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Determination of shear wave velocity and shear modulus estimation of peat soil using seismic geophysical method

Determination of shear wave velocity and shear modulus estimation of peat soil using seismic geophysical method

by using multi-channel analysis of surface wave (MASW) method and seismic refraction method. The estimation of shear modulus is based on shear wave velocity and soil bulk density using the sampler with 0.5 m depth each. Peat sampler was used to verify the soil profiles at every location except for soft clay. The shear wave velocity for peat is ranging from 26.02 – 95.89 m/s. Meanwhile, for soft clay, it has velocity from 61.25 – 86.37 m/s. As for shear modulus of peats, the range is between 0.82 – 7.26 MPa while for soft clay, the range is between 7.29 MPa – 13.92 MPa. The variations of shear wave velocity and shear modulus of peat are due to the differences in peat soils properties in term of organic content, fibre content, void ratio and moisture content for every research location. Furthermore, seismic attenuation in peat is also affected the seismic wave velocity. The dynamic behaviour of peat and soft clay have slight changes in shear wave velocity. However it has significant difference in shear modulus due to the existence of organic content that contributes to their differences. Shear wave velocity was obtained by applying seismic refraction method. The data shows the increment of velocity with depth. The determination of dynamic behaviour of peats was achieved by using seismic geophysical method have shown good findings.
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Post cyclic behaviour of Malaysian peat soil

Post cyclic behaviour of Malaysian peat soil

Peat is known as a one of the most problematic soil in the construction industry. Construction on peat soils has proven to be a challenging task to civil engineers since this soil type has a very low bearing capacity and the settlement is high. Conversion and draining of peatland for construction, infrastructure, housing and industrial projects are occurring at an alarming technology to solve the maintenance issue after construction that increase significantly. The peat layers itself in the subsoil lead to irregular subsidence of roads, railways and foundations. In settlement analysis, it is often that the long term compressibility parameters of peat is underestimated or neglected. This situation can lead to problem regarding on the structure stability in the future. For many years, in road design as an example, conventional method was applied in designed the road by considering soil shear strength through static load and do not take into account the vehicular dynamic loading and shear strength thereafter. Shafiee et al., (2013) in prior study was investigated volume change characteristics of peats associated with cyclic loading. The researcher has stated that, the pore pressure generates during cyclic loading relatively low and undergoing cyclic softening and induced strength lost but not has been formally investigated. This research carried out to investigate the post-cyclic behaviour of peat soil and changes in shear strength accordingly.
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Effects of decomposition on the compressibility of fibrous peat   A review

Effects of decomposition on the compressibility of fibrous peat A review

The compressibility and consolidation behaviour of peat is quite distinct from other soils since its response is greatly influenced by the size, shape, fabric and arrangement of the constituent fibres (Mesri and Ajlouni, 2007; Wong et al., 2009; O’Kelly, 2009) and requires special considerations in laboratory testing procedures and interpretation of results. Peat is extremely compressible under loading, experiencing high initial rates of primary consolidation and substantial creep (Landva and La Rochelle, 1983; Santagata et al., 2008; Wong et al., 2009), with the creep component often greater than the primary consolidation (hydrodynamic) component (Farrell, 2012). In addition to the secondary compression component (i.e. strain increasing in direct proportion to logarithm of elapsed time), a tertiary compression stage usually occurs for fibrous peat, in which case the creep strain rate can increase substantially (Dhowian and Edil, 1980); the higher the fibre content, the greater the tertiary strain (Colleselli et al., 2000; Wong et al., 2009). The compression behaviour of peat generally deviates significantly from Terzaghi’s consolidation theory, which strictly means that geotechnical methods intended for analysing the compression response of mineral soils are inapplicabile for peat (Ng and Eischens, 1983; Hobbs, 1986; Wong et al., 2009; Farrell, 2012). Peat generally has high values of primary compression index (C c ), secondary compression index (C α ) and of the C α /C c ratio (Mesri and Ajlouni, 1997;
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Dynamic behaviour of Western Johore Peat, Malaysia

