The effects of unloading on undrained deformation of a kaolin clay under cyclic loading

Li, Yong; Xue, Jianfeng; Yaghoubi, Mohammadjavad

doi:10.1016/j.soildyn.2020.106434

Cited by 12 publications

(6 citation statements)

References 31 publications

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“…7a. In addition, the exponential relationship supports the claims by Liu et al [16] that, the enlargement of axial strain and EPWP accumulation after including stress disturbance between loading cycles is attributed to the increase of static deviatoric stress ratio (q/p 0 ) and soil's ability in memorizing the previous loading history, as the soil's ability in memorizing the previous loading history increases with the increase of static deviatoric stress.…”

Section: Increase Static Deviatoric Stresssupporting

confidence: 85%

“…Table 2 illustrates the axial strain and EPWP developed in each loading stage. For consistency, the axial strains due to monotonic stress disturbances are excluded from the accumulated strains in all the analyses as recommended by Liu et al [16].…”

Section: Resultsmentioning

confidence: 99%

“…The samples were isotropically consolidated under the effective confining pressure of 100 kPa, followed by anisotropic consolidation to the deviatoric stress of 25 kPa. As recommended by Liu et al [16], a few pieces of filter paper strips were put along the sides of samples to accelerate the saturation and consolidation process. Consolidation duration was kept long enough to allow the full dissipation of excess pore water pressures in all samples.…”

Section: Sample Preparationmentioning

confidence: 99%

“…As recommended by Liu et al [16], after including the stress disturbances into the samples, the static deviatoric stresses were held for about 10 min to allow the stabilization of induced EPWP before applying subsequent bundle of loading cycles. Due to the low permeability of kaolin clay, the drainage valves were closed during all loading stages to simulate an undrained condition.…”

Section: Test Programmentioning

confidence: 99%

“…There are very limited studies on the effects of including stress disturbance between loading cycles on the long-term deformation behaviour of soft clay. Liu et al [16] considered the effects of unloading lateral stress between loading cycles on the deformation of a kaolin clay. The authors reported that including lateral unloading increases the strain accumulation and the greater the reduction in lateral stress, the greater the strain accumulation during the subsequent loading cycles.…”

Section: Introductionmentioning

confidence: 99%

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The impact of stress disturbance on undrained cyclic behaviour of a kaolin clay and settlement of tunnels under cyclic loading

Xue

Mei

2021

Acta Geotech.

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The excavation of a pit or tunnel induces stress disturbances in soils under different stress paths. The cyclic deformation behaviour of soft clay would be affected by the induced stress disturbances. A series of undrained cyclic triaxial tests were performed on a normally consolidated kaolin clay. The stress disturbance was simulated by changing the radial and axial stresses between loading cycles under different stress paths. The effects of stress disturbance schemes on the axial strain and excess pore water pressure accumulation in the clay were presented and discussed. The results indicate that for the samples experiencing stress disturbance with no change in static deviatoric stress, during the subsequent bundle of loading cycles, the axial strain and excess pore water pressure accumulate slightly in the early few cycles and then roughly follow the accumulation tendency similar to that of the sample under continuous cyclic loading. If the static deviatoric stress reduces, after including stress disturbance, axial strain and excess pore water pressure accumulate slightly in the early few cycles and keep almost constant afterwards, regardless of stress disturbance schemes. The accumulation rates of axial strain and excess pore water pressure during the subsequent loading cycles increase if positive static deviatoric stress is induced, and the greater the induced additional static deviatoric stress, the greater the strain accumulation. The axial strain accumulation is governed by static deviatoric stress ratio (q/p 0 ), and independent to stress disturbance schemes. Based on the variation of axial strain accumulation under different stress disturbance schemes, two examples are presented to explain the impact of nearby excavations to the long-term deformation of existing tunnels under cyclic loading.

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Section: Increase Static Deviatoric Stresssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

Section: Test Programmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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