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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>THERMAL INFRARED IMAGERY AND ITS APPLICATION TO STRUCTURAL MAPPING IN SOUTHERN CALIFORNIA</title>
      <link>https://trid.trb.org/View/121388</link>
      <description><![CDATA[THERMAL INFRARED IMAGERY IS OBTAINED BY AIRBORNE SCANNING DEVICES THAT DETECT THERMAL RADIATION FROM THE EARTH'S SURFACE AND RECORD IT AS AN IMAGE IN WHICH BRIGHT TONES REPRESENT RELATIVELY WARM TEMPERATURES. SCANNERS SENSITIVE TO WAVELENGTHS BETWEEN 8 AND 14 MICRONS SPAN THE RADIATION POWER PEAK OF THE EARTH AT 9.7 MICRONS AND COINCIDE WITH AN ATMOSPHERIC 'WINDOW'. AN EXAMPLE OF 8 TO 14 MICRON NIGHTTIME INFRARED IMAGERY FROM THE IMPERIAL VALLEY, CALIFORNIA, IS INTERPRETED AND COMPARED WITH AERIAL PHOTOGRAPHS OF THE SAME AREA. IN THIS MONOTONOUS-APPEARING DESERT TERRAIN THE IMAGERY EXHIBITS GREATER CONTRAST AND GEOLOGIC DETAIL THAN THE PHOTOGRAPHY. ON THE IMAGERY, DEFORMED TERTIARY SEDIMENTARY BEDROCK (RELATIVELY COOL) IS DISTINGUISHED FROM HOLOCENE WIND-BLOWN SAND COVER (RELATIVELY WARM). OF ESPECIAL GEOLOGIC INTEREST IS A FAULTED PLUNGING ANTICLINE IN FLAT TERRAIN. IT IS OBSCURE BOTH ON AERIAL PHOTOGRAPHS AND TO A GROUND OBSERVER. ON NIGHTTIME INFRARED IMAGERY, HOWEVER, THE FOLD IS CLEARLY SHOWN BY THE OUTCROP CONFIGURATION OF THE INDIVIDUAL SILSTONE AND SANDSTONE STRATA COMPRISING THE STRUCTURE. APPARENTLY THE RADIOMETRIC TEMPERATURE DIFFERENCES BETWEEN STRATA ARE SUFFICIENT TO OUTLINE THE FOLD ON THE IMAGERY. THE OBSCURE EXPRESSION OF THE FOLD ON AERIAL PHOTOGRAPHS MAY BE DUE TO INSUFFICIENT CONTRAST IN LIGHT REFLECTANCE BETWEEN THE DIFFERENT STRATA.]]></description>
      <pubDate>Sun, 15 Aug 2004 02:39:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/121388</guid>
    </item>
    <item>
      <title>A MICROWAVE RADIOMETRIC STUDY OF BURIED KARST TOPOGRAPHY</title>
      <link>https://trid.trb.org/View/121301</link>
      <description><![CDATA[THEORETICAL STUDIES AND SOME MICROWAVE MEASUREMENTS OF SOIL PENETRATION CAPABILITIES SUGGESTED THAT MICROWAVE RADIOMETERS MAY BE ABLE TO DETECT SUBSURFACE VOIDS ASSOCIATED WITH KARST DEVELOPMENT BENEATH RELATIVELY THICK SOIL COVER. HOWEVER, FROM A THEORETICAL ASPECT, IT IS DIFFICULT TO MODEL THE EFFECTS OF SURFACE ROUGHNESS, MOISTURE CONTENT, VEGETATION COVERAGE, AND A NONHOMOGENEOUS SKY. TO PROVE THE POTENTIAL OF MICROWAVE SURVEYS IN LOCATING AND MAPPING SUBSURFACE VOIDS, A MOBILE LABORATORY UNIT WAS USED TO OBTAIN IN SITU DATA. THIS UNIT IS EQUIPPED WITH PASSIVE MICROWAVE RADIOMETERS OPERATING AT 13.4 GHZ (2.22 CM), 37 GHZ (8.1 MM), AND 94 GHZ (3.2 MM), AS WELL AS GEOPHYSICAL SUPPORT EQUIPMENT. AN AREA NEAR THE TOWN OF COOL, EL DORADO COUNTY, CALIFORNIA, WAS USED TO OBTAIN DATA. THIS AREA IS KNOWN TO HAVE WELL-DEVELOPED SUBSURFACE KARST DEVELOPMENT AND HAS BEEN SURVEYED BY BOTH THE CALIFORNIA HIGHWAY DEPARTMENT AND THE CALIFORNIA ROCK AND GRAVEL COMPANY. THE MICROWAVE SURVEY SHOWED SIGNIFICANT RADIOMETRIC COLD ANOMALIES ASSOCIATED WITH VOID-SPACE DEVELOPMENT BENEATH SEVERAL TENS OF FEET OF SOIL COVER. DETECTION WAS POSITIVE IN ALMOST ALL CASES, EVIDENCE OF THE STRONG PROBABILITY THAT MICROWAVE SYSTEMS MAY BE USED TO DETECT AND RAPIDLY MAP KARST SYSTEMS FROM A REMOTE PLATFORM. THIS WILL GREATLY REDUCE SURVEYING AND CONSTRUCTION COSTS IN AREAS WHERE CAVES AND SINK HOLES HAVE DEVELOPED BENEATH OBSCURING SOIL COVER. /AUTHOR/]]></description>
      <pubDate>Sun, 15 Aug 2004 02:38:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/121301</guid>
    </item>
    <item>
      <title>APPLICATION OF GEOLOGY TO ENGINEERING PRACTICE</title>
      <link>https://trid.trb.org/View/121157</link>
      <description><![CDATA[CONTENTS: CHARLES PETER BERKEY, JOHN L SAVAGE, ROGER RHOADES THE GEOLOGIST IN THE ENGINEERING ORGANIZATION, EDWARD B. BURWELL, JR., GEORGE D. ROBERTS GEOLOGY IN DAM CONSTRUCTION, EDWARD B. BURWELL, JR., BERLEN C. MONEYMAKER ENGINEERING GEOLOGY IN THE DESIGN AND CONSTRUCTION OF TUNNELS, JAMES F. SANBORN MECHANICS OF LANDSLIDES, KARL TERZAGHI FAULTS AND ENGINEERING GEOLOGY, GEORGE D. LOUDERBACK GEOLOGY AND ENGINEERING IN THE PRODUCTION AND CONTROL OF GROUND WATER, O.E. MEINZER ENGINEERING GEOLOGY OF HIGHWAY LOCATION, CONSTRUCTION, AND MATERIALS, E.F. BEAN GEOLOGICAL ASPECTS OF BEACH ENGINEERING, W.C. KRUMBEIN PETROLOGY OF CONCRETE AFFECTED BY CEMENT-AGGREGATE REACTION, DUNCAN MCCONNELL, RICHARD C. MIELENZ, WILLIAM Y. HOLLAND, KENNETH T. GREENE GEOLOGY ENGINEERING IN THE PETROLEUM INDUSTRY, K.C. HEALD GEOLOGY IN THE DISCOVERY, DEVELOPMENT, AND EXPLOITATION OF MINERAL DEPOSITS, MURL H. GIDEL MILITARY GEOLOGY, CHAS. B. HUNT]]></description>
      <pubDate>Sun, 15 Aug 2004 02:38:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/121157</guid>
    </item>
    <item>
      <title>SOIL: ITS GEOLOGY AND USE</title>
      <link>https://trid.trb.org/View/121137</link>
      <description><![CDATA[A BRIEF HISTORICAL REVIEW AND SUMMARY IS PRESENTED OF THE APPLICATIONS OF GEOLOGY IN THE SERVICE OF MAN, AGRICULTURAL STUDIES, MINERALOGICAL CHARACTERISTICS AND SOIL ENGINEERING CONCEPTS AND APPLICATIONS. THE WORK OF ATTERBERG AND TERZAGHI ARE SPECIFICALLY REVIEWED. THE VITAL IMPORTANCE OF SOIL STRUCTURE IN ENGINEERING PRACTICE IS EMPHASIZED. SOIL SAMPLING AND TEST METHODS ARE DISCUSSED.]]></description>
      <pubDate>Sun, 15 Aug 2004 02:38:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/121137</guid>
    </item>
    <item>
      <title>HANDBOOK OF PHYSICAL CONSTANTS</title>
      <link>https://trid.trb.org/View/121061</link>
      <description><![CDATA[IN THE HANDBOOK OF PHYSICAL CONSTANTS, A SPECIAL PAPER PUBLISHED BY THE SOCIETY IN 1942, THE EDITORS COMPILED FOR THE FIRST TIME A WIDE VARIETY OF PHYSICAL CONSTANTS NEEDED FOR GEOLOGICAL AND GEOPHYSICAL CALCULATIONS. THE FOLLOWING SECTIONS COMPRISE THIS BOOK' COMPOSITION OF ROCKS, SYDNEY P. CLARK, JR. ABUNDANCES OF THE ELEMENTS, A.G.W. CAMERON. ISOTOPIC ABUNDANCES AND 1961 ATOMIC WEIGHTS, SYDNEY P. CLARK, JR. DENSITY OF ROCKS, R.A. DALY AND OTHERS. X-RAY CRYSTALLOGRAPHIC DATA, DENSITIES, AND MOLAR VOLUMES OF MINERALS, R.A. ROBIE AND OTHERS. THERMAL EXPANSION, B.J. SKINNER. COMPRESSIBILITY'  ELASTIC CONSTANTS, FRANCIS BIRCH. INTERNAL FRICTION IN ROCKS, J.J. BRADLEY AND A.N. FORT, JR. SEISMIC VELOCITIES, FRANK PRESS. GEODETIC DATA, G.J.F. MACDONALD. STRENGTH AND DUCTILITY, JOHN HANDIN. VISCOSITY, SYDNEY P. CLARK, JR. MELTING AND TRANSFORMATION POINTS IN OXIDE AND