Géotechnique Letters
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Géotechnique Letters provides a vehicle for the rapid international dissemination of the latest and most innovative geotechnical research and practice. As an online journal, it is aimed at publishing short papers within eight weeks of submission, intending to foster the quick exchange of the latest advances and most current ideas without the delays imposed by printed journals, whilst still maintaining rigorous peer reviewing standards. Paper are limited to 2000 words (main text only, excluding article title, 200-word abstract, figures, tables, figure captions and references).
- - 2012 average time to first peer review decision 28.4 consecutive days. Papers published from 16 countries and six continents.
- - Join the journal's Group on LinkedIn here.
- - To submit an article, write for us or read our policy on Open Access click on More details below and then Publish with Us.
- - Read inaugural themed issue: Geomechanics across the scales, Volume 2, October, 2012
Featured image of the month: Figure 5 from CIL and ALSHIBLI 2012. SMT of laboratory-size compression tests and DEM images of column of three particles.
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Compaction evolution observed via the HVSR of microtremors
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The non-invasive measurement of horizontal to vertical spectral ratio (HVSR) of microtremors is proposed as a means to evaluate field compaction. The HVSR technique is a surface wave method that is quite distinct from the class of array-based surface wave techniques. This is because the basis of the former is the recording and fitting of the HVSR of microtremors, while the latter relies on the recording and fitting of the surface wave velocity dispersion curves of ground vibrations. This paper presents a controlled study of the evolution of compaction, showing it is possible to identify levels of field compaction by observing changes in HVSR data. The results from this study suggest that the fast and operationally simple HVSR technique could be used to assess near-surface ground compaction. It is further envisaged that the technique could be applied to ‘cover the gaps’ left from traditional and expensive invasive techniques (e.g. cone penetration test, standard penetration test, dilatometer test, etc.), particularly for extensive and deep-filled areas such as would occur in dynamically compacted sites.
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Discussion: 3D assessment of fracture of sand particles using discrete element method- + Show Description- Hide Description
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Discussion: Laboratory measurement of strength mobilisation in kaolin: link to stress history
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Editorial
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Disintegration energy of sensitive clays
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The accurate assessment or prediction of landslides in sensitive clays is not a straightforward task due to the complexity associated with understanding such material during the sliding process. There have, however, been several attempts to assess flow slide potentials by looking at certain aspects of sensitive clays, one of which is studying the energy involved in the disintegration of sensitive clays from an intact to a remoulded state. This energy is referred to as disintegration energy (DE). Here, an analytical approach is proposed to evaluate the DE of sensitive clays based on an integrated study of strength and stiffness properties of sensitive clays in intact and remoulded states. The proposed approach is illustrated by studying the DE involved in Norwegian landslides. In addition, the proposed equation is shown to be in line with an equation used for Canadian sensitive clays. Furthermore, this article attempts to illustrate that the extent of flow slides is related to the DE involved in sensitive clays using five selected Norwegian landslides. The study shows that the amount of required DE can be used to estimate the extent of landslides in soft sensitive clays.
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Cyclic shear response of fibre-reinforced cemented paste backfill
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In order to investigate techniques to improve tailings backfill stability in stopes, the cyclic shear response of fibre-reinforced cemented mine tailings was studied. Cyclic simple shear tests were conducted on fibre-reinforced and non-reinforced cemented mine tailings. The tailings, produced from gold mining, are classified as sandy silt with traces of clay. Portland cement (5%) and polypropylene fibres (zero and 0·5%) were added to the material. Under monotonic shear conditions, the addition of fibres confers hardening behaviour to the cemented material. Under shear strain controlled cyclic conditions, fibres increased the shear stress values of the cemented samples after successive load cycles. The agreement of the strength envelopes of both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analysed under different loading conditions.
