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Study on Geotechnical aspects related to rehabilitation of deteriorated sewer pipelines

Research Project

Project/Area Number 15360257
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Geotechnical engineering
Research InstitutionOsaka City University

Principal Investigator

TOHDA Jun  Osaka City University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (90128744)

Co-Investigator(Kenkyū-buntansha) YOSHIMURA Hiroshi  Anan National College of Technology, Department of Construction System Engineering, Associate Professor, 建設システム工学科, 助教授 (20342561)
Project Period (FY) 2003 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥9,000,000 (Direct Cost: ¥9,000,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2003: ¥4,900,000 (Direct Cost: ¥4,900,000)
KeywordsSewer Pipeline / Backfill Soil / Deformation Modulus / Time History / Repeated Vehicle Load / Deflection Ratio / Plastic Pipe / Soil-structure Interaction / 乾湿繰返し / たわみ性管 / 老朽管 / 復旧 / 空洞 / 長期挙動 / 剛性
Research Abstract

In Japan, many old sewer pipelines installed in urban areas were severely deteriorated to decrease their functions and increase the possibility of ground depression. Sewer pipes are not pressure pipes. If the old pipes are deteriorated, therefore, soil particles tend to flow into the pipes with water, easily developing voids in the ground to cause ground depression. However, mechanism and actual condition of void development in the ground have not been clarified yet. Also, since excavation for replacing the deteriorated pipes by new pipes is difficult in urban areas, no-dig rehabilitation methods using plastic inner liners have been developed and are increasingly being used in the world. The plastic inner liners have long lives, but their rigidity decreases according to the elapsed time due to relaxation. On the contrary, the rigidity of backfill soils around the pipes increases according to the elapsed time. Therefore, mechanical behavior of buried pipes that is governed by relative rigidity between soil and pipe will be changed according to the elapsed time. However, this problem has not been studied hitherto.
This study was carried out to clarify mechanism of void development in the ground around deteriorated old sewer pipelines and to investigate long-term change in soil-structure interaction. The main conclusions can be summarized as follows:
1) Inflow of soil through opening at joints of the pipeline develop the voids in the ground. The location of the voids is at the upper part of the pipe, but not at the top of the pipe. Cracks along the long axis of the pipe do not produce the voids in the ground.
2) Apparent rigidity of backfill soils decrease due to repeated vehicle loading, resulting in increase in deflection of plastic pipes. The relaxation of plastic pipes during the elapsed time remarkably strengthens the deflection of plastic pipes.

Report

(5 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • 2003 Annual Research Report
  • Research Products

    (1 results)

All 2003

All Patent(Industrial Property Rights) (1 results)

  • [Patent(Industrial Property Rights)] 地中空洞充填用注入管及びこれを用いた地中空洞充填方法2003

    • Inventor(s)
      東田 淳
    • Industrial Property Rights Holder
      東田淳, 岡島洋一, (株)バーナム
    • Industrial Property Number
      2003-345538
    • Filing Date
      2003-10-03
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary

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Published: 2003-04-01   Modified: 2016-04-21  

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