ASTM C12-17 pdf download.Standard Practice for Installing Vitrified Clay Pipe Lines.
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 ofbedding, 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. Compaction of embedment and backfill materials, beside and above the sewer pipe, produces a temporary live load on the pipe. The magnitude of the live load from compactive effort varies with soil type, degree of saturation, degree of compac- tion and depth of cover over the pipe. Care must be used in selection of compaction methods so that the combined dead load and live load does not exceed the field supporting strength of the pipe, or cause a change in its line or grade. N OTE 1—For generally accepted criteria and methods for determining loads and supporting strengths, see Gravity Sanitary Sewer Design and Construction, Water Pollution Control Federation Manual ofPractice No. FD-5, American Society of Civil Engineers—Manuals and Report on Engineering Practice—No. 60. 4
6. Bedding and Encasement 6.1 Classes ofbedding and encasements for pipe in trenches are defined herein. The load factors indicated are for conver- sion of minimum bearing strength to field supporting strength.
6.1.1 The soil groups used in each bedding class are defined in Table 1.
6.1.2 The gradation for Class I and Class II soil for Class C bedding (Fig. 3) shall have a maximum particle size of1 in. (25 mm).
6.1.3 The gradation for Class I and Class II bedding material for Class B (Fig. 4), Crushed Stone Encasement (Fig. 5), and CLSM installation (Fig. 6) shall be as follows: 100 % passing a 1 in. (25 mm) sieve 40-60 % passing a 3 ⁄ 4 in. (19 mm) sieve 0-25 % passing a 3 ⁄ 8 in. (9.5 mm) sieve 6.1.4 For Class I, all particle faces shall be fractured.
6.1.5 Class II soils shall have a minimum of one fractured face. For Class B (Fig. 4), Crushed Stone Encasement (Fig. 5), and CLSM installations (Fig. 6) where high, or changing water tables, or both, are present; Class II material shall have a minimum percentage by particle count of one fractured face- 100 %, two fractured faces-85 %, and three fractured faces- 65 % in accordance with Test Method D5821. 6.1.6 Class I material is considered to be more stable and provide better support than Class II material that have some rounded edges.
6.1.7 All bedding material shall be shovel-sliced so the material fills and supports the haunch area and encases the pipe to the limits shown in the trench diagrams. 6.2 Class D (Fig. 2): 6.2.1 The pipe shall be placed on a firm and unyielding trench bottom with bell holes provided (Fig. 7). 6.2.2 The initial backfill shall be either Class I, II, III, or IV having a maximum particle size of 1 in. (25 mm). 6.2.3 The load factor for Class D bedding is 1.1.ASTM C12 pdf download.