Study on the Permeability of Reinforced Soil with Herb Fiber under Different Salt Solution Concentration

2011 ◽  
Vol 308-310 ◽  
pp. 2291-2296
Author(s):  
Geng Sheng Yan ◽  
Hu Yuan Zhang ◽  
Xiao Dong Wang ◽  
Min Li ◽  
Tian Yu Zhao
Keyword(s):  
Diffusion Layer ◽  
Permeability Coefficient ◽  
Particle Surface ◽  
Water Film ◽  
Solution Concentration ◽  
Soil Mass ◽  
Reinforced Soil ◽  
Wet Processing ◽  
Exchange Adsorption ◽  
Flexible Wall

The best is to read these instructions and follow the outline of this text. n this investigation, laboratory permeability tests were conducted on the wet-processing reinforcement specimens to study the feasibility of reinforced soil as a material of construction. Two kinds of reinforced specimens with different reinforcement materials (wheat straw (C) and flax (M)) were mixed with 3% contents of soil mass, and product to the cylindroid for measurement of permeability by a flexible-wall permeameter. The variation relationship between permeability coefficient and Na2SO4 concentrations was analyzed. Test results show that the liquidity reduced with incrassate diffusion layer caused by the increasing Na+ concentrations in the diffusion layer of soil particles, and then a decrease of permeability is found. With the increasing time of permeability, it is found that the permeability coefficient decreased due to the consolidation and decreasing porosity of specimens caused by the change of stress state. At the same time, ion exchange adsorption and water film incrassate occurs in soil particle surface which also benefit to the decrease of permeability coefficient.

Determination of oxygen transfer rate to a rotating biological contactor by microelectrode measurement

1994 ◽  
Vol 29 (10-11) ◽  
pp. 471-477 ◽  
Author(s):  
K. Nishidome ◽  
T. Kusuda ◽  
Y. Watanabe ◽  
M. Yamauchi ◽  
M. Mihara
Keyword(s):  
Diffusion Layer ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Water Film ◽  
Ammonia Nitrogen ◽  
Concentration Profiles ◽  
Rotating Biological Contactor ◽  
Transfer Rates ◽  
Do Concentration

With an oxygen microelectrode developed by the authors for the measurement of dissolved oxygen (DO) concentration profiles of biofilms in a rotating biological contactor (RBC), DO concentration profiles in the inside and outside of rotating biofilms were measured continuously in the air and water phases. Thicknesses of attached-water film (Lw) and the diffusion layer (Ld) formed on the biofilms were estimated from DO concentration profiles. The oxygen transfer rate to the biofilm was determined with measured DO concentration profiles and a steady state biofilm kinetic model by use of the thicknesses of attached-water film and the diffusion layer. The oxygen transfer rates obtained by two independent methods agreed well, so that the method of the measurement of DO concentration profilesis considered highly reliable. The conclusions in this study are summarized as follows: (1) Lw and Ld on a biofilm attached on a partially submerged rotating biological contactor were 50 and 70 μm thick, respectively; (2) The measured oxygen fluxes were about 10 g-O2/m2/day, and reasonably agreed with those calculated from removing rates of ammonia nitrogen.

Research on Influencing Factors of Drainage Performance in Engineering

2012 ◽  
Vol 212-213 ◽  
pp. 671-678
Author(s):  
Xu Shu Sun ◽  
Jian Lin Li ◽  
Xiao Liang Xu ◽  
Jian Rrong Li ◽  
Fei Liu
Keyword(s):  
Influencing Factors ◽  
Small Angle ◽  
Permeability Coefficient ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Vertical Permeability ◽  
Horizontal Drainage ◽  
Drainage Hole ◽  
Better Than

In order to control the seepage and eliminate the adverse effects, influencing factors of drainage in engineering are discussed in this paper. The drainage holes are simulated by rod element to study the influence of drainage performance on angle and length. Compared the drainage performance of drainage galleries in different location, the optimal assembly is obtained. Meanwhile, drainage performance is analyzed by different permeability coefficient and anisotropy of rock and soil mass. The results show that: (1) Drainage flow of small angle and short drainage hole is close to big angle and long one, the small angle flows more than the big angle when increasing the same length. (2) Shallow drainage galleries can significantly drop the free surface and the deep one can greatly decrease the pore water pressure. Drainage galleries built at the upstream side and bottom, as the optimum assembly, can enormously change the seepage field. (3) For anisotropy materials, the horizontal drainage performance is better than vertical when Ky/Kx decreases. On the contrary, vertical is superior to the horizontal. Increasing vertical permeability coefficient is benefit to drainage.

scholarly journals Consistency between parameterisations of aerosol hygroscopicity and CCN activity during the RHaMBLe Discovery cruise

