<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <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" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <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>CONCRETE TECHNOLOGY REPORTS 1973</title>
      <link>https://trid.trb.org/View/1065698</link>
      <description><![CDATA[RHEOLOGICAL PROPERTIES OF CEMENT PASTE AND FRESH CONCRETE (MEASUREMENTS OF THE FLOW BEHAVIOUR OF HARDENED CEMENT PASTE AND CEMENT MORTARS OF VARIOUS COMPOSITIONS BY MEANS OF THE ROTATION RHEOMETER).  DAM CONSTRUCTION AND SLOPE CLADDING WITH SOIL-CEMENT (LABORATORY TESTS WITH CEMENT STABILIZED SOILS; CALCULATION METHODS FOR REPETITIVE LOADING AND SEEPAGE OF CEMENT STABILIZED SLOPES).  AIR VOID CONTENT OF CONVENTIONAL CONCRETES.]]></description>
      <pubDate>Sun, 21 Nov 2010 09:58:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1065698</guid>
    </item>
    <item>
      <title>Measurement of Soil Air Suction Change during Freezing-Thawing Process</title>
      <link>https://trid.trb.org/View/902782</link>
      <description><![CDATA[This paper introduces a new instrument and experimental procedure that estimates the change of air suction in soils during the freeze-thaw process. The experimental procedures include a nondestructive measurement by Time Domain Reflectometry (TDR) sensor, which captures the freezing-thawing status. The change of air suction causes change of soil volume, which is estimated from the volume change and soil deformation modulus. The experimental data indicates there is a graduated decrease in the magnitude of the negative air suction, which resulted in volume expansion in soils. The observed bulk volume change is the combined effects of the volume contraction due to ice melting and the volume expansion due to the reduction in the negative air suction. The magnitude of air suction reduction estimated is achieved by fusion of the information from both mechanical and electromagnetic measurement.]]></description>
      <pubDate>Fri, 30 Oct 2009 09:25:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/902782</guid>
    </item>
    <item>
      <title>Analysis of Two-Dimensional Consolidation of Unsaturated Soils</title>
      <link>https://trid.trb.org/View/899556</link>
      <description><![CDATA[It is essential to study the practicality of consolidation and simplified approach of unsaturated soils with high degree of saturation. The water and air in the pores can be regarded as a mixed fluid in unsaturated soils when degree of saturation is between 70% and 95%. Mass balance, mixed fluid continuity, modified water continuity equations are then established regarding the compressibility of the mixed fluid in the pores. The influence of permeability and initial degree of saturation of soils are analyzed with the new method. The conclusions are: there is a strong interaction between the pore-air and pore-water in the consolidation of unsaturated soils with low permeability; the degree of pore-air pressure influence on consolidation of unsaturated soils is related to initial degree of saturation of soils.]]></description>
      <pubDate>Fri, 18 Sep 2009 07:08:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/899556</guid>
    </item>
    <item>
      <title>Effect of Backfill Erosion on Moments in Buried Rigid Pipes</title>
      <link>https://trid.trb.org/View/802342</link>
      <description><![CDATA[The service life of rigid sewer pipes is often controlled by joint integrity. Leakage at the joint can result in ingress of water and the development of a void where soil has been eroded from beside the pipe. The influence of soil voids on the stability of buried rigid pipes is investigated, considering the effects of void size, void location and void shape. A series of simplified void geometries are defined, and elastic and elastic-plastic finite element analyses are performed to study how those voids influence bending moments in the rigid sewer. Erosion voids at the springlines lead to increased