COLLAPSIBLE SOILS IN LOUISIANA

IN SOUTHWEST LOUISIANA, SOME SURFACE SILTS (UP TO 3 FEET DEEP) COLLAPSE UNDER LOAD AFTER MOISTURE IS ADDED. THESE SOILS WERE INDISTINGUISHABLE FROM NEARBY NORMAL SILTS THROUGH ROUTINE TESTS. THE DEPOSITS OCCUR AS LOW, GENTLY- SLOPING RIDGES. VERY SIMILAR COLLAPSIBLE SOILS WERE FOUND IN THE WELL-KNOWN PIMPLE MOUNDS OF THE AREA. IN THE STABLE SILTS, VERMICULITE IS THE DOMINANT CLAY MINERAL; IN THE COLLAPSIBLE SILTS, MONTMORILLONITE, KAOLINE AND ILLITE ARE ALSO PRESENT. MOISTURE IS HELD IN THE PORES OF COLLAPSIBLE SILTS BY ELECTRO-CHEMICAL FORCES. WHEN COLLAPSIBLE SILTS WERE REMOLDED WITH WATER OR ETHYLENE GLYCOL (BOTH POLAR LIQUIDS), NO WATER PASSED THROUGH UNDER 2 METERS OF HEAD. IN SETTLED MIXTURES OF COLLAPSIBLE SILTS AND A SOLUTION OF CALGON, (COMMERCIAL BRAND OF SODIUM HEXAMETA PHOSPHATE) THE SUPERNATANT LIQUID WAS BLACK. THE COLOR CHANGE IS ATTRIBUTED TO LIGNINS. FOUR CRITERIA WERE ESTABLISHED FOR IDENTIFYING COLLAPSIBLE SILTS: AN IN-PLACE UNIT WEIGHT LESS THAN 80 LBS/CU FT; A MAXIMUM DRY UNIT WEIGHT LESS THAN 104 LBS/CU FT; A BLACK LIQUID AFTER THE SOIL SOLIDS HAVE SETTLED OUT IN A 3% SOLUTION OF CALGON; AND A TOTAL STRAIN OF AT LEAST 15% IN THE COLLAPSE TEST (A MODIFIED CONSOLIDATION TEST OF AN OVEN-DRIED, UNDISTURBED SAMPLE THAT IS THEN SATURATED UNDER PRESSURE TO 16 TONS/SQ FT).

• Supplemental Notes:
  • APP
• Corporate Authors:

  Louisiana State University and Agriculture & Mechanical College, Baton Rouge

  Baton Rouge, LA  United States  70803
• Authors:
  • Arman, A
  • Thornton, S I
• Publication Date: 1972

Media Info

• Features: Figures; References; Tables;
• Pagination: 131 p.
• Serial:
  • Issue Number: 111

Subject/Index Terms

• TRT Terms: Collapse; Moisture content; Silts; Soil stabilization; Soil tests
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 00230218
• Record Type: Publication
• Report/Paper Numbers: Bull
• Files: TRIS
• Created Date: Aug 5 1973 12:00AM