Civil Engineering Reference
In-Depth Information
TABLE 14.5
Excavation, Grading, and Fill (
Continued
)
Topic
Discussion
Compaction
of fill per
Section
1803.5.8
Compacted fill material is also discussed in Sec. 1803.5.8 of the
International
Building Code,
as follows:
“Section 1803.5.8 Compacted fill material. Where shallow foundations will bear
on compacted fill material more than 12 inches (305 mm) in depth, a geotechnical
investigation shall be conducted and shall include all of the following:
1.
Specifications for the preparation of the site prior to placement of compacted
fill material.
2.
Specifications for material to be used as compacted fill.
3.
Test methods to be used to determine the maximum dry density and optimum
moisture content of the material to be used as compacted fill.
4.
Maximum allowable thickness of each lift of compacted fill material.
5.
Field test method for determining the in-place dry density of the compacted
fill.
6.
Minimum acceptable in-place dry density expressed as a percentage of the
maximum dry density determined in accordance with Item 3.
7.
Number and frequency of field tests required to determine compliance with
Item 6.”
Grading
Appendix J of the
International Building Code
(2012) provides additional grading
recommendations, which may be required if they are adopted by local ordinance.
In terms of fill compaction, Appendix J states that all fill material shall be com-
pacted to a relative compaction of 90 percent based on the Modified Proctor.
This is the usual requirement in California for structural fill, where the minimum
relative compaction is 90 percent (using the Modified Proctor test specifications,
ASTM D 1557). For some types of construction projects, such as the compaction
of road subgrade or for the lower portions of deep canyon fill, a minimum relative
compaction of 95 percent based on the Modified Proctor is often recommended
by the geotechnical engineer.
Appendix J also provides regulations concerning the construction of fill slopes.
For example, the construction of a fill slope over an existing slope that is steeper
than an inclination of 5:1 (horizontal:vertical) requires the construction of a key
and benching. Appendix J also deals with permits, inspections, excavations,
setbacks, drainage, terracing, and erosion control regulations. If adopted by local
ordinance, the reader should review Appendix J of the code concerning these
items.
foundation design and retaining wall design. The foundation report as prepared by the
geotechnical engineer will usually specify these load-bearing values. For the load-bearing
values, the
International Building Code
(2012) states:
Section 1806.2 Presumptive load-bearing values. The load-bearing values used in design for
supporting soils near the surface shall not exceed the values specified in Table 1806.2 unless
data to substantiate the use of higher values are submitted and approved. Where the building
official has reason to doubt the classification, strength or compressibility of the soil, the require-
ments of Section 1803.5.2 [i.e., a required geotechnical investigation] shall be satisfied.