bending moments at crown, invert and springlines. Elastic analysis indicates that the bending moments approximately double once the void contacts the external surface of the pipe over a 90 degree arc. If shear failure is included and the loosened backfill is modeled, the moments approximately triple for that void geometry. In contrast, a void under the invert leads to decreases in the magnitude of bending moments, and for large void size, the moments can reverse sign. The moment increases slowly when a void starts to grow at the springline, but these moment changes accelerate once the void contacts the pipe over a 45 degree arc. This preliminary study suggests that efforts to arrest the growth of erosion voids at the springlines should be undertaken before the voids reach this size. All results presented are theoretical in nature, and physical testing is needed to evaluate the performance of these calculations.]]></description>
      <pubDate>Fri, 16 Mar 2007 10:55:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/802342</guid>
    </item>
    <item>
      <title>Soil Air Voids Method for Compaction Control</title>
      <link>https://trid.trb.org/View/776275</link>
      <description><![CDATA[The soil air voids method represents an alternate approach to the traditional Proctor method of field compaction control.  The evaluation procedure is based on the premise that the future performance of a compacted layer of soil can be evaluated by comparing the measured air voids to a predetermined limiting value.  In theory, a field inspector can rapidly determine if a soil layer meets the specified compaction criteria without obtaining a soil sample for laboratory Proctor compaction testing.  Recently, there has been renewed interest in this approach by state departments of transportation because of its timesaving benefits and relative simplicity.  The results of this study indicate the air voids method provides an indirect check on the dry density of the compacted layer; however, the soil water content is not directly assessed during the field evaluation.  Using results from laboratory and field tests, examples are provided of problems that could occur with certain soil types if inherent water content limits are relied upon during compaction.  Potential problems include excessive shrink or swell, excessive settlement, reduced bearing capacity, and stability problems due to high excess pore water pressures.  It was demonstrated in this study that some materials could pass the air voids test, but fail the conventional Proctor criteria (for example, 95% of the Proctor maximum dry density).  This condition can be identified in the laboratory, prior to construction, if Proctor compaction and specific gravity tests are conducted and the relationship between air voids and percent relative compaction is carefully established.]]></description>
      <pubDate>Thu, 27 Jul 2006 09:48:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/776275</guid>
    </item>
    <item>
      <title>FROM PRACTICE TO THEORY IN SOIL COMPACTION</title>
      <link>https://trid.trb.org/View/119562</link>
      <description><![CDATA[THE THEORY OF SOIL COMPACTION IS DISCUSSED. PROCTOR SAID THAT TO THE LEFT OF THE OPTIMUM MOISTURE CONTENT MORE WATER GIVES BETTER LUBRICATION. HE ALSO INDICATED THE IMPORTANCE OF CAPILLARY WATER IN HOLDING THE SOIL GRAINS TOGETHER AND GIVING STRENGTH, WHICH WE NOW CALL NEGATIVE PORE PRESSURE. MEASUREMENTS OF NEGATIVE PORE PRESSURES AND STUDY RESULTS ARE DISCUSSED. SUBSEQUENT LOADING CAUSING PORE PRESSURE TO GO POSITIVE, REDUCING SOIL STRENGTH EVEN THOUGH DENSITY IS INCREASED IS DISCUSSED. AS THE WATER CONTENT APPROACHES SATURATION, PERMEABILITY OF THE SOIL FOR AIR DECREASES TO THE POINT WHERE NO MORE AIR CAN BE EXPELLED AND DENSITY IS A MAXIMUM. FURTHER ADDITIONS OF WATER ABOVE THIS OPTIMUM MOISTURE CONTENT TEND TO CAUSE POSITIVE PORE PRESSURES WHICH WEAKEN THE SOIL. WITH A HIGHER COMPACTIVE EFFORT (SUCH AS MODIFIED PROCTOR DENSITY), THE ABOVE EFFECTS LOGICALLY OCCUR