The Changing Rule of Rock Strength under True Triaxial Condition

2014 ◽  
Vol 522-524 ◽  
pp. 1410-1413
Author(s):  
Ze Kang Wen ◽  
Ke Min Wei ◽  
Jia Quan Hu ◽  
You Ling Fang
Keyword(s):  
Principal Stress ◽  
Rock Strength ◽  
Quadratic Function ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
True Triaxial Test ◽  
True Triaxial ◽  
Minimum Principal Stress ◽  
Stress Coefficient ◽  
Intermediate Principal Stress Effect

The intermediate principal stress effect of the rock has been demonstrated. By analyzing true triaxial test results of Dunham dolomite and Mizuho trachyte, we studied relationship between minimum principal stress and the rock strength under the same intermediate principal stress coefficient, and the relationship between intermediate principal stress and the rock strength under the same minimum principal stress condition. Research shows that the minimum principal stress has a linear relation with the rock strength, the intermediate principal stress coefficient of a quadratic function relation with the rock strength. And the mathematic expression of the intermediate principal stress effect function was calculated.

scholarly journals Failure Probability Model considering the Effect of Intermediate Principal Stress on Rock Strength

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yonglai Zheng ◽  
Shuxin Deng
Keyword(s):  
Principal Stress ◽  
Failure Probability ◽  
Rock Strength ◽  
Probability Model ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
New Model ◽  
Uniformity Coefficient ◽  
Intermediate Principal Stress Effect

A failure probability model is developed to describe the effect of the intermediate principal stress on rock strength. Each shear plane in rock samples is considered as a micro-unit. The strengths of these micro-units are assumed to match Weibull distribution. The macro strength of rock sample is a synthetic consideration of all directions’ probabilities. New model reproduces the typical phenomenon of intermediate principal stress effect that occurs in some true triaxial experiments. Based on the new model, a strength criterion is proposed and it can be regarded as a modified Mohr-Coulomb criterion with a uniformity coefficient. New strength criterion can quantitatively reflect the intermediate principal stress effect on rock strength and matches previously published experimental results better than common strength criteria.

scholarly journals Ultimate Bearing Capacity of Strip Foundations in Unsaturated Soils considering the Intermediate Principal Stress Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qing Yan ◽  
Junhai Zhao ◽  
Changguang Zhang ◽  
Jintai Wang
Keyword(s):  
Bearing Capacity ◽  
Principal Stress ◽  
Unsaturated Soils ◽  
Matric Suction ◽  
Ultimate Bearing Capacity ◽  
Intermediate Principal Stress ◽  
Shallow Foundations ◽  
Hyperbolic Function ◽  
Stress Effect ◽  
Intermediate Principal Stress Effect

The reasonable determination of ultimate bearing capacity is crucial to an optimal design of shallow foundations. Soils surrounding shallow foundations are commonly located above the water table and are thus in an unsaturated state. The intermediate principal stress has an improving effect on the unsaturated soil strength. In this study, the ultimate bearing capacity formulation of strip foundations in unsaturated soils is presented by using Terzaghi’s theory. The unified shear strength equation of unsaturated soils under a plane strain condition is utilized to capture the intermediate principal stress effect. Furthermore, two profiles of matric suction are considered and a hyperbolic function of the friction angle related to matric suction (φb) is adopted to describe strength nonlinearity. The validity of this study is demonstrated by comparing it with model tests and a theoretical solution reported in the literature. Finally, parameter studies are conducted to investigate the effects of intermediate principal stress, matric suction, and base roughness on the ultimate bearing capacity of strip foundations. Besides, the effect of strength nonlinearity is discussed with two methods representing the angle φb.

scholarly journals Seepage Flow Properties of a Columnar Jointed Rock Mass in a True Triaxial Experiment