2009 ◽  
Vol 9 (5) ◽  
pp. 22659-22692 ◽  
Author(s):  
N. Good ◽  
D. O. Topping ◽  
J. D. Allan ◽  
M. Flynn ◽  
E. Fuentes ◽  
...  
Keyword(s):  
Water Activity ◽  
Water Uptake ◽  
Particle Surface ◽  
Solution Concentration ◽  
Single Parameter ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Saturated Water ◽  
Refractory Composition ◽  
Ccn Activity

Abstract. Results from a measurement study performed in the Tropical Atlantic on board the RHaMBLe Discovery Cruise D319 are presented. Measurements of aerosol composition, hygroscopicity and CCN activity were used to test the ability of a single parameter model to describe water uptake in sub- and supersaturated conditions. It was found that the magnitude and variability of the sub-saturated water uptake could be well represented using the non-refractory composition to derive the model input when most of the aerosol mass is non-refractory. As may be expected, when a significant fraction of the aerosol mass is refractory the sub-saturated water uptake is not well predicted by the non-refractory composition. When predicting the cloud activation potential from the composition and the hygroscopicity there is a consistent under-prediction of the CCN activity. The prediction of CCN activity from the sub-saturated water uptake gives a better prediction of the CCN activity than the composition when the non-refractory components are not fully representative of the aerosol composition. Based on these observations it appears that a single parameter cannot always capture the behavior fully across the sub- and supersaturated regimes when the surface tension is assumed to be that of water. The magnitude of the discrepancy varies according to the air mass sampled and the reasons for the difference may vary too. It is postulated that this is a result of a lack of characterisation of the behaviour of components at the particle surface or that the water activity dependence on the solution concentration is not sufficiently constrained by the single parameter approach. The water activity appears satisfactorily represented by a single parameter derived at 90% relative humidity (RH) for RHs less than 94%. To reconcile the CCN activity with the aerosol composition, surface tensions in the range of 52 to 60 mN/m are required at the point of activation.

The influence of facing stiffness on the performance of two geosynthetic reinforced soil retaining walls

2006 ◽  
Vol 43 (12) ◽  
pp. 1225-1237 ◽  
Author(s):  
Richard J Bathurst ◽  
Nicholas Vlachopoulos ◽  
Dave L Walters ◽  
Peter G Burgess ◽  
Tony M Allen
Keyword(s):  
Limit Equilibrium ◽  
Retaining Walls ◽  
Reinforced Soil ◽  
Test Facility ◽  
Geosynthetic Reinforced Soil ◽  
State Highway ◽  
Current Limit ◽  
Reinforced Soil Wall ◽  
Simplified Method ◽  
Flexible Wall

Current limit equilibrium-based design methods for the internal stability design of geosynthetic reinforced soil walls in North America are based on the American Association of State Highway and Transportation Officials (AASHTO) Simplified Method. A deficiency of this approach is that the influence of the facing type on reinforcement loads is not considered. This paper reports the results of two instrumented full-scale walls constructed in a large test facility at the Royal Military College of Canada. The walls were nominally identical except one wall was constructed with a stiff face and the other with a flexible wrapped face. The peak reinforcement loads in the flexible wall were about three and a half times greater than the stiff-face wall at the end of construction and about two times greater at the end of surcharging. The stiff-face wall analysis using the Simplified Method gave a maximum reinforcement load value that was one and a half times greater than the measured value at the end of construction. Furthermore, the surcharge pressure required to reach the creep-limited strength of the reinforcement was about two times greater than the predicted value. The results demonstrate quantitatively that a stiff facing in a reinforced soil wall is a structural component that can lead to significant reductions in reinforcement loads compared to flexible facing systems.Key words: geosynthetics, retaining walls, reinforced soil, wrapped face, structural facings.

scholarly journals Performance of Geosynthetic-Reinforced Soils Under Static and Cyclic Loading

2017 ◽  
Vol 7 (2) ◽  
pp. 1523-1527 ◽  
Author(s):  
M. Touahmia
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Soil Mass ◽  
Reinforced Soil ◽  
Geosynthetic Reinforcement ◽  
Great Resistance ◽  
Geosynthetic Reinforced Soil ◽  
Confining Pressures ◽  
Pullout Failure ◽  
Static And Cyclic Loading

This paper investigates and discusses the composite behavior of geosynthetic reinforced soil mass. It presents the results of a series of large-scale laboratory tests supported by analytical methods to examine the performance of geogrid reinforcement subjected to static and cyclic pullout loading. The testing equipment and procedures used for this investigation are outlined. The results show that geosynthetic reinforcement can mobilize great resistance to static pulling load under high confining pressures. The reinforcement exhibits gradual deformation under cyclic loading showing no sign of imminent pullout failure for all levels of applied loads. In general, the results demonstrate that geosynthetic can be used in situations where loads are non-static, although care will be required in ensuring that appropriate factors of safety are applied to control the resulting deformation. A simplified analytical model for calculating the pulling capacity of geosynthetic reinforcement is proposed.

