A principal stress cap model for stresses in eccentric, circular hoppers

Abstract In this study, elastoplastic model for the surrounding rock of axisymmetric circular tunnel is investigated under three-dimensional (3D) principal stress states. Novel numerical solutions for strain-softening surrounding rock were first proposed based on the modified 3D Hoek–Brown criterion and the associated flow rule. Under a 3D axisymmetric coordinate system, the distributions for stresses and displacement can be effectively determined on the basis of the redeveloped stress increment approach. The modified 3D Hoek–Brown strength criterion is also embedded into finite element software to characterize the yielding state of surrounding rock based on the modified yield surface and stress renewal algorithm. The Euler implicit constitutive integral algorithm and the consistent tangent stiffness matrix are reconstructed in terms of the 3D Hoek–Brown strength criterion. Therefore, the numerical solutions and finite element method (FEM) models for the deep buried tunnel under 3D principal stress condition are presented, so that the stability analysis of surrounding rock can be conducted in a direct and convenient way. The reliability of the proposed solutions was verified by comparison of the principal stresses obtained by the developed numerical approach and FEM model. From a practical point of view, the proposed approach can also be applied for the determination of ground response curve of the tunnel, which shows a satisfying accuracy compared with the measuring data.

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Failure criterion for soft rocks considering intermediate principal stress

International Journal of Mining Science and Technology ◽

10.1016/j.ijmst.2021.05.005 ◽

2021 ◽

Author(s):

Zhongwei Wang ◽

Quansheng Liu

Keyword(s):

Principal Stress ◽

Failure Criterion ◽

Intermediate Principal Stress ◽

Soft Rocks

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Elastic Simulation of Joints with Particle-Based Fluid

Applied Sciences ◽

10.3390/app11156900 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6900

Author(s):

Su-Kyung Sung ◽

Sang-Won Han ◽

Byeong-Seok Shin

Keyword(s):

Principal Stress ◽

Human Body ◽

Yield Condition ◽

Maximum Principal Stress ◽

Human Motion ◽

The Difference ◽

The Moment ◽

External Forces ◽

Physical Changes ◽

Elastic Simulation

Skinning, which is used in skeletal simulations to express the human body, has been weighted between bones to enable muscle-like motions. Weighting is not a form of calculating the pressure and density of muscle fibers in the human body. Therefore, it is not possible to express physical changes when external forces are applied. To express a similar behavior, an animator arbitrarily customizes the weight values. In this study, we apply the kernel and pressure-dependent density variations used in particle-based fluid simulations to skinning simulations. As a result, surface tension and elasticity between particles are applied to muscles, indicating realistic human motion. We also propose a tension yield condition that reflects Tresca’s yield condition, which can be easily approximated using the difference between the maximum and minimum values of the principal stress to simulate the tension limit of the muscle fiber. The density received by particles in the kernel is assumed to be the principal stress. The difference is calculated by approximating the moment of greatest force to the maximum principal stress and the moment of least force to the minimum principal stress. When the density of a particle increases beyond the yield condition, the object is no longer subjected to force. As a result, one can express realistic muscles.

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Effect of initial deviatoric stress on anisotropy of marine clay during principal stress rotation

Marine Georesources and Geotechnology ◽

10.1080/1064119x.2020.1865489 ◽

2020 ◽

pp. 1-14

Author(s):

Heng Zhuang ◽

Xiuqing Hu ◽

Lin Guo ◽

Li Mingfeng ◽

Wang Chaoliang ◽

...

Keyword(s):

Principal Stress ◽

Deviatoric Stress ◽

Principal Stress Rotation ◽

Marine Clay ◽

Stress Rotation

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Numerical simulation on the simultaneous stress interference of parallel multiple hydraulic fractures

Energy Exploration & Exploitation ◽

10.1177/01445987211001955 ◽

2021 ◽

pp. 014459872110019

Author(s):

Weiyong Lu ◽

Changchun He

Keyword(s):

Principal Stress ◽

Hydraulic Fracture ◽

Stress Ratio ◽

Fracture Network ◽

Hydraulic Fractures ◽

Fracture Spacing ◽

Induced Stress ◽

Minimum Principal Stress ◽

Fracturing Process ◽

Stress Ratios

During horizontal well staged fracturing, there is stress interference between multiple transverse fractures in the same perforation cluster. Theoretical analysis and numerical calculation methods are applied in this study. We analysed the mechanism of induced stress interference in a single fracture under different fracture spacings and principal stress ratios. We also investigated the hydraulic fracture morphology and synchronous expansion process under different fracture spacings and principal stress ratios. The results show that the essence of induced stress is the stress increment in the area around the hydraulic fracture. Induced stress had a dual role in the fracturing process. It created favourable ground stress conditions for the diversion of hydraulic fractures and the formation of complex fracture network systems, inhibited fracture expansion in local areas, stopped hydraulic fractures, and prevented the formation of effective fractures. The curves of the maximum principal stress, minimum principal stress, and induced principal stress difference with distance under different fracture lengths, different fracture spacings, and different principal stress ratios were consistent overall. With a small fracture spacing and a small principal stress ratio, intermediate hydraulic fractures were difficult to initiate or arrest soon after initiation, fractures did not expand easily, and the expansion speed of lateral hydraulic fractures was fast. Moreover, with a smaller fracture spacing and a smaller principal stress ratio, hydraulic fractures were more prone to steering, and even new fractures were produced in the minimum principal stress direction, which was beneficial to the fracture network communication in the reservoir. When the local stress and fracture spacing were appropriate, the intermediate fracture could expand normally, which could effectively increase the reservoir permeability.

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