Radial Drainage Research Articles

Fluvial systems of the drylands of western India: a synthesis of Late Quaternary environmental and tectonic changes

The fluvial systems and landscape of the drylands of western India have preserved evidence of Late Quaternary environmental and tectonic changes. Data on the fluvial systems of Mainland Gujarat, Saurashtra and Kachchh have been synthesised to evaluate the roles of geological factors in the evolution of these drylands. Mainland Gujarat is largely underlain by the flat alluvial plain, and has a structurally controlled fluvial system that originates in the eastern uplands. The fluvial system of Mainland Gujarat shows deeply incised valleys, entrenched meanders, extensively developed ravines and uplifted terraces, which have preserved a Late Quaternary succession of continental (fluvial and aeolian) and marine sediments dating back to ∼125 ka . Marine sediments correspond to the transgressive phases of the last interglacial (∼125 ka) and post-glacial maximum (6 ka) . The overlying alluvial sediments suggest deposition by ephemeral rivers in varied fluvial depositional environments under a semi-arid to sub-humid climatic regime with periods of intense pedogenesis. The sedimentation can be correlated with marine isotopic stages (MIS) 5 and 3. The fluvial sediments are buried under a thick blanket of aeolian sediments, which are indicative of enhanced dune building activity in the Thar Desert and are correlatable to the global arid phase of the last glacial maximum. The post-aeolian tectonic uplift triggered severe erosion of Late Pleistocene sediments and 40– 50 m deep incised fluvial valleys were formed. This erosional phase suggests a resumption of fluvial activity, which coincided with the rapidly rising sea level on the west coast during the Early Holocene. The Holocene marine and fluvial aggradation was initiated within the incised fluvial valleys around 6 ka and continued uninterrupted until ∼2 ka . These sediments now occur as raised valley fill terraces suggesting a Late Holocene uplift further corroborated by low to moderate seismic activity during historical times. The landscape of Saurashtra is marked by flat-topped basaltic (trappean) ridges and a highly varied coastline where a narrow belt of low ridges and cliffs of miliolite limestones and other shore deposits are found. The fluvial system of Saurashtra shows a radial drainage pattern. The channels have steep banks in the hilly regions and show significant deflections before meeting the sea. Evidence of last interglacial high sea levels (∼125 ka) are found on the coastal cliffs of southern Saurashtra in the form of oyster reefs and notches of various types which now occur at higher levels. A net sea level rise of +7 m consistent with the global sea level estimates at 125 ka has been obtained by recent studies after decoupling the tectonic component. Dating of Late Pleistocene and Holocene sea levels on this coast suggest continued uplift of Saurashtra since 125 ka even though the sea level continued to fluctuate. The Holocene high sea submerged a considerable stretch of land including the Okha Rann on the northern Saurashtra coast and isolated patches in and around the river mouths on the southern coast. The short, straight and parallel courses of rivers in the direction of tectonic slope, incised and confined channel belts also suggest a strong component of tectonic uplift. The continental sediments exposed in these river valleys have however remained uninvestigated leading to lack of palaeoclimatic data. A remarkable control of structure on landscape evolution is depicted by the Kachchh peninsula. The fluvial system exhibits the characteristics of drainage flowing along tectonically provided slopes. The overall drainage pattern of Kachchh shows excellent correlation with N–S trending transverse fault patterns. The transverse fault system has brought out changes in the landscape of Kachchh though the Kachchh rift basin evolved along E–W latitudinal faults. The Quaternary deposits occur in the form of miliolite limestones, colluvial and alluvial fans, fluvial sands and silts, and Rann sediments. Significant sedimentologic details on these sediments are lacking. However, the marine incursions seem to correlate with the adjacent Saurashtra and Mainland Gujarat.

The role of mantle plumes in the development of continental-scale drainage patterns: The southern African example revisited

Mantle plumes that precede continental break-up have been postulated to exert a major influence on continental drainage patterns. In this model, a radial drainage develops away from the centre of the plumes, while failed arms of the associated rift system provide conduits for rivers from the continental interior towards the newly formed ocean. This paper summarises drainage evolution in southern Africa from the Permo-Carboniferous to the lower Cretaceous in order to test this model. A major reorganisation of the river system occurred at the time of eruption of the Karoo volcanics, or during subsequent fragmentation of Gondwana. The Karoo and Parana Plumes imposed a first-order imprint on the drainage pattern. The superimposition of the Parana plume pattern on the earlier Karoo plume drainage is responsible for the dominant eastward drainage system from the Early Cretaceous to the present-day. The post-Gondwana river network has been modified by at least three other major factors: structural controls, exhumed ancient land surfaces, and post-Gondwana epeirogenic flexing of the sub-continent and resulting river capture. Understanding the factors responsible for initiation and evolution of continental–scale drainage patterns has important economic implications - for example, the identification of primary sources of diamond placers.

Use of morphostructural analysis to show halokinesis during Mio-Plio-Quaternary in the South-West part of Aquitain Basin

In the South Aquitain sector, salt bodies of varying sizes present two geographical gradients. The first gradient, south to north, associated with the proximity of the Pyrenees shows a decreasing deformation of the structures towards the north. The second gradient explains their increasing depth of burial from the west (extrusive structures) to the east (intrusive structures). This organization has been studied from the western sector (Tercis-Benesse and Bastennes-Louer) to the eastern sector (Viella-Labarthete and Nogaro-Lussagnet). Other more modest structures, revealed by hydrographical anomalies, illustrate halokinetic events during the Quaternary. Then the detailed study of the Geaune dome shows a neotectonic phenomenon dating from the Mio-Pliocene. The radial annular drainage pattern of this structure is guided by recurrent faulting during the Quaternary. Thus the halokinetic dynamics consist in three phases: deformation of the diapirs (overthrusts) during the Oligocene, resuming of halokinesis during the middle of the Miocene and recurrent faulting during the Riss. A model of geomorphological evolution of the domes is then proposed. The first phase (stages of positive relief) is characterized by the centrifugal drainage pattern of the dome. The second phase (stages of inverted relief) is distinguished by the erosion of the center of the structure, by an inversion of the drainage pattern and by the sedimentary accretion in the central depression.

Modelling the Effects of Surcharge to Reduce Long Term Settlement of Reclamations over Soft Clays: A Numerical Case Study

Long-term settlement of reclamations constructed over soft soils may be reduced by the use of temporary pre-loading, although there is often uncertainty over how much surcharge to use, and how long it should be maintained. An elastic visco-plastic constitutive model is described and its application in assessing surcharging strategy for reclamation schemes is discussed. The model is incorporated in a one-dimensional finite difference consolidation analysis with vertical and radial drainage of a multi-layer soil profile. The analysis allows the inclusion of vertical drain resistance, a zone of peripheral smear around the drain, permeabilities that vary with void ratio, and creep both during and after primary consolidation. Drawing on data from the Bothkennar soft clay research site, the model is used to predict settlements beneath a hypothetical test fill, including the creep settlement behaviour when a surcharge is removed after different time periods. The behaviour during primary consolidation is back-analysed using Asaoka’s and the hyperbolic observational methods, and both are found to under-predict the magnitude of the settlement.

Modelling consolidation accelerated by vertical drains in soils subject to creep

The settlement of embankments and reclamations over soft soils is frequently accelerated by the use of vertical drains. The magnitude of long-term settlement is sometimes reduced by the use of surcharge, although there is often uncertainty about how long the surcharge should be maintained to minimise creep movement. The design of vertical drains is generally based on closed-form solutions of Terzaghi's consolidation equation, and rarely takes into account non-linear stiffness and creep of the soil. In this paper a one-dimensional finite difference consolidation analysis is outlined showing how vertical and radial drainage of a multi-layer soil profile in the zone of influence of a vertical drain may be modelled. The analysis allows inclusion of a zone of peripheral smear around the drain and drain resistance, permeabilities may be varied with void ratio, and creep is modelled both during and after primary consolidation. The application of the model is illustrated with back-analysis of field data from construction of an embankment with temporary surcharge over estuarine alluvium.

Modelling consolidation accelerated by vertical drains in soils subject to creep

The settlement of embankments and reclamations over soft soils is frequently accelerated by the use of vertical drains. The magnitude of long-term settlement is sometimes reduced by the use of surcharge, although there is often uncertainty about how long the surcharge should be maintained to minimise creep movement. The design of vertical drains is generally based on closed-form solutions of Terzaghi's consolidation equation, and rarely takes into account non-linear stiffness and creep of the soil. In this paper a one-dimensional finite difference consolidation analysis is outlined showing how vertical and radial drainage of a multi-layer soil profile in the zone of influence of a vertical drain may be modelled. The analysis allows inclusion of a zone of peripheral smear around the drain and drain resistance, permeabilities may be varied with void ratio, and creep is modelled both during and after primary consolidation. The application of the model is illustrated with back-analysis of field data from cons...

