In the past, proof of stability for self-supporting liners was generally provided in the Federal Republic of Germany using ATV-M 143 Part 3 [ATVM143-3] and in a manner similar to ATV-A 127 [ATVA127b], although this latter guideline was developed exclusively for new laid pipes and is based on a pipe-soil structural system (elastically bedded circular ring). As its kinematic permissible deformation figures and its resulting loading deviates from that …

The basis for carrying out the structural calculations are the cross sectional values of the wall structure being used. These are not only dependent on the material and the geometry but also on the loading.

The Bild 5.3.2.6.2.3, Bild 5.3.2.6.2.3 and Bild 5.3.2.6.2.3 show the loading ability of liners of various wall thicknesses produced according to the grouted-in-place lining process, whereby the thickness of the HD-PE hose is 2 mm in all cases and …

Structural Calculations of Liners Inserted by the Anchor Hose process

The force F for pulling-in a continuous pipe with rise or fall (Bild 5.3.2.6.3.1.1.1) is determined from the equation [FI-Hoech] :

When pulling-in curved piping, the sum of the created individual extensions with pulling and bending of 3 to 4 % must not be exceeded.

If an extension of 2 % is permitted during pulling-in, then the permissible extension caused by bending in the region of the curve is still approx. 1 to 2 %.

(Image: Pull head with pin connection with reference to [FI-Hoech] [Koch85] [Image: S&P GmbH])

The permissible tensile forces are limited not only by the tensile stress but also by the stresses arising in the region of the pull head. Depending on the design of the pull head, the forces are transmitted to the pipe via a welding joint (for welded-on pull-in cone), a flange joint with welding collar or a bolted connection (Bild 5.3.2.6.3.1.2.1).

The …

The tensile forces determined above must be smaller than the permissible forces given in Tabelle 5.3.2.6.3.1.2.

In the grouting of the annular space between the old pipe and the pulled-in HD-PE pipe with a material of specific gravity γ_D > γ_R (γ_R = specific gravity of the pipe), the ungrouted HD-PE pipe is subjected to the force (Bild 5.3.2.6.3.2.1) :

When grouting the annular space, a hydrostatic pressure P_h(Bild 5.3.2.6.3.2.2) acts on the pipe. This pressure must not be greater than the permissible buckling pressure p_k.perm of the pipe in order to avoid damage (Bild 5.3.2.6.3.2.2) [WRC90]. From Bild 5.3.2.6.3.2.2 there can be taken for pipes of HD-PE and PP copolymer the buckling pressures p_k with reference to the time of the various pipe rows or pressure loads at 20 °C. For higher temperatures, …

If the inserted pipe without annular space is used as a pressure pipe, then the pipe including pipe joints and fittings must be so sized that it can absorb the internal pressure during the desired lifespan - in the municipal field at least 50 years.

This is valid also for the case that the annular space is grouted and the grouting material, including the old pipe still cannot absorb the internal pressure. In this case, the inserted plastics pipes …

(Image: Loading due to hydrostatic pressure [FI-Hoech] [Koch85])

If the pipes to be rehabilitated lie in the groundwater region, then with leaking or porous pipes, the plastics liner is loaded by the groundwater column above the pipe middle point (Bild 5.3.2.6.4.2). For un-grouted gravity operated HD-PE pipes without side support effect, for instance, the buckling pressures pk determined in the investigations to Bild 5.3.2.6.3.2.2 are then valid. …

The coefficient of linear extension of HD-PE and PP pipes is approx, 0.17 mm/(m·K).

If a plastics pipe is anchored between two points then, due to the prevented thermal expansion, pressure is built up on warming and tensile stress on cooling. In the temperature region of -40 ° C to +20 ° C investigated, a tensile stress of 9.3 N/mm² was measured for cooling and a compressive stress of 5.8 N/mm² for warming. These stresses, which relax over the course …

In case I (Bild 5.3.2.6.4.2) the internal pressure for rigid piping generally forms the decisive load condition whereby an accompanying effect of the grouting material or the old pipe is not included for reasons of safety.

For a given internal diameter d_i and internal pressure p_i, there is applicable for the calculation of the wall thickness with a constant assumed stress distribution, that is, ignoring thick walling:

In contrast to the static and hydraulic process, in the pneumatic pipe bursting process the kinetic energy of the percussion piston in the inside of the bursting body results in percussions that are transferred to the environment and can be connected with:

• High levels of noise;
• Uncontrolled advancing destruction or collapse of the sewer to be replaced;
• Undesired compaction of the soil in the region of the embedment in connection with settling of the …

(Image: Bearing effects of the soil in the secondary condition II initiated by a dynamic bursting process (schematic depiction) [Falk95b])

The determination of the required bursting force, especially the part attributable to soil displacement, as well as discussion on the form and radius of the plastic zone, are not only important for the testing of possible effects on the pipe run but make an important contribution to the definition of the loading …

(Image: Decision process for the selection of structural solutions with reference to DIN EN 752-5 [DINEN752-5b])

As description of damage, its extent and its cause as well as the piping-specific limiting conditions in sewer systems are so different, the correct selection of the respective application case and the applicable structural rehabilitation measures are of great importance [Stein89c] [Stein95f].

All repair, renovation and replacement processes …