SILICATE SYSTEMS AT LOW PRESSURE, F.C. KRACEK AND SYDNEY P. CLARK, JR. PHASE RELATIONS IN SULFIDE-TYPE SYSTEMS, G. KULLERUD. HIGH-PRESSURE PHASE EQUILIBRIA, SYDNEY P. CLARK, JR. PRESSURE-VOLUME-TEMPERATURE AND PHASE RELATIONS OF WATER AND CARBON DIOXIDE, G.C. KENNEDY AND W.T. HOLSER. BINARY MIXTURES OF VOLATILE COMPONENTS, H.J. GREENWOOD AND H.L. BARNES. IONIZATION CONSTANTS IN AQUEOUS SOLUTIONS, H.L. BARNES AND H.C. HELGESON. SOLUBILITY, SYDNEY P. CLARK, JR. THERMODYNAMIC PROPERTIES OF MINERALS, R.A. ROBIE. THERMAL CONDUCTIVITY, SYDNEY P. CLARK, JR. HEAT FLOW AND VOLCANIC TEMPERATURES, W.H.K. LEE AND SYDNEY P. CLARK, JR. RADIOACTIVE DECAY CONSTANTS AND ENERGIES, G.W. WETHERILL. ABUNDANCES OF URANIUM, THORIUM, AND POTASSIUM, SYDNEY P. CLARK, JR. AND OTHERS. MAGNETIC PROPERTIES OF ROCKS AND MINERALS, G.V. KELLER. CONVERSION FACTORS, NUMERICAL CONSTANTS, ATOMIC CONSTANTS, SYDNEY P. CLARK, JR.]]></description>
      <pubDate>Sun, 15 Aug 2004 02:37:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/121061</guid>
    </item>
    <item>
      <title>INTERPRETING LOCAL GEOLOGY FROM RADAR IMAGERY</title>
      <link>https://trid.trb.org/View/121058</link>
      <description><![CDATA[THE INTENSITY OF RADAR RETURN ENERGY, WHICH IS DEPENDENT ON MANNER OF RADAR ILLUMINATION, SURFACE ROUGHNESS, AND GEOMETRY OF THE OBJECT, IS DISCUSSED AS APPLICABLE TO THE INTERPRETATION OF LOCAL GEOLOGY. THE PRINCIPLES OF RADAR INTERPRETATION OF LOCAL GEOLOGY ARE DESCRIBED AND ILLUSTRATED WITH RADAR IMAGES AND PHOTOGRAPHS OF AREAS IN THE SOUTHWESTERN UNITED STATES. ALSO DESCRIBED IS THE USE OF RADAR PRINCIPLES IN CONJUNCTION WITH KNOWLEDGE OF GEOMORPHIC PRINCIPLES TO OBTAIN A MAXIMUM OF INFORMATION. APPLICATIONS OF RADAR IMAGERY TO MILITARY TERRAIN INTELLIGENCE, NATURAL RESOURCES EXPLORATION, AND PLANETARY EXPLORATION ARE EXAMINED. /AUTHOR/]]></description>
      <pubDate>Sun, 15 Aug 2004 02:37:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/121058</guid>
    </item>
    <item>
      <title>ROLE OF COHESIVE STRENGTH IN THE MECHANICS OF OVERTHRUST FAULTING AND OF LANDSLIDING</title>
      <link>https://trid.trb.org/View/127298</link>
      <description><![CDATA[THE MOHR-COULOMB CRITERION FOR FAILURE, MODIFIED IN LIGHT OF THE CONCEPT OF EFFECTIVE STRESS, IS STATED. HUBBERT AND RUBEY (1959) ASSUMED THAT ONCE A FRACTURE IS STARTED THE EMPIRICAL CONSTANT OF COHESIVE STRENGTH IS ELIMINATED AND FURTHER MOVEMENT RESULTS WHEN THE CRITICAL STRESS AT FAILURE EQUALS TANGENT THETA OF THE QUANTITY NORMAL PRESSURE MINUS THE PORE PRESSURE ACROSS THE PLANE OF INTERNAL SLIPPAGE AT FAILURE, THEY PROCEED, HOWEVER, TO USE THIS FORMULA FOR THE FRICTIONAL SLIDING OF COHESIONLESS BLOCK AS THE CRITERION OF FAILURE OF LARGE THRUSTS, AFTER THEY ASSUMED THAT THE EMPIRICAL CONSTANT OF COHESIVE STRENGTH COULD BE ELIMINATED THROUGH A CONCENTRATION OF STRESS. THIS ASSUMPTION LED TO THEIR CONCLUSIONS THAT VERY LONG OVERTHRUST BLOCKS ARE POSSIBLE AND THAT SUCH BLOCKS MAY HAVE MOVED BY GRAVITATIONAL SLIDING ALONG VERY GENTLE SLOPES. ARGUMENTS ARE PRESENTED TO SHOW THAT THEIR ASSUMPTION OF ZERO EMPIRICAL CONSTANT OF COHESIVE STRENGTH WAS BASED UPON A FAULTY ARGUMENT AND TO POINT OUT THAT THIS TERM SHOULD NOT BE OMITTED UNLESS IT