Case Histories of Foundations With Stone Columns

The paper presents case histories of performance of foundations where stone columns were provided, along with relevant data regarding structural systems, soil conditions, construction methods and field control criteria. A wide range of applications are included comprising stone columns for area treatment and stone column in small and large groups for isolated footings, pipe pedestals and bridge abutments. In some of the cases design load exceeded the estimated yield load over a part of the stone column length yet collapse did not occur because the soil stress around the stone column increased as more load was passed on to the soil when yield stress was exceeded. There was also the benefit of drainage afforded by the stone columns. Load test data are furnished to substantiate the design approach which takes into consideration the strengthening of the soil annulus around the stone column resulting from compaction and subsequent consolidation

Ground Versus Soil: A New Paradigm in Geotechnical Engineering Education

me of the practitioners of geotechnical engineering tend to confuse Ground with Soil. It is not just semantics but the terms have d eeper technical and philosophical implications. Soi l is a material which can be handled, felt, seen, sme lt, tasted, and tested in small to medium size samples while ‘Ground’ is an entity that exists in- situ. Just as the adage, ‘The total is more than th e sum of the individual parts’, predicting the behavi or of ground from the so-called properties measured on samples collected from the field is muc h more complex and involves judgment. Ground is an intricate natural entity very similar to ‘Humans’ and exhibits behavioral responses rather than merely possess properties like other en gineering materials. Humans have organs and traits such as being jovial, sad, friendly, angry, misanthropic, etc. but do not have properties. Thei r behavioral responses depend on genetics, environmen t in which they grow, personality they develop and to impetus they experience. Similarly, the genetics of ground is defined by its formation (alluvial, marine, residual, colluvial, a eolin, etc.) depending upon how physiogamy forms the deposit. Ground, one tends to believe, is a sol id mass on which structures are built, becomes suddenly a fluid under specific aggravating circums tances such as consisting loose saturated sand with small amount of fines but subjected to seismic activity of medium to high intensity. On the other hand, a river in flood can erode the ground b y removing particles by its high velocity leading to scour. Slopes on which civilizations thrive, bec ome unstable and sometimes even catastrophic under heavy rainfall, coupled with human activities of deforestation, cutting/steepening of slopes, saturating it by ignorance or callousness, etc. The paper presents a new paradigm that emphasizes the need to visualize Ground, not just as a materia l but rather an entity, and view Geotechnical Engineering comprehensively, beyond a mechanistic s tandpoint

Settlement Analysis of Circular Footings on Layered Soil Systems

Many studies are available on the settlement analysis of footings on a homogeneous soil deposit underlain by a rigid base. However, the soil profile is seldom homogenous and typically a layered soil system is encountered in practice. The present study deals with the settlement profiles of soil underneath a circular footing of radius equal to a, and resting on a finite two-layered soil system with thicknesses equal to H1 and H2. The deformation moduli and Poisson’s ratios of the two layers are E1, υ1, and E2, υ2. The settlement profiles are proposed for varying H1/a and H2/a ratios (H1/a= 0.2, 0.5, 1, 2, 4 and 6, and H2/a= 1, 2, 4 and 6). The moduli ratio E1/E2is varied as 0.01, 0.05, 0.1, 0.5, 1, 2, 5 and 20. The extent of settlement due to load is also proposed from the surface settlement profile which can help in determining the influence of a footing on the neighboring footing or structure. The analysis is carried out using PLAXIS 2D vAE. In addition, the settlement influence factors are proposed for the above mentioned ratios to estimate the maximum settlement of the footing on a layered system. The results are also compared with the settlement measured in a building on a layered system in Adelaide, Southern Australia, and the results are found to be comparable

Modelling Ground-Foundation Interactions

Geotechnical practice deals with designing foundations and earth structures. Structure – Foundation –\ud Grou nd interaction is a unique field or topic that concerns both structural and geotechnical engineers. Most geotechnical problems are very sensitive to foundation geometry (length, diameter, spacing), flexural stiffness etc. Even basic parameters such as bearing capacity of shallow foundations, ultimate axial and lateral load capacities of deep/pile foundations, are influenced by the foundation characteristics. More importantly, the serviceability criterion can be satisfied only by proper and rational estimates of structure – found ation – ground interactions. The paper summarizes modelling approaches for foundation – ground interactions, a leaning instability approach for tall structures, and analysis of geosynthetic-reinforced foundation beds