AT PROGRESSIVELY LOWER MOISTURE CONTENTS. THE THESIS IS EXAMINED THAT LATERAL RATHER THAN VERTICAL CONFINING PRESSURES ARE A DOMINANT CONTROL ON THE COMPACTION PROCESS. TRIAXIAL TESTS OF GRANULAR SOILS INDICATE THAT INCREASED LATERAL PRESSURES REDUCES THE CRITICAL VOID RATIO. PRELIMINARY MODEL STUDIES SHOW THE COMPRESSION ZONE APPROXIMATELY COINCIDES WITH THE ELASTIC THEORY. HEAVY LOADING WILL CAUSE A BEARING CAPACITY FAILURE WHICH MAY BE PREDICTED FROM A TERZAGHI EQUATION. VIBRATORY COMPACTION IS REVIEWED. VIBRATION REDUCES THE CRITICAL VOID RATIO, AND THUS ALLOWS SHEARING TO REACH THIS VOID RATIO. IT IS CONCLUDED THAT VIBRATORY COMPACTION MUST BE CONDUCTED AT AN OPTIMUM MOISTURE CONTENT, IS MOST EFFECTIVE WITH COARSE GRAIN SIZES, AND THE VIBRATORY COMPACTOR SHOULD NOT INCORPORATE MUCH DEAD WEIGHT. SINCE VIBRATORY EQUILIBRIUM VOID RATIO IS A FUNCTION OF VIBRATION AMPLITUDE, COMPACTION IS MOST EFFECTIVE AT RESONANCE.]]></description>
      <pubDate>Sun, 15 Aug 2004 02:24:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/119562</guid>
    </item>
    <item>
      <title>A NEW APPARATUS FOR MEASURING OXYGEN DIFFUSION AND WATER RETENTION IN SOILS</title>
      <link>https://trid.trb.org/View/677588</link>
      <description><![CDATA[Soil covers are used to cover waste rock and tailings to minimize oxygen contact with the waste.  An important concern with the use of soil covers is their long-term performance and how to measure parameters related to the cover, such as oxygen diffusion.  This paper discusses a new laboratory apparatus developed for measuring the diffusion of oxygen, or any gas, into soils.  The apparatus uses nitrogen pressure to change a soil sample's degree of saturation and can therefore minimize the effects of structural changes due to remixing and packing. Some innovative methods are employed to simulate oxygen concentration versus time data obtained with the apparatus.  A one-dimensional semianalytic diffusion model is used to back-calculate diffusion coefficients based on laboratory data. Results for a local silt and a sand are presented to illustrate the utility of the apparatus.  The apparatus is shown to perform well and provide gas diffusion coefficients similar to those reported by other researchers.  The apparatus' major advantage over other published methods lies in the fact that both the soil-water characteristic curve and oxygen diffusion coefficient at any degree of saturation can be obtained on the same soil sample in a single set of tests.  These two parameters are required for several geotechnical and geoenvironmental engineering designs involving unsaturated soils, such as the aforementioned use of soil covers for mitigating acid drainage in mine waste containing sulfides.]]></description>
      <pubDate>Wed, 18 Apr 2001 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/677588</guid>
    </item>
    <item>
      <title>TOMOGRAPHIC EVALUATION OF AIR AND WATER FLOW PATTERNS IN SOIL COLUMN</title>
      <link>https://trid.trb.org/View/675292</link>
      <description><![CDATA[Transport of air and water in soil is an important issue in many engineering problems.  This paper describes the use of computerized tomography (CT) as a nondestructive method to estimate the three-dimensional spatial distributions of porosity, air, and water saturations during air-water displacement tests in a soil column.  Local porosity was found to be a critical factor in controlling the air and water flow patterns.  In nonhomogeneous soil, high local porosity promotes early development of isolated air channel breakthrough that maintains a high average water retention saturation.  In homogeneous soil, micro air channels are established uniformly, resulting in a low water saturation.  Interpretation of data based on overall porosity could lead to unreliable flow analysis for water and/or air movement in unsaturated soil.  In addition, this paper investigates the use of gas exsolution to enhance the delivery of air within soil media.  Gas exsolution is a process whereby a gas dissolved in solution is allowed to evolve from the solution.]]></description>
