Cyclic Torsional Shear Tests Research Articles

Experimental study on the influence of cyclic loading frequency on liquefaction characteristics of saturated sand

A series of undrained cyclic torsional shear tests was conducted to investigate the effect of cyclic loading frequency on the liquefaction characteristics of saturated sand using a hollow cylinder apparatus. The test results show that the dilative and contractive tendencies of various saturated sands are not only related to the physical properties of the sand, but are also affected by loading frequency. Under low-frequency loading, the saturated sand has a dilative behaviour, excess pore water pressure fluctuates after initial liquefaction and the soil maintains the ability to resist liquefaction to some extent after the initial liquefaction. The liquefaction mode in terms of the stress–strain relationship generally performs as the ‘cyclic mobility’. However, under high-frequency loading, the saturated sand has a contractive behaviour, and excess pore water pressure generally remains stable after the initial liquefaction. The liquefaction mode in terms of stress–strain relationship generally exhibits as ‘cyclic instability’. The deformation caused by low-frequency loading is significantly larger compared with that caused by high-frequency loading. At higher loading frequencies, the phase transformation stress ratio increases with the increase of loading frequency, and gradually approaches the failure stress ratio.

Geomechanical Characterization of Crushed Concrete–Rubber Waste Mixtures

The present study investigates the dynamic and cyclic behavior of mixtures of waste materials, i.e., rigid anthropogenic mineral aggregates (RCA) mixed with recycled soft particles (RTW), based on a series of standard resonant column tests and cyclic torsional shear tests. The laboratory tests presented in this article are part of a larger research project that aims to provide useful insights to facilitate the application of RCA–RTW compositions as geotechnical materials. The impacts of various parameters including shear strain, mean effective stress, and, in particular, rubber content on the shear modulus (G), and damping ratio (D), are considered in detail. Rubber content is considered by the percentage of rubber in the mix weight. In general, the results show that as the RTW content increases, the shear modulus decreases while the damping ratio increases. The largest reduction in the G−modulus values occurs for the highest rubberized mix. The observed damping ratio for pure RCA is approx. three times lower versus rubber-reinforced specimens. The compliance of the behavior of the new RCA–RTW mixtures and pure recycled concrete waste tested under dynamic and cyclic loading is demonstrated. The effects of crushing of the RCA material itself during cyclic loading are visible, and dilution of this process due to the addition of rubber. Furthermore, the test data reveal that the values of the G−modulus and D−ratio at small and medium strain levels are considered independent of the time of vibration.

Effects of consolidation conditions on the dynamic shear modulus of saturated coral sand over a wide strain range

The utilization of coral sand as a construction material for ports and other infrastructure systems in coral reefs is prevalent, wherein the soil elements within slopes and embankments typically experience an anisotropic stress state. It is imperative to accurately characterize the degradation behavior of the stratigraphic material's stiffness across a wide range of strains. In this study, the maximum and strain-dependent shear modulus (G0 and G) characteristics of saturated coral sand under isotropic and anisotropic consolidations were investigated by performing multi-stage stress-controlled undrained cyclic torsional shear tests with cyclic hollow cylinder shear apparatus. The experimental results indicated that G0 and G generally rose with increasing initial effective consolidation pressure but decreased with increasing inclination of initial major principal stress from the vertical (αc). In contrast, the effect of consolidation stress ratio (kc) on G0 and G was nonmonotonic, and that of kc and αc on the strain-dependent shear modulus reduction (G/G0) curve was slight. By defining anisotropic consolidation indexes δ0 and δr used for quantifying the effect of consolidation-induced anisotropy on the G0 and the G/G0, respectively. A unified formula of G0 obtained by multiplying Hardin's model by δ0, as well as a unique formula of G/G0 obtained by correcting γr in the Davidenkov skeleton curve expression as a linear function of δr were established under various consolidation conditions, respectively. The proposed G formula over a wide strain range is well validated by the experimental data for siliceous sandy soils from the literature.

