A case record of electroosmotic consolidation of soft clay with improved soil–electrode contact

2004 ◽  
Vol 41 (6) ◽  
pp. 1038-1053 ◽  
Author(s):  
Fabien Burnotte ◽  
Guy Lefebvre ◽  
Gilles Grondin
Keyword(s):  
Chemical Treatment ◽  
Soft Clay ◽  
Soil Improvement ◽  
Field Application ◽  
Large Field ◽  
Published Data ◽  
Power Losses ◽  
Case Record ◽  
Clay Deposits ◽  
Electrode Contact

Electroosmotic (e.o.) consolidation of clays has been known in geotechnical engineering for many decades but is in fact seldom used. The analysis of published data from case records indicates that the power losses at the soil–electrode contact constitute a major problem for the field application of e.o. consolidation. A laboratory study, where field conditions were reproduced, has demonstrated the efficiency of a chemical treatment at the electrodes to enhance potential transfer to soil. The chemical treatment was evaluated in a large field demonstration test where over 700 m3 of clay was consolidated by electroosmosis. The paper describes the site, the field setup, and the results and analysis of the monitoring during the 48 days of the e.o. treatment. The results of the post-treatment geotechnical investigation after 12% of clay compression due to electroosmotic consolidation are also presented and discussed. These results confirm that soft clay deposits can be successfully treated by e.o. consolidation, at a competitive cost compared with other alternatives, when power losses at the soil–electrode contact are controlled.Key words: case record, electroosmosis, soft clays, consolidation, soil improvement.

Unconventional concepts for dykes and dams on soft clay foundation

1984 ◽  
Vol 21 (3) ◽  
pp. 581-586
Author(s):  
O. Eide ◽  
S. Lacasse ◽  
B. Kjærnsli ◽  
P. S. Hafskjold
Keyword(s):  
Key Words ◽  
Soft Clay ◽  
Earth Pressure ◽  
Soil Improvement ◽  
Construction Time ◽  
Sloping Ground ◽  
Vertical Drains ◽  
Clay Deposit ◽  
Clay Deposits ◽  
Improvement Measures

As an alternative to a stage-construction embankment dyke equipped with vertical drains, two buttress-type concrete dams are proposed for deep, soft clay deposits where the building of embankment dykes would involve serious difficulties and sizable expenditures. These concepts avoid the loading of the soft clay deposit with high embankments and thus reduce problems of stability and settlement. High embankment dykes may not be feasible in the case of sloping ground, even gently so, because of the lack of stability in a flake-type sliding. The advantages of the proposed concept include the absence of soil improvement measures, shorter construction time, and reduced settlements. Specific drawbacks relate to the lack of experience with buttress-type dams on soft clay foundations. Key words: dam, clay, concrete, earth pressure, embankment, pile.

Numerical Simulations of Dynamic Embedment During Pipe Laying on Soft Clay

2009 ◽  
Author(s):  
D. Wang ◽  
D. J. White ◽  
M. F. Randolph
Keyword(s):  
Soft Clay ◽  
Simple Approach ◽  
Published Data ◽  
Vertical Load ◽  
Centrifuge Model ◽  
Upper Limit ◽  
Different Types ◽  
Element Approach ◽  
Pipeline Design ◽  
Centrifuge Model Tests

Prediction of the as-laid embedment of a pipeline, which affects many aspects of pipeline design, is complicated by the dynamic motions that occur during the lay process. These motions cause pipelines to embed deeper than predicted based on static penetration models, as the seabed soils are both softened and physically displaced by the pipeline motion. This paper describes the results of 2D numerical analyses using a large displacement finite element approach aimed at quantifying pipeline embedment due to cyclic lateral motion at various fixed vertical load levels. The validity of the numerical results is first assessed by comparison with published data from centrifuge model tests in two different types of clay. A parametric study varying the normalized vertical load is then presented, which suggests a simple approach for estimating an upper limit to the dynamic embedment.

Treatment of Tar Sand Wastewaters with Activated Carbon, Ozone and Reverse Osmosis

1986 ◽  
Vol 18 (1) ◽  
pp. 43-54
Author(s):  
Raymond A. Sierka ◽  
Paul H. King
Keyword(s):  
Activated Carbon ◽  
Reverse Osmosis ◽  
Ferric Chloride ◽  
Chemical Treatment ◽  
Applied Pressure ◽  
Large Field ◽  
Foam Fractionation ◽  
Solution Ph ◽  
Steam Flooding ◽  
Energy Needs

Tar sand deposits offer long-term potential for satisfying future energy needs. Two large field-scale extraction experiments near Vernal, Utah, employed either a sequenced reverse-forward combustion technique (TS-2C) or a steam flooding procedure (TS-1 S) to recover in-place bitumen. This report documents the evaluation of activated carbon, ozone and reverse osmosis in treating the two types of tar sand wastewaters. Substrates included untreated and pretreated (filtration, foam fractionation, chemical treatment with ferric chloride) TS-1S and TS-2C wastewaters. Activated carbon, at a dose of 1,000 mg/L, reduced the Total Organic Carbon (TOC) of TS-1 S wastewater after treatment by 350 mg/L of ferric chloride to 2.3 mg/L TOC, a reduction of 91.6%. At the same adsorbent dos, activated carbon reduced the TOC in TS-2C wastewater from 678 mg/L to 546 mg/L. A study of the six commercially available adsorbents yielded little difference in adsorption capability for either wastewater. Ozonation of TS-lS wastewater after pretreatment by either foam fractionation or chemical treatment with ferric chloride then activated carbon yielded residual TOC levels of less than 1.2 mg/L. Reverse osmosis (RO) studies included investigation of four membrane types (cellulose acetate, poly-ether amide, poly-ether urea and a noncellulosic on a poly-sulfone base), three applied pressure levels (250, 400 and 550 psig) and two solution pH levels (5.5 and 7.8) with 5.0 µ (micron) filtered TS-2C wastewater as the substrate. A two-stage RO process achieved maximum organic and inorganic rejections of 98% and 97%, respectively.

