scholarly journals Compressibility and consolidation properties of Santos soft clay near Barnabé Island

2021 ◽  
Vol 44 (4) ◽  
pp. 1-18
Author(s):  
Vitor Aguiar ◽  
Maurício Andrade ◽  
Ian Martins ◽  
Jean Rémy ◽  
Paulo Santa Maria
Keyword(s):  
Standard Procedure ◽  
Soft Clay ◽  
Total Duration ◽  
Clay Layer ◽  
Test Program ◽  
High Quality ◽  
Criterion A ◽  
Undisturbed Samples ◽  
Current Standards ◽  
Incremental Loading

A geotechnical study based on characterization tests and seventy incremental loading onedimensional consolidation tests was carried out on high-quality undisturbed samples taken from Santos Harbor Channel subsoil near to Barnabé Island, where a pilot embankment was built. The characterization profiles revealed a stratigraphy following the pattern described by Massad (2009), with a 9 m-thick fluvial-lagoon-bay sediments (SFL) clay layer. The consolidation tests were performed following two loading criteria. In criterion A (series one tests), a new loading was applied whenever the strain rate (ε) reached 10-6 s-1, the highest integer power of 10 after the “end of primary” consolidation for double drained 2 cm-thick specimens. In criterion B (series two tests), the standard procedure of 24 hour-long stages was adopted. Criterion A reduced the total duration of the consolidation tests from ten to about three days. The preconsolidation (yield) stress (σ’p) and the compressibility parameters Cc and Cr obtained from “e versus σ’v (log)” compression curves of all tests are provided. Series two tests showed that the 24-hour “e versus σ’v (log)” compression curves are translated to the left of the ε = 10-6 s-1 “e versus σ’v (log)” compression curves, keeping Cr and Cc average values unchanged, but decreasing σ’p by about 8%. The SFL clay Cc/(1+e0) values obtained herein are higher than those presented by Massad (2009) due to the higher-quality samples tested in this study. It is shown that it is feasible to carry out a high-quality laboratory test program for design purposes following current standards.

Characterization of a smear zone around vertical drains by large-scale laboratory tests

2000 ◽  
Vol 37 (6) ◽  
pp. 1265-1271 ◽  
Author(s):  
J S Sharma ◽  
D Xiao
Keyword(s):  
Large Scale ◽  
Soft Clay ◽  
Excess Pore Pressure ◽  
Laboratory Model ◽  
Clay Layer ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Undisturbed Samples ◽  
Oedometer Tests ◽  
Excess Pore

Installation of prefabricated vertical drains using a mandrel causes disturbance of clay surrounding the drain, resulting in a "smear" zone of reduced permeability. In this paper, an attempt is made to characterize the smear zone using large-scale laboratory model tests. Two tests, simulating the cases of "no smear" and "with smear," were conducted. Excess pore-water pressures were monitored at seven different locations along the radial direction. In addition, undisturbed samples were collected at various locations in the clay layer for conducting oedometer tests. The distribution of excess pore pressure due to drain installation gave a clear indication of the extent of the smear zone. The effect of reconsolidation on the properties of clay was found to be much greater than that of the remoulding of the clay. The extent of the smear zone was also confirmed from the change in permeability of the clay layer in the smear zone obtained from oedometer tests. The radius of the smear zone is about four times that of the mandrel, and the horizontal permeability of the clay layer in the smear zone is approximately 1.3 times smaller than that in the intact zone.Key words: consolidation, permeability, smear zone, soft clay, vertical drains.

scholarly journals Assessing the undrained strength of very soft clays in the SPT

2021 ◽  
Vol 44 (4) ◽  
pp. 1-6
Author(s):  
Francisco Lopes ◽  
Osvangivaldo Oliveira ◽  
Marcio Almeida
Keyword(s):  
Standard Procedure ◽  
Soft Clay ◽  
Test Procedure ◽  
State Theory ◽  
Technical Note ◽  
Construction Site ◽  
Soft Clays ◽  
Design Engineers ◽  
Present Information ◽  
Undrained Strength

The log of a SPT in very soft clay may simply indicate a zero blow-count, or present information on the penetration – under self-weight – of the composition (sampler, rods and hammer) as recommended by some standards. The second type of information is often disregarded by design engineers due to the lack of a standard procedure for measuring these penetrations or because the test is regarded as not sensitive enough to give an indication on the undrained shear strength of soft clays. The penetration under the composition’s selfweight, however, can indicate the magnitude of Su, which, along with other more specific and sensitive tests, can help in assessing the spatial distribution of clay consistency in a large deposit. A proposed test procedure and interpretation had been given in an earlier technical note. This note presents an extended formulation and an evaluation of Su via the SPT at a construction site in Rio de Janeiro, including comparisons with results of piezocone and vane tests. The values of Su obtained with the SPT lie between the profiles given by vane tests, corrected by Plasticity Index, and the Critical State Theory, the latter representing a lower bound to the clay strength.