      <pubDate>Fri, 09 Feb 2001 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/675292</guid>
    </item>
    <item>
      <title>TIME-SERIES ANALYSIS FOR DETERMINING VERTICAL AIR PERMEABILITY IN UNSATURATED ZONES</title>
      <link>https://trid.trb.org/View/498314</link>
      <description><![CDATA[The air pressure in the unsaturated subsurface changes dynamically as the barometric pressure varies with time. Depending on the material properties and boundary conditions, the intensity of the correlation between the atmospheric and subsurface pressures may be evidenced in two persistent patterns: the amplitude attenuation and the phase lag for the principal modes, such as the diurnal, semidiurnal, and 8-h tides.  The amplitude attenuation and the phase lag generally depend on properties that can be classified into two categories:  the barometric pressure parameters, such as the apparent pressure amplitudes and frequencies controlled by the atmospheric tides and others; and the material properties of porous media, such as the air viscosity, air-filled porosity, and permeability.  Based on the principle of superposition and a Fourier time-series analysis, an analytical solution for predicting the subsurface air pressure variation caused by the atmospheric pressure fluctuation is presented.  The air permeability (or pneumatic diffusivity) can be quantitatively determined by using the calculated amplitude attenuations (or phase lags) and the appropriate analytical relations among the parameters of the atmosphere and the porous medium.  An analysis using the field data shows that the Fourier time-series analysis may provide a potentially reliable and simple method for predicting the subsurface barometric pressure variation and for determining the air permeability of unsaturated zones.]]></description>
      <pubDate>Thu, 18 Feb 1999 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/498314</guid>
    </item>
    <item>
      <title>URBAN STREET TREES..</title>
      <link>https://trid.trb.org/View/630157</link>
      <description><![CDATA[No abstract provided.]]></description>
      <pubDate>Mon, 16 Dec 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/630157</guid>
    </item>
    <item>
      <title>CHARACTERIZATION OF CONSTRUCTION CONDITIONS IN A TOXIC AND COMBUSTIBLE GAS ENVIRONMENT FOR A TRANSIT PROJECT.</title>
      <link>https://trid.trb.org/View/525199</link>
      <description><![CDATA[SUBWAY CONSTRUCTION IN LOS ANGELES IN THE PRESENCE OF HYDROGEN SULFIDE AND OTHER GASES.]]></description>
      <pubDate>Fri, 21 Jun 1996 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/525199</guid>
    </item>
    <item>
      <title>SOIL PHYSICS</title>
      <link>https://trid.trb.org/View/125290</link>
      <description><![CDATA[CONTENTS: INTRODUCTION THE SOIL AS A DISPERSE SYSTEM THE MECHANICAL COMPOSITION OF SOILS PHYSICAL BEHAVIOR OF SOIL-WATER SYSTEMS SOIL STRUCTURE SOIL AIR SOIL WATER PRINCIPLES OF SOIL IRRIGATION PRINCIPLES OF SOIL DRAINAGE SOIL TEMPERATURE PHYSICAL PROPERTIES OF SOILS AND TILLAGE PHYSICAL PROPERTIES OF SOILS IN RELATION TO EROSION]]></description>
      <pubDate>Fri, 12 Aug 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/125290</guid>
    </item>
    <item>
      <title>PROTECTING TREES FROM PHYSICAL DAMAGE ON CONSTRUCTION SITES</title>
      <link>https://trid.trb.org/View/107933</link>
      <description><![CDATA[CITY TREES SUFFER MORE FROM DEFICIENCIES IN SOIL AERATION THAN FROM DEFICIENCIES OF SOIL MOISTURE OR SOIL NUTRIENTS. IT IS SUGGESTED THAT AN "AIR CONDITIONING" SYSTEM CAN BE BUILT AROUND THE ROOT ZONE OF A TREE WHICH IS TO BE SAVED. FOR NEW PLANTINGS OF TREES IN PARKS AND ALONG CITY STREETS IT IS SUGGESTED THAT SPECIES THAT ARE TOLERANT TO POOR SOIL AERATION BE USED.]]></description>
      <pubDate>Sun, 07 Mar 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/107933</guid>
    </item>
  </channel>
</rss>