Undrained Shear Strength Anisotropy of Cohesive Soils Caused by the Principal Stress Rotation

Wrzesiński, Grzegorz; Pawluk, Katarzyna; Lendo-Siwicka, Marzena; Miszkowska, Anna

doi:10.1088/1757-899x/471/4/042006

Cited by 5 publications

(6 citation statements)

References 12 publications

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“…To determine the change of soil shear strength parameters depending on the principal stress rotation α, there are many empirical equations [32][33][34][35][36]. However, the use of these equations requires the prior determination of many physical properties of the investigated soil and is therefore rarely used.…”

Section: Discussionmentioning

confidence: 99%

Archives of Civil Engineering

Wrzesiński

2021

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The paper presents the phenomenon of principal stress rotation in cohesive subsoil resulting from its loading or unloading and the impact of this phenomenon on the values of soil shear strength parameters: undrained shear strength τfu, effective cohesion c', effective angle of internal friction φ'. For this purpose, tests in a triaxial apparatus and torsional shear hollow cylinder apparatus on selected undisturbed cohesive soils: sasiCl, saclSi, clSi, Cl, characterized by different index properties were carried out. Soil shear strength parameters were determined at angle of principal stress rotation α equal to 0° and 90° in tests in triaxial apparatus and α equal to 0°, 15°, 30°, 45°, 60°, 75°, 90° in tests in torsional shear hollow cylinder apparatus. The results of laboratory tests allow to assess the influence of the principal stress rotation on the shear strength parameters that should be used to determine the bearing capacity of the subsoil.

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Section: Discussionmentioning

confidence: 99%

Archives of Civil Engineering

Wrzesiński

2021

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“…However, in fact, due to the natural deposition and the change of soil stress, the strength of soil is anisotropic. Lo [16] verified the anisotropy equation of soil strength derived by Casagrande [17] with experiments; Wrzesinski et al [18,19] used laboratory tests to study the anisotropy of undrained shear strength of cohesive soil caused by principal stress rotation. The Casagrande anisotropy equation has been widely used in the study of slope stability [20], foundation pit anti-uplift stability [21] and foundation bearing capacity [22].…”

Section: Introductionmentioning

confidence: 87%

Study on the Ultimate Supporting Force of Shield Excavation Face Based on Anisotropic Strength Theory

Dai

Sui

2020

Applied Sciences

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The determination of the ultimate supporting force of the shield excavation face is an important problem to be solved in shield construction. Considering that the tunnel burial depth ratio has a significant effect on the instability mode of the excavation face, the classic “wedge-prism” limit equilibrium model is improved. Based on the rotation effect of principal stress axis, the Casagrande anisotropic strength equation is introduced into the modified limit equilibrium model of “wedge-prism”, and then the limit equilibrium solution of the ultimate supporting force of shield excavation face in anisotropic soil is deduced. Finally, the influence of each calculation parameter on the ultimate supporting force is analyzed by examples. The research results show that the results of the modified “wedge-prism” calculation model proposed in this paper are slightly larger than those of the centrifugal test. If the influence of the instability mode of excavation face and the anisotropy of soil strength on ultimate supporting force of the shield excavation face is not taken into account, the calculation result will be unsafe. The limit supporting force of shield tunnel excavation surface has a simple linear relationship with the anisotropy ratio. When the anisotropy ratio is greater than 1, the ultimate supporting force of shield excavation face decreases first and then tends to be stable with an increase in the buried depth ratio. When the anisotropy ratio is less than 1, the law is reversed. The more obvious the anisotropy of soil strength, the greater the rate of change of ultimate supporting force. The limit supporting force of the shield excavation face decreases linearly with the exertion of loosening earth pressure, linearly decreases with the increase in soil cohesion, and decreases nonlinearly with the increase in the angle of internal friction in soil. The relevant conclusions will provide theoretical guidance for controlling the reasonable chamber pressure of shield tunneling, and ensure the safety of construction.

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“…The load-transfer method evaluated the pile response by solving the load transfer differential equation of the single pile, i.e., Equation (6). Hence, the shaft resistance τ sp (z) should be determined to solve the load transfer differential equation.…”

Section: Load Transfer Relationship Of a Single Pilementioning

confidence: 99%

“…Piles are often installed beneath these infrastructures to bear the uplift or compression loads. As excavation results in stress relief, principal stress rotation, and disturbance to soil [5][6][7][8], the shaft resistance of the piles will decrease [6,9,10]. Therefore, it is crucial to investigate the load-displacement behavior of piles subjected to uplift load in order to check the safety of the pile design.…”

Section: Introductionmentioning

confidence: 99%

Analysis on Response of a Single Pile Subjected to Tension Load Considering Excavation Effects

Liu

et al. 2022

Applied Sciences

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With the development of urbanization, numerous excavations are carried out to facilitate the development of underground space. As a support for tunnel structures, uplift piles are often installed prior to tunnel excavation. The excavation inevitably causes disturbance to the soil below the excavation surface, changing the soil’s mechanical behavior and stress state significantly. However, there is still a lack of a method to evaluate the change in pile capacity due to excavation. This paper proposes a semi-analytical approach for estimating the change in load-settlement behavior of an uplift pile considering the effects of excavation. A hyperbolic model was adopted to simulate the nonlinear interaction of the pile–soil interface. The nonlinear shear-induced soil displacement outside the pile–soil interface is introduced to obtain a more realistic load-displacement behavior of the uplift pile. An effective iterative program was implemented based on the proposed semi-analytical approach. The comparisons between the results from the proposed methods, well-documented field tests, centrifuge tests, and other analytical methods showed that the proposed approach is suitable for analyzing an uplift pile considering excavation effects. A parametric study was conducted to investigate the effects of main soil properties on the pile capacity loss caused by excavation. The results showed that the soil friction angle and the ratio of the excavation depth to the pile effective length have a great influence on the loss in pile uplift capacity caused by excavation. However, the loss of pile uplift capacity caused by excavation is not affected by the soil’s shear modulus or Poisson’s ratio.

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Undrained Shear Strength Anisotropy of Cohesive Soils Caused by the Principal Stress Rotation

Cited by 5 publications

References 12 publications

Archives of Civil Engineering

Archives of Civil Engineering

Study on the Ultimate Supporting Force of Shield Excavation Face Based on Anisotropic Strength Theory

Analysis on Response of a Single Pile Subjected to Tension Load Considering Excavation Effects

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