scholarly journals Numerical Study of Laterally Loaded Piles in Soft Clay Overlying Dense Sand

2021 ◽  
Vol 7 (4) ◽  
pp. 730-746
Author(s):  
Amanpreet Kaur ◽  
Harvinder Singh ◽  
J. N. Jha
Keyword(s):  
Layer Thickness ◽  
Soft Clay ◽  
Bending Moment ◽  
Layered Soil ◽  
Clay Layer ◽  
Pile Groups ◽  
Dense Sand ◽  
Lateral Capacity ◽  
Laterally Loaded ◽  
Pile Length

This paper presents the results of three dimensional finite element analysis of laterally loaded pile groups of configuration 1×1, 2×1 and 3×1, embedded in two-layered soil consisting of soft clay at liquid limit overlying dense sand using Plaxis 3D. Effects of variation in pile length (L) and clay layer thickness (h) on lateral capacity and bending moment profile of pile foundations were evaluated by employing different values of pile length to diameter ratio (L/D) and ratio of clay layer thickness to pile length (h/L) in the analysis. Obtained results indicated that the lateral capacity reduces non-linearly with increase in clay layer thickness. Larger decrease was observed in group piles. A non-dimensional parameter Fx ratio was defined to compare lateral capacity in layered soil to that in dense sand, for which a generalized expression was derived in terms of h/L ratio and number of piles in a group. Group effect on lateral resistance and maximum bending moment was observed to become insignificant for clay layer thickness exceeding 40% of pile length. For a fixed value of clay layer thickness, lateral capacity and bending moment in a single pile increased significantly with increase in pile length only up to an optimum embedment depth in sand layer which was found to be equal to three times pile diameter and 0.21 times pile length for pile with L/D 15. Scale effect on lateral capacity has also been studied and discussed. Doi: 10.28991/cej-2021-03091686 Full Text: PDF

scholarly journals The Molding Influence

1999 ◽  
Vol 121 (10) ◽  
pp. 70-72
Author(s):  
Hutchinson Harry
Keyword(s):  
Design Process ◽  
Cad Model ◽  
Test Program ◽  
High Quality ◽  
The Core ◽  
The One ◽  
Beta Testing ◽  
Standard Components ◽  
Beta Test

This article presents study that shows beta testing shapes software to the users’ hands so the product will fit the marketplace. MoldWizard is intended to reduce the time necessary to design complex mold tooling, such as this mold used to manufacture the plastic housings for high-quality nail guns. Depending on the complexity of a mold and its eventual use, the design process can require as many as 50 different steps, including tasks such as importing and cleaning up the CAD model of the part, adjusting its size for shrinkage, separating the core and cavity, generating mold bases, and adding sliders, inserts, and other standard components. Minco Tool & Mold uses Unigraphics to design molds like the one shown in the article for an automobile hubcap. Minco participated in the MoldWizard beta test program. A news group at the website let the test users communicate directly with each other. When beta testers had questions about how to use the program, they posted them in the news group and other testers would respond.

Behaviour of friction piles in soft sensitive clays

1980 ◽  
Vol 17 (2) ◽  
pp. 203-224 ◽  
Author(s):  
R. Blanchet ◽  
F. Tavenas ◽  
R. Garneau
Keyword(s):  
Precast Concrete ◽  
Soft Clay ◽  
Load Test ◽  
Pile Groups ◽  
Test Program ◽  
Shear Creep ◽  
Soft Clays ◽  
The North ◽  
Effective Stress Analysis

During the construction of heavy structures, such as bridges and overpasses, on soft clays on the north shore of the St. Lawrence Valley, a detailed load test program on friction piles was performed to establish the characteristics of the most suitable type of pile and to study its long-term behaviour. Three types of piles, timber, steel pipe with closed end, and precast concrete Herkules H-420 piles, were tested. Four timber piles driven in a group and submitted to a 712 kN load served to study the long-term settlement of a small group of piles. Three deep settlement gauges were installed in the centre of this group for measuring settlements in clay at various depths.This test program was completed by the instrumentation of two bridge piers in order to verify the behaviour of larger groups of piles.The paper presents the results of the test piles, the long-term behaviour (4 years) of the bridge pier foundations resting on friction piles in soft clay, and the interpretation of the results.This study shows that the pore pressures induced by pile driving are related to the pre-consolidation of the clay and that they are much larger for tapered piles. It is demonstrated that the effective stress analysis method proposed in 1976 by Meyerhof determines adequately the ultimate pile bearing capacity, but that the effect of the timber pile taper doubles the skin friction.The settlement analysis of pile groups shows that settlements are due to the reconsolidation of the clay and shear creep deformations in the clay close to the pile wall.