Finite Element Modeling of Ground - Structure Interaction Considering Non-Linear Response of the Ground

Response of the ground on which the structure rests will have a bearing on the distribution of forces in the structural members. Conventional method s of structural analysis and design a ssume often fixed bases for various loading conditions. A realistic analysis and design procedure should includ e actual support flexibility, no nlinear and heterogeneous nature of the soil together with nonlinear soil-structure in teraction effects. Such an analysis would resu lt in overall stiffne ss of the soil-foundation-structure system , realistic to the existing conditions. This work focuses on the computational modeling of ground-structure interaction usi ng finite element package ANSYS. To demonstrate the behavior of structure while considering actual nature of ground response , a simple portal frame is analyzed. Portal frame is modeled as linear elastic, whereas the ground is modeled as both linear elastic and non-linear elastic-plastic behavior. The study gives insight into variation of displacement of portal frame while considering linear and non-linear behavior of ground

Local canted spin behaviour in Co_1.4-xZn_xGe_0.4Fe_1.2O₄ spinels: a macroscopic, mesoscopic and microscopic study

DC magnetization, neutron depolarization and neutron diffraction (with both polarized and unpolarized neutrons) measurements have been reported for the Co1.4-xZnxGe0.4Fe1.2O4 spinels with x=0.5, 0.6 and 0.7. Neutron depolarization and neutron diffraction measurements confirm the presence of a long range ferrimagnetic ordering of the local canted spins in these ferrite samples. The observed features of low field magnetization have been explained under the framework of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins. An important role of magnetic anisotropy (due to the presence of Co2+ ions) in establishing the magnetic ordering and domain kinetics in these ferrites has been observed

A non-mechanistic perspective of geotechnical engineering

Engineers deal mostly with materials that have unique and specific properties. On the other hand, entities are somewhat like living beings that do not possess unique properties but exhibit behavioral responses to stimuli (actions) . Clays and sands can exist in different state s ranging from liquid to solid and loosest to densest respectively. Responses of soils in general and ground in particular a re examined and analyzed under different test and design conditions. Similarly , the state in which ground exist s can be quantified though the over consolidation ratio. The most commonly used parameter, the undrained shear strength, is sensitive to the manne r in which it is determined . The paper emphasizes the need to visualize soil in the specific sense and ground in a broader perspective as entities rather than as strictly engi neering materials. It is suggested that g eotechnical engineering should be viewed compreh ensively and beyond a simple mechanistic perspective . A unique comparison of ground with a human being elu cidates the concepts enunciated

Cancer epithelia-derived mitochondrial DNA is a targetable initiator of a paracrine signaling loop that confers taxane resistance.

Stromal-epithelial interactions dictate cancer progression and therapeutic response. Prostate cancer (PCa) cells were identified to secrete greater concentration of mitochondrial DNA (mtDNA) compared to noncancer epithelia. Based on the recognized coevolution of cancer-associated fibroblasts (CAF) with tumor progression, we tested the role of cancer-derived mtDNA in a mechanism of paracrine signaling. We found that prostatic CAF expressed DEC205, which was not expressed by normal tissue-associated fibroblasts. DEC205 is a transmembrane protein that bound mtDNA and contributed to pattern recognition by Toll-like receptor 9 (TLR9). Complement C3 was the dominant gene targeted by TLR9-induced NF-κB signaling in CAF. The subsequent maturation complement C3 maturation to anaphylatoxin C3a was dependent on PCa epithelial inhibition of catalase in CAF. In a syngeneic tissue recombination model of PCa and associated fibroblast, the antagonism of the C3a receptor and the fibroblastic knockout of TLR9 similarly resulted in immune suppression with a significant reduction in tumor progression, compared to saline-treated tumors associated with wild-type prostatic fibroblasts. Interestingly, docetaxel, a common therapy for advanced PCa, further promoted mtDNA secretion in cultured epithelia, mice, and PCa patients. The antiapoptotic signaling downstream of anaphylatoxin C3a signaling in tumor cells contributed to docetaxel resistance. The inhibition of C3a receptor sensitized PCa epithelia to docetaxel in a synergistic manner. Tumor models of human PCa epithelia with CAF expanded similarly in mice in the presence or absence of docetaxel. The combination therapy of docetaxel and C3 receptor antagonist disrupted the mtDNA/C3a paracrine loop and restored docetaxel sensitivity