scholarly journals Climate and litter C/N ratio constrain soil organic carbon accumulation

2019 ◽  
Vol 6 (4) ◽  
pp. 746-757 ◽  
Author(s):  
Guoyi Zhou ◽  
Shan Xu ◽  
Philippe Ciais ◽  
Stefano Manzoni ◽  
Jingyun Fang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Field Survey ◽  
Co2 Concentration ◽  
Carbon Accumulation ◽  
Atmospheric Co2 ◽  
Large Field ◽  
Published Data ◽  
Wetness Index ◽  
Atmospheric Co2 Concentration

Abstract Soil organic carbon (SOC) plays critical roles in stabilizing atmospheric CO2 concentration, but the mechanistic controls on the amount and distribution of SOC on global scales are not well understood. In turn, this has hampered the ability to model global C budgets and to find measures to mitigate climate change. Here, based on the data from a large field survey campaign with 2600 plots across China's forest ecosystems and a global collection of published data from forested land, we find that a low litter carbon-to-nitrogen ratio (C/N) and high wetness index (P/PET, precipitation-to-potential-evapotranspiration ratio) are the two factors that promote SOC accumulation, with only minor contributions of litter quantity and soil texture. The field survey data demonstrated that high plant diversity decreased litter C/N and thus indirectly promoted SOC accumulation by increasing the litter quality. We conclude that any changes in plant-community composition, plant-species richness and environmental factors that can reduce the litter C/N ratio, or climatic changes that increase wetness index, may promote SOC accumulation. The study provides a guideline for modeling the carbon cycle of various ecosystem scales and formulates the principle for land-based actions for mitigating the rising atmospheric CO2 concentration.

Ormen Lange Gas Field, Immediate Settlement of Offshore Rock Supports

2007 ◽  
Author(s):  
Guus de Vries ◽  
Joop van der Meer ◽  
Harald Brennodden ◽  
Stein Wendel
Keyword(s):  
Continental Shelf ◽  
Soft Clay ◽  
Back Analysis ◽  
Processing Plant ◽  
Gas Field ◽  
Clay Deposits ◽  
Calculation Results ◽  
The Uk ◽  
Rock Supports ◽  
Norwegian Continental Shelf

Located approximately 120 km offshore, Ormen Lange, with an estimated 400 billion m3 of natural gas, is the second-largest gas discovery on the Norwegian shelf. The water depth is up to 850 meters, making Ormen Lange the first deepwater project on the Norwegian Continental Shelf. The development of Ormen Lange is under shared operatorship between Norsk Hydro and Shell. Ormen Lange’s untreated well stream will be transported to shore in two 120 km long, 30-inch diameter pipelines to a processing plant at Nyhamna, Norway. From there, gas will be exported via a 42” 1200 km sub sea pipeline (Langeled) to Easington at the east coast of the UK. The pipelines have to pass over the Storegga slide edge which rises 200–300 meters toward the continental shelf in very steep slopes, which are also encountered in the nearshore Bjo¨rnsundet area. The uneven and steep seabed conditions require the use of approximately 2.8 million tons of rock to support and stabilize the pipelines. The sea bottom conditions on the Norwegian continental shelf are characterized by many outcrops as well as very soft clay deposits. The immediate settlement of the rock supports during installation form a significant amount of the total required rock volume. In this paper a procedure is presented on how to assess these immediate settlements recognizing four contributing components all being discussed separately. The calculation results are compared to a back-analysis, performed during the execution of the Ormen Lange rockworks, proving the suitability of the calculation method.

EFFECT OF REPLACING CRUSHED STONE IN STONE COLUMNS BY WASTE MATERIAL ON SOIL IMPROVEMENT RATIO

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Nahla Mohammed Salim ◽  
Shatha Hasan ◽  
Kawther Al-Soudany
Keyword(s):  
Bearing Capacity ◽  
Soft Clay ◽  
Soil Improvement ◽  
Waste Material ◽  
Stone Columns ◽  
Crushed Stone ◽  
Stone Column ◽  
University Of Technology ◽  
The University ◽  
Building Demolition

Many researchers’ studies have shown that stone column is the best material to use to improve the bearing capacity of clayey soils. There are millions of waste volumes resulting from daily human activities. This excess waste leads to disposal problems and also causes environmental contamination and health risks. Demolished concrete is such one waste material that is produced from building demolition in Baghdad, Iraq. This paper describes experimental work conducted at the University of Technology that was carried out to investigate the improved bearing capacity of soft clay using crushed stone, followed by replacing crushed stone with concrete waste with the same relative density and grain size. The replacement was carried using waste concrete with different percentages corresponding to 25%, 50%, 75%, and 100%. The main conclusion drawn is that the bearing capacity increased to 119% by using crushed stone column, while the bearing capacity increased to 155% by using 100% of crushed concrete waste.

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