Determination of permeability of soils using the multiple piezo-element penetrometer

The current method of determining the hydraulic properties of soils using piezocone penetration test (PCPT) requires the advancement of the piezocone penetrometer to the desired depth and holding (or arresting) it for the dissipation test. In order to obtain the hydraulic properties, one analyses the pore water dissipation test results by two-dimensional or three-dimensional radial drainage consolidation. This conventional procedure is methodologically simple and presents relatively reliable values of permeability compared to other field test methods. However, it is still challenging for field engineers and needs to be improved. The piezocone penetrometer intrudes into the ground with the speed of 2 cm/s. Thus, the test mechanism is a kind of strain-controlled condition with partial drainage. Therefore, the excess pore pressure during the piezocone penetration is a function of the permeability of the soil as well as the stress–strain parameters. Thus, with the proper coupled theory of mixtures which can take into account the coupling of solid and pore water flow, one can predict the permeability of the soil from the pore pressure response during PCPT. In this study, the coupled theory of mixtures of the soil grains and the pore water is used in order to predict the permeability of the soil from the excess pore pressure generated from the multiple piezo-element PCPT ‘on the fly’. An elasto-plastic, finite strain constitutive equation in an updated Lagrangian reference frame is used in this work. Using the proposed method, a reliable value of the permeability of soil is obtained conveniently without the use of the pore pressure dissipation tests. Copyright © 1999 John Wiley & Sons, Ltd

Volcanic geomorphology of northern Viti Levu, Fiji

Analysis of radial, centripetal and gutter drainage in the volcanic region of northern Viti Levu, Fiji, enabled the delineation of several distinct volcanoes, despite the early Pliocene age and considerable later erosion. Three main shields with calderas and several smaller volcanoes are mapped. The results are consistent with some other geological and geophysical facts, but do not support the idea that these volcanoes were dominantly submarine eruptions. The method picks out known centres of gold mineralisation and may be applicable, in conjunction with other techniques, in mineral exploration.

Fractured Well Performance: Key to Fracture Treatment Success

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Summary Best production practice requires the optimum production rate from a well with maximum bottomhole flowing pressure (BHFP). This can be engineered only by reducing pressure losses in the reservoir-flow conduit that comprises the reservoir rock and the near-wellbore completion at or near the perforation. Under most producing conditions, an induced fracture with appropriate geometry minimizes near-wellbore pressure losses very efficiently. This paper explores this role of the hydraulic fracture, which results in many applications under different reservoir conditions. Problems concerning placement of an optimally designed hydraulic fracture and common solutions also are discussed. Introduction The basic objectives of hydraulic fracturing are to increase productivity or injectivity and to improve the efficiency of steam injection in thermal floods. A more fundamental and alternative view to explain the role of induced fracturing comes from Prats'1 contention that hydraulic fractures extend the wellbore radius. There are a few ways to explain the profound implications of extended wellbores.2 The most practical explanation derives from understanding the pressure losses in the area of drainage. Darcy'slaw states that the pressure gradient in the direction of flow is directly proportional to the velocity. This is stated mathematically in consistent unitsby dp/dx=vµ/k, (1) where v=q/A. This relationship also implies that the lower the velocity, the lower the pressure gradient in the path of flow. In radial drainage, with constant volumetric rate, the flow velocity in the radial-flow path is maximum at the wellbore. Fig. 1 explains this point with real dimensions. The velocity at a wellbore of 6-in. radius is 2,000 times that at the entry into the drainage (1,000 ft from the wellbore), assuming negligible fluid entry within this drainage. From Darcy's law, this implies that, at the wellbore perimeter, the pressure gradient is 2,000 times greater than at the drainage surface 1,000 ft from the wellbore. This also suggests that, if the wellbore diameter is increased to 100 ft from 6 in., the entry velocity into this wellbore increases 10 times that at drainage. This translates to a substantial net increase in BHFP by effectively increasing the wellbore radius from 6 in. to 100 ft. Such an increase in the BHFP can be used to produce the well at higher rates; at lower drawdown; or at a combination that considers sand-, water-, or gas-control problems. For a fixed velocity, Darcy's law also implies that the pressure gradient is inversely proportional to the reservoir permeability: the lower the effective permeability of the flowing phase, the higher the pressure gradient. Near the wellbore, permeability is reduced through different radial-damage mechanisms, such as drilling-fluid invasion and production-induced mechanisms (e.g., condensate dropout from gas, solids/fines deposit, sublimation of sulfur, paraffin deposit, and other scale deposits). Consequently, the pressure gradient at the wellbore increases as a result of both increased velocity and the reduced permeability caused by damage. Induced hydraulic fractures not only reduce pressure gradients near the wellbore by increasing the surface area of fluid entry but also inhibit some production-induced-damage mechanisms by reducing drawdown and physically bypassing these damaged areas. In many such production-induced-damagemitigations, fracturing can postpone the need for frequent matrix acid treatments. Fracture Optimization A fracture can be idealized as a slot induced in the rock, possibly open between acid-etched surfaces or filled with proppant to resist closure. It can be shown analytically that the permeability of an open slot is proportional to the square of slot width; this can be presented as k=54.4×10 6w2, (2) where permeability, k, is in darcies and slot width, w, is in inches. The permeability of a 0.01-in.-wide open slot is 5,440 darcies.3Because permeability is inversely proportional to the pressure loss through porous media, the pressure losses at or near the wellbore can be minimized if the fluid flow can be directed through a fracture or a high-permeability slot from the reservoir to the wellbore. Consequently, the extent of this pressure-loss control determines the major fracture properties, such as its physical dimensions and the permeability with or without proppant.

