ASTM C 12 : – Standard Practice for Installing Vitrified Clay Pipe Lines
This practice covers the proper methods of installing vitrified clay pipe lines by open trench construction methods in order to fully utilize the structural properties of such pipe.
DESIGN CONSIDERATIONS
4. Supporting Strength
4.1 The field supporting strength of vitrified clay pipe is
materially affected by the methods of installation. The field
supporting strength of a pipe is defined as its capacity to
support dead and live loads under actual field conditions. It is
dependent upon two factors: (1) the inherent strength of the
pipe and (2) the bedding of the pipe.
4.2
The minimum bearing strength requirement in accordance with Specification C700, as determined by the 3-edgebearing test of Test Methods C301, is a measure of the inherent
strength of the pipe.
4.3
The tests used to measure bearing strength determine
relative pipe strengths but do not represent actual field conditions. Therefore, an adjustment called a load factor is introduced to convert minimum bearing strength to field supporting
strength. The magnitude of the load factor depends on how the
pipe is bedded. The relationship is:
Field supporting strength 5 minimum bearing strength 3 load factor
4.4
A factor of safety >1.0 and ≤1.5 shall be applied to the
field supporting strength to calculate a safe supporting strength.
The relationship is:
5. External Loads
5.1 The external loads on installed vitrified clay pipe are of
two general types: (1) dead loads and (2) live loads.
5.2 For pipes installed in trenches at a given depth, the dead
load increases as the trench width, measured at the top of the
pipe, increases. Pipe failure may result if the design trench
width is exceeded. If the trench width exceeds the design
width, a higher class of bedding, stronger pipe, or both, must be
investigated.
5.3 Live loads that act at the ground surface are partially
transmitted to the pipe. Live loads may be produced by wheel
loading, construction equipment or by compactive effort.
TABLE 1 Uniform Soil Groups for Pipe Installation