Effect of cyclic loading frequency on cyclic behaviour of saturated sand

In practical engineering, sand fill or sediments subjected to cyclic loadings at varying frequencies due to earthquakes, traffic, and waves may cause complex soil responses. To investigate the effect of loading frequency on the cyclic behaviour of saturated sand, a series of undrained cyclic torsional shear tests covering a wide range of loading frequencies were conducted on Fujian sand. The excess pore water pressure (EPWP) in saturated sand can be divided into two components: residual and transient. Special focus was on the effect of loading frequency on the development of residual EPWP, transient EPWP, and shear strain amplitude. The key finding demonstrates that the loading frequency has a considerable effect on the association between the double amplitude of transient EPWP and shear strain amplitude. Based on the test data, a threshold strain is proposed that can be used to predict the onset of shear dilatancy in saturated sand. The liquefaction strength in the cyclic torsional shear tests was also investigated and was found to be significantly influenced by the loading frequency. The cyclic resistance ratio (CRR15) of saturated sand shows an increasing trend with the increase in loading frequency.

Experimental study on cyclic deformation properties of saturated Fujian sand at different loading frequencies

In this study, a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction (shearing contractive (SC) period and initial shearing dilative (ISD) period) and post-liquefaction (late shearing dilative (LSD) period) deformation properties of saturated Fujian sand. The secant shear modulus G and damping ratio λ in the entire cyclic loading process, and the unloading tangent shear modulus GL1 and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude γa. The test results show that the effect of f on G of saturated Fujian sand in the SC period is not apparent. However, all the G-γa, GL1-γa, and GL2-γa curves in the ISD and LSD periods showed a downward trend with an increase in f. This study also proposes a modified method for calculating λ to compensate for the analytical error caused by the non-closure of hysteresis loop. Compared with the classical curves that mainly applied in geotechnical engineering, the λ first increases and then decreases with the increase of γa. Furthermore, the λ evaluated by the modified method is approximately 10%–15% more than the λ evaluated by the traditional method when the λ reaches its peak value.

Development characteristics of excess pore water pressure in saturated marine coral sand based on shear strain characteristics: An experimental study

Using a hollow-cylinder torsional shear apparatus, we experimentally investigated the development characteristics of excess pore water pressure (EPWP) in saturated marine coral sand. These coral sand specimens were tested under various values of nonplastic fines content (FC), relative density (Dr), and cyclic stress ratio (CSR). A laboratory cyclic torsional shear test under isotropic consolidation showed that the development rate of the EPWP ratio (Ru) versus the number of cycles (N) increased with increasing FC and CSR but decreased with increasing Dr. Additionally, the increase in FC significantly reduced the cyclic resistance ratio (CRR) of marine coral sand. For a given Dr and FC, Ru of the specimens under different CSR was uniquely related to the amplitude of the shear strain (γa). Moreover, a pore pressure evaluation model based on shear strain characteristics was established. The measurements showed that the EPWP model parameter A is a soil-specific constant, and the density-corrected EPWP model parameter B/(Dr)1.5 has a single negative-power relationship with the equivalent skeleton void ratio (esk*.

Analysis of the handling and preparation of samples in the resonant column and cyclic torsional shear equipment

In many geotechnical applications, the shear modulus G is the one that governs the dynamic behaviour of the soil, and many fields and laboratory methods are focused on calculating it. This is the case of the resonant column and cyclic torsional shear tests, which allow both the modulus G and the damping D to be obtained in different strain ranges. These laboratory tests are carried out in a triaxial cell and in both tests, torsion is applied to the upper part of the specimens, which has allowed new commercial devices to group both techniques in a piece of a single equipment. The combination of the two tests makes it possible to obtain the dynamic properties of the soil over a wide range of strains, 10-4≤γ≤1%.Due to the small strains reached in these tests, less than 1%, the correct preparation of the specimens and their mounting in the triaxial cell are factors of vital importance for the reliability of the test results. In undisturbed samples, the sample should be handled, and the specimen carved with special care, trying not to alter the structure of the original soil. For remoulded clay specimens, static compaction in an external press and subsequent mounting on the triaxial cell pedestal are recommended. Saturation can present difficulties, as in these tests drainage and saturation can only be carried out from the bottom of the specimen. Consolidation times can be long. Sand specimens should be made by placing a mould on the pedestal of the triaxial cell and applying a vacuum. The method of freezing the specimen is discarded due to the long assembly time.