Development of the smear zone around vertical band drains

This study describes the effect of smear on the settlements of soft clay foundations which have been improved by installation of vertical drains. The smear zone propagation around a band-shaped drain was monitored using a large, radial drainage consolidometer. The test results reveal that a significant reduction in the horizontal permeability takes place towards the central drain, whereas the vertical permeability remains relatively unchanged. The estimated smear zone was about 3–4 times the cross-section area of the band-shaped drain (mandrel). In the analysis, the classical axisymmetric solution for consolidation by vertical drain has been converted into an equivalent 2D plane strain analysis. The plain strain model is subsequently applied to a number of embankments stabilized with vertical drains. It is revealed that the inclusion of smear effects improves the settlement prediction significantly.

Analysis of Consolidation Data by a Non-Graphical Matching Method

Abstract Conventionally the laboratory time-compression data from an odometer test are analyzed by graphical methods. This involves the determination of initial compression, δi, total primary consolidation, δ100, and coefficient of consolidation, Cv. The advent of computer-controlled data-logging systems calls for adoption of non-graphical techniques for analysis of consolidation test data. In this Technical Note a non-graphical matching method is proposed for analyzing the time-compression data. The values of δi, δ100, and Cv can be obtained by direct matching with the theory. The computed time-compression curve for this Cv value matches very well with the experimental data in the primary consolidation phase. The proposed method is also applicable to consolidation under conditions of radial drainage. The method will be very useful if the data are collected through computer-driven data-logging systems.

Closure to “Discussion on ‘Consolidation Behavior of Clayey Soils Under Radial Drainage’ by Jiunnren Lai and Roy E. Olson” by A. Sridharan, K. Prakash, and S. R. Asha

Closure to “Discussion on ‘Consolidation Behavior of Clayey Soils Under Radial Drainage’ by Jiunnren Lai and Roy E. Olson” by A. Sridharan, K. Prakash, and S. R. Asha

Discussion on “Consolidation Behavior of Clayey Soils Under Radial Drainage” by A. Sridharan, K. Prakash, and S. R. Asha

A discussion of an article with the aforementioned title, by A. Sridharan, K. Prakash, and S. R. Asha, published in this journal (Vol. 19, No.4, December 1996) is presented. The discussers criticize the authors' statements about a lack of a previously developed curve fitting method. The discussers suggest that the authors' method is tedious to use and appears to yield erroneous results. Discussion is followed by closure from the authors.

Consolidation Behavior of Clayey Soils Under Radial Drainage

Abstract For Barron's degree of consolidation, Ur, versus the time factor, Tr, relationship for soils undergoing consolidation with radial drainage for the equal vertical strain condition, a simple method has been developed to determine the value of the coefficient of consolidation with radial drainage, cr. Theoretical log10(d2e/t) versus Ur curves where de is the diameter of influence and t is the real time for the different known value of cr have been generated. A method has been developed wherein both the theoretical and experimental behaviors of soils undergoing consolidation with radial drainage can be simultaneously compared and studied on the same plot. The experimental log10(d2e/t) versus Ur curves have been compared with the theoretical curves. Effects of initial compression, secondary compression, and duration of load increment are studied. Simple procedures are presented for calculating the values of cr using the experimental log10(d2e/t) versus Ur curves. A comparative study of the coefficient of consolidation and the coefficient of permeability between the cases of vertical and radial drainage has been done.

Evaluation of Cyclic Model Tests on Anchor Piles in Clay

The response of anchor piles in clay subjected to cyclic loading was investigated in a series of tests on small size model piles, 40 cm long and 1.9 cm in diameter, jacked into a reconstituted and normally consolidated clay. Evaluation of the test results focusses upon the degradation of cyclic pile stiffness, the accumulation of permanent displacements, the degradation of cyclic pullout capacity, as well as the short time effects of cyclic loading on the post-cyclic static pile response. The cyclic response of the model piles was correlated to that of the surrounding soil elements, observed in a series of undrained cyclic triaxial tests. In addition, the influence of the small scale of the model piles on the experimental results was assessed through comparison to similar data from large scale model and field tests reported in the literature. Cyclic load and displacement magnitudes, number of cycles and cyclic preshearing were identified as the main factors which control the pile response. The small size of the pile influences the experimental results at low cyclic loading intensities when radial drainage leads to partially drained conditions during cyclic loading.

Excess pore pressure during consolidation and swelling with radial drainage : A. Al-Tabbaa, Geotechnique, 45(4), 1995, pp 701–707

Excess pore pressure during consolidation and swelling with radial drainage : A. Al-Tabbaa, Geotechnique, 45(4), 1995, pp 701–707

Excess pore pressure during consolidation and swelling with radial drainage

Excess pore pressure during consolidation and swelling with radial drainage

Effect of Interfacial Mobility on Thin Film Drainage

Analytical equations for the radial drainage of uniform thin viscous films are obtained in terms of the variation in surface velocities and velocity gradients with position and time. These allow the effect of circulation in the adjacent phases and radial surface or interfacial tension gradients to be allowed for. The resultant coalescence time t c may be estimated from the equation t c= 3πμn 2r 4 f 16fh 2 c where n is given by 4 n 2 = 1 + 3μr d μ dh i 1 + πr 3 r 2fh i ∂σ ∂r h for a drop of radius r d approaching its homophase. Good agreement with available experimental values is obtained for drops resting at a stationary interface or moving along an inclined film.

Case for the Gamburtsev Subglacial Mountains of East Antarctica originating by mid-Carboniferous shortening of an intracratonic basin

Research Article| July 01, 1994 Case for the Gamburtsev Subglacial Mountains of East Antarctica originating by mid-Carboniferous shortening of an intracratonic basin J. J. Veevers J. J. Veevers 1Australian Plate Research Group, School of Earth Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information J. J. Veevers 1Australian Plate Research Group, School of Earth Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1994) 22 (7): 593–596. https://doi.org/10.1130/0091-7613(1994)022<0593:CFTGSM>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J. J. Veevers; Case for the Gamburtsev Subglacial Mountains of East Antarctica originating by mid-Carboniferous shortening of an intracratonic basin. Geology 1994;; 22 (7): 593–596. doi: https://doi.org/10.1130/0091-7613(1994)022<0593:CFTGSM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The present drainage of East Antarctica, with ice radiating from a central dome draped over the thick crust of the Gamburtsev Subglacial Mountains, recapitulates the Early Permian scene, including the south polar paleolatitude. The Permian radial drainage was on the same scale as the present drainage around the thick crust of the Tibetan Plateau. Another high region in Carboniferous- Permian time was the upland of Europe on crust thickened during the Variscan collision to form Pangea. The ancestral Gamburtsev Subglacial Mountains and a central Australian upland may have formed because of long-distance stress from the Variscan collision acting on zones of weak crust attenuated during prolonged subsidence of intracratonic basins. The mid-Carboniferous inception of widespread glaciation was possibly linked with vast uplands in northern and southern Pangea through the effects of Variscan topography and the removal of atmospheric CO2 during accelerated erosion and weathering. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Prediction of Clay Behaviour in Undrained and Partially Drained Cyclic Triaxial Tests

Results from undrained cyclic triaxial tests followed by drainage on a reconstituted marine clay with high plasticity have been formulated to model the generation and dissipation process of cyclic induced excess pore pressure in clay. Through the introduction of two stress parameters in the formulation related to the relative cyclic strength and position in the effective p'—q stress space a unique relationship was found between the peak stress ratio on the extension side and the double amplitude shear strain under undrained cyclic loading. The excess pore pressure model proposed using this unique relation between the two defined parameters was then combined with the theory of axisymmetrical consolidation with radial drainage to predict the behaviour of clay under partially drained cyclic loading. The results of analyzing the behaviour during partially drained conditions were compared with the observed values of pore pressures and shear strains in drained-cyclic triaxial tests. It is suggested from comparisons that the proposed model for cyclic-induced pore pressures and shear strains should provide a practical tool for evaluating the settlements and stability of clay under partially drained cyclic loading.