Abstract 205: Does Overuse of Telemetry Impede Cost-effective Patient Care?

2020 ◽  
Vol 13 (Suppl_1) ◽  
Author(s):  
Kenneth B Brownell ◽  
Sowjanya Yenigalla ◽  
Parth Shah ◽  
Evan B Kudron ◽  
Abasin Amanzai ◽  
...  
Keyword(s):  
Quality Care ◽  
Tertiary Care ◽  
Total Duration ◽  
Heart Association ◽  
Cost Effective ◽  
The United States ◽  
Cardiac Monitoring ◽  
High Quality ◽  
Healthcare Expenditures ◽  
Evidenced Based

Background: Telemetry was first introduced in the 1950s in cardiac intensive care units (ICU) and has since expanded to beyond the ICU setting. With this expansion, concerns regarding the overutilization of telemetry have emerged. In response to these concerns, the American Heart Association (AHA) and the American College of Cardiology (ACC) released guidelines for evidenced-based telemetry utilization in 2004. Following this publication, numerous studies have shown that a significant number of non-ICU patients on telemetry do not meet evidenced-based indications leading to costly overutilization of a valuable resource. This overutilization is expensive in both the direct costs of equipment and labor as nurses spend an average of 20 minutes per patient day on telemetry related tasks. As healthcare expenditures in the United States continue to rise, efforts are needed to contain these rising costs if we wish to continue to provide high quality, affordable care. Methods: Using the electronic medical record (EMR) at our urban, tertiary-care, 482 bed teaching hospital, we performed an observational study looking at all admissions to a medical floor that were ordered telemetry in June 2019. We investigated if telemetry was ordered based upon the 2004 AHA guidelines. We then examined the total duration of telemetry utilized for non-AHA guideline indications. Next, we applied the average additional daily cost of $53.44, as reported in the literature, for monitored vs. non-monitored patients and then calculated an estimated total monthly expenditure for inappropriate use to cardiac monitoring. Annual costs were then projected based upon this figure. Results: There were 395 patients admitted in June 2019. After all inclusion criteria were applied, our sample consisted of 226 patients. Seventy-nine of these patients had telemetry ordered for an AHA guideline-based indication, while 147 patients had telemetry ordered for a non-AHA guideline indication for a total of 711 patient days, which adds $37,995.84 to monthly healthcare expenditures. Of the 147 patients that had telemetry ordered for non-AHA guideline indications, only one patient had a documented benefit, which was the detection of new-onset paroxysmal atrial fibrillation. Conclusions: Telemetry monitoring is frequently overused for patients admitted to non-critical care services. An effort to educate House Staff about the indications for ordering telemetry based on AHA guidelines can reduce healthcare-associated costs and help provide cost-effective, high-quality care to our patients.

scholarly journals Effects of the Stiffness of Soft Clay Layer on Strong Motion Response.

2002 ◽  
Vol 42 (1) ◽  
pp. 17-33 ◽  
Author(s):  
AKIRA YAMAGUCHI ◽  
MOTOKI KAZAMA ◽  
HIROFUMI TOYOTA ◽  
MASAKI KITAZUME ◽  
TAKAHIRO SUGANO
Keyword(s):  
Soft Clay ◽  
Strong Motion ◽  
Clay Layer ◽  
Motion Response

scholarly journals Numerical Modelling of Prefabricated Vertical Drain for Soft Clay Using ABAQUS

2015 ◽  
Vol 773-774 ◽  
pp. 1502-1507
Author(s):  
Saiful Azhar Ahmad Tajudin ◽  
Mohd Fairus Yusof ◽  
I. Bakar ◽  
Aminaton Marto ◽  
Muhammad Nizam Zakaria ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Elastic Model ◽  
Clay Layer ◽  
Soil Consolidation ◽  
Consolidation Process ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain

Construction, buildings and infrastructure founded on soft clays are often affected by settlement problem. Therefore, Prefabricated Vertical Drain (PVD) is one of the best solutions to accelerate soil consolidation by shortening the drainage path. In this study, numerical investigation was carried out to pursue a better understanding of the consolidation behavior of soft clay improved with PVD. The consolidation process accelerated by PVD with surcharge of 50 kPa was analysed using the ABAQUS software by adopting an elastic model. The aim of this study is to compare the settlement and the required time to fully consolidate the soft soil at different drain spacings (1.0 m, 1.5 m and 2.0 m) for two different thickness of the clay layer. The results shows that the time required to completely consolidate the soft soil for 12 m and 20 m thickness of clay layer with different spacings are in the range of 3 months to 66 months. The settlement rate and excess pore water pressure dissipation are increased when the spacing of the drain closer.

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