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Yanxin He ◽  
Zhende Zhu ◽  
Wenbin Lu ◽  
Yunjin Hu ◽  
Xinghua Xie ◽  
...  
Keyword(s):  
Rock Mass ◽  
Principal Stress ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intermediate Principal Stress ◽  
True Triaxial ◽  
Minimum Principal Stress ◽  
Baihetan Hydropower Station ◽  
Columnar Jointed Rock Mass ◽  
Seepage Characteristics

A columnar jointed rock mass is a type of rock mass with strong geometric anisotropy and high interface permeability. Its seepage characteristics pose new challenges to the construction and maintenance of the Baihetan Hydropower Station on the Jinsha River. The research object in this study is the columnar jointed rock mass (basalt) in the dam area of Baihetan Hydropower Station. Similar-material model samples of the columnar jointed rock mass with different column dip angles ( α = 0 ° ~90°) were prepared following a similar principle. A true triaxial seepage–stress coupling test was conducted to evaluate the seepage characteristics of similar-material samples with different dip angles under intermediate principal stress and minimum principal stress. The experimental results showed that the columnar jointed rock mass exhibited apparent seepage anisotropy. The relationship curve between the volume flow rate Q and the pressure gradient − d P / d L of the samples with different dip angles showed evident nonlinear seepage under intermediate principal stress, which could be well expressed using the Forchheimer equation. It shows the characteristics of a typical linear Darcy flow under minimum principal stress. The law of variations in the permeability of the samples with different dip angles under intermediate principal stress can be well expressed using the one-dimensional quadratic function equation k = a + b σ 2 + c σ 2 2 , and the law of variations in the permeability of the samples with different dip angles under minimum principal stress can be well expressed using the logarithmic function k = a + b ln σ 3 . The permeabilities of the columnar jointed rock mass with dip angles of 0°, 15°, 30°, and 60° were most sensitive to changes in stress, and the seepage characteristics increased in complexity after changes in stress.

Study on the Ultimate Pullout Force of Prestressed Cable Based on Triple Shear Unified Yield Criterion

2012 ◽  
Vol 594-597 ◽  
pp. 840-843
Author(s):  
Xiao Yan Luo ◽  
Wei Ping Liu
Keyword(s):  
Principal Stress ◽  
Yield Criterion ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Pullout Force ◽  
Grouting Pressure ◽  
Effect Parameter ◽  
Ultimate Equilibrium ◽  
Intermediate Principal Stress Effect ◽  
Prestressed Cable

Based on the triple shear unified yield criterion and the ultimate equilibrium principle, the ultimate pullout force of prestressed cable is studied. The ultimate pullout force of prestressed cable is related to the rock type, the shapes of rapture surface, grouting pressures and compressive strength of rock, etc. The results show that the intermediate principal stress effect parameter b have influences on the ultimate pullout force of prestressed cable. With the increase of the intermediate principal stress effect parameter b, the ultimate pullout force of prestressed cable increases too. When the grouting pressure increases, the ultimate pullout force of prestressed cable increases also.

Influence of Intermediate Principal Stress Effect on Flat Punch Problems

2013 ◽  
Vol 535-536 ◽  
pp. 300-305
Author(s):  
Zong Yuan Ma ◽  
Hong Jian Liao ◽  
Fa Ning Dang
Keyword(s):  
Principal Stress ◽  
Three Dimensional ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Strength Theory ◽  
Lagrangian Analysis ◽  
Flat Punch ◽  
Unified Strength Theory ◽  
Intermediate Principal Stress Effect ◽  
Punch Problem

Using the finite difference code FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) and UST (Unified Strength Theory), the influence of the intermediate principal stress effect on the problems of flat punch are analyzed in this paper. The values of the ultimate bearing capacity resulting from numerical analyses and the analytical solution of Prandtl’s strip punch problem are compared. The three-dimensional problems of strip, rectangular, square and circular punches on a semi infinite metallic medium have been analyzed.

