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At-rest and compaction-induced lateral earth pressures of moist soilsIshihara, Katsuji 12 July 2007 (has links)
An instrumented oedometer was designed and constructed for the purpose of investigating at-rest and compaction-induced earth pressures in moist soils. The device has a split oedometer ring, and horizontal stresses are measured using load cells which support one half of the ring. Rapid cyclic loading was applied to compacted soil specimens, using a digital pressure regulator and a computer-based data acquisition system. The performance of the device was validated by performing tests on silicon rubber and Monterey sand. / Ph. D.
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Soil stabilization by microbial activityPaulse, Arnelia N. (Arnelia Natalie) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Microorganisms play an important role in the stability and maintenance of the
ecosystem and in the condition of the soil. However, in their natural environment,
microorganisms often experience changing and hostile conditions. They therefore
need to be able to adapt physiologically and modify their micro-environment. Biofilm
formation is one mechanism to establish favorable micro-environments. The
extracellular polymeric substances (EPS) that are typically associated with biofilm
formation may also have an impact on soil structure. The aim of this project was to
evaluate the potential of microbial manipulation on EPS production and the possible
impact thereof on soil structure in order to improve water retention.
Specific objectives of this study included the screening of natural environments for
EPS-producers, developing techniques to observe EPS production and accumulation
in the pores between soil particles, measuring the effect of EPS production on soil
water hydraulic gradient, as well as determining the fate and impact of EPS-producers
when introduced to naturally-occurring soil microbial communities. Several
environmental samples have been screened for EPS-producing microorganisms. Soil
columns were then inoculated with these EPS-producers and the passage of 20 mlaliquots
water through the columns measured at 3 or 4-day intervals. Microbes
isolated from soil, through their EPS production capability proved to retain water
more effectively than was the case for water-borne EPS-forming microbes. This
phenomenon was further studied using flow cells, filled with soil and inoculated with
the EPS-producers isolated from either soil or water. Fluorescence microscopy
showed that the soil microbes produced EPS that clogged pores between sand
particles more effectively. This clogging resulted in lowering the soil water hydraulic
gradient. To evaluate the effect of EPS-producers on existing soil microbial
communities, cell counts, Biolog™whole-community carbon utilization studies and
T-RFLP (terminal-restriction fragment length polymorphism) analyses were
performed. Shifts in the soil microbial community could not be readily seen by
observing microbial numbers and T-RFLP-analysis, but was noticeable in carbon
utilization patterns. / AFRIKAANSE OPSOMMING: Mikroorganismes speel 'n belangrike rol in die stabiliteit en instandhouding van die
ekosisteem en in die kondisie van die grond. In hul natuurlike omgewing ervaar
mikroorganismes dikwels veranderlike en ongunstige toestande. Mikroorganismes
het dus nodig om hulself fisiologies aan te pas en verander hul mikro-omgewing
daarvolgens. Biofilm-vorming is een meganisme om gunstige mikro-omgewings te
skep. Die ekstrasellulêre polimeriese produkte (EPP) wat tydens biofilm-vorming
gevorm word, mag ook 'n impak hê op die grondstruktuur. Die doel van hierdie
projek was om die potensiaal van mikrobiese manipulasie op EPP-vorming te
evalueer asook die moontlike impak daarvan op grondstruktuur wat sodoende
waterretensie kon bevorder.
Die spesifieke doelwitte van hierdie studie het ingesluit die isolasie van EPPproduseerders
vanuit natuurlike omgewings, die ontwikkeling van verskeie tegnieke
waarvolgens EPP-produksie en die akkumulasie daarvan in die porieë tussen
gronddeeltjies bestudeer kon word, die effek van EPP-produksie op hidrouliese
gradiënt van grondwater en om die lot en impak wat EPP-produseerders op natuurlike
grondmikrobiese populasies te bepaal. Verskeie grond- en watermonsters was getoets
vir die voorkoms van EPP-produserende mikroorganismes. Grondkolomme is
geïnokuleer met EPP-produseerders en die vloei van 20 ml-volumes water deur die
kolomme is gemeet met 3 of 4-dag intervalle. Grond-geïsoleerde mikrobes het beter
waterretensie tot gevolg gehad as water- geïsoleerde mikrobes. Hierdie verskynsel
was verder bestudeer deur die gebruik van vloeiselle, gevul met grond of sand en
geïnokuleer met EPP-produseerders geïsoleer vanuit grond of water. Fluoressensie
mikroskopie het aangetoon dat grondmikrobes EPP produseer wat die porieë tussen
gronddeeltjies meer effektief verstop. Dié verstopping het gelei tot die verlaging van
die grondwater se hidrouliese gradiënt wat bepaal is deur die gebruik van die
konstante-vlak bepalingsmetode. Om die effek van EPP-produseerders op bestaande
mikrobiese populasies te bepaal, is seltellings, Biolog™ heel-gemeenskap koolstofverbruik
studies en T-RFLP (terminale-restriksie fragment-lengte polimorfisme)
analises uitgevoer. Veranderinge in die mikrobiese populasie kon nie geredelik bloot
deur die bepaling van mikrobiese getalle en T-RFLP-analise waargeneem word nie,
maar wel met die koolstofverbruikspatrone.
