UFC 4-150-07
19 June 2001
Once the scope of repair requirements, including priorities, is
established, then determine if the repairs should be done in-house or by contract.
10-3
REPAIR PROCEDURES OF EARTH-FILLED STRUCTURES. The
procedures contained below describe the general approach involved in most
repairs.
10-3.1
Problem. Erosion or settlement has occurred. Any breaching of, or
impairment to, an earth structure exposed to moving water sharply increases its
susceptibility to damage. For this reason it is critical that any required main-
tenance be identified and carried out as quickly as possible.
10-3.2
Description of Repair/Maintenance
10-3.2.1 Replacing Soil. Where there is evidence of erosion or loss of soil,
protective coverings, such as rock fill or armor units, should be removed and the
internal fill material inspected. Any necessary repairs in the form of replacement
of properly compacted soil should be made, and the protective slope-covering
replaced in a manner that ensures no further erosion. A series of soil layers of
varying coarseness may be used to ensure that the finer, central materials
cannot be washed out through the coarser, shell materials. The use of a
geotextiles (see below) might be appropriate. In some cases, it may be
economical to protect the side slopes with asphalt concrete, soil cement, or even
reinforced Portland cement concrete. In cases where the side slopes are
exposed only to atmospheric erosion, vegetation such as ice plant or grasses
may be adequate.
10-3.2.2 Geotextiles. A rapidly emerging geotechnical engineering technology
involves use of geotextiles for seepage and erosion control, and for soil strength
reinforcement, see Koerner (Koerner, R. M. (1990), Designing with
Geosynthetics, 2nd Edition, Prentice-Hall, Inc., Englewood Cliffs, NJ).
Geotextiles are porous, flexible polymeric fabrics used for separating soil types,
soil retention, and strength reinforcement. When used for soil retention, the fabric
must meet permeability or permittivity requirements (ASTM D 4491, Standard
Test Method for Water Permeability of Geotextiles by Permittivity) relative to the
permeability of the retained soil. Also the openings in the fabric must be small
enough to impede loss of soil particles. This usually requires a fabric opening
size not more than twice the 85% size of the soil (sieve size through which 85%
of the soil grains will pass). Where a geotextile is used to provide drains for
pressure relief, the transmissivity or flow capacity in the plane of the fabric is the
important parameter.
Geotextile strength must also be considered in any design, see ASTM
D 4595, Standard Test Method for Tensile Properties of Geotextiles by the Wide-
Width Strip Method and ASTM D 774, Standard Test Method for Bursting
should have design strength factors of safety in the range of 2 to 4. This is
10-2
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