Page 8 - Buried Pipe Design

vi Contents
Chapter 3. Design of Gravity Flow Pipes 65

Soils 65
Soil classes 65
Soil-pipe interaction 69
Embedment 71
Compacting techniques 72
Trench Width 74
Wheel loads 76
Water table 76
Soil particle migration 76
Voids in the embedment 77
Heavy equipment 77
Rigid Pipe Analysis 78
Three-edge bearing strength 78
Bedding factors and classifications 79
Installation design 79
Flexible Pipe Analysis 83
Installation design 83
Spangler’s Iowa formula 84
Use of the constrained soil modulus for flexible pipe design 91
Deflection lag and creep 95
Watkins’s soil-strain theory 103
Empirical method 106
Pipe Design Criteria 109
Performance limits 109
Safety factors 120
Parallel Pipes and Trenches 121
Rigid pipes 128
Safety factors 129
Parallel trench 129
Vertical trench walls 129
Sloped trench walls 133
Excavation 134
Analytical Methods for Predicting Performance
of Buried Flexible Pipes 137
Introduction 137
Flexible pipe design and analysis 137
Methods for predicting pipe performance 139
Conclusions 146
Finite Element Methods 146
Introduction 146
A general description of FEA solutions for buried pipe 148
PIPE5 analysis procedure 150
Example applications 165
Summary and conclusions 177
References 178

Chapter 4. Design of Pressure Pipes 183
Pipe Wall Stresses and Strains 183
Hydrostatic pressure 183
Surge pressure 186
External loads 192
Combined loading 193
Longitudinal stresses 195