Experimental study on liquefaction characteristics of saturated marine coral sand based on dissipated energy evaluation

The liquefaction of saturated marine coral sand is of a great issue for the safety of ocean engineering. A series of undrained cyclic torsional shear tests on saturated coral sand are carried out to further explore the liquefaction characteristics of coral sand. Based on the energy method, the effects of relative density (D r), effective mean principal stress (), and cyclic stress ratio (CSR) on undrained responses of saturated coral sand are investigated. Two failure criteria are discussed to evaluate the dissipated energy required to cause initial liquefaction (W l). The test results show that the W l is significantly affected by D r and The generation patterns of excess pore water pressure (EPWP) and single amplitude torsional strain amplitude (γ SA) along with cumulative dissipated energy (W c) are described, and the unified generation model of both u e and γ SA along with W c are established. The liquefaction resistance curves for various D r and are strongly related to W l. Analyzing the cumulative dissipated energy required to trigger liquefaction, a modified stress level index termed CSR e is proposed to normalize the liquefaction resistance curves of saturated coral sand under different D r and The test data in literature also verify the applicability of CSR e.

Comparisons of cyclic response and reconsolidation volumetric strain of saturated coral sand and siliceous sand

Reported here are undrained cyclic torsional shear tests and reconsolidation tests carried out to compare the characteristics of the undrained cyclic response and reconsolidation volumetric strain (ε v) of saturated coral sand and siliceous sand (Nanjing fine sand and Ottawa sand). An important finding is that the cyclic resistance ratio of saturated coral sand increases with increasing relative density (D r) and decreases with increasing consolidation confining pressure () under isotropic consolidation. For given D r and the liquefaction resistance of saturated coral sand is higher than that of saturated siliceous sand. There is good correlation between ε v and the excess pore water pressure (u e) of sand before liquefaction. For a given consolidation stress with increasing maximum shear strain (γ max), ε v of saturated coral sand tends to stabilize at a value defined as the ultimate reconsolidation volumetric strain, which decreases with increasing D r. Also, ε v of saturated siliceous sand is less than that of saturated coral sand, and with increasing and D r, the measured ε v approaches the theoretical post-liquefaction maximum volumetric strain. Prediction models for ε v of saturated coral sand are developed based on the liquefaction level and γ max, respectively.

Resonant column and cyclic torsional shear tests on Sutlej river sand subjected to the seismicity of Himalayan and Shivalik hill ranges: A case study

The study of site-specific dynamic properties of soil holds vital importance in many geotechnical engineering problems for the region holding high active seismicity. The Sutlej River basin, a valley and high-risk seismic zone in the north-eastern part of the Punjab state, has been considered for the study. The site-specific shear modulus reduction curves and material damping ratio curves for a range of shear strain amplitudes have been developed under varying experimental conditions of confining pressure, relative density, and loading frequency using the resonant column (RC) tests and cyclic torsional shear (CTS) tests. The study addresses the usage of two testing approaches, i.e., resonant column test (RC) and cyclic torsional shear test (CTS), for the estimation of shear modulus and damping ratio values at varying shear strain amplitudes. The regression analysis has been performed for the two testing techniques viz. RC and CTS to study the sensitivity of shear modulus values and material damping ratio values towards varying experimental conditions. The shear modulus and damping ratio values determined from cyclic torsional shear tests were observed to have great dependency on the frequency of loading. The knowledge of site-specific dynamic properties will support practical interpretation for the geotechnical engineering problems in the region.

Softening and deformation characteristics of Tianjin soft soil under principal stress rotation induced by traffic loading

The vibration caused by moving traffic loading can create additional shear stress in the soil element, thereby resulting in the rotation of the principal stress axis, which can, in turn, accelerate soil softening and increase the cumulative deformation of soft clay. Nevertheless, the designed parameters are often obtained by the cyclic triaxial test (i.e., the rotation of the principal stress axis cannot be considered), or the cumulative axial plastic strain prediction is inaccurate, and these are some of the main reasons for geotechnical engineering problems. In this study, cyclic triaxial and cyclic torsional shear tests were performed to understand the softening and deformation characteristics of soft clay. The influences of the cyclic stress ratio, shear stress ratio, and loading frequency on the softening index and cumulative axial plastic strain of soft clay were analyzed. When the rotation of the principal stress axis was considered, the softening index decreased by 19.57%–51.09%, or the cumulative axial strain increased by 35.49%–74.39%, and failure occurred under higher cyclic stress ratios and shear stress ratios. Additionally, increasing the cyclic stress ratio and shear stress ratio and reducing the loading frequency will cause a surge in the softening index and cumulative axial plastic strain of soft clay. A cumulative axial plastic strain prediction equation considering the influences of cyclic stress ratio, shear stress ratio, and loading frequency was established and verified on the basis of literature. The availability of the prediction equation was verified by comparison with monitoring data. The relevant results can provide a theoretical reference for the prevention of urban engineering geological disasters.