Dynamic behaviour of Western Johore Peat, Malaysia

Most of the past researchers have conducted investigations on the dynamic loading of soft soils such as sand and clay but there are still lacks of information on discovering the behaviour of peat in terms of static and dynamic loadings. Hence, this paper presents the dynamic behaviour of Western Johore peat pertaining to four different effective stresses which are 13kPa, 25kPa, 50kPa and 100kPa by using 1Hz loading frequency. The main objectives of this study is to establish the shear modulus and damping characteristics of Parit Nipah peat and Pontian peat located in West Johore, Malaysia. The Index Properties test, Monotonic Triaxial test and Cyclic Triaxial Test have been performed to determine the parameters required by using one way loading and stress-controlled method. All tests were conducted in the laboratory in Research Centre of Soft Soil, Universiti Tun Hussein Onn Malaysia. The analysis describes that the variation of shear modulus increase as the effective stresses increases from 200kPa to 1200kPa for PNpt and from 100kPa to 1150kPa for POpt. Meanwhile, the damping ratio shows a reduction when effective stresses increases from 0.25 to 0.03 for Parit Nipah peat. Besides, damping ratio of Pontian peat reduce from 0.30 to 0.05. For a better comprehension of the subject, further investigations on dynamic loading of peat soil required to critically identify the consequences on dynamic parameters.
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Instrumented physical model studies of the peat soil engineering structure interaction

Instrumented physical model studies of the peat soil engineering structure interaction

The unique characteristics of peat have led to the problems of the construction (Hashim and Islam, 2008a). Melling (2009) stated that peat is one of the softest and problematic soils and it is subjected to instability and massive primary and long-term consolidation settlements. Huat (2004) stated that peat are commonly occurring as extremely soft, wet unconsolidated surficial deposits that are integral parts of the wetland systems. This peat soil also has the mechanical behaviour which is different from the other mineral soils such as clay which is high porosity, extremely compressible, strong dependence on permeability and porosity, large change in properties under stress, high degree or spatial variability in properties, fibrosity and high strength due to fibre reinforcement. Hence, peat is considered unsuitable for supporting the foundation in its natural state (Hashim and Islam, 2008a). The content of peat soil varies from location to location due to the factor such as origin fibre, temperature and humidity (Huat et al, 2009).
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Soil archives of a Fluvisol: subsurface analysis and soil history of the medieval city centre of Vlaardingen, the Netherlands – an integral approach

Soil archives of a Fluvisol: subsurface analysis and soil history of the medieval city centre of Vlaardingen, the Netherlands – an integral approach

System 6: the (dark) grey to grey black silty clay with peat banding and humus staining, which resembles similar inter- preted shallow-water flood basin deposits in previous sys- tems has a significantly higher proportion of EM1 + EM2 (∼ 27 %). EM3 and EM4 are similar in this anthropogeni- cally influenced deposit. Grey silty clay resembles deeper flood basin deposits with a dominant EM3 proportion and with EM1 + EM2 being ∼ 19 %. Especially the remaining deposits of sand, (humic) sandy clay, clayey sand, and silty sand vary from entirely grey to various colours and have ex- tremely high proportions of EM1 + EM2 of 60–90 % (Ta- bles 3, 4). Observations of the carbonate content and compar- isons with lower systems show that system 6 has significantly lower carbonate values (Table 4). This may be due to the fact that soil-forming processes were going on when this mate- rial was exposed after it was piled up. An alternative option would be that the material from system 6 is transported from elsewhere with a substrate with a lower carbonate value. The very coarse nature of the grain size may support the latter explanation.
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Geotechnical Characteristics of Peat

Geotechnical Characteristics of Peat

Shear strength is a fundamental property required in geotechnical design and analysis. Various researchers have studied this property and the reported results indicate important differences in behaviour from inorganic soils both qualitatively and quantitatively. Haan (1997), reported that both undrained shear strength and effective strength parameters of many peats increase with increasing water content or decreasing unit weight. This result seemingly supports the intuitive behaviour that can be attributed to the fiber effects and the fact that the fiber content, in general, increases with increasing water content and decreasing unit weight.
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Vacuum Consolidation in Peat