Processing High Quality Toughened Zirconia Ceramics by Controlling the Chemistry at the Particle-Particle Interface

1993 ◽  
Vol 318 ◽  
Author(s):  
S.T. Thuraisingham ◽  
J.L. Henshall
Keyword(s):  
Surface Chemistry ◽  
Lower Cost ◽  
Particle Surface ◽  
Processing Technique ◽  
Complex Geometries ◽  
Zirconia Ceramics ◽  
High Quality ◽  
Wet Processing ◽  
Ca 50 ◽  
Sintered Materials

ABSTRACTA novel lower cost wet-processing technique, for producing toughened zirconia ceramics with complex geometries, is presented. It is based mainly on modifications to the particle surface chemistry. The sintered materials produced so far are significantly harder (ca 50%) as well as being tougher (ca 10%) than a commercial CeTZP.

scholarly journals Stability Assessment of Coastal Cliffs Incorporating Laser Scanning Technology and a Numerical Analysis

2019 ◽  
Vol 11 (16) ◽  
pp. 1951 ◽  
Author(s):  
Rafal Ossowski ◽  
Marek Przyborski ◽  
Pawel Tysiac
Keyword(s):  
Laser Scanning ◽  
Soil Mass ◽  
Reinforced Soil ◽  
Stability Assessment ◽  
Change Analysis ◽  
Geotechnical Parameters ◽  
Limit Value ◽  
Simplifying Assumptions ◽  
Coastal Cliffs ◽  
The Stability

We investigated the cliff coast in Jastrzebia Gora, Poland. The measurements that were taken between 2014 and 2018 by applying terrestrial, mobile, and airborne laser scanning describe a huge geometric modification involving dislocations in a 2.5 m range. Differential maps and a volumetric change analysis made it possible to identify the most deformed cliff’s location. Part of the monitoring of coastal change involved the measurement of a cliff sector in order to determine the soil mass flow down the slope. A full geometric image of the cliff was complemented by a stability assessment that incorporated numerical methods. The analysis showed that the stability coefficients, assuming a particular soil strata layout and geotechnical parameters, are unsafely close to the limit value. Moreover, the numerical computations, which were performed under simplifying assumptions, were not able to capture a multitude of other random factors that may have an impact on the soil mass stability. Thus, displacements of both reinforced soil and gabions were detected that are intended to prevent the cliff from deforming and to protect the infrastructure in its vicinity. The array of applied measurement methods provides a basis for the development of research aimed at optimization of applied tools, safety improvements, and a rapid reaction to threats.

Evaluation and Recommendations for Flowfill and Mechanically Stabilized Earth Bridge Approaches

2008 ◽  
Vol 2045 (1) ◽  
pp. 51-61
Author(s):  
Naser M. Abu-Hejleh ◽  
Dennis Hanneman ◽  
Trever Wang ◽  
Ilyess Ksouri
Keyword(s):  
Filter Material ◽  
Soil Mass ◽  
Reinforced Soil ◽  
Mechanically Stabilized Earth ◽  
Repair Costs ◽  
Bridge Approach ◽  
Class B ◽  
Class 1 ◽  
Backfill Materials ◽  
Mechanically Stabilized

To alleviate the common bridge bump problem, the Colorado Department of Transportation (CDOT) has employed three new alternatives for bridge abutment backfill since 1992: flowfill, mechanically stabilized earth (MSE) using well-graded granular Class 1 backfill (reinforced soil mass as in MSE walls), and MSE using free-draining Class B filter material. However, the occurrence of bridge bump problems is still reported. A study evaluated CDOT current practice for design and construction of bridge approaches and then developed recommendations to improve this practice (improve performance and reduce costs) on the basis of the results of the following: (a) best practices for bridge approaches collected from CDOT staff and reported in the literature, (b) evaluation of the performance and cost-effectiveness of Colorado's MSE and flowfill bridge approaches, and (c) identification of the causes of significant bridge approach settlement problems observed in some of Colorado's MSE and flowfill bridge approaches. Evaluation procedures and forensic investigations were developed and applied to obtain the information needed for the first two items. Flowfill should remain a viable alternative for certain field and construction scenarios that justify its higher costs. MSE approaches with both Class B and Class 1 backfill materials should be routinely used in future CDOT projects with documentation of their performance and cost (construction and repair costs) for a future evaluation. Comprehensive recommendations are presented to mitigate the observed bridge approach settlement problem; the most important recommendations are for improved support and drainage systems for the sleeper slab where the settlement problem occurs.

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