1,036 research outputs found
The Pursuit of the Source, or The Inevitability of Death
The purpose of this article is to apply the method of the genre of studying chains of references to an instance of a secondary source of the contested concept of âresistance to changeâ back to the primary source and thereby exercise criticism of the sources. This includes discussing whether the theory itself is empirically sustainable or sufficiently scientifically grounded. In the article, we adopt a theoretical lens of Critical Realist Discourse Analysis, mainly because it is sensitive to the importance of the influence of nondiscursive social positions on discourses. The primary source of the chain of theories of resistance to change turns out to be KĂŒbler-Rossâs model of stages of dying patientsâ reactions to their immanent death. We find that the model is systematically mis-interpreted to fit the empirically false idea of resistance to change of the ideological discourses of management research.publishedVersio
Permanent Sheet Pile Wall in Soft Sensitive Clay
Reports on the serviceability stage and long-term performance of embedded retaining structures are scarce, even more so in areas with background settlements. This paper presents a case study of an excavation with a permanent sheet pile wall in soft sensitive clay in Uppsala, Sweden. The monitoring data span the short-term and four years of the serviceability stage. The monitoring data are compared with finite element analyses using the rate-dependent Creep-SClay1S model. A historic groundwater drawdown is accounted for in the modeling and challenges with respect to the proper initialization of the in situ stress state, preconsolidation pressure, fabric, and bonding are discussed. The results show that even though the background settlements are somewhat underpredicted, the horizontal displacements as well as anchor forces were captured rather accurately. This valuable case study of the short- and long-term behavior of a permanent sheet pile wall in soft sensitive clay confirms the performance of using this cost-effective solution for a permanent construction. Furthermore, the paper highlights the challenges of an accurate description and modeling of the initial in situ state
Impact of installation on the recovery of the bearing capacity of displacement piles in sensitive clay
Deep foundations are essential for the soft soil deposits that are ubiquitous in the Nordic countries. Precast driven displacement piles are commonly used, due to the ease of installation and their low cost. The stiffness and strength of the clay surrounding the piles will change during and after the pile installation process. This paper presents an effective stress based numerical framework that elaborates the pile set-up and pile ageing mechanisms observed empirically. For the trial case studied, it is demonstrated that the magnitude of the increase in axial bearing capacity over time is strongly linked to the pile installation stage. Furthermore, it is found that classic effective stress based soil mechanics concepts readily describe the observed behaviour
Modelling of undrained shearing of soft natural clays
stress-strain response of soft natural clays is characterised by anisotropy, destructuration and rate-dependency. An accurate constitutive description of these materials should take into consideration all of the characteristics above. In this paper, two constitutive models for soft soils, namely the SCLAY1S and Creep-SCLAY1S models are used to simulate the undrained response of two soft natural clays, Gothenburg clay from Sweden and Otaniemi clay from Finland. The SCLAY1S model accounts for the effect of inherent and induced anisotropy and destructuration, while the Creep-SCLAY1S accounts also for the creep and rate effects. The model simulations are compared against triaxial compression and extension tests on anisotropically consolidated samples. The results demonstrate the need to incorporate all features represented in the Creep-SCLAY1S model when modelling structured natural clays
Modeling Aging of Displacement Piles in Natural Soft Clay
A multitude of mechanisms will affect the evolution of the pile response over time, each with their respective time scale. It is shown that most of the processes can be linked to the pile installation stage, which alters the soil surrounding the pile. As a result, there is a change in the mechanical properties of the soil that will influence the subsequent pile response over time. These long-term mechanisms include the dissipation of excess pore pressures from pile installation and the creep in the soil. This paper presents a numerical approach that combines the strain-path method, an advanced effective stress-based constitutive model for soft soils, and a multiphase numerical framework that enables the modeling of the pile installation and subsequent change of pile bearing capacity over time. The presented results demonstrate that the degree of remolding of the soil during the pile installation stage is closely linked to the subsequent pile response. For the Ons\uf8y test case studied, the increase in shaft capacity over time, demonstrated to be linked to undrained strength recovery, could be faithfully reproduced during and after dissipation of excess pore pressures. Hence, pile aging of displacement piles installed in clay is strongly linked to installation effects and the creep and relaxation processes in the soil. Further study is required to fully reveal the physicochemical mechanisms that underpin these processes
The Noble Art of Procrastination : Writer\u27s Block as a Motif in Watakushi ShĆsetsu"
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Standard Error of Empirical Bayes Estimate in NONMEMÂź VI.
The pharmacokinetics/pharmacodynamics analysis software NONMEMÂź output provides model parameter estimates and associated standard errors. However, the standard error of empirical Bayes estimates of inter-subject variability is not available. A simple and direct method for estimating standard error of the empirical Bayes estimates of inter-subject variability using the NONMEMÂź VI internal matrix POSTV is developed and applied to several pharmacokinetic models using intensively or sparsely sampled data for demonstration and to evaluate performance. The computed standard error is in general similar to the results from other post-processing methods and the degree of difference, if any, depends on the employed estimation options
Modeling of wide-band MIMO radio channels based on NLoS indoor measurements
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Simulation of CPT penetration in sensitive clay
This paper presents the results from numerical simulations of CPTu penetration in a natural clay combining the SCLAY1S constitutive model with a large deformation Finite Element framework including a coupled deformation and porewater pressure formulation. The hierarchical model formulation of SCLAY1S captures many features of a natural sensitive clay, such as the evolving anisotropic strength-stiffness response, as well as the degradation of the initial bonding. A sensitivity analysis is performed varying the overconsolidation ratio (QCR), bonding and anisotropy, also the hydraulic conductivity (hence, cv) of the clay. The findings indicate that some soil properties (the cv and OCR) impact both the normalised cone resistance Qt and the generation of excess porewater pressures. In contrast the sensitivity St of soft soils primarily affects Qt. In the current work it seems that the effects of the inherent and stress induced (from CPT penetration) anisotropy is not detected using these normalised plots
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