Unprecedented liquefaction flow of gentle slopes containing non-plastic fines

In two recent earthquakes in Hokkaido, Japan, liquefied sand unusually flowed underground in very gentle man-made fill slopes, creating large ground surface depressions. In both cases, a significant amount of non-plastic fines was present in the loose fine sands. When tested in undrained triaxial tests, these sands were found far more contractive and easier to flow than the sand of the same density without fines. This strongly suggested that the high fines content was the major cause of the strange flow failures because it made the sand flowable on the contractive side of the steady-state line. Another series of cyclic torsional simple shear tests on contractive sands with fines under initial shear stress indicated that the flow failure can initiate even in a gentle slope. This is when the effective stress path comes across a straight yield line drawn from the origin on the τ − σc′ diagram uniquely defined irrespective of stress paths. A scenario to replicate the unusual flow failures was developed based on the field study and test results.

Liquefaction of sands subjected to principal stress rotation caused by generalized seismic loading

A comprehensive experimental study that quantifies the influence of coupled compression and shear wave loading on liquefaction susceptibility of sands is presented. Such loading is typical in situ, and leads to complex principal stress rotation, which in turn impacts the potential for liquefaction in soils even if the cyclic loading intensity remains constant. The nature and degree of principal stress rotation caused by this coupled loading are significantly influenced by the initial consolidation stress state, and the cyclic shear (ΔS), cyclic normal (ΔN) stress increments, the ratio ΔS/ΔN, and the phase shift (δ) between the waves. Cyclic hollow cylinder torsional shear tests were carried out on Fraser River sand specimens isotropically consolidated to different effective mean normal stress [Formula: see text] and subjected to coupled cyclic loading with representative ΔS/ΔN. For a given cyclic stress ratio (CSR) and initial [Formula: see text], the liquefaction resistance decreases with increasing s-wave intensity relative to p-wave intensity, which are proxies to stress increments ΔS and ΔN, respectively. Liquefaction resistance decreases with an increase in ΔS/ΔN up to a limiting value of about 2 beyond which increasing ΔS/ΔN does not significantly influence the cyclic resistance. The finding that cyclic resistance ratio [Formula: see text] decreases with increasing ΔS/ΔN is consistent with the understanding that the cyclic resistance is lower under simple shear loading mode compared to triaxial shear. Tests results also demonstrate that the liquefaction resistance of sand decreases with increasing initial effective confining stress regardless of the nature of the cyclic shear. This indicates that the correction Kσ factor (ratio of cyclic resistance at [Formula: see text] to resistance at [Formula: see text] = 100 kPa) can be considered even under generalized coupled loading conditions.

A modified pressure dependent multi-yield surface model for simulation of LEAP-Asia-2019 centrifuge experiments

A modified flow rule has been introduced into a pressure dependent multi-yield surface model for predicting the liquefaction of laboratory soil element tests and centrifuge experiments. The plastic potential function within the contractive phase in the flow rule of the constitutive model has been adjusted for better estimating the accumulation rate of plastic volumetric strain and the generation rate of excess pore water pressure. The modification of flow rule was mainly employed for achieving successful calibration of model parameters with the laboratory soil element tests and obtaining better predictions of the seismic response of LEAP-Asia-2019 centrifuge model tests. A calibration process of the constitutive model was firstly performed through numerical simulation of cyclic torsional shear tests of Ottawa F-65 sand samples with different relative densities under various cyclic stress ratios, and the estimation procedures of new parameters are provided. Then Type-B and Type-C numerical simulations were carried out for centrifuge experiments of a mildly sloping ground of Ottawa F-65 sand subjected to ramped sinusoidal input motions. The modified constitutive model could reasonably simulate the seismic response for almost all centrifuge model tests using the same set of model parameters.