COULD BE PROVED THE MOVING BLOCK SLID ALONG AN ALREADY EXISTING FRACTURE PLANE. THE FIRST PART OF THIS PAPER CONSISTS MAINLY OF CONCLUSIONS BASED ON COMPUTATIONS. CLEARLY, AN UNJUSTIFIED OMISSION OF A 200-BAR COHESIVE STRENGTH WOULD LEAD TO ERRONEOUS AND MISLEADING RESULTS, PARTICULARLY, GRAVITATIONAL SLIDING CANNOT BE AN IMPORTANT MECHANISM IF SUCH A COHESIVE STRENGTH HAS NOT BEEN ELIMINATED DURING OVER-THRUST FAULTING. THE SECOND PART PRESENTS EVIDENCE TO DISTINGUISH BETWEEN MOVEMENTS OF COHESIVELY BOUND BLOCKS AND COHESIONLESS BLOCKS. THE GLARUS OVERTHRUST, CHARACTERIZED BY PRESENCE OF A DUCTILELY DEFORMED LIMESTONE LAYER WITHIN THE THRUST ZONE, IS CONSIDERED A TYPICAL EXAMPLE OF THRUSTING OF COHESIVELY BOUND BLOCKS. THE HEART MOUNTAIN THRUST, CHARACTERIZED BY A SHATTERING OF THE UPPER PLATE AND ABSENCE OF A WEAK LAYER ABOVE THE THRUST CONTACT, IS INTERPRETED AS AN EXAMPLE OF THRUSTING OF COHESIONLESS BLOCKS. THE FORMER IS COMPARED TO SLOWLY CREEPING SLIDES MOVING AT RATES OF CENTIMETERS OR LESS PER YEAR, AND THE LATTER WITH CATASTROPHIC LANDSLIDES (SUCH AR THE FLIMS, GOLDAY, AND VAIONT SLIDES) MOVING AT SPEEDS OF MANY METERS PER SECOND. THE CONCLUSION OF RALEIGH AND GRIGGS (1963) THAT LARGE THRUSTS CAN ONLY FORM WHEN A TOE OF THE THRUST IS CONTINUALLY ERODED IS ALSO TRACED TO ASSUMPTION OF ZERO COHESIVE STRENGTH ALONG THRUST PLANE. OTHERWISE, THE TOE EFFECT WOULD PRODUCE A ZONE OF IMBRICATION AT THE FRONT OF OVER THRUST BLOCKS, PARTICULARLY THOSE SLIDING DOWNSLOPE UNDER THEIR OWN WEIGHT. /AUTHOR/]]></description>
      <pubDate>Thu, 15 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/127298</guid>
    </item>
    <item>
      <title>ROLE OF COHESIVE STRENGTH IN THE MECHANICS OF OVERTHRUST FAULTING AND OF LANDSLIDING: DISCUSSION AND REPLY</title>
      <link>https://trid.trb.org/View/127299</link>
      <description><![CDATA[THE DISCUSSION INDICATES THAT THE CONFUSION CONCERNING THE EFFECT OF THE COHESIVE STRENGTH MAY HAVE THREE PRINCIPAL SOURCES: (1) AN ADMITTEDLY ERRONEOUS ASSUMPTION THAT THE SURFACES MAY BE TREATED AS GEOMETRICAL PLANES, (2) AN UNTENABLE ASSUMPTION THAT ROCKS UNDER THE STRESS CONDITIONS EXISTING IN LARGE OVERTHRUSTS STILL OBEY THE SIMPLE LABORATORY LAW OF FRICTIONAL SLIDING, AND (3) A SEMANTIC DIFFICULTY ARISING FROM CALLING UNLIKE THINGS BY THE SAME NAME. THE COULOMB LAW OF FRICTIONAL SLIDING IN ROCK DEFORMATION DOES NOT HOLD UNDER CONDITIONS OF EXTREME STRESS ACCORDING TO DATA OBTAINED BY TRIAXIAL TESTING. HSU USED A TERM TO SIGNIFY BOTH THE COHESIVE STRENGTH OF THE INITIALLY UNFRACTURED ROCK AND THE RESISTANCE TO SLIPPING ALONG A SURFACE OF FRACTURE. THIS SYMBOL ACTUALLY REPRESENTS THE ORDINATE OF THE POINT OF INTERSECTION ON THE MOHR DIAGRAM OF THE MOHR ENVELOPE OBTAINED BY A SERIES OF TRIAXIAL TESTS ON SUCCESSIVE SPECIMENS OF THE SAME ROCK. IT, THEREFORE, IS A MEASURE OF THE SHEAR STRENGTH OF A PREVIOUSLY UNFRACTURED ROCK ALONG A SURFACE ACROSS WHICH THE NORMAL STRESS IS ZERO. THE REPLY DISCUSSES THE MOHR-COULOMB LAW AS A GENERAL CRITERION OF SHEAR FAILURE. SINCE THE ANALYSIS OF THE MECHANICS OF THRUSTING AND LANDSLIDING WAS BASED UPON THE MOHR-COULOMB RELATION AS A GENERAL CRITERION, THE TREATMENT IS APPLICABLE NOT ONLY TO OVERTHRUSTS