초록 ▼

본 연구에서는 영하온도에서의 지반재료의 다짐 특성을 파악하기 위해 상온(18℃)과 영하온도(-3℃, -8℃)에서 다짐시험을 수행하였으며, 동결 및 융해를 반복 적용시킨 지반재료의
일축압축시험, 체적변형측정, 불포화특성시험을 통해 동결 및 융해에 따른 해빙기 지반재료의
성능변화를 평가함. 영하온도에서 다짐 시 얼음의 생성으로 인한 다짐효과의 감소를 발견하였으며, 일축압축시험결과 –8℃에서 다짐된 시료의 경우 50%이상의 강도감소를 보임. 또한,
불포화 시험을 통해 동결융해에 따른 흡수력의 감소를 확인하였음. 본 연구에

본 연구에서는 영하온도에서의 지반재료의 다짐 특성을 파악하기 위해 상온(18℃)과 영하온도(-3℃, -8℃)에서 다짐시험을 수행하였으며, 동결 및 융해를 반복 적용시킨 지반재료의
일축압축시험, 체적변형측정, 불포화특성시험을 통해 동결 및 융해에 따른 해빙기 지반재료의
성능변화를 평가함. 영하온도에서 다짐 시 얼음의 생성으로 인한 다짐효과의 감소를 발견하였으며, 일축압축시험결과 –8℃에서 다짐된 시료의 경우 50%이상의 강도감소를 보임. 또한,
불포화 시험을 통해 동결융해에 따른 흡수력의 감소를 확인하였음. 본 연구에서 실시한 시험
결과를 바탕으로 영하온도 –3℃까지는 동절기 다짐시공이 가능하다고 판단되지만, -8℃이하의 온도에서는 다짐효과의 저하가 구조물의 안전성에 영향을 미칠 것으로 판단되어 다짐시공을 실시하기에 부적절하다고 판단됨.

Abstract ▼

Construction activities are thought to be stopped during the winter season, but many
construction companies are enforcing construction for the reasons of shortening the period
of construction and pursuing profits. Particularly, it does not have a definite standard and
field tests for the ev

Construction activities are thought to be stopped during the winter season, but many
construction companies are enforcing construction for the reasons of shortening the period
of construction and pursuing profits. Particularly, it does not have a definite standard and
field tests for the evaluation of degree of compaction at the frozen temperature. Therefore,
it is difficult to predict the potential problems of geotechnical materials compacted at the
winter season. It is necessary to understand mechanical properties of soils compacted at
sub-zero temperature and performance changes with temperature to prevent possible
accidents in the thawing season. Furthermore, in the seasonally frozen ground region such
as Korea, freezing and thawing are repeatedly applied on the ground and it is expected to
change the mechanical characteristics in the unsaturated state. It is thus important to
understanding unsaturated soil characteristics under freezing and thawing condition and
sub-zero temperature. Therefore, in this research, the compaction tests on sandy materials
with various fine contents and domestic weathering soil were conducted under various
temperature at 18℃, -3℃ and -8℃. In addition, the unconfined compression test,
volumetric strain measurements and unsaturated soil characteristics tests were conducted
with various freezing and thawing cycles to evaluate the performance of the geotechnical
material throughout the years. