Characterizing the deformation behavior of Tertiary sandstones

Weng, Meng-Chia; Jeng, Fu‐Shu; Huang, Tsung-Yu; Lin, Meng-Hsuan

doi:10.1016/j.ijrmms.2004.12.004

Cited by 38 publications

(25 citation statements)

References 25 publications

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“…However, if the basal friction prevents the desired longer distance of fault propagation, it is recommended that either a smooth base or more densely packed sand can be adopted to achieve the intended goal. Overall, since sand possesses non-linear stress and constitutive relations, which are similar to the behavior of soft rocks (Jeng et al 1996(Jeng et al , 2002Weng et al 2004) and may dominate the outcomes of simulations under various depth scales, these material properties should be cautiously controlled to enable a reasonable simulation and a common ground for comparison.…”

Section: Discussion Of Scale Factorsmentioning

confidence: 99%

Sandbox Experiments of Plate Convergence - Scale Effect and Associated Mechanisms

Lin¹,

Chen²,

Chang³

et al. 2005

Terr. Atmos. Ocean. Sci.

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ABSTRACT1 Department of Civil Engineering, National Taiwan University, Taipei, Taiwan, ROC 2 Institute of Geoscience, National Taiwan University, Taipei, Taiwan, ROC 3 Department of Civil Engineering, National Central University, Chung-Li, Taiwan, ROC * Corresponding author address: Prof. Fu-Shu Jeng, Department of Civil Engineering, National Taiwan University, Taipei, Taiwan, ROC; E-mail: fsjeng@ntu.edu.tw When using a sandbox to simulate tectonic activities, it is essential to thoroughly understand scale effect and its consequence so as to ensure an adequate model with representative simulation results. This paper investigates the topography, faulting lineaments, and internal structures of different scales associated with the simulation of plate convergence using sandbox modeling, based on three major test series. In the first test series, plate convergence is performed using simple models with flat bases to investigate fundamental behavior and observe the scale effect. The scales of sandbox models are altered either by varying the thickness of sand or by applying centrifugal conditions. The models have a relative depth scale of 1 : 2 : 20 : 40. In the second test series, the scale effects of a sandbox modeling given more realistic conditions are studied, i.e., models with underlain basement highs based on the configuration of western Taiwan. In the third test series, the impact of rougher base friction, and the effects of compaction are investigated to identify possible factors related to scale effect. Based on the observed scale effect, the possible factors accounting for scale effects are also discussed in this paper.Just like most sands, the sand tested is characterized by two phenomena: (1) its internal frictional angle increases from 34° to 41° under greater degrees of compaction, with a relative density ranging from 55 to 90%; and (2) it possesses nonlinear constitutive behavior, whereby the deformational modulus increases upon greater confining stress. Such behavior inherently accounts for scale effect in the way that the embedded stress of sand is TAO, Vol. 16, No. 3, August 2005 596 proportional to its depth; however, the frictional angle and the stiffness of sand cannot be retained constant.Results obtained from the first test series indicate that models with greater depth scale tend to have less deformation concentration near the backstop, quicker thrust faulting and longer fault propagation distances. Meanwhile, internal structures of models with greater depth scales, characterized by more pop-up structures, differ from those of small-scale models. Based on the critical wedge theory, the smaller slope angle yielded under a greater depth scale indicates stronger material strength, which results from greater confining stress or compaction. Moreover, the hardening, or increased stiffness of sand may facilitate forward propagation of convergence stress thereby contributing to the occurrence of scale effect.For the second test series, the yielding of three major fault groups, and curved faults is c...

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Section: Discussion Of Scale Factorsmentioning

confidence: 99%

Sandbox Experiments of Plate Convergence - Scale Effect and Associated Mechanisms

Lin¹,

Chen²,

Chang³

et al. 2005

Terr. Atmos. Ocean. Sci.

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“…According to Jeng et al (2002), Weng et al (2005), and Tsai et al (2008), triaxial results show that the plastic potential surface of sandstone coincides with the yield surface in the prepeak stage. Therefore, the associated flow rule, n ¼ n gL=U and M f ¼ M g , can be used when formulating the constitutive model for sandstone.…”

Section: Dilatancy and Viscoplastic Flowmentioning

confidence: 93%

A Generalized Plasticity-Based Model for Sandstone Considering Time-Dependent Behavior and Wetting Deterioration

Weng

2013

Rock Mech Rock Eng

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Based on the concept of generalized plasticity, this study proposes a constitutive model to describe the time-dependent behavior and wetting deterioration of sandstone. The proposed model (1) exhibits nonlinear elasticity under hydrostatic and shear loading, (2) follows the associated flow rule for viscoplastic deformation, (3) adopts a creep modulus that varies with the stress ratio, (4) considers the primary and secondary creep behaviors of rock, and (5) considers the effect of wetting deterioration. This model requires 13 material parameters, comprising 3 for elasticity, 7 for plasticity, and 3 for creep. All parameters can be determined easily by following the suggested procedures. The proposed model is first validated by comparison with triaxial tests of sandstone under different hydrostatic stress and cyclic loading conditions. In addition, the model is versatile in simulating time-dependent behavior through a series of multistage creep tests. Finally, to consider the effects of wetting deterioration, triaxial and creep tests under dry and water-saturated conditions are simulated. Comparison of the simulated and experimental data shows that the proposed model can predict the behavior of sandstone in dry and saturated conditions.

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“…In order to separate the effects of volumetric and shear stresses on the volumetric deformation, the pure shear stress path is used in triaxial tests. Triaxial tests with pure shear stress paths make it possible to separate the effect of shear stresses and volumetric stresses on deformations, and have been adopted in recent years to study the mechanical behavior of rocks in the three-dimensional stress space [13][14][15][16][17]. In triaxial tests with pure shear stress paths, the confining pressure is held constant by decreasing the cell pressure increments to one-half of the increment of the axial stresses ðDs 2 ¼ Ds 3 ¼ À0:5Ds 1 Þ.…”

Section: Methodsmentioning

confidence: 99%

“…Maranini and Yamaguchi [10] and Cristescu [12] proposed empirical expressions of the linear elastic modulus, in which the influence of confining pressures on the deformational behavior of granite and rock salt is considered. However, experimental results [13][14][15] suggest that rocks can exhibit nonlinear elastic deformation, and coupling between shear stress and elastic volumetric strains, e.g. shear dilation or shear contraction, is obvious.…”

Section: Introductionmentioning

confidence: 99%