Unified Solution of Expansion of Cylindrical Cavity of Elastic-Brittle-Plastic Strain-Softening Materials with Different Elastic Modulus in Tensile and Compression

2006 ◽  
Vol 324-325 ◽  
pp. 823-826
Author(s):  
Jian Zhong Xia ◽  
Zhan You Luo ◽  
Wei Tang Wang ◽  
Wei Liu
Keyword(s):  
Elastic Modulus ◽  
Plastic Zone ◽  
Cylindrical Cavity ◽  
Strain Softening ◽  
Strength Theory ◽  
Displacement Fields ◽  
Unified Strength Theory ◽  
Expansion Pressure ◽  
Stress And Displacement Fields ◽  
Pressure Stress

For strain-softening materials with different elastic modulus of tensile compression, two controlling parameters were introduced to take into account the different modulus and strainsoftening properties. By means of twin shear unified strength theory, unified solutions calculating stress and displacement fields of expansion of cylindrical cavity were derived. The effects caused by different elastic modulus in tensile and compression, different models and strain-softening rates on stress and displacement fields, development of plastic zone were analyzed. The results show the ultimate expansion pressure, stress and displacement fields and development of plastic zone vary with the changes of different elastic modular, different models and strain-softening properties.

Elastic-Plastic Analytical Solution of Deep-Buried Circle Pervious Tunnel Based on Unified Strength Theory

2012 ◽  
Vol 602-604 ◽  
pp. 2155-2162
Author(s):  
Qing Ma ◽  
Jun Hai Zhao ◽  
Dong Fang Zhang
Keyword(s):  
Stress Distribution ◽  
Analytical Solution ◽  
Plastic Zone ◽  
Wall Rock ◽  
Adjustment Coefficient ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Pressure Tunnel ◽  
Elastic Plastic ◽  
Inner Pressure

Mohr-Coulomb strength theory has been used to analyses the elastic-plastic analytical solution of pressure tunnel in the field of rock engineering for many years. Because it could only solve the problems with one kind of material, the application of the theory was greatly restricted. In order to reflect the effects of stress redistribution, the stress adjustment coefficient is introduced in this paper to develop the elastic-plastic analytical solution of deep buried circle tunnel based on the unified strength theory. The applicability formulas is gained based on the critical pressures, which can be obtained in other situations or strength thoeries simplified by assuming the parameter value in the formula. An example is analyzed, and the yield range versus the inner pressure and stress distribution are presented. The results show that the parameter in unified strength theory has significant effects on the radius of plastic zone and the magnitude of stresses of the wall rock of tunnel, comparing with theory of Mohr-Coulomb.

scholarly journals Fracturing Pressure of Shallow Sediment in Deep Water Drilling

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Chuanliang Yan ◽  
Jingen Deng ◽  
Lianbo Hu ◽  
Baohua Yu
Keyword(s):  
Plastic Zone ◽  
Pore Pressure ◽  
Deep Water ◽  
Excess Pore Pressure ◽  
Theoretical Formula ◽  
Plastic State ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Gas Drilling ◽  
Excess Pore

The shallow sediment in deep water has weak strength and easily gets into plastic state under stress concentration induced by oil and gas drilling. During drilling, the formation around a wellbore can be divided into elastic zone and plastic zone. The unified strength theory was used after yielding. The radius of the plastic zone and the theoretical solution of the stress distribution in these two zones were derived in undrained condition. The calculation model of excess pore pressure induced by drilling was obtained with the introduction of Henkel’s excess pore pressure theory. Combined with hydraulic fracturing theory, the fracturing mechanism of shallow sediment was analyzed and the theoretical formula of fracturing pressure was given. Furthermore, the influence of the parameters of unified strength theory on fracturing pressure was analyzed. The theoretical calculation results agreed with measured results approximately, which preliminary verifies the reliability of this theory.

scholarly journals The Plastic Zone of Tunnel Surrounding Rock under Unequal Stress in Two Directions Based on the Unified Strength Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zongshan Zou ◽  
Jun Yang ◽  
Zhongming Wang ◽  
Hongyan Liu
Keyword(s):  
Plastic Zone ◽  
Principal Stress ◽  
Interaction Mechanism ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
Surrounding Rock ◽  
Elastic Displacement ◽  
Strength Theory ◽  
Support Structure ◽  
Unified Strength Theory

For the deficiencies that the existing calculation theory for the Plastic Zone of Tunnel Surrounding Rock (PZTSR) does not consider the effect of the intermediate principal stress σ2 and interaction between the surrounding rock and support structure on the PZTSR under unequal stress, the Unified Strength Theory (UST) for the rock is adopted to replace the often used Mohr-Coulomb (M-C) strength criterion to consider the effect of σ2 on the PZTSR. Meanwhile, the interaction mechanism between the surrounding rock and support structure is also considered in the proposed model. Finally, the effect of the initial elastic displacement of the surrounding rock, stiffness of the support structure, and the coefficient b of the intermediate principal stress on the plastic zone is discussed. The results show that the PZTSR will increase nonlinearly with increasing the initial elastic displacement of the surrounding rock, and when it increases to a certain value, its increase extent will be much obvious. With increasing the stiffness of the support structure, the PZTSR will gradually decrease nonlinearly, but the decrease extent is not very much. With increasing b, the PZTSR will decrease; namely, σ2 can improve the stress condition of the surrounding rock and reduce the PZTSR.

