Unified Solution To Drained Expansion Of A Spherical Cavity In Clay And Sand

This paper presents a novel unified solution to drained expansion of a spherical cavity in both clay and sand. The large-strain theory and a critical state model with a unified hardening parameter are used to describe the elastoplastic behavior of the soils after yielding. The elastoplastic constitutive tensor of the critical state model is developed to be a system of first-order differential equations for the drained expansion of a spherical cavity. The problem is formulated as an initial value problem in terms of the Lagrangian scheme by introducing an auxiliary variable and is solved numerically. With the present solution, curves for the expansion pressures, the distributions of stress components, and the stress paths are plotted to illustrate the different expansion responses in clay and sand. The proposed solution not only incorporates the dilatancy and peak strength of dense sand, but it can also reduce to the solution for clay and loose sand when ignoring the dilatancy and peak strength. Therefore, the present solution can be applied to interpret the cone penetration test and the pile installation, as well as to evaluate the pile end bearing capacity in various kinds of soils

Analysis Of Time-dependent Bearing Capacity Of A Driven Pile In Clayey Soils By Total Stress Method

This paper proposes an analytical approach to evaluate the time-dependent bearing capacity of a driven pile in clayey soils by taking the pile installation and subsequent reconsolidation effects into consideration. The process of pile installation is modeled by undrained expansion of a spherical cavity at the pile tip and a cylindrical cavity around the pile shaft. The cavity expansion solution, which is based on a K0-consolidated anisotropic modified Cam-clay model (K0-AMCC), is used to capture the pile installation effects. After pile installation, the dissipation of the excess pore water and the increase of the effective stress in the surrounding soil are evaluated by the radial consolidation theory. Based on the effective stress, the strength of the remolded soil is quantified by the modified Cam-clay (MCC) model and the spatially mobilized plane (SMP) criterion. With the three-dimensional strength of the surrounding soil, the time-dependent bearing capacity of the driven pile is evaluated by the total stress (α) method. To verify the proposed analytical approach, three groups of centrifuge model tests were performed, and the proposed approach was applied to predict the time-dependent bearing capacity of the tested piles. It is shown that reasonable predictions can be made by the method proposed in this paper

A Feasible Approach To Predicting Time-dependent Bearing Performance Of Jacked Piles From CPTu Measurements

In this paper, a simple but feasible approach is proposed to predict the time-dependent load carrying behaviors of jacked piles from CPTu measurements. The corrected cone resistance, which considers the unequal area of the cone rod and the cone, is used to determine the soil parameters used in the proposed approach. The pile installation effects on the changes in the stress state of the surrounding soil are assessed by an analytical solution to undrained expansion of a cylindrical cavity in K0-consolidated anisotropic clayey soil. Considering the similarity and scale effects between the piezocone and the pile, the CPTu measurements are properly incorporated in the shaft and end resistance factors as well as in the load-transfer curves to predict the time-dependent load carrying behaviors of the pile. Centrifuge model tests are conducted and the measured load carrying behaviors of the model piles are compared with the predictions to validate the proposed approach. The proposed approach not only greatly saves the time of conducting time-consuming pile load tests, but also effectively avoids solving the complex partial differential equations involved in the consolidation analysis, and hence is feasible enough to determine the time-dependent load carrying behaviors of jacked piles in clay

Genetic Drivers of Heterogeneity in Type 2 Diabetes Pathophysiology

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P \u3c 5 × 10-8) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores5 in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care