Infrastructure · buried pipes & trenchless · studio

Buried pipes & trenchless studio

Design the pipe in the ground and the way it gets there. Soil and traffic loads against cover; deflection, strain and buckling of flexible pipes with the native soil taken into account; the strength class of concrete and clay pipes for the bedding; the trench, its width and its support. Then choose how to install it — the method selector ranks open cut, HDD, microtunnelling, pipe jacking, auger boring, ramming and bursting — and design the crossing: HDD profile, pullback and frac-out, jacking forces and interjack stations, settlement and the cost against open cut.

Scope & limitations

Preliminary design. Flexible pipe checks follow the modified Iowa / AWWA M45 / AS/NZS 2566.1 methods, rigid pipes the indirect (bedding factor) method; HDD follows ASTM F1962 and the Delft frac-out method. Confirm pipe classes and stiffness with the manufacturer, ground parameters with a geotechnical investigation, and costs with contractors.

What the buried pipes & trenchless studio does

Choose the pipe — PVC-U, PE100, GRP, ductile iron, steel, reinforced concrete or vitrified clay — its size and stiffness or class, the cover, trench width, embedment, native soil and groundwater. The studio works out the soil load (the prism load for flexible pipes, the Marston trench load capped at the embankment load for rigid pipes) and the traffic load for the code's design vehicle spread through the fill with its dynamic allowance, and plots both against cover.

Flexible pipes: long-term deflection by the modified Iowa formula with the Leonhardt correction for soft native soil, ring bending strain, buckling under soil, water, vacuum and traffic (AWWA M45 / AS/NZS 2566.1), hoop stress under pressure, flotation and thrust blocks. Rigid pipes: the required test load, D-load or crushing strength with the bedding factor, and the first standard class (AS/NZS 4058, ASTM C76 or EN 1916 / EN 295).

Trench: minimum width by code, depth, when support is mandatory, batter slopes by soil type, apparent earth pressure on shields and struts and base heave in soft clay. Trenchless: a method selector ranks open cut, HDD, microtunnelling, pipe jacking, auger boring, pipe ramming, guided boring and pipe bursting for the size, length, ground, groundwater and surface.

HDD: the bore profile from the entry and exit angles, depth and radius, the ASTM F1962 pullback at each point with fluid drag, safe pull strength, collapse in the bore and the Delft frac-out margin along the bore. Pipe jacking and microtunnelling: face and skin friction, the permissible jacking load and the intermediate jacking stations needed. A Peck settlement trough, an open cut against trenchless cost comparison, 3D scenes, an A3 drawing set, calculation sheets, Excel and a priced BOQ complete it.