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A framework of a national slope safety system for MalaysiaJaapar, Abd Rasid Bin. January 2006 (has links)
published_or_final_version / abstract / Applied Geosciences / Master / Master of Science
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Engineering behaviour of Hong Kong marine clay during vacuum preloadingSo, Tze-chung., 蘇子頌. January 2009 (has links)
published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
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Soil nailing: a robust design for joint-controlled weathered rock in Hong KongLee, Chun-fai, Julian., 李俊暉. January 2003 (has links)
published_or_final_version / Applied Geosciences / Master / Master of Science
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Mini piles design and construction in current engineering practiceYiu, Wai-kei, Ricky., 姚偉基. January 2001 (has links)
published_or_final_version / Applied Geosciences / Master / Master of Science
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An accelerated conjugate direction procedure for slope stability analysisMusa, Zulkarnain, 1964- January 1988 (has links)
CSLIP2 (De Natale, 1987) is the only slope stability program that utilizes a "direction set" optimization routine in its search for the minimum safety factor. However, CSLIP2 which employs Powell's Conjugate Direction Method permits only the horizontal and vertical directions (x and y) to be used as the initial direction set. The efficiency of the existing search routine is improved by replacing the x-y coordinate directions with initial directions that are parallel to and perpendicular to the principal axis of the safety factor contours.
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Stockpile life of foam stabilised material and the implications for labour intensive constructionChasi, Brian Takaona January 1998 (has links)
A project report submitted to the Faculty of Engineering, University of the
Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree
of Master of Science in Engineering. Johannesburg 1998. / Various studies have been done to show that labour-based construction can meet the
high standards normally required in the construction of roads. The organisational
requirements that were needed to ensure the efficient use of labour have also been
dealt with in various studies. Tile need for alleviation of poverty, unemployment and the
negative social impact thereof by increasing the labour input in construction is
understood by all concerned.
A further step is however necessary before the idea of increasing the . labour
component in any kind of roadwork can be taken seriously. Engineers need to move
forward from the policy and organisational issues associated with labour intensive
construction and start to provide designers with sound and innovative engineering
solutions to overcome the hurdles experienced on the ground.
The study looks at the process of foam bitumen stabilisation of soils and gravels with
a view of utilising this innovative method for labour intensive construction. The material
after having been stabilised can be placed in a stockpile. Actual durations that the
material can safely remain in stockpile have been determined in this study to be in
excess of six months for recycled asphalt and in excess of four months for the foam
stabilised sand. Foam stabilised gravel was also studied and showed that after a year
in stockpile the material failed probably due to a weakening of the bitumen and
aggregate bond. Covering the stockpiled material did not show any significant
difference to that of a similar uncovered stockpile. The position within the stockpile also
did not have much effect on the engineering properties of the stoc piled material.
The fact that the foam stabilised material can be worked on when cold and that it can
be stockpiled for several months implies that the material is labour friendly and can be
used in labour intensive construction of road base course layers or wearing course
layers. / AC2017
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The use of chemical stabilisers in labour intensive road construction.Van Steenderen, Willem Pieter Cornelis January 1995 (has links)
A project report submitted to the Faculty of
Engineering, University of the Witwatersrand in
partial fulfilment of the requirements for the degree
of Master of Science in Engineering. / Until recently use of ionic chemical soil stabilisers
seemed hit or miss. The paper by paige-Green and
Bennett explains that the stabilisers work only on
soils containing reactive clays. The author's findings
confirm this conclusion. It was shown that a CBR test,
which can be done in any road soils laboratory, can be
used to measure the chanqe in strength caused by the
treatment of the soil with a chosen ionic stabiliser.
South Africa is faced with a serious unemployment
problem. The World Bank and the International Labour
Organisation have shown that employment in construction
can be significantly increased by the use of labour
instead of machinery. Field trials showed that ionic
stabilisers can readily be applied labour intensively.
These stabilisers could improve marginal materials to
road-building standard and this could further reduce
the dependence on machinery by reducing the need to
transport quantities of high quality gravel. / Andrew Chakane 2019
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Soil water supplying capacity as a factor affecting revegetation of cut slopes.January 2007 (has links)
Chiu, Ming Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 139-155). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.v / Table of Contents --- p.vii / List of Tables --- p.xi / List of Figures --- p.xiii / List of Plates --- p.xiv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Environment of Hong Kong --- p.1 / Chapter 1.1.1.1 --- Flat land area --- p.1 / Chapter 1.1.1.2 --- Population --- p.2 / Chapter 1.1.1.3 --- Climate --- p.2 / Chapter 1.1.2 --- Landslides in Hong Kong --- p.4 / Chapter 1.1.2.1 --- Landslide history --- p.4 / Chapter 1.1.2.2 --- Government actions on landslide prevention --- p.7 / Chapter 1.1.3 --- Slopes in Hong Kong --- p.8 / Chapter 1.1.4 --- Slope stabilization --- p.10 / Chapter 1.1.4.1 --- Conventional methods of slope stabilization --- p.10 / Chapter 1.1.4.2 --- Biotechnical stabilization --- p.13 / Chapter 1.2 --- Situation in Hong Kong --- p.16 / Chapter 1.2.1 --- Slope protection in the past --- p.16 / Chapter 1.2.2 --- Government action on improving slope appearance --- p.16 / Chapter 1.2.3 --- Proprietary slope greening techniques --- p.19 / Chapter 1.3 --- Vegetation growth on slopes --- p.22 / Chapter 1.3.1 --- Basic requirements of plants --- p.22 / Chapter 1.3.2 --- Potential problems of proprietary systems on shotcreted cut slopes --- p.24 / Chapter 1.3.2.1 --- Steep gradient --- p.24 / Chapter 1.3.2.2 --- Thin soil --- p.24 / Chapter 1.3.2.3 --- Rainfall seasonality --- p.25 / Chapter 1.4 --- Current study --- p.26 / Chapter 1.4.1 --- Objectives --- p.26 / Chapter 1.4.2 --- Significance --- p.26 / Chapter 1.4.3 --- Thesis layout --- p.27 / Chapter Chapter 2 --- Soil water status and vegetation of cut slopes --- p.30 / Chapter 2.1 --- Introduction --- p.30 / Chapter 2.2 --- Materials and methods --- p.36 / Chapter 2.2.1 --- Study site --- p.36 / Chapter 2.2.2 --- In situ measurements and substrate sampling --- p.43 / Chapter 2.2.3 --- Physical properties of substrates on slopes --- p.43 / Chapter 2.2.3.1 --- Slope angle --- p.43 / Chapter 2.2.3.2 --- Substrate thickness --- p.43 / Chapter 2.2.3.3 --- Soil moisture --- p.43 / Chapter 2.2.3.4 --- Soil texture --- p.43 / Chapter 2.2.3.5 --- Bulk density --- p.44 / Chapter 2.2.3.6 --- Water retention capacity --- p.44 / Chapter 2.2.4 --- Chemical properties of substrates on slopes --- p.44 / Chapter 2.2.4.1 --- pH --- p.44 / Chapter 2.2.4.2 --- Conductivity --- p.45 / Chapter 2.2.4.3 --- Organic matter --- p.45 / Chapter 2.2.4.4 --- Total Kjeldahl nitrogen --- p.45 / Chapter 2.2.4.5 --- Mineral nitrogen (ammonium and nitrate) --- p.45 / Chapter 2.2.4.6 --- Carbon:Nitrogen --- p.46 / Chapter 2.2.4.7 --- Total phosphorus --- p.46 / Chapter 2.2.4.8 --- Available phosphorus --- p.46 / Chapter 2.2.4.9 --- Major extractable cations --- p.46 / Chapter 2.2.5 --- Green coverage on slopes --- p.46 / Chapter 2.2.6 --- Statistical analysis --- p.47 / Chapter 2.3 --- Results --- p.47 / Chapter 2.3.1 --- Rainfall characteristics --- p.47 / Chapter 2.3.2 --- Soil moisture --- p.49 / Chapter 2.3.3 --- Green coverage --- p.52 / Chapter 2.3.4 --- Physical properties of substrate on slopes --- p.55 / Chapter 2.3.5 --- Chemical properties of substrate on slopes --- p.57 / Chapter 2.4 --- Discussion --- p.61 / Chapter 2.4.1 --- Soil moisture and vegetation growth --- p.61 / Chapter 2.4.2 --- Soil nutrients and vegetation growth --- p.66 / Chapter 2.4.3 --- Other substrate properties and vegetation growth --- p.69 / Chapter 2.5 --- Summary --- p.75 / Chapter Chapter 3 --- Surface runoff and soil erosion of cut slopes --- p.76 / Chapter 3.1 --- Introduction --- p.76 / Chapter 3.2 --- Materials and methods --- p.84 / Chapter 3.2.1 --- Study site --- p.84 / Chapter 3.2.2 --- Experimental setup --- p.84 / Chapter 3.2.3 --- Surface runoff and soil loss --- p.88 / Chapter 3.2.4 --- Nutrient loss in runoff --- p.89 / Chapter 3.2.4.1 --- Total Kjeldahl Nitrogen --- p.89 / Chapter 3.2.4.2 --- Mineral nitrogen (ammonium and nitrate) --- p.89 / Chapter 3.2.4.3 --- Total phosphorus --- p.89 / Chapter 3.2.4.4 --- Available phosphorus --- p.90 / Chapter 3.2.5 --- Other substrate properties --- p.90 / Chapter 3.2.5.1 --- Soil texture --- p.90 / Chapter 3.2.5.2 --- Bulk density --- p.90 / Chapter 3.2.5.3 --- Soil compaction --- p.90 / Chapter 3.2.5.4 --- Water retention capacity --- p.90 / Chapter 3.2.5.5 --- Organic matter --- p.90 / Chapter 3.2.6 --- Vegetation coverage and green coverage on slope --- p.91 / Chapter 3.2.7 --- Statistical analysis --- p.91 / Chapter 3.3 --- Results --- p.91 / Chapter 3.3.1 --- Meteorological characteristics --- p.91 / Chapter 3.3.2 --- Surface runoff and runoff coefficient --- p.92 / Chapter 3.3.2.1 --- Surface runoff and runoff coefficient between different treatments --- p.92 / Chapter 3.3.2.2 --- Surface runoff and runoff coefficient between different proprietary systems --- p.97 / Chapter 3.3.3 --- Soil loss --- p.98 / Chapter 3.3.3.1 --- Soil loss between different treatments --- p.98 / Chapter 3.3.3.2 --- Soil loss between different proprietary systems --- p.99 / Chapter 3.3.4 --- Nutrient loss --- p.99 / Chapter 3.3.4.1 --- Nutrient loss between different treatments --- p.99 / Chapter 3.3.4.2 --- Nutrient loss between different proprietary systems --- p.104 / Chapter 3.3.5 --- Substrate properties of proprietary systems --- p.104 / Chapter 3.3.6 --- Vegetation coverage and green coverage --- p.107 / Chapter 3.3.7 --- Relationship between rainfall and erosional parameters --- p.110 / Chapter 3.4 --- Discussion --- p.117 / Chapter 3.4.1 --- Surface runoff and runoff coefficient between different treatments --- p.117 / Chapter 3.4.2 --- Relationship between rainfall characteristics and surface runoff --- p.122 / Chapter 3.4.3 --- Soil loss between different treatments --- p.125 / Chapter 3.4.4 --- "Relationship between rainfall characteristics, surface runoff and soil loss" --- p.126 / Chapter 3.4.5 --- Nutrient loss between different treatments --- p.128 / Chapter 3.4.6 --- Surface runoff and erosional losses between different proprietary systems --- p.129 / Chapter 3.5 --- Summary --- p.132 / Chapter Chapter 4 --- Conclusions --- p.134 / Chapter 4.1 --- Summary of major findings --- p.134 / Chapter 4.2 --- Implications of the study --- p.136 / Chapter 4.3 --- Limitations of the study --- p.137 / Chapter 4.4 --- Suggestions for further investigation --- p.138 / References --- p.139 / Appendices --- p.156
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