STUDY ON SOFTENING CONSTITUTIVE MODEL OF SOFT ROCK USING STRAIN SPACE BASED UNIFIED STRENGTH THEORY

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5375-5380 ◽  
Author(s):  
LI SONG ◽  
CHONGDU CHO ◽  
SHENG LU ◽  
HONGJIAN LIAO
Keyword(s):  
Constitutive Model ◽  
Constitutive Equations ◽  
Strain Softening ◽  
Soft Rock ◽  
Elastoplastic Strain ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Softening Behavior ◽  
Simulation Results ◽  
Strain Space

This study attempts to modify the unified strength theory by considering compression as a positive load in geotechnical engineering. It also aims to establish a unified elastoplastic strain softening constitutive model which can accurately describe the strain softening behavior of one kind of soft rocks distributed in Japan. The hardening function parameters of the unified elastoplastic strain softening constitutive model are determined from experiments. In addition, numerical simulations of this model are performed to compare the pre-peak, post-peak and the residual strengths of soft rock predicted by this study and experimental results. Simulation results demonstrated that the proposed constitutive equations in strain space can well describe the softening behavior and accurately predict the peak and residual strengths of soft rock. While the proposed equation is applicative for normally consolidated state and overconsolidated state according to the simulation results.

Study on Rockmass Deterioration Model Based on the Unified Strength Theory

2012 ◽  
Vol 468-471 ◽  
pp. 2521-2527
Author(s):  
Xue Ying Zhang
Keyword(s):  
Finite Difference ◽  
Strain Softening ◽  
Triaxial Tests ◽  
Strength Theory ◽  
Elastoplastic Model ◽  
Unified Strength Theory ◽  
True Triaxial ◽  
New Model ◽  
Deterioration Model ◽  
Model Based

Strain softening model;Unified strength theory;Rockmass deterioration model;FLAC3D Abstract:Aiming at the problem that traditional elasto-plastic constitutive models have not been successful in predicting the depth and extent of brittle failed of hard rocks under high geo-stress condition, a new rockmass deterioration model(RDM) based on the unified strength theory is put forward in the basis of strain softening model and cohesion weaking and friction strengthening (CWFS)model. In the new model, the influence of intermediatemain stress to characteristic of rockmechanics is considered. Based on the method of lagrangian finite difference, a finite difference format of unified strain- softening elastoplastic model with strength parameters of c and φ is established. The constitutive unified elastoplastic model is imported into FLAC3D using a dynamic-link library file developed by VC++.Based on the new model, the traditional triaxial tests (with different confining pressure) and true triaxial tests (with intermediate principal stress ratio) are simulated in FLAC3D, and the measured data are compared with the results that are are simulated by strain softening model and CWFS model. The analytic results suggest that the rockmass deterioration model based on the twin shear unified strength theory has more strong applicability

scholarly journals Through-wall yield collapse pressure of casing based on unified strength theory

2016 ◽  
Vol 43 (3) ◽  
pp. 506-513 ◽  
Author(s):  
Yuanhua LIN ◽  
Kuanhai DENG ◽  
Yongxing SUN ◽  
Dezhi ZENG ◽  
Tianguo XIA
Keyword(s):  
Strength Theory ◽  
Unified Strength Theory ◽  
Collapse Pressure

A Stress Singularity Parameter Approach for Evaluating the Interfacial Reliability of Plastic Encapsulated LSI Devices

1989 ◽  
Vol 111 (4) ◽  
pp. 243-248 ◽  
Author(s):  
T. Hattori ◽  
S. Sakata ◽  
G. Murakami
Keyword(s):  
Adhesive Strength ◽  
Evaluation Method ◽  
Stress Singularity ◽  
The Finite Element Method ◽  
Displacement Fields ◽  
Stress And Displacement Fields ◽  
Ni Alloy ◽  
Base Resin ◽  
Interfacial Reliability ◽  
Parameter Approach

Since the stress and displacement fields near a bonding edge show singularity behaviors, the adhesive strength evaluation method, using maximum stresses calculated by a numerical stress analysis such as the finite element method, is generally not valid. In this paper, a new method, which uses two stress singularity parameters, is presented for evaluating adhesive strength. This method is applied to several kinds of molded models, composed of epoxy base resin and Fe-Ni alloy sheets, and plastic encapsulated LSI models. Predictions about the initiation and extension of delamination are compared with the results of observations made by scanning acoustic tomography on these models.

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