AND SLIDES WHICH MOVED BY FLOWAGE, BUT ALSO TO THOSE WHICH SLID ALONG PRE-EXISTING FRACTURE SURFACES. THE DEVIATION OF THE MOHR ENVELOPE FROM STRAIGHT LINES GIVES A MEASURE OF THE ERROR INTRODUCED THROUGH THE ASSUMPTION OF CONSTANTS. THE BEHAVIOR OF DIFFERENT SEDIMENTARY ROCKS IS SO DIFFERENT THAT A JUDGMENT OF THE APPLICABILITY OF THE MOHR-COULOMB LAW MUST BE MADE FOR THE INDIVIDUAL CASES. THE GRAVITATIONAL SLIDING OF A BLOCK ALONG A PRE-EXISTING FRACTURE SURFACE WOULD LEAD TO A CATASTROPHIC SLIDE ONLY IF ITS MOVEMENT IS NOT CHECKED. THE REPLY AGREES THAT A NEW SYMBOL SHOULD BE PROPOSED TO DESIGNATE THE RESISTANCE TO SLIPPING ALONG A SURFACE OF FRACTURE WHEN THE EFFICTIVE NORMAL PRESSURE IS ZERO. THE SYMBOL USED ORIGINALLY WAS MEANT FOR THE INITIAL SHEAR STRENGTH OF UNFRACTURED ROCK EVEN WHEN THE CASES OF REDUCED COHESION WERE DISCUSSED. THE EXPRESSION 'INITIAL SHEARING RESISTANCE TO FRICTIONAL SLIDING ALONG PREEXISTING FRACTURE SURFACE' IS SUGGESTED RATHER THAN ADHESIVE STRENGTH, OR INITIAL SHEARING RESISTANCE.]]></description>
      <pubDate>Thu, 15 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/127299</guid>
    </item>
    <item>
      <title>EPISODES OF VERTICAL ACCRETION AND CATASTROPHIC STRIPPING: A MODEL OF DISEQUILIBRIUM FLOOD-PLAIN DEVELOPMENT</title>
      <link>https://trid.trb.org/View/288110</link>
      <description><![CDATA[This paper describes flood plains formed episodically by vertical accretion along high-energy, laterally stable channels in southeastern Australia.  Overbank deposition gradually builds a flood plain of fine-textured alluvium over a period of hundreds or thousands of years, following which catastrophic erosion by a single large flood, or a series of more moderate floods, strips the flood plain to a basal lag deposit from which it slowly reforms.  This periodic destruction appears due to the progressive development of large levee banks and flood-plain surfaces of highly variable relief.  As the levees and flood plain grow, overbank flow is gradually displaced from the broad flood plain into the main channel and flood-plain backchannels, with a resulting concentraion of erosional energy. Eventually, high flows greatly exceed erosional thresholds, and wholesale scour of the channel boundary and flood plain occurs.  Vertical-accretion flood plains at different stages of development result in a wide range of bankfull recurrence intervals, even along the same river.  Some of these flood plains are so infrequently flooded that they can be mistaken for terraces formed under a prior flow regime.  The almost random but catastrophic nature of this flood-plain erosion means that sediment supply and transport are highly variable and probably impossible to predict.  This model of flood-plain formation is seen as only part of a continuum of alluvial environments ranging from vestigial, coarse-grained, traction-load flood plains along high-energy rivers in narrow gorges to extensive low-gradient flood plains in which alluvial stratigraphy is dominated by fine-grained overbank deposition.]]></description>
      <pubDate>Wed, 30 Sep 1987 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/288110</guid>
    </item>
    <item>
      <title>BED MICROTOPOGRAPHY AND ENTRAINMENT THRESHOLDS IN GRAVEL-BED RIVERS</title>
      <link>https://trid.trb.org/View/217074</link>
      <description><![CDATA[Although increasingly acknowledged as an important factor in bedload transport, few data on the effects of bed conditions on entrainment in gravel-bed rivers exist.  This reflects to some degree the substantial difficulties involved in obtaining accurate threshold measurements in such channels.  Using a sensor which allows initial movement of labeled particles to be detected during flood flow, the entrainment thresholds of clasts incorporated into the bed microtopography have been compared with those in exposed, open plane-bed positions.  The threshold velocity of clasts from cluster bedforms, the most prevalent type of bed microtopography, is found to be above that of more exposed particles of like size and shape.  Measurements indicate that the initial movement of approximately 70% of particles in gravel-bed rivers will be directly influenced by the presence of neighboring grains. Bed microtopography plays an important role in delaying incipient motion.  The influence of microtopography may be invoked to account for phenomena such as discontinuous particle movement and variations in the composition of bedload during discharge events. (Author)]]></description>
      <pubDate>Thu, 31 Oct 1985 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/217074</guid>
    </item>
    <item>
      <title>FUNDAMENTAL CHARACTERISTICS OF STREAM MEANDERS</title>
      <link>https://trid.trb.org/View/204248</link>
      <description><![CDATA[The development of very regular sinuous meanders in laminar-flow surface-tension streams on a Perspex plate produces regularity of the meanders in the absence of random influences, which suggests that meander information is not an essentially random process.  The conspicuously convex-downslope shape of individual curves, often recognizable in regular river meanders, suggests that models which predict symmetrical meander curves are incomplete; study of the propagation sequence of meanders suggests that no intrinsic hydraulic phenomenon, such as reversal of secondary circulation, is needed to explain the regular reversal of meander curvature; the increasing irregularity of meanders as fluid turbulence increases suggests that meander irregularity results from random disturbances to the basically regular meandering tendency.  Similarities of shape and behavior suggest that surface-tension meanders offer a useful analogy through which river meanders may be better understood.  (Author)]]></description>
      <pubDate>Thu, 30 Aug 1984 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/204248</guid>
    </item>
    <item>
      <title>LANDSLIDES CAUSED BY EARTHQUAKES</title>
      <link>https://trid.trb.org/View/204249</link>
