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The undrained shear strength of contractive fine-grained soils changes with time, reducing due to pore pressure generation and increasing during consolidation. There is an increasing appetite to recognise these temporal soil strength changes in offshore geotechnical design, as it provides a basis for potentially less conservative designs. Contributions to this endeavour are reported across two companion papers. This first paper extends an existing effective stress framework that relates the generation of pore pressure to accumulated plastic shear strain, allowing undrained shear strength to be calculated within the context of critical-state soil mechanics. The main development is the extension of the computational domain to two dimensions, allowing calculations to be made for boundary value problems that cannot be satisfactorily simplified to one-dimensional conditions. The magnitude and distribution of accumulated shear strain surrounding objects buried in soil are quantified through a series of large deformation finite element analyses. These spatial distributions are described using a strain influence function in the new 2D framework to calculate the extent and magnitude of excess pore pressure, and in turn the mobilised soil strength around the buried object. The performance of the 2D framework is examined in the companion paper through retrospective simulations of experimental and numerical data. [ABSTRACT FROM AUTHOR]

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Plate anchors are an attractive technology for mooring floating facilities; as relative to piles, suction caissons, and drag anchors, they provide a much higher capacity relative to their mass. Plate anchors may experience an extreme loading event that will cause geotechnical failure, although they will still retain a residual capacity. The displacement associated with bringing the anchor to failure will induce excess pore pressures that initially reduce soil strength but will dissipate over time, leading to regains in soil strength and hence anchor capacity. This paper considers the time scales and magnitude of this anchor capacity regain through a series of model scale experiments conducted in a geotechnical centrifuge. The experiments involved vertical loading of pre-embedded horizontally orientated circular anchors in normally consolidated kaolin clay. The results show that anchor capacity regain is a function of consolidation time and the level of resistance maintained on the anchor, with the longest consolidation time and highest maintained resistance leading to a capacity regain of approximately 60%. These capacity increases are described here using a simple hyperbolic function, which provides a basis for estimating the time needed for the residual anchor capacity to regain sufficient capacity following a movement event. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Assessing foundation response to cyclic loading is vital when designing transport infrastructure, such as road pavements and rail tracks, as well as offshore, port, and tall tower structures. While detailed guidance is available on characterizing many soil types' cyclic behavior, relatively few studies have been reported on stiff, geologically aged, plastic clays. This paper addresses this gap in knowledge by reporting cyclic loading experiments on three natural stiff UK clays that were deposited and buried between the Jurassic Age and Eocene Epoch before geological unloading to their currently heavily over-consolidated states. High-quality samples taken at relatively shallow depths were reconsolidated to nominally in situ K0 stresses in triaxial and hollow cylinder apparatus before imposing cyclic loading. The completely stable, metastable, or unstable outcomes invoked by different levels of undrained cyclic loading are interpreted within a kinematic yielding framework that is compatible with monotonic control experiments' outcomes. The cyclic limits marking the onset of significant changes in permanent strain accumulation, pore pressure development, and stress–strain hysteresis demonstrate that the weathered Gault clay offers the lowest cyclic resistance. The experiments show that energy considerations provide a promising way of evaluating undrained pore pressure generation and stiffness degradation. They also provide a basis for developing cyclic constitutive models and analysis procedures for cyclic foundation design in stiff, high-OCR, plastic clay strata. [ABSTRACT FROM AUTHOR]

The p–y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p–y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress–strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load–displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of cyclic nonsymmetrical thermally loaded model-scale tests conducted on floating pile groups, with and without a rigid cap in saturated clay. The energy pile in each group was subjected to 10 two-way (heating–cooling) thermal cycles with an amplitude of 15 °C to investigate the potential effects of a rigid cap on the thermomechanical behavior of energy pile groups. It was found that the rigid cap restrained the expansion/contraction of the energy pile in response to temperature change and reduced its irreversible settlement, resulting in a lower differential settlement between the energy and nonenergy piles. Consequently, a lower tilting was observed in the pile group with a rigid cap. In addition, the thermally induced axial load was significantly increased (especially in cooling mode) due to the restriction of a rigid cap. The thermomechanical load transfer profile of the energy pile was also affected by it, resulting in the downward transmission of shaft resistance. [ABSTRACT FROM AUTHOR]

