Permeability of Clays under Organic Permeants

A Magnesium Montmorillonite and a Kaolinite Clay Are Subjected to Organic and Inorganic Permeants to Study the Changes in Permeability Caused by the Reaction between Clays and Permeants. the Permeants Are Acetic Acid, Aniline, Methanol, and Xylene. Tests Are Conducted in Specially Designed and Constructed Flexible Wall Permeameters that Provide Precise Measurements of Pressures and Flows. Increases in Clay Permeability Due to Clay-Permeant Chemical Reactions Are Measured to Be on the Order of Two to Three Times the Original Permeability. This is in Contrast to the 100 to 1,000 Times Increases Reported by Others. the Writers Believe that the Large Increases Reported by Others is Probably Due to the Use of Fixed-Wall Permeameters. the Writers\u27 Results Show that Methanol Doubles the Permeability of Montmorillonite. Acetic Acid Reacts with the Carbonates in Montmorillonite and Liberated Carbon Dioxide. the Resulting Loss of Mass Triples the Clay\u27s Permeability. Aniline and Xylene Will Not Flow through Saturated Montmorillonite but Will Flow through Saturated Kaolinite at Reduced Flow Rates. Hydraulic Fracturing of the Montmorillonite Occurred When Methanol Passed through It under a High Gradient and Low Confining Pressure. © ASCE

Design Methods for Auger CIP Piles in Compression

This Paper Reports on a Study of 43 Compression Load Tests (Five Fully Instrumented) and Ten Pullout Tests of Auger Cast-In-Place (ACIP) Piles in Sand. Eight Design Methods Reported in the Literature Were Used to Predict the Measured Pile Capacities. Ultimate Load Capacities of the ACEP Load Tests Were Determined using Two Different Definitions of Ultimate Capacity and Compared with Predictions. Load Transfer Behavior Was Determined from a Study of the Fully Instrumented Pile Tests and Compared to Predicted Values. Recommendations Are Made Regarding the Design Approach Most Appropriate for These Foundations and the Best Procedure for Estimating Ultimate Capacity from Pile Load Tests. © 2004 ASCE

Temperature Effects on the Compressional Wave Velocities of Asphalt-Aggregate Mixtures

Civil Engineerin

Transverse-Earthquake Induced Deformations of a Bridge Approach Embankment in the New Madrid Seismic Zone

It is predicted that strong earthquakes, larger than M 7.0, may occur within next 50 years in the New Madrid Seismic Zone (NMSZ), the location of three of the most powerful earthquakes in United States history. Large displacements may occur during strong earthquakes that can cause an embankment to fail or lose its function. The hyperbolic stress-strain model with Masing rules was modified to account for strength and stiffness reduction due to change in the effective confining pressure. The Byrne model was combined with a hyperbolic model to calculate the pore water pressure caused by seismic shaking. This modified hyperbolic model was implemented into the computer code, FLAC, and calibrated against the 1971 Upper San Fernando Dam failure. It appears that the modified model is superior to the built-in Finn model in FLAC to predict the earthquake-induced deformation of the embankments. Then it was applied to study the seismically induced deformation of an approach embankment to Bridge A1466 in the NMSZ near Hayti, Missouri

A Slurry Consolidation Approach to Reconstitute Low-Plasticity Silt Specimens for Laboratory Triaxial Testing

Silt Specimen Reconstitution using a Slurry Consolidation Approach is Commonly Used for Laboratory Testing. This Paper Presents a New Slurry Consolidation Approach to Reconstitute Silt Specimens for Use in Triaxial Testing. Silt Specimens Were Reconstituted in a Split Vacuum Mold Mounted on a Special Experimental Setup. the Uniformity of the Reconstituted Specimens Was Verified by Measuring the Water Content and Grain Size Distribution throughout the Specimens. the Testing Program Was Expedited using a Special Sample Handling Technique to Move the Specimen from the Special Experimental Setup to the Triaxial Chamber Base Platen. the Handling Process Did Not Disturb the Specimens to a Measurable Degree. Further, the Replicas of the Reconstituted Specimens Were Verified by Submitting Them to Basic Volumetric Measurements Followed by Static and Cyclic Triaxial Tests. the Triaxial Test Results Reported Very Small Differences. Copyright © by ASTM Int\u27l (All Rights Reserved)

Ultrasonic Pulse Velocity Tests on Compacted Soil

In This Paper, Results of a Series of Ultrasonic Pulse Velocity Tests on Compacted Soil Were Presented and Discussed. Ultrasonic Pulse Velocity Tests Provide Compression and Shear Wave Velocity Information that Can Be Used in Calculating Dynamic Elastic Moduli Such as Young\u27s Modulus and Shear Modulus. from the Test Results, Calculated Poisson\u27s Ratio Shows a Linear Relation with the Water Content in Compacted Soil, Which Leads to a Linear Trend in Both P and S Wave Velocity Against Water Content. Furthermore, Presenting Plots in Bulk Density Versus Wave Velocity Gives a Clearer Trend Than Dry Density Versus Wave Velocity. © 2009 ASCE

Liquefaction Behavior of Mississippi River Silts

Civil Infrastructure Built on Alluviums and Recent Deposits, Such as Dams, Contain Significant Amount of Silts. the Static and Dynamic Behavior of These Fine-Grained Soils Has Been Investigated Less Than the Clay-Like or Sand-Like Soils. Low Plasticity Silts (PI = 6) Obtained East of St. Louis in Illinois Are Known as Loess that Has Been Re-Deposited by Water in the Floodplains of the Mississippi River. These Silts Were Reconstituted in the Laboratory by Slurry at Water Content above the Liquid Limit and Then Consolidated to an Initial Effective Stress. the Initial Laboratory Characterization under Monotonic Loading Included a Series of Consolidated Undrained Triaxial Compression Tests at Different Effective Confinement to Determine the Critical State Parameters. a Series of Stress-Controlled Cyclic Triaxial Compression Tests Were Run under Normally and over consolidated Conditions. the Liquefaction Behavior of the Silt at Different over Consolidation Ratios and its Relationship to the Monotonic Behavior is Presented and Discussed. © 2008 ASCE

The Influence of Large Prestrains on Dynamic Properties of Sand

The development of the UMR Resonant Column/Torsional simple Shear device has provided the means to evaluate high and low amplitude shear moduli on a single sand specimen. Results of cyclic torsional simple shear tests showed that progressive strain increases w1th the cyclic strain amplitude and the number of cycles and decreases with density of the sand. Large accumulated prestrains were found to decrease the maximum dynamic shear modulus by 30 to 35%