지반조사계획과 지반개량설계

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영남대학교 토목공학과 기초공학 설계과제로

목차

1.0 서 언 ······································ 1
1.1 설계 개요 및 목적 ······························· 1
1.2 설계 내용 ·································· 1

2.0 조사 내용 ···································· 1
2.1 조사 개요 ·································· 1
(1) 조사명 ··································· 1
(2) 조사 목적 ·································· 1
(3) 조사수행방향 ·································1
(4) 조사 위치 ·································· 2
(5) 조사 장비 ·································· 2
(6) 조사 내용 ·································· 2
(7) 조사 기간 ·································· 3

2.2 지층 개요 ·································· 3
(1) 지형 ···································· 3
(2) 지질 ···································· 3

2.3 조사 결과 ·································· 3
(1) 시추 조사 ·································· 3
(2) 지하수위 ·································· 7
(3) 현장시험 ·································· 7
(4) 실내시험 ·································· 8

2.5 성과분석 및 검토 ······························ 8
(1) 지반 현황 ·································· 8
(2) 토질 특성 ·································· 8

3.0 연약지반의 공학적 특성 ····························· 9

3.1 개요 ····································· 9
3.2 연약지반의 설정 및 분포현황 ························· 9
3.3 연약지반의 지역구분 ····························· 10
3.4 연약지반의 공학적 특성 ··························· 11

4.0 연약지반 설계기준 ······························· 12
4.1 허용 잔류침하량 및 추가 적용하중의 산정 ··················· 12
(1) 허용 잔류침하량 ······························ 12
(2) 추가 적용 하중의 산정 ··························· 13
(3) 허용 잔류 침하량 및 추가 적용하중 설정 ··················· 14

4.2 기타 설계기준의 산정 ····························· 14
(1) 성토사면에 대한 안전율 ··························· 14
(2) 성토속도 ·································· 14
(3) 재하성토 유용계획방안 ··························· 14
(4) 연약지반 처리기간 산정 ··························· 14

5.0 연약지반 설계 ········································· 15

5.1 대표단면 위치 선정 및 침하량 산정 ······················ 15
(1) 대표 단면위치선정 ······························15
가. 설계입력정수 결정(압밀대상층) ······················· 16
나. 공용하중 ································· 16
다. 예상 압밀침하량 계산 ··························· 17
(2) 압밀소요시간 계산 ····························· 18
(3) PBD 배치간격 및 프리로딩 높이결정 ····················· 18
가. PBD 배치간격 및 프리로딩 높이 결정 ···················· 18
나. 프리로딩 높이(H)의 결정 ·························· 20

본문내용

1.1 설계 개요 및 목적
본 과업은 계획적·종합적 산업단지 조성으로 공장시설 용지에 부응한 저렴한 시설 용지 제공을위하여 경산시 갑제동 일원에 위치한 경산시 갑제동 산업단지 개발사업을 시행하기 위한 기본 및 실시 설계의 일환으로 300만로서 본지구의 대부분이 연약지반으로 지면 12~18m에 불규칙하게 연약층이 분포하고 있는 상태로 다음과 같은 목적을 가지고 설계를 수행하였다.
①지반조사 실시로 설계에 필요한 지반 공학적 기초자료수집
②지반조사 결과에 의한 연약지반의 생성기원,분포규모,성층상태의 확인 및 연약지반 구간의 설정
③현장 및 실내 시험 결과에 대한 토질정수의 검토 및 결정
④안정검토에 대한 적용성 검토
⑤계획 구조물에 대한 안정성과 변형에 대한 검토,문제점 도출 및 처리기준 제시
⑥문제에 대한 합리적이고 경제적인 해결 방안 제시 및 적용 공법에 대한 상세해석과 그에 대한 시공 관리방안

5.0 연약지반 설계
다. 예상 압밀침하량 계산
계획구조물 건설로 인하여 예상되는 총침하량을 계산하여 허용침하량(Sa=10.0cm)기준까지 적합한지 여부를 파악하면 다음과 같다.
① 1차 압밀침하량 계산
- 상부 연약점토층 : Po` ≒ Pc 이므로 정규압밀토로 보고 침하량을 Cc법으로 구하면,

여기서, : 1차 압밀침하량(cm) : 압축지수
: 초기간극비 H : 압밀대상층의 두께 (m)
: 유효상재하중 () △P : 작용하중 (tf/)
(지하수위 : GL-0.4,단위중량 지하수위 상단 : 1.85 t/)
=1.85 x 0.4 +{(1.85-1) x (8/2 -0.4)} = 3.8 tf/

∴ 계산된 침하량(74cm)이 허용침하량(10cm)을 초과하므로 연약지반처리가 필요하다.

참고 자료

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