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2022 Vol.38, Issue 4 Preview Page

Research Article

A Study on Clogging during Installation of Compaction Pile

다짐말뚝 시공 시 공극 막힘 현상 분석 연구

Jeong Ho Choi1
,
Seong Jin Park2
,
Yun Wook Choo3*
,
Il Gon Kim4
,
Byeong Kyu Kim5
최 정호1
,
박 성진2
,
추 연욱3*
,
김 일곤4
,
김 병규5
1Member, Graduate Student, Dept. of Civil & Env. Eng., Kongju Nat. Univ.
2Under Graduate Student, Dept. of Civil & Env. Eng., Kongju Nat. Univ.
3Member, Prof., Dept. of Civil & Env. Eng., Kongju Nat. Univ.
4Member, Vice Chairman, Chosuk Construction corp.
5Member, Managing director, Korea port Engrg. corp.
1정회원, 공주대학교 건설환경공학과 석사과정
2비회원, 공주대학교 사회환경공학과 학사과정
3정회원, 공주대학교 사회환경공학과 교수
4정회원, ㈜초석건설산업 부회장
5정회원, ㈜한국항만기술단 기술연구소 상무
*Corresponding Author
30 April 2022. pp. 33-45
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Abstract

A series of model tests were performed in this study to demonstrate the clogging mechanism created during the installation of a compaction pile to improve soft ground. The application of an air-jet to extrude sand or aggregates from a casing during the installation of a compaction pile imposes a remarkably high-pressure difference between the composite soil layers of clay and sand (or aggregates), resulting in severe clogging. Therefore, a one-dimensional testing system was developed to simulate composite soil layers consisting of clay and sand (or aggregates) and to apply a high-pressure differential at both boundaries, thus replicating the extrusion process used in compaction pile installation. Herein, the performance of two construction materials for compaction piles of crushed stone and grading-controlled aggregates was compared. A series of one-dimensional model tests were performed under multiple pressure settings, with clogging depth and permeability measured in each case. Results indicate that, blinding clogging mechanisms and blocking defined by previous studies were observed for crushed stone, and a new mechanism of “infiltration” was revealed and defined. Whereas, the controlled aggregates performed excellently against clogging because only blinding was observed.

Keywords
Clay
Clogging
Compaction pile
Controlled aggregate
Crushed stone

본 논문에서는 연약지반개량을 위해 활용되고 있는 다짐말뚝공법 시공 시 발생하는 공극 막힘을 규명하고자 일련의 축소모형실험을 수행하였다. 다짐말뚝 타설 시 Air-jet에 의한 골재 압출 공정 과정에서 점토-골재 복합지반 사이에 상당한 압력이 재하 되어 소산되는 과정에서 공극 막힘이 심화되는 것으로 알려져 있다. 따라서, 다짐말뚝이 시공된 연약지반을 1차원 점토-골재 복합지반으로 모사하고 양단경계에 시공 시 발생하는 압력 차이를 재하하는 실험시스템을 개발하였다. 개발된 실험시스템을 이용하여 다짐말뚝 시공 조건에서 발생하는 공극 막힘의 메커니즘을 규명하고자 하였다. 본 연구에서는 쇄석과 공극 막힘 현상을 개선하기 위해 제안된 입도조정골재에 대하여 압력재하실험을 수행하여 재료에 따른 공극 막힘을 비교하였다. 실험 결과, 압력 조건에 따른 쇄석과 입도조정골재의 점토 혼입 메커니즘을 관찰하고, 점토-골재 복합지반으로의 유입과 유출 유량의 측정을 통하여 통수능을 비교·분석하였다. 다짐말뚝의 시공 조건에서는 일반적인 공극 막힘 형태인 Blinding과 Blocking현상이 관측되었고, 이에 더하여 Infiltrating현상이 새롭게 발견되었다. 또한, 쇄석은 Blinding, Blocking과 Infiltrating 현상이 모두 관찰되었으나, 입도조정골재는 Blinding현상만이 관측되어, 공극 막힘이 거의 발생하지 않아, 쇄석에 비하여 배수성능이 우수하게 나타났다.

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 38
  • No :4
  • Pages :33-45
  • Received Date : 2022-02-15
  • Revised Date : 2022-03-21
  • Accepted Date : 2022-03-21
  • DOI :https://doi.org/10.7843/kgs.2022.38.4.33
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