Seismic microzonation in a complex volcano-tectonic setting: the case of northern and western Ischia Island (southern Italy)

On August 21, 2017, the volcanic island of Ischia was struck by a Mw 3.9 (http://cnt.rm.ingv.it/event/16796811) earthquake which caused two victims and heavy damages on wide portions of the Casamicciola Terme, Lacco Ameno and Forio municipalities.Following the Decree 1/2018 of the Government Commission for the reconstruction of damaged areas of Ischia Island, a Grade 3 Seismic Microzonation study was committed by each municipality to private consultants, who were scientifically supported by a multidisciplinary team of geologists, geophysicists and geotechnical engineers from CNR, INGV and University of Naples “Federico II”.The existing data from previous geological and geotechnical investigations were integrated with the results of new geo-lithological surveys and geophysical measurements (HVSR, MASW, Down hole tests) carried out by the consultants. The whole amount of data was quality checked, homogenized and collected in a SQLite/SpatiaLite geodatabase using a QGIS open source software by the support team.A geo-lithological map of northern and western sides of the island was then produced, and the results of routine geophysical tests were coupled with those of seismic 2D ambient vibration arrays, to obtain shear wave velocity profiles (several hundreds of meters deep) down to the seismic bedrock, made of lithic tuffs and lavas, and to define its buried morphology. This in turn enabled to draw a map of seismically homogeneous microzones of the entire study area. Cyclic torsional shear tests were carried out on 10 undisturbed soil samples, mainly taken from epiclastic cover deposits, to characterize their non-linear behavior to be adopted for seismic response analyses.These latter were carried out along 1D profiles characterizing each microzone and along selected 2D cross sections running from the Mount Epomeo to the coast. The dynamic analyses allowed to detect and map areas characterized by variable amplification factors, of spectral accelerations throughout different ranges of periods (0.1- 0.5s, 04.-0.8s, 0.7-1.1 s). The zones most prone to site amplification are those corresponding to localized graben-like depressions at the toe of Mount Epomeo, such as Maio neighborhood of Casamicciola, where thickened epiclastic covers are entrenched into blocks of uplifted bedrock and where a combination of 1D stratigraphic amplification and 2D reflection and diffraction effects is expected.

Evaluation of post-liquefaction volumetric strain of reconstituted samples based on soil compressibility

In this study, we performed undrained cyclic–torsional–shear tests on clean and silty sands to examine post-liquefaction volumetric strain. Accordingly, we proposed a novel density index—ultimate volumetric strain—to evaluate the density of clean sand and silty soils; the proposed density index is based on soil compressibility. We discussed the test results with respect to relative density, skeleton void ratio, and ultimate volumetric strain. Consequently, we confirmed that ultimate volumetric strain showed good correlation with post-liquefaction volumetric strain irrespective of soil type, whereas values for relative density and skeleton void ratio were discordant. Further, we observed that, compared to maximum shear strain, accumulated shear strain was a better index for representing the effect of loading history. From these results therefore, we proposed a chart to evaluate post-liquefaction volumetric strain based on ultimate volumetric strain and accumulated shear strain.

Deformation Behavior of Saturated Soft Clay under Cyclic Loading with Principal Stress Rotation

Under long-term traffic loading, the soil elements in subgrade are subjected to continuous principal stress rotation. In order to study the deformation properties of soft clays under traffic loading with principal stress rotation, a series of cyclic torsional shear tests were conducted on Wenzhou soft clays under different torsional cyclic stress ratios and degrees of principal stress rotation. The test results showed the stiffness softening of soil under long-term traffic loading. In addition, the principal stress rotation induced by traffic loading aggravated the deformation of clay samples and pore pressure accumulation. A modified dynamic pore pressure model was applied to consider the effect of principal stress rotation on undrained cumulative pore pressure, predicting the growth of cumulative pore pressure at different cycles. Considering loading cycles and the principal stress rotation, a modified Hardin–Drnevich (H-D) backbone curve model under traffic loading with principal stress rotation was proposed, and the predictive values of this model agreed well with the experimental values. Compared with the traditional H–D model, this model better reflects the cyclic deformation of soft clays under long-term traffic loading with principal stress rotation.