Vacuum Consolidation in Peat

PRINCIPLES OF VACUUM CONSOLIDATION • Vacuum consolidation is a construction method used to accelerate ground settlement by reducing the air pressure at the ground surface.. • Normally at[r]

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A review of techniques for monitoring the success of peatland restoration

A review of techniques for monitoring the success of peatland restoration

Surface or peat-dwelling invertebrates can be collected in peat monoliths or cores and the invertebrates extracted in the lab from dry or wet peat. Microfauna (e.g. protozoa), and mesofauna (e.g. Rotifers, Tardigrades, Nematodes, Enchytraids) can be extracted from soil and peat by techniques described in more detail in Coleman et al. (1998). Soil animals play an important role in ecosystem element cycling. By `pre-digesting' large amounts of detritus they facilitate further decomposition of the substrate by soil microbes (e.g. Standen, 1978). On peatland sites, the hydrological component of the habitat is often regulating the abundance of soil fauna: the higher the water level, the smaller the soil fauna populations (Kozlovskaja, 1974; Standen and Latter, 1977; Markkula, 1981; 1982; Vilkamaa, 1981). Also, on pristine mires the litter material is often mostly Sphagnum moss remains that are of low quality from the soil invertebrate viewpoint (Smirnov, 1961; Latter and Howson, 1978). Thus these invertebrates may be important indicators of habitat and site restoration success. Enchytraid worms, for example, have been determined using the wet funnel method of O’Connor (1962) and numbers were found to relate to both temperature and DOC in upland blanket bog (Cole et al. 2002). Recently, Carrera et al. (2009) have shown that enchytraeids are a crucial control on peatland C fluxes in response to warming. They may therefore by relevant to peatland restoration relative to potential impacts of climate change. Also, van Dijk (in press) determined soil community composition in restored peat meadows with different groundwater levels and soil pH. They found that Community composition of microorganisms, Collembola and Enchytraeidae differed considerably between meadows and were correlated with differences in groundwater levels and soil pH. Collembolan and enchytraeid species from wet and neutral environments were more abundant at meadows with higher groundwater levels. Lower fungal to bacterial PLFA ratios and higher numbers of protozoa indicated an increased importance of the bacterial part of the food web at meadows with higher groundwater levels. Food web model calculations suggested that the observed changes in community composition would lead to higher rates of C and N mineralization at meadows with high groundwater levels. They concluded that understanding changes in soil community composition in response to specific restoration measures may help us to better understand ecosystem responses to wetland restoration schemes, especially regarding soil biogeochemical processes. For information on restoration measures to rehabilitate microinvertebrates in raised bogs see Van Duinen et al. (2004).
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High-Resolution Atmospheric Lead Pollution during the Roman Period Recorded in Belgian Ombrotrophic Peat Cores

High-Resolution Atmospheric Lead Pollution during the Roman Period Recorded in Belgian Ombrotrophic Peat Cores

cumulative, anthropogenic, atmospheric lead deposition using peat cores from bogs: Pb in 588. eight Swiss peat bog profiles[r]

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Relationships between humification and productivity in peat based and peat free growing media

Relationships between humification and productivity in peat based and peat free growing media

In order to estimate the nitrogen supplying ability, the proportion of the hydrolyzable nitrogen in rela- tion to the total nitrogen was determined. It was found that the mixture of low-moor and high-moor peat had the most favourable nitrogen-supplying ability, because the proportion of the hydrolyzable nitrogen was highest in this medium (Fig. 1). Correspondingly, the yield of green pepper was highest when grown on this medium, albeit the difference between the mixture of the two types of peat and the low-moor peat was not significant in that respect (Fig. 2). Dur- ing the vegetation period, with decreasing content of hydrolyzable nitrogen content, the yields decreased. In green waste compost, significantly lower yields were recorded; this apparently resulted from its lower hydrolyzable nitrogen content and from the fact that humificated composts could not preserve their stable structure during the whole vegetation period. According to Dickinson and Carlile (1995) the decrease of the structure stability was faster in all organic peat-free media than in peats because the microbiological activity of peat-free materials was more intense. Under greenhouse conditions the frequent irrigation and high temperature provided favourable environment for microorganisms.
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Influence of Leadership Behaviour, Academic Culture and Innovative Behaviour in Effective Teaching of Lecturers

