Theoretical Solutions for a Circular Opening in an Elastic–brittle–plastic Rock Mass Incorporating the Out-of-plane Stress and Seepage Force

Zou Jin-feng,Li Shuai-shuai,Xu Yuan,Dan Han-cheng,Zhao Lian-heng 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

Seepage force is simplified as seepage volumetric force in the stress field along the radial direction. Out-of-plane stress and seepage force are incorporated, and the theoretical solutions for stress, displacement, and plastic radius of a circular opening for the elastic-brittle-plastic and elastic-plastic rock mass are proposed based on the Mohr–Coulomb (MC) and generalized Hoek-Brown (HB) failure criteria. The presented solution and Wang’s solution (2012) are compared, and the corrected version of the proposed method is validated. Numerical examples of the proposed method based on the MC and generalized HB failure criteria reveal that the distributions of stress and displacement in the surrounding rock of the tunnel are significantly influenced by seepage force and out-ofplane stress. Displacement and plastic radius when seepage force and out-of-plane stress are considered are larger than those when the seepage force is not considered; the regulations of stress, however, run opposite. The results of displacement and plastic radius based on the generalized HB failure criterion are larger than those based on the MC failure criterion.

Influences of seepage force and out-of-plane stress on cavity contracting and tunnel opening

Zou, Jin-Feng,Chen, Kai-Fu,Pan, Qiu-Jing Techno-Press 2017 Geomechanics & engineering Vol.13 No.6

The effects of seepage force and out-of-plane stress on cavity contracting and tunnel opening was investigated in this study. The generalized Hoek-Brown (H-B) failure criterion and non-associated flow rule were adopted. Because of the complex solution of pore pressure in an arbitrary direction, only the pore pressure through the radial direction was assumed in this paper. In order to investigate the effect of out-of-plane stress and seepage force on the cavity contraction and circular tunnel opening, three cases of the out-of-plane stress being the minor, intermediate, or major principal stress are assumed separately. A method of plane strain problem is adopted to obtain the stress and strain for cavity contracting and circular tunnel opening for three cases, respectively, that incorporated the effects of seepage force. The proposed solutions were validated by the published results and the correction is verified. Several cases were analyzed, and parameter studies were conducted to highlight the effects of seepage force, H-B constants, and out-of-plane stress on stress, displacement, and plastic radius with the numerical method. The proposed method may be used to address the complex problems of cavity contraction and tunnel opening in rock mass.

An improved radius-incremental-approach of stress and displacement for strain-softening surrounding rock considering hydraulic-mechanical coupling

Zou, Jin-Feng,Wei, Xing-Xing Techno-Press 2018 Geomechanics & engineering Vol.16 No.1

This study focused on the mechanical and hydraulic characteristics of underwater tunnels based on Mohr-Coulomb (M-C), Hoek-Brown (H-B) and generalized H-B failure criteria. An improved approach for calculating stress, displacement and plastic radius of the circular tunnel considering hydraulic-mechanical coupling was developed. The innovation of this study was that the radius-incremental-approach was reconstructed (i.e., the whole plastic zone is divided into a finite number of concentric annuli by radius), stress and displacement of each annulus were determined in terms of numerical method and Terzaghi's effective stress principle. The validation of the proposed approach was conducted by comparing with the results in Brown and Bray (1982) and Park and Kim (2006). In addition, the Rp-pin curve (plastic radius-internal supporting pressure curve) was obtained using the numerical iterative method, and the plastic radius of the deep-buried tunnel could be obtained by interpolation method in terms of the known value of internal supporting pressure pin. Combining with the theories in Carranza and Fairhurst (2000), the improved technique for assessing the reliability of the tunnel support was proposed.

A new approach for the quasi-plane strain-softening problem of cylindrical cavity expansion based on Cam-Clay model

Zou Jin-feng,Du Jia-min 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3

This paper focuses on the quasi-plane strain-softening problem of cylindrical cavity expanding in Cam-Clay soil mass. The quasi-plane strain-softening problem is defined based on the assumptions that the initial axial total strain is a non-zero constant and the axial plastic strain is not zero. A new approach for the major, intermediate, and minor principal strains are proposed based on the associated flow rule, 3-D plastic potential function, Hooke’s law, stress equilibrium equation and Cam-Clay model. The correctness of the proposed approach is validated by the results in Cao and Teh. Parametric studies were performed to investigate the influences of the intermediate principal stress on the radial and circumferential stresses and the radial displacement, respectively.

A new approach for the cylindrical cavity expansion problem incorporating deformation dependent of intermediate principal stress

Zou, Jin-Feng,Xia, Ming-yao Techno-Press 2017 Geomechanics & engineering Vol.12 No.3

The problem of cylindrical cavity expansion incorporating deformation dependent of intermediate principal stress in rock or soil mass is investigated in the paper. Assumptions that the initial axial total strain is a non-zero constant and the axial plastic strain is not zero are defined to obtain the numerical solution of strain which incorporates deformation-dependent intermediate principal stress. The numerical solution of plastic strains are achieved by the 3-D plastic potential functions based on the M-C and generalized H-B failure criteria, respectively. The intermediate principal stress is derived with the Hook's law and plastic strains. Solution of limited expansion pressure, stress and strain during cylindrical cavity expanding are given and the corresponding calculation approaches are also presented, which the axial stress and strain are incorporated. Validation of the proposed approach is conducted by the published results.

Theoretical solutions for displacement and stress of a circular opening reinforced by grouted rock bolt

Zou, Jin-Feng,Xia, Zhang-Qi,Dan, Han-Cheng Techno-Press 2016 Geomechanics & engineering Vol.11 No.3

This paper presented solutions of displacement and stress for a circular opening which is reinforced with grouted rock bolt. It satisfies the Mohr-Coulomb (M-C) or generalized Hoek-Brown (H-B) failure criterion, and exhibits elastic-brittle-plastic or strain-softening behavior. The numerical stepwise produce for strain-softening rock mass reinforced with grouted rock bolt was developed with non-associative flow rules and two segments piecewise linear functions related to a principle strain-dependent plastic parameter, to model the transition from peak to residual strength. Three models of the interaction mechanism between grouted rock bolt and surrounding rock proposed by Fahimifar and Soroush (2005) were adopted. Based on the axial symmetrical plane strain assumption, the theoretical solution of the displacement and stress were proposed for a circular tunnel excavated in elastic-brittle-plastic and strain-softening rock mass compatible with M-C or generalized H-B failure criterion, which is reinforced with grouted rock bolt. It showed that Fahimifar and Soroush's (2005) solution is a special case of the proposed solution for n = 0.5. Further, the proposed method is validated through example comparison calculated by MATLAB programming. Meanwhile, some particular examples for M-C or generalized H-B failure criterion have been conducted, and parametric studies were carried out to highlight the influence of different parameters (e.g., the very good, average and very poor rock mass). The results showed that, stress field in plastic region of surrounding rock with considering the supporting effectiveness of the grouted rock bolt is more than that without considering the effectiveness of the grouted rock bolt, and the convergence and plastic radius are reduced.

Morphological abnormalities and lethality in silkworm (Bombyx mori) larvae treated with high concentrations of insect growth-blocking peptide

Feng Ming Zou,이광식,Hu Wan,Zhong Zheng Gui,진병래 한국응용곤충학회 2014 Journal of Asia-Pacific Entomology Vol.17 No.1

Insect growth-blocking peptides (GBPs) exhibit growth-blocking and paralytic activity. Low concentrations ofGBP stimulate larval growth, whereas high concentrations of GBP significantly retard larval growth. Here, weshow that morphological abnormalities and lethality were induced in silkworm (Bombyx mori) larvae by highconcentrations of GBP. Active B. mori GBP (BmGBP) was produced by treating recombinant proBmGBP(expressed in baculovirus-infected insect cells) with bovine factor Xa. When silkworm larvae on day 1 of thefifth-instar stage were injected between the seventh and eight abdominal segments with BmGBP (100 or500 ng/larva), the larval–pupal and pupal–adult transformations of these silkworms were delayed in a dosedependentmanner. However, a high concentration (2000 ng/larva) of BmGBP or Spodoptera exigua GBP(SeGBP) acutely induced morphological abnormalities and death in silkworm larvae. In silkwormlarvae treatedwith high concentrations of GBPs, the ingested food excessively accumulated in the foregut, which caused extremeswelling in both the thorax and the foregut and resulted in larval death. Therefore, these results notonly provide insight into the effect of insect GBPs on gut physiology but also reveal a novel function of insectGBPs.

ABS ALGORITHMS FOR DIOPHANTINE LINEAR EQUATIONS AND INTEGER LP PROBLEMS

ZOU, MEI FENG,XIA, ZUN QUAN 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.17 No.1

Based on the recently developed ABS algorithm for solving linear Diophantine equations, we present a special ABS algorithm for solving such equations which is effective in computation and storage, not requiring the computation of the greatest common divisor. A class of equations always solvable in integers is identified. Using this result, we discuss the ILP problem with upper and lower bounds on the variables.

Expression profiles of glutathione S-transferase genes in larval midgut of Bombyx mori exposed to insect hormones

Zou, Feng-Ming,Lou, De-Shuai,Zhu, Ya-Hong,Wang, Sheng-Peng,Jin, Byung-Rae,Gui, Zhong-Zheng Springer-Verlag 2011 Molecular biology reports Vol.38 No.1

Differential and spatial regulation of the prophenoloxidase (proPO) and proPO-activating enzyme in cuticularmelanization and innate immunity in Bombyx mori pupae

Feng Ming Zou,이광식,김보연,김홍자,Zhong Zheng Gui,Guozheng Zhang,Xijie Guo,진병래 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.4

Insect cuticular melanization is regulated by the prophenoloxidase (proPO)-activating system, which is also involved in the innate immune reaction. Here, we demonstrate how the differentiation of the proPO-activating system is regulated toward a cuticular melanization or innate immunity function in silkworm (Bombyx mori) pupae. Our results indicate that the differential and spatial regulation of key components, such as the proPOactivating enzyme and proPOs, primes the proPO-activating system for either cuticular melanization or innate immunity. This dual strategy for cuticular melanization in development and innate immunity upon infection demonstrates a two-pronged defense mechanism that is mediated by the priming of the proPO system.