Numerical study of random material properties within a soil specimen

Material properties derived from laboratory soil tests often assume that the property is uniform throughout the specimen. For some exceptional soils, this may hold true, but for many others it is obviously false. We have been performing cyclic and irregular torsional simple shear (TOSS) tests on hollow cylinder samples for decades and were intrigued by the idea of how to model inherently non-uniform specimens. As an added corollary, we wanted to understand the influence of imperfections (voids, inclusions) on the measured stress-strain behaviour in these tests. This paper examines two general classes of problems: (a) uniform specimens with inclusions of voids or imperfections, and (b) non-uniform specimens with random distributions of material properties within the specimen. Finite element modelling was performed on a TOSS specimen (ID = 4cm, OD = 6cm, L = 14cm) using a set of over 500 different elastoplastic material properties within the specimen. Various distributions (Normal, Log-normal, Bimodal) of stiffness and strength properties were examined. The results were examined as torque vs. twist curves since those values are typically measured in the TOSS laboratory test before being converted (with assumptions of uniformity) to shear stress-shear strain hysteresis. The Bimodal distributions were used to represent soils with distinct hard and soft zones. Additionally, distributions with some degree of spatial correlation were also examined.

Cyclic strength of loose anisotropically-consolidated calcareous sand under standing waves and assessment using the unified cyclic stress ratio

Progressive and standing waves can produce instability of the seabed and seabed-supported marine structures. In this paper, the stress paths induced by standing waves were deduced to provide a theoretical basis for laboratory element tests to establish the cyclic behavior of marine sediments, which can serve to improve the understanding of seabed liquefaction triggering and its consequences. The cyclic response of loose, isotropically- and anisotropically-consolidated (IC and AC, respectively) calcareous sand under the stress paths derived for standing waves was examined using hollow cylinder torsional shear (HCTS) tests. The stress paths corresponding to standing waves are a vertical line, horizontal line, and ellipse, in a coordinate system consisting of the axial stress difference and the horizontal shear stress, for a soil element located at the nodes, antinodes, and intermediate horizontal positions, respectively. The phase difference, θ, between axial stress difference and horizontal shear stress appears to range from −45° ~ 7° for wave and seabed characteristics representative of the North Sea. The ratio of axial stress difference and horizontal shear stress amplitudes, λ, varies in the real number field. The experimental results indicated that the failure modes of IC and AC specimens are cyclic mobility and residual deformation failure, respectively, irrespective of the stress paths imposed. With the same consolidation state and cyclic stress ratio, CSR, the number of cycles to failure, Nf, is strongly affected by θ and λ. The unified cyclic stress ratio, USR, is proposed to establish a single USR-Nf curve that can suitably describe the general cyclic strength of the calcareous sand specimens under different stress paths for a given consolidation stress ratio. The proposed USR enables estimation of the cyclic strength of IC and AC soils under complex stress paths based on the CSR-Nf curve obtained from conventional cyclic torsional shear or triaxial tests.

Deformation and cyclic resistance of sand in large-strain undrained torsional shear tests with initial static shear stress

This paper presents the findings from an experimental study focusing on the undrained cyclic behavior of sand in the presence of initial static shear stress. A series of undrained cyclic torsional shear tests was performed on saturated air-pluviated Toyoura sand specimens up to single amplitude shear strain (γSA) exceeding 50%. Two types of cyclic loading conditions, namely, stress reversal (SR) and stress non-reversal (SNR), were employed by changing the amplitude of the combined initial static shear and cyclic shear stresses. The tests covered a broad range of initial states in terms of relative density (Dr = 20–74%) and the initial static shear stress ratio (α = 0–0.30). The following five distinct modes of deformation were identified from the tests based on the density state, the transient undrained peak shear stress, and the combined cyclic and static shear stresses: 1) static liquefaction, 2) cyclic liquefaction, 3) cyclic mobility, 4) shear deformation failure, and 5) limited deformation. Of these, cyclic liquefaction and static liquefaction are the most critical. They occur in very loose sand (Dr ≤ 24%) under SR and SNR, respectively, and are characterized by abrupt flow-type shear deformation. Cyclic mobility occurs under SR in loose to dense sand with Dr ≥ 24%. Contrarily, shear deformation failure typically occurs under SNR in sand with 24 < Dr < 65%, and limited deformation may take place in dense sand with Dr ≥ 65%. In this paper, a stress-void ratio-based predictive method is proposed to identify the likely mode of deformation/failure in sand under undrained shear loading with static shear. Furthermore, the cyclic resistance is evaluated at three different levels of γSA (i.e., small, γSA = 3%; moderate, γSA = 7.5%; and large, γSA = 20%). The results show that, independent of the density state, the cyclic resistance continuously decreases with an increase in α at the small γSA level, while it first decreases and then increases for both loose and dense sand at the moderate and large γSA levels.