.mechmat.2016.09.003

Cited by 19 publications

(20 citation statements)

References 42 publications

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“…Simulating heavy equipment alone at real-time with good accuracy is challenging but feasible using rigid multibody dynamics and a welloptimized solver [1,2]. It may seem out of reach to include also the environment, involving vast amount of soil with complex dynamics on scales that cross six orders of magnitude [3].…”

Section: Researchmentioning

confidence: 99%

“…Soil and granular media are strongly dissipative multiphase materials with multiple length-and timescales [3,16]. They consist of contacting grains with size ranging from clay at 10 −6 m to cobble and boulders at 10 0 m. Natural soil has a certain moisture content, that may significantly increase the strength of the soil by cohesive forces.…”

Section: Modelling and Simulation Of Soil And Earthmoving Equipmentmentioning

confidence: 99%

“…The excavation test with dirt-1 can be seen in Fig. 14 We analysed also the computational speed of the multiscale model and the reference model, aware that the results depend on implementation, optimization efforts and the hardware specification [3] The analysis was performed on the excavation test system shown in Fig. 14 Finally, the multiscale model is demonstrated in use with full vehicle models in complex earthmoving scenarios.…”

Section: Simulation Testsmentioning

confidence: 99%

“…The active zone in the cutting direction, discretised in five parallel wedges, is visualized in the right image. There are also [3] The tests were run on a desktop computer with Intel Core i7-7800X CPU at 3.5…”

Section: Simulation Testsmentioning

confidence: 99%

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A Multiscale Model of Terrain Dynamics for Real-Time Earthmoving Simulation

Servin

Berglund

Nystedt

2020

Preprint

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A multiscale model for real-time simulation of terrain dynamics is explored. To represent the dynamics on different scales the model combines the description of soil as a continuous solid, as distinct particles and as rigid multibodies. The models are dynamically coupled to each other and to the earthmoving equipment. Agitated soil is represented by a hybrid of contacting particles and continuum solid, with the moving equipment and resting soil as geometric boundaries. Each zone of active soil is aggregated into distinct bodies, with the proper mass, momentum and frictional-cohesive properties, which constrain the equipment's multibody dynamics. The particle model parameters are pre-calibrated to the bulk mechanical parameters for a wide range of different soils. The result is a computationally efficient model for earthmoving operations that resolve the motion of the soil, using a fast iterative solver, and provide realistic forces and dynamic for the equipment, using a direct solver for high numerical precision. Numerical simulations of excavation and bulldozing operations are performed to validate model and measure the computational performance. Reference data is produced using coupled discrete element and multibody dynamics simulations at relatively high resolution. The digging resistance and soil displacements with the real-time multiscale model agree with the reference model up to 10-25%, and run more than three orders in magnitude faster.

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Section: Researchmentioning

confidence: 99%

Section: Modelling and Simulation Of Soil And Earthmoving Equipmentmentioning

confidence: 99%

Section: Simulation Testsmentioning

confidence: 99%

Section: Simulation Testsmentioning

confidence: 99%

See 2 more Smart Citations

A Multiscale Model of Terrain Dynamics for Real-Time Earthmoving Simulation

Servin

Berglund

Nystedt

2020

Preprint

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“…In order to incorporate the granularity and structural characteristics of soil in FE calculations, based on the multi-scale effect of soil, Fang (2015, 2016) and Fang and Li (2016) established a new cell element model of the soil.…”

Section: Introductionmentioning

confidence: 99%

Secondary development of finite-element method based on the calculation of scale effect of soil particles

Fang

et al. 2021

Arab J Geosci

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Soil, regarded as a homogeneous continuous medium in the classical soil mechanics, actually comprises mineral particles of different scales and has the basic characteristics of a heterogeneous discontinuous medium. During the deformation, particles of different scales contained in the soil demonstrate diverse deformation states and produce scale effects. At the same time, the rotation of the particles significantly changes the deformation and strength characteristics of the soil and produces a rotation effect. However, the current finite-element calculations are lacking in the calculation methods that take into account the effects of scale and rotation. In the previous work, one of the authors of this paper introduced an intrinsic scale factor and established a constitutive relationship according to the particle scale effect. Based on the constitutive formula of soil particle scale effect, the UEL subroutine of ABAQUS is used to express particle rotation by node rotation, and secondary development of the finiteelement calculation program is carried out to solve the specific calculation problem of soil deformation scale effect caused by particle rotation. The results of a verification example involving a round hole display that the stress concentration factor of the hole decreases to a stable value with the increase of the intrinsic scale factor of the particles, which conforms to the influence mechanism of soil particle deformation and basically verifies the reliability of the secondary development program. Furthermore, using the secondary development program to calculate the stability of a slope illustrates that the shear band uncertainty and the element sensitivity in slope instability analysis are eliminated by considering the particle scale effect of the soil.

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The experiment and analysis of the repose angle and the stress arch-caused stress dip of the sandpile

Fang

Guo

et al. 2021

Granular Matter

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The repose angle and characteristics of the vertical stress distribution beneath the sandpile can help to understand the physical and mechanical properties of the granular matter and guide the foundation design of the rock-soil deposits such as the rockfill dam and the storage structures of granular materials. Researches previously found that the stress dip phenomenon exists in piles constructed by the localized-source procedure, where the maximum vertical stress underneath the pile deviates from the center. The repose angle and the stress dip are affected by many internal and external factors and exhibit highly nonlinear and sensitive characteristics. However, the variation of the repose angle and the stress dip with influencing factors and the cause of the stress dip have not yet been fully explored. Based on the localized-source conical sandpile experiments and the discrete element method (DEM) simulation analysis, this paper studied the influences of the internal friction angle of granular matter and the construction history (the slowly raising funnel method SRFM and the fixed funnel method FFM) on the repose angle and the vertical stress dip beneath the pile; while the formation mechanism of the stress dip phenomenon was analyzed. The experimental results showed that the repose angle, physically different from the internal friction angle, has a relatively larger value and is positively related to the internal friction angle in the sandpile constructed by the FFM; the localized-source procedure and the internal friction angle are conducive to the formation of the macroscopic force chain arch structure in granular matter, which produces the arching effect and the stress shielding effect and leads to the stress dip beneath the pile; and the ratio of the stress dip RSD decreases with the increase of the local impact effect and the internal friction angle.

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Multiscale problems and analysis of soil mechanics

Cited by 19 publications

References 42 publications

A Multiscale Model of Terrain Dynamics for Real-Time Earthmoving Simulation

A Multiscale Model of Terrain Dynamics for Real-Time Earthmoving Simulation

Secondary development of finite-element method based on the calculation of scale effect of soil particles

The experiment and analysis of the repose angle and the stress arch-caused stress dip of the sandpile

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