Influence of Leadership Behaviour, Academic Culture and Innovative Behaviour in Effective Teaching of Lecturers

particular and the Indonesian education method and this innovative Behaviour will also invite other lecturers to keep trying to support and improve educational methods in general. The most recent method at this time is the online teaching method because this innovation is very popular with millennials. This must be accommodated by schools and especially universities because it will provide more effective learning motivation and ultimately will also improve effective teaching. If this is improved, it will produce reliable, quality graduates in the future. This research still needs to be developed by adding better and more accurate variables to be implemented so that the final results of Teaching Effectiveness can be achieved to the maximum.
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Peat initiation in the Faroe Islands: climate change, pedogenesis, or human impact?

Peat initiation in the Faroe Islands: climate change, pedogenesis, or human impact?

was selected on the island of Sandoy (Figs 1 and 2) where a large area of blanket peat extends across a wide valley, glacial in origin, around Sto´ravatn and Lı´tlavatn (literally ‘large lake’ and ‘small lake’). The valley floor runs from about 25 m above sea level (asl) at its western end, where it terminates in cliffs at the coast, to about 75 m asl at the watershed with the next valley to the east. The valley is surrounded by steep, stepped slopes, with surrounding peaks between c. 400 and 480 m asl; soils on the steep slopes are thinner and more minerogenic than the thick peats on the floor of the valley, which range up to more than a metre in thickness. At one location at least (Millum Vatna, literally ‘between the lakes’) the peats are underlain by limnic sediments rather than the more usual regolith. Numerous streams and rivers carry water and sedi- ment down from the surrounding hills; the primary drainage system runs through the two lakes and terminates in a water- fall at the coastal cliffs. The vegetation on the peats consists of a mosaic of communities, with Carex, Sphagnum and Eriopho- rum angustifolium dominating in the wettest areas, and Calluna vulgaris, Potentilla erecta, Nardus stricta, Festuca vivipara and other grasses on drier peats. Grass moorland vegetation dominates on more minerogenic soils (Fosaa 2001). There is evidence of peat cutting in the past, but today the valley and surrounding hills are primarily used for rough grazing. Known archaeological remains are limited to a number of ruined walls or field banks and several structures that may have been shielings or for stock control (Lawson et al. 2005).
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Consolidation parameters of reconstituted peat soil: oedometer testing

Consolidation parameters of reconstituted peat soil: oedometer testing

Peat soil is a dark brown soil and a mixture of fragments of fibrous organic materials partly from decomposed plant matter remains and undergoes chemical and physical reactions. Peat can be found throughout the world and Malaysia is included. Malaysia has about 25,000 km 2 of peat land and Leete (2006), as cited in [8] has stated about 228,960ha of peat were located in Johor. This type of soil are unsuitable to resist loads and generally unable to perform for most engineering projects in their natural state [5]. Whitlow [13] highlighted that the peat soil has high of compressibility of with range of 0.9 – 1.5, high in moisture content (may up to 1000%); high organic content (>75%) and high fiber content which poses serious settlement issue. The permeability and bearing capacity of the soil is low and thus unable to withstand heavy loads. The soil will have an excessive settlement and the settlement occurs for a long period of time. For site investigation, the difficulty is based on soil sampling purposes and this due to the behavior of peat soil which is extremely soft and has high moisture content and hence, it requires meticulous work to collect the soil sample in a natural condition. The normal sampling process to obtain undisturbed sample is almost impossible to be conducted. The process of obtaining undisturbed samples using ‘block sample’ technique was only the other best option to obtain the undisturbed sample. However, the technique is only limited to obtain samples at shallow depth.
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Formulation of Trichoderma Based Biopesticide for Controlling Damping off Pathogen of Eggplant Seedling

