The structural design of large non-circular GRP prefabricated linings
Jun 19, 2008
As happened in the UK, 20 years ago, when the WRc started to work on the Sewer Rehabilitation Manual (SRM), in 1999 the French ministry of Public Works decided to launch a National Project of Research and experimentation program called RERAU, covering the “Rehabilitation of Urban Network Sewers” in order to increase the knowledge in regard to the area of sewer system rehabilitation.
- a simplified design formula which extends Glock’s analysis for evaluation of safety with regard to buckling
- a new design method based on finite element method analysis (F.E.M.) specially for large (man-entry), non-circular GRP linings and special non conventional loads. The design principles of this F.E.M. approach and two case studies are presented in the paper.
The second case study is a corrugated steel pipe arch buried in a motorway’s embankment and relined by a horseshoe GRP prefabricated lining. In this case, because of the heavy corrosion of the steel, it was considered that the host steel pipe arch would loose its hoop compressive stiffness after lining.
- Ability to sustain the grouting pressure during installation (where appropriate).
- Ability to sustain the external head of groundwater pressure that must be considered to arise once hydraulic integrity is restored.
- And eventually ability to sustain soil loading transfer if the sewer loses its hoop compressive stiffness after lining.
- Height : 1761 mm
- Width : 866 mm
- Thickness : 17 mm
- Radius of the straight section : 2278 mm
- Mean Perimeter : 4430 mm
- Young modulus : 11000 MPa
- Long term modulus (wet cree value): 3700 MPa
- Bending strength : 60 MPa
pw = 10 ⋅ (2.3 - 0.7) = 16 kPa
pcr = 0.455 ⋅ k0.4 ⋅ EL ⋅ [t2.2 / (P0.4R1.8)]
pcr = 0.455 ⋅ 1.32 ⋅ 3700 ⋅ [172.2 / (44300.422871.8)] = 35 kPa
The safety factor for the stability is:
γF = 35/16 = 2.2 > 2
The safety factor for stability security must be greater than 2.
- If the host sewer loses its hoop compressive stiffness after lining.
- If a subsequent excavation near the renovated pipe is undertaken.
- If the host sewer is obviously in an unstable ground, where the source of instability is not eliminated by lining.
- The first method is for linings that form a bond to the grout, so that the renovated sewer acts as a composite section (WRc type I linings)
- The second method is for linings that form no bond with the grout (type II linings).
- The old sewer and the grout act like the surrounding soil.
- The lining is behaving like a flexible structure in interaction with the soil.
- The effect of time is introduced by multiplying the elastic modulus by a creep factor.
- Height of soil above the crown: 12.0 m.
- Height of the table water above the invert: 2.3 m.
- Elastic modulus of soil Es = 10 MPa.
- Specific weight of soil γ = 20 kN/m3.
- Embedment: mixed grained soils with low fine fraction, relative compaction Dr > 95% OPN.
- Height: 1557 mm
- Width: 2469 mm
- Thickness: 33 mm
- Radius of the invert section: 3567 mm
- Mean Perimeter: 6500 mm
- Young modulus: 11000 MPa
- Long term modulus: 3700 MPa
- Bending strength: 60 MPa
pw = 10 ⋅ (1.6 + 0.5) = 21 kPa
pcr = 0.455 ⋅ k0.4 ⋅ EL ⋅ [t2.2 / (P0.4R1.8)]
pcr = 0.455 ⋅ 3700 ⋅ [332.2 / (65000.435671.8)] = 44.4 kPa
In this case, k=1 because there is only one lobe (at the invert).
γF = 44.4/21 = 2.1 > 2
The safety factor for stability security must be greater than 2.
- the vertical deflection must be less than 3% of the lining height;
- the maximal bending stress must be less than the bending strength divided by a safety factor of 1.5.
[2] WRc/WAA - Sewerage rehabilitation manual. UK Water Research Center / Water Authorities Association, 1994-2000.