The main objective of this paper is investigation of clayey soil setup effects on axial "resistance" and "stiffness" of small-scale piles with special attention on "overconsolidation ratio" (OCR) and "installation method". A consolidation chamber is developed and an instrumented model pile is either driven or jacked-in through saturated consolidated Kaolinite clay at different OCRs of 1.2 (normally consolidated, NC) and 4.8 (over consolidated, OC). The pile was static load tested at different time intervals of 1 h through 90 days. Higher pore pressures are induced during pile installation in NC compared to OC clay. The frictional resistance of OC soil is higher than NC at end of drive as well as end of setup in both driven and jacked-in piles. The frictional resistance of jacked-in piles is greater than driven piles at end of drive, but due to higher rate of setup, the long-term frictional resistance of driven piles is shown to be greater, attributed to more disturbance of the soil during installation of driven piles. Attempts are made to differentiate between the contributions of dissipation of excess pore pressure and non-pore pressure components for each consolidation condition and pile installation method. A relation is proposed to quantify the pile stiffness variations over time due to soil setup. [ABSTRACT FROM AUTHOR]

This note presents the application of the mobilisable strength design (MSD) method to the monitoring results of the multi-propped excavation in the south area of the British Library Euston, constructed in a highly overconsolidated stiff clay deposit. The MSD method is an energy-based approach (a nonlinear finite-element method for a single-degree-of-freedom soil-wall system) introduced to develop a simplified design methodology that satisfies both ultimate and serviceability limit states. Wall displacement predictions based on the MSD method are compared with considerable field monitoring data. The sensitivity of the method to reasonable variations in input parameters is considered. A spreadsheet and python code demonstrating the MSD analysis from this paper are provided in the online supplement alongside details of the mathematical formulation. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a unified critical state parameter model for evaluating sand and overconsolidated clay, which is named as CASM-S. The model is formulated in terms of the modification of the clay and sand model, i.e., CASM, by incorporating the subloading surface theory with an overconsolidation state parameter R. Although the standard CASM proves to be useful in modelling overconsolidated clay and sand, the model (1) requires the rate of overconsolidated ratio to be constant which is in contrast to the observed behaviour of soils and (2) only allows elastic deformation to develop at the overconsolidated state that may underestimate the deformation corresponding to the peak stress or be unable to predict the actual stress path. By introducing a new material parameter u to those material properties of the standard CASM, the rate relationship of stress–strain for the CASM-S model is developed. The standard CASM can be either recovered or approximated as a special case of the overconsolidation state assumed in the CASM-S. The numerical integration of the newly proposed model is performed by the modified forward Euler method. Validation with undrained and drained overconsolidated clay and sand have demonstrated the capability of the CASM-S model to well predict the observed soil behaviours. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tunnel face stability is critical for tunneling safety, especially in constructing a tunnel adjacent to another. In tunnel construction, if there is an adjacent existing tunnel and the active failure of the tunnel face happens, there will be severe consequences. Therefore, the active stability of shield tunnel face should be studied considering existing tunnels nearby. In this work, a series of transparent clay model tests were conducted to investigate the active stability of a shield tunnel face adjacent to an existing tunnel based on the development process, failure mode, influence range and support force. In addition, discrete element method was used to study the shield tunnel face stability under various conditions. The role of existing tunnels on the shield tunnel face stability was discussed. The failure mode of the shield tunnel face is an overall failure mode and similar to a wedge shape and ladder shape along the longitudinal and transverse section, respectively. The critical support force ratio is approximately 4.5%. The relative vertical and horizontal distance have significant influences on failure mode, while the influence of burial depth and overlapping angles are not significant. [ABSTRACT FROM AUTHOR]

This study investigated a new predictive model of the shear modulus reduction ( G G max − Log (γ c)) and damping ratio (ξ − Log (γc)) curves for sensitive eastern Canada clays. The model was established based on experimental measurements of G G max and ξ performed on 69 sensitive clay specimens from eastern Canada. The compiled database was first analyzed to qualitatively assess the influences of different soil parameters on the measurements. Next, statistical analyses using regression analysis and the modified hyperbolic model were performed. It was found that the G G max and ξ values of sensitive eastern Canada clays were influenced mainly by the plasticity index (Ip), mean effective stress (σ m ′) , and structure, which was quantified by the liquidity index (IL). Based on the statistical analysis performed, new equations for G G max and ξ were proposed. The newly proposed model was compared with previously published models. The comparison clearly showed that the proposed model was more representative of sensitive eastern Canada clays. Consequently, it is suggested that the proposed model is more appropriate for use in the dynamic analysis of sensitive eastern Canada clay deposits as well as other similar soils. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)