      <description><![CDATA[Study of a sample of 40 historical earthquakes shows that 14 types of landslides are caused by seismic events.  In order of decreasing abundance, these are: rock falls, disrupted soil slides, rock slides, soil lateral spreads, soil slumps, soil block slides, soil avalanches, soil falls, rapid soil flows, rock slumps, subaqueous landslides, slow earth flows, rock block slides, and rock avalanches.  This study has identified several materials that are especially susceptible to earthquake-induced landslides.  These materials and the predominant types of landslides in each are: (1) weakly cemented, weathered, sheared, intensely fractured, or closely jointed rocks (rock falls, slides, avalanches, slumps, and block slides), (2) more-indurated rocks with prominent discontinuities (rock falls, slides, block slides, and, possibly, slumps), (3) unsaturated residual or colluvial sand (disrupted soil slides and soil avalanches), (4) saturated residual or colluvial sand (rapid soil flows), (5) saturated volcanic soils containing sensitive clay (disrupted soil slides, soil avalanches, and rapid soil flows), (6) loess (rapid soil flows), (7) cemented soils (soil falls), (8) deltaic sediments containing little or no clay (soil lateral spreads and subaqueous landslides), (9) flood-plain alluvium containing little or no clay (soil slumps, block slides, and lateral spreads), and (10) uncompacted or poorly compacted man-made fill containing little or no clay (soil slumps, block slides, lateral spreads, and rapid soil flows).  (Author)]]></description>
      <pubDate>Thu, 30 Aug 1984 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/204249</guid>
    </item>
    <item>
      <title>BED-MATERIAL ENTRAINMENT AND HYDRAULIC GEOMETRY OF GRAVEL-BED RIVERS IN COLORADO</title>
      <link>https://trid.trb.org/View/203844</link>
      <description><![CDATA[Twenty-four gravel-bed rivers in the Rocky Mountain region of Colorado were selected for a detailed investigation of bed-material mobility and hydraulic geometry.  The criteria for choosing the study reaches were: a nonbraided channel with self-formed bed and banks, evidence of quasi-equilibrium, minimal flow regulation, and a streamflow-gaging station record of at least ten years.  In each river reach, several cross sections and longitudinal profiles of the riverbed, water surface, and bankfull elevation were surveyed.  Samples of bed surface and subsurface material were collected for size analysis. The median diameter of the bed-material surface ranged from 23 mm to 120 mm.  Computed values of the dimensionless shear stress showed that the threshold of particle motion was exceeded at flows slightly less than bankfull. Transport of bed-material particles is a relatively frequent occurrence.  Large bed-material transport rates, however, are extremely rare.  Empirical evidence obtained at these and other streams indicates that a stable, self-formed gravel-bed channel cannot be maintained at a dimensionless shear stress greater than about 0.080.  The 24 river reaches were divided into 2 groups, depending upon bank stability as indicated by bank vegetation.  Separately determined bankfull hydraulic-geometry equations for each group were found to have the same exponents, but slightly different coefficients.  An analysis of variance determined that 67% of the observations were within plus or minus 15% to 20% of the predicted values for most hydraulic variables. The bankfull hydraulic-geometry equations for the Colorado rivers studied were compared with those of British gravel-bed rivers that had been similarly divided according to the extent of bank vegetation.  