Formulation of Trichoderma Based Biopesticide for Controlling Damping off Pathogen of Eggplant Seedling

substrates while used for mass multiplication of Trichoderma isolates. Another study showed that black gram bran gave the highest cfu both in room and freezing temperature up to 210 days after inoculation with Trichoderma harzianum and peat soil [25]. Several other workers also used different agro-products for multiplication of Trichoderma sp. but they did not include peat soil based black gram brans in their study [33, 34].The peat soil based Trichodermal formulation were evaluated in the nursery house against Sclerotium rolfsii for the management of eggplant seedlings. The data recorded on percent seed germination, post-emergence damping off, pre-emergence damping off, tip over, plant height and vigor index of at different days after sowing (DAS). In case of eggplant seedlings, the results revealed that the treatment T 5
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Impact of long term drainage on summer groundwater flow patterns in the Mer Bleue peatland, Ontario, Canada

Impact of long term drainage on summer groundwater flow patterns in the Mer Bleue peatland, Ontario, Canada

Piezometers were constructed from 2.6 cm ID PVC pipe screened with 55 round inlets of 35 mm diameter each per piezometer, distributed over a 10 cm interval and covered with a nylon mosquito mesh. The length of the screened sec- tion was chosen according to Waddington and Roulet (1997). The design provided 26 % inner-diameter screening, or “in- take”, area (see Supplement, Fig. S1, for images). A total of eleven piezometer nests (P1–P11, Fig. 1) were installed across the transect in hollows 0, 3, 15, 30, 60 and 200 m dis- tance from the ditch at depths of 0.25, 0.50, 0.75, 1.0, 2.0 and 3.0 m, where peat depth permitted. Two additional piezome- ters were installed at the ditch and at the 3 m Forest site at 1.75 and 2.25 m depth. Additional piezometer nests were in- stalled; one at 600 m distance west of the ditch at the Bog and two piezometer nests at both sides at 45 m and 30 m distance perpendicular from the ditch and the transect, respectively. All piezometers were “developed” (Baird et al., 2004) be- fore any other measurement by pumping them empty at least once, depending on an examination of the sediment load in the extracted water; additional pumping preceded the deter- mination of hydraulic conductivity by slug tests (see below). Before hydraulic head measurements were carried out, the rebound of water tables to previous equilibrium levels was awaited. Hydraulic head was monitored with an electric dip stick every two to nine days. The most shallow, yet water- filled piezometer was used to approximate water table posi- tion, as referred to hereafter, which was always within 15 cm of a slotted portion of a shallow piezometer. Two potentio- metric water level loggers, reading every half-hour, were in- stalled in piezometers with slotted heads at 0.75 and 2.0 m depth at the 200 m sites of the transect. An atmospheric pres- sure sensor allowed for barometric compensation of the wa- ter level loggers.
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Dwelling on peat; fissures as a recurrent feature of prehistoric stuctures built on peat in the Western Netherlands

Dwelling on peat; fissures as a recurrent feature of prehistoric stuctures built on peat in the Western Netherlands

b. Subsurface erosion must have aggravated the subsidence of the peat and occupation layers within farmsteads surviving above the erosive zone. After retraction of the waler these layers slowly sank down and tilted as coherent levels in some places. However the tilting can Only bc partially the result of this process, as witnessed by MD site 16.10 and site Q for example. In othcr parts within a building the floors lost their coherence and were broken up into chunks and pieces. Moreover the washing down of ash and dung to the deepest levels, which was noted often, is probably also a post-depositional feature. Clearly the postdepositional processes alone cannot explain why the subsurface erosion always resulted in 'faults' along longitudinal axis, always more or less the same way and the same place. This must be duc to already existing conditions, that is to previously formed differences in subsidence and density of the occupation layers within the farmstcad. These conditions detennined the specific influence of post depositional processes on the occupational remains.
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Chemical properties of small peatlands deposits (Eastern Polesie)