Elastoplastic Analysis of Surrounding Rocks of the Pressure Tunnel

2013 ◽  
Vol 353-356 ◽  
pp. 1644-1647
Author(s):  
Shen Qiong
Keyword(s):  
Plastic Zone ◽  
Mechanical Behavior ◽  
Principal Stress ◽  
Yield Criterion ◽  
Intermediate Principal Stress ◽  
Hydraulic Pressure ◽  
Stress Effect ◽  
Pressure Tunnel ◽  
Effect Parameter ◽  
Intermediate Principal Stress Effect

According to the triple shear unified yield criterion, the mechanical behavior of the pressure tunnel was put forward. The calculation formulas of the radius of plastic zone were deduced with considerations of the effects of the intermediate principal stress. The results show that the intermediate principal stress effect parameter b has influences on the radius of plastic zone. With the increase of the intermediate principal stress effect parameter b, the radius of plastic zone decreases. The radius of plastic zone is increased, because of the increase of the porous hydraulic pressure.

Mechanics Behavior of Concrete-Filled Square Steel Tube Columns

2012 ◽  
Vol 256-259 ◽  
pp. 662-665
Author(s):  
Xiao Yan Luo ◽  
Wei Ping Liu
Keyword(s):  
Bearing Capacity ◽  
Principal Stress ◽  
Analytical Method ◽  
Yield Criterion ◽  
Steel Tube ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Effect Parameter ◽  
Intermediate Principal Stress Effect ◽  
Square Steel Tube

This study presents a simplified analytical method for predicting the ultimate strength of compressed concrete filled square steel tube columns based on the triple shear unified yield criterion. Based on the triple shear unified yield criterion theory solutions of thick tube, the calculation formulas of axial bearing capacity of the concrete-filled square steel tube columns were deduced with considerations of the restriction effects of steel tube and the effects of the intermediate principal stressed. The results show that the intermediate principal stress effect parameter b has influences on the ultimate bearing capacity. The formulas in the paper have significance in exerting material potential and save material.

scholarly journals Numerical Investigation and Analysis of Intermediate Principal Stress Effects on Rock Failure Behaviors

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Shuxin Deng ◽  
Yonglai Zheng ◽  
Cuizhou Yue ◽  
Le Van Tuan
Keyword(s):  
Principal Stress ◽  
Rock Sample ◽  
Intermediate Principal Stress ◽  
Rock Failure ◽  
Normal Direction ◽  
Numerical Results ◽  
Stress Effect ◽  
Rock Samples ◽  
Stress Effects ◽  
Intermediate Principal Stress Effect

A series of numerical experiments have been conducted to investigate the intermediate principal stress effects on rock failure behaviors. The numerical results show that the strength and deformation of the rock samples are significantly affected by the intermediate principal stress. The effects are inconsistent in different intervals. As intermediate principal stress ratio b increases, the rock strength increases initially and finally decreases. When b is approximately equal to 0.5, the strength of the rock sample reaches the maximum. In the microlevel, the intermediate principal stress affects the number and distribution of microcracks. The increase of the intermediate principal stress makes the projection of the microcracks on the loading plane change from uniform to uneven. On the one hand, the intermediate principal stress restricts the propagation of microcracks in the normal direction along the intermediate principal stress (or with a component in this direction), which will lead to an increase in the strength of the rock samples. On the other hand, the propagation of microcracks along the normal direction with small principal stress (or with a component in this direction) is promoted, which leads to a decrease in the strength of the rock sample. End friction can make the intermediate principal stress effect more significant because the friction of the loading end to the rock sample can result in stress deviation between the actual value and experimental value. Inhomogeneity of stress field induced by the change of stress states or end friction forces is the external factor of the intermediate principal stress effect. Also, the inhomogeneity of rock material itself is the internal factor. Intermediate principal stress will promote or restrict the failure of certain directions, thus affecting the overall strength of the rock samples. The numerical results can be very meaningful for stability analysis of rock masses in practical engineering.

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