MEASUREMENT OF HORIZONTAL AND VERTICAL SWELL PRESSURES FROM A TRIAXIAL LABORATORY TEST; FEASIBILITY STUDY. FINAL REPORT

Work is reported which developed a double chamber triaxial apparatus and test procedure to measure vertical and horizontal swell pressures caused by introducing water to a 1.4-inch diameter by 3.5-inch high soil specimen subject to no volume change. This equipment and test procedure eliminate lateral skin friction normally present during 1-dimensional consolidation testing and should provide improved results compared with tests performed in a 1-dimensional consolidometer. Results of 3 series of tests performed on 2 different expansive soils trimmed from undisturbed boring samples indicated no difference in swell pressure between vertical and horizontal orientations of the specimen. Optical analysis of two thin sections of intact soil prepared from one of the soil samples indicated birefringence or anisotropy. Consolidation and strength parameters determined using the double chamber triaxial apparatus are also consistent with those performed on similar specimens using other test apparatus. An exception is that the elastic modulus evaluated for soil specimens tested in the double triaxial chamber provides an upper bound limit up to two times (4 times for soft soils) of that evaluated from standard triaxial tests. This is attributed partly to friction from an O-ring required to pass the vertical loading ram through the outer chamber into the inner chamber and use of a solid piece of geotextile filter fabric to promote flow of water in and out of the specimen. This study has shown that measurement of vertical and horizontal swell pressures prior to consolidation or strength tests is feasible.

• Corporate Authors:

  Army Corps of Engineers

  Geotechnical Laboratory, P.O. Box 631
  Vicksburg, MI  United States  39180
• Authors:
  • Johnson, L D
• Publication Date: 1987-8

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 89 p.

Subject/Index Terms

• TRT Terms: Feasibility analysis; Geotextiles; Laboratory tests; Swelling; Swelling soils; Triaxial shear tests
• Uncontrolled Terms: Swell pressure; Triaxial testing machine
• Subject Areas: Geotechnology; Highways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00475173
• Record Type: Publication
• Report/Paper Numbers: Miscell Pap GL-87-23
• Files: TRIS
• Created Date: Nov 30 1987 12:00AM