Chemical properties of small peatlands deposits (Eastern Polesie)

lands, an attempt was made to determine the state of preservation of peat forming processes as a condition for the proper functioning of those areas. By addressing this question, we hoped to determine whether the peat bogs and mires of the Łęczna-Włodawa Plain currently act as carbon sources. The aim of the present study was to compare the ash content and the contents of selected macro- and micronutrients in the deposits. The research was carried out in the years 2010-2013 and covered eight peatland areas (three mid- field and five mid-forest peatlands). The ash content, as well as the content of biogens, and selected macro- and micronutrients of the studied deposits varied and depended on the type of the depos- it forming a given layer. In all the studied deposits, the carbon content was high, especially in the transitional Sedge-Sphagnum peat and the raised pine peat. The marsh layers, in relation to the studied peat minerals and gyttja, were characterized by a lower carbon content, and the restriction of C:N and N:P ratios. In all the studied peat bogs, located in the Łęczna-Włodawa Plain, the accu- mulation phase dominated, so they do not act as carbon suppliers. Ke y w o r d s: organic deposits, macronutrients, micronutri- ents, lithology
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Strength Changes in Peat-Polymer Stabilization Process; An Introduction of New Material for Peat Condition

Strength Changes in Peat-Polymer Stabilization Process; An Introduction of New Material for Peat Condition

Abstract: Peat is known as a kind of soft soil that subjected to instability. In order to reduce the scarcity of land for construction purpose, it is necessary to stabilize a soft and weak foundation such as peat. The engineers commonly faced with the constraint of accessibility and stability problem when dealing with peat. This paper describes a study on peat stabilization to enhance its strength by using an organic polymer soil stabilizer. To identify the strength change for the stabilization of peat by using Vinyl Acetate - Acrylic Copolymer (VAAC), laboratory tests on unconfined compression test was performed for 1, 7, 14 and 28 days of curing periods. The additive that works as a binder material such as sand, lime and cement were used in this study. The effect of this additive on the strength gained based on percentage materials used is highlighted. The unconfined compression test results showed that the peat soil gained higher strength due to the addition of 70% of VAAC at 14 days of curing periods. The VAAC have a greate mechanism to agglomorate the fibre together because VAAC can cementing the fibre during the dying process by forming clear plastic and resin bond. Hence, the solid bond produced the hard surface that flexible to withstand the load exerted. The addition of 30%, 50% and 70% binder into stabilized peat with 20% and 70% of VAAC were reduced the strength of VAAC-P because of the disturbance occurred in the VAAC-P bonded.
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Constitutive models for peat   A review

Constitutive models for peat A review

The 3D creep model should be a straightforward extension of the 1D creep model, but this is hampered since current 1D isotache models have not been formulated as differential equations. The Soft Soil (SS) and Soft Soil Creep (SSC) models [43, 46] implemented in the PLAXIS finite element code are proposed to deal with soft soils; e.g. near normally- consolidated clays, clayey silts and peat. These models formulate a constitutive law in differential form to solve transient or continuous loading problems. In essence, the SSC model is an isotache model. Having determined the ellipses in the p-q stress plane (Figure 6) from the modified Cam-Clay model [41] , an equivalent pressure p eq , in the form of Eq. 2, has been defined. The elastic part of the total strain rate employs Hook‟s law and the equivalent pressure p eq is taken as a plastic potential function for deriving individual creep strain-rate components. Osorio Salas [40] used the SS and SSC models incorporated in PLAXIS to back- analyse vacuum consolidation test data for a pseudo-fibrous peat deposit and reported acceptable results for predicted vertical displacements, although these models overestimated the ground heave measured following removal of the vacuum pressure. The parameters of the SS and SSC models can be determined either from isotropic compression tests or oedometer testing.
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