Handbook of Civil Engineering Calculations

6. Select the bedding method for the pipe
   Figure 14 shows methods for bedding sewer pipe and the strength developed. Thus, earth
   embedment, type 2 bedding, develops a load factor of 1.5. Since the computed load fac-
   tor, step 5, is 1.48, this type of bedding is acceptable. (In choosing a type of bedding be
   certain that the load factor of the actual pipe is less than, or equals, the developed load
   factor for the three-edge-bearing strength.)
   The type 2 earth embedment, Fig. 14, is a highly satisfactory method, except that the
   shaping of the lower part of the trench to fit the pipe may be expensive. Type 3 granular
   embedment may be less expensive, particularly if the crushed stone, gravel, or shell is
   placed by machine.
   7. Compute the direct load transmitted to the sewer pipe
   The weight of the drainage flume is carried by the soil over the sewer pipes. Hence, a por-
   tion of this weight may reach the sewer pipe. To determine how much of the flume weight

Type-4 Type-5 Type-6

Granular Embedment Partial Concrete Encasement

3/4 (19mm) crushed Concrete Embedment Load factor 4.5 for

stone or gravel or shell Load factor 2.4 standard strength pipe

Load factor 2.4

FIGURE 14. Strengths developed for various methods of bedding sewer pipes. (W. S.
Dickey Clay Manufacturing Co.)

Type-l

Eorth Embedment

Load factor 1. 1

Type -2

Earth Embedment

Load factor 1.5

Type -3

Granular Embedment

3/4" (19 mm ) crushed

stone or gravel or shell

Load factor 1.9