Most viewed this month in this journal:
- Undrained vertical bearing capacity factors for shallow foundations
- The undrained vertical bearing capacity of a shallow foundation is a fundamental problem in geotechnics. Bearing capacity factors based on analytical and numerical methods have been published for strip and circular, surface and shallowly embedded foundations, with rough and smooth foundation–soil interfaces in soils with uniform and linearly increasing shear strength profiles – although not comprehensively for all combinations. Furthermore, in the case of limit analysis solutions, considerable disparity can exist between upper and lower bound solutions for some foundation and soil conditions. This letter presents a coherent set of bearing capacity factors based on finite element and finite-element limit analysis, for strip and circular shallow foundations across a practical range of foundation embedment ratio, foundation–soil interface roughness and soil shear strength heterogeneity.
- Stability criteria for unsaturated shallow slopes
- This letter focuses on the mechanical conditions governing the initiation of landslides in unsaturated shallow slopes. The goal is to provide mathematical criteria for predicting the onset of slope instabilities and capturing the interplay between saturation conditions and shear failure. For this purpose, the standard scheme of infinite slope is used and the mechanical response of the deposit is represented through simple shear kinematics. This assumption enables the study of different perturbation scenarios using a modelling strategy that: (i) incorporates the constraints describing the interaction with the pore fluids into the control conditions and (ii) allows the analytical derivation of stability indices for each scenario. The theoretical results show that, in unsaturated slopes, the coupling between the solid skeleton and the pore fluid can exacerbate the tendency to undergo mechanical instabilities. This general aspect is clearly disclosed by the analytical expression of the stability index for water-undrained shearing. It is found that, because of hydro-mechanical coupling, the failure mode originated by these perturbations embodies some characteristics of both shear localisation and static liquefaction. As a result, depending on soil properties and initial conditions, the unstable response resulting from its activation can resemble either phenomena and predictive models are necessary to distinguish between the two scenarios.
- Simple method for correcting dynamic cone penetration test results for rod friction
- This letter presents a simple method for evaluating the effect of rod skin friction on dynamic cone penetration test results in cohesive soils. The proposed method is simple and requires neither additional equipment nor special test procedures, and thus represents an improvement on existing dynamic probing practice. In a field trial, the proposed approach was shown to work well when compared with the results of a special dynamic cone test where a casing was used to reduce the effect of rod skin friction. However, more field tests at different ground conditions are required to fully confirm the validity of the proposed approach.
- Compression and shear wave propagation in cemented-sand specimens
- Ultrasonic and bender element tests in the laboratory are typically used to measure elastic modulus and damping ratio. However, interpretation of the results is challenging for a variety of reasons, including the influence of experimental details, geometrical effects and the analytical techniques used for data processing. It is therefore convenient to cross-check results by performing several independent measurements. Three different types of measurements were performed on cemented-sand specimens. Longitudinal waves or constrained compressional waves in a cylindrical specimen were generated in a high-frequency range (20–70 kHz) using a newly designed transducer interface. Full dynamic characterisation was made possible by independent measurement of the transducer response. Pure unconstrained compressional waves or simply compression waves were measured in the same specimens with high-frequency transducers. The shear modulus was computed and used to predict the arrival of shear waves on independent bender element measurements. The predicted arrival was close to first-break estimates, and bender measurements were therefore confidently employed to track cement curing effects on a different set of specimens. The specimen frequency response function obtained from the longitudinal wave measurements was examined in detail and damping ratios were estimated for the compression vibration modes in a rod.
- Compaction evolution observed via the HVSR of microtremors
- The non-invasive measurement of horizontal to vertical spectral ratio (HVSR) of microtremors is proposed as a means to evaluate field compaction. The HVSR technique is a surface wave method that is quite distinct from the class of array-based surface wave techniques. This is because the basis of the former is the recording and fitting of the HVSR of microtremors, while the latter relies on the recording and fitting of the surface wave velocity dispersion curves of ground vibrations. This paper presents a controlled study of the evolution of compaction, showing it is possible to identify levels of field compaction by observing changes in HVSR data. The results from this study suggest that the fast and operationally simple HVSR technique could be used to assess near-surface ground compaction. It is further envisaged that the technique could be applied to ‘cover the gaps’ left from traditional and expensive invasive techniques (e.g. cone penetration test, standard penetration test, dilatometer test, etc.), particularly for extensive and deep-filled areas such as would occur in dynamically compacted sites.