No significant difference between the hydraulic geometries of Colorado and British gravel-bed rivers with thick bank vegetation was found. The comparison of hydraulic-geometry equations for those rivers with thin bank vegetation determined that there was not difference in the width-versus-discharge relations. No significant difference was found for the exponents of the depth, velocity, and slope equations; however, the coefficient values were slightly different.]]></description>
      <pubDate>Thu, 28 Jun 1984 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/203844</guid>
    </item>
    <item>
      <title>A SYSTEM MODEL OF STREAM-CHANNEL SHAPE AND SIZE</title>
      <link>https://trid.trb.org/View/203019</link>
      <description><![CDATA[Models of stream-channel development typically focus on the effects of discharge and sediment.  Missing from the traditional models is an explicit representation of the mechanism through which channel cross-section elements interact and adjust.  The multiple-equations model presented here includes the effects of mutual adjustment of channel characteristics, as well as of discharge and sediment.  It incorporates both channel shape and size as endogenous variables.  The results of analysis indicate that discharge has primarily indirect effects.  Given that the adjustment mechanism is represented as a set of indirect effects, these results imply that the channel adjustment process is dependent principally on sediment rather than on discharge.  The utility of this type of model in an impact assessment context is also discussed.]]></description>
      <pubDate>Wed, 30 May 1984 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/203019</guid>
    </item>
    <item>
      <title>ENTRAINMENT OF GRAVEL FROM NATURALLY SOOTED RIVERBED MATERIAL</title>
      <link>https://trid.trb.org/View/196925</link>
      <description><![CDATA[The critical dimensionless shear stress, required to entrain a given size particle, was computed from extensive bedload-transport measurements in three self-formed rivers that have naturally sorted gravel and cobble bed material. The value of critical dimensionless shear stress was determined to be significantly affected by the size distribution of the riverbed material.  This analysis shows that critical dimensionless shear stress varies almost inversely proportional to the particle diameter for a nonuniform bed material.  An investigation of the hydraulic characteristics and bed-material mobility of 24 self-formed gravel-bed rivers in Colorado determined that particles as large as the median diameter of the bed surface were entrained by discharges equal to the bankfull stage or less.  Particles as large as the 90th-percentile fraction were entrained by the bankfull discharge in nine of the rivers studied.  Consequently, in these rivers, a significant fraction of the riverbed was entrained rather frequently over a period of years, although the transport rate was very small.]]></description>
      <pubDate>Wed, 29 Feb 1984 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/196925</guid>
    </item>
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