[3] Thépot O., 2000, A new design method for non-circular sewer linings. Trenchless Technology Research, Vol. 15, No. 1, 25-41.
[4] Thépot O. 2001, Structural design of oval-shaped sewer linings, Thin-Walled Structures, Vol. 39, 499-518.
[5] Avis Technique CSTB NC Line 17/04-155 , HOBAS France. Technical specifications of GRP panels.
1 HOBAS France, BP 216 F-95523 Cergy Pontoise, France, jeanmarie.joussin@hobas.com
2 EAU DE PARIS, 21-23 rue de la Vanne, 92120 Montrouge, France, thepot@eaudeparis.fr
More News and Articles
Mar 27, 2024
News
USU Study Looks at Water Main Break Rates in the U.S. and Canada
Report Highlights Correlation Between Material and Diameter
Mar 26, 2024
News
Update BE-21: New Material in Course and Modules on Trenchless Pipe Installation
Online training on the topic of pipeline installation in civil engineering: Trenchless technology for underground drainage construction can be a resource-efficient, environmentally friendly, time-saving, and cost-effective alternative to open cut methods. The UNITRACC e-learning course "Utility Tunnelling" has been enhanced …
Mar 25, 2024
Article
Bacteria as a new weapon in wastewater treatment
In early November, San Diego based startup Aquacycl officially opened its first European office and test center at the Water Campus in Leeuwarden. The Netherlands Foreign Investment Agency (NFIA) and the Investment and Development Agency for the Northern Netherlands (NOM) …
Mar 22, 2024
News
A superior HDD offering
Building on its relationships with leading horizontal directional drilling companies, TRACTO Australia has delivered three new rigs to operator Superior HDD.
Mar 20, 2024
News
New portable water filtration technology could improve access to clean drinking water worldwide
The University of Texas at Austin has developed an injectable water filtration system with the aim to aid the over two billion people worldwide who are without clean drinking water.
Mar 18, 2024
News
Global Student Innovation Challenge Calls on Next-Generation Leaders to Tackle Water Security
High School and University Students Worldwide Invited to Expand Water Access and Community Resilience
Mar 15, 2024
News
New water treatment wins Prestigious Award
Introducing a advancement in water treatment, developed by Cardiff University researchers in collaboration with Origin Aqua, the FreeOxTM technology has garnered acclaim by winning a prestigious challenge award at the World Water Tech Innovation Summit. This single-step process not only …
Mar 13, 2024
News
Satellite-based river monitoring technique could provide early warning of flooding
A satellite-based method for monitoring the flow of rivers from orbit could provide a valuable early warning system for flood risk, University of Glasgow researchers have claimed.
Mar 11, 2024
News
Revitalising infrastructure with HDD
Through the use of horizontal directional drilling, TasWater is delivering a new sewer pipeline to improve sewer and stormwater transfer capacity in Launceston, Tasmania.
Mar 06, 2024
News
Picking up the pace on climate action: Building momentum from COP28
At the halfway point of the Paris Agreement, the legally binding international treaty on climate action, average global temperatures are already hitting 1.8°C above pre-industrial levels and future projections are stark. At COP28 in December, we could not escape the reality …
Mar 01, 2024
News
Luminescent sensor detects ‘forever chemical’ pollution in water
Researchers in the UK and Germany have developed a new approach for detecting pollution from ‘forever chemicals’ in water through luminescence.
Feb 28, 2024
Article
BETT installation demonstrating GHG emissions reduction of wastewater treatment
This study presents BioElectrochemical Treatment Technology (BETT) as a new wastewater management solution toward the Net-Zero future. The results reported herein were collected from a BETT pilot system installed at a large brewery in Los Angeles, CA, United States processing …
Contact
Dipl. Eng. JM. Joussin [HOBAS France SAS]
95523 Cergy Pontoise, Cedex, France
Phone:
+33 1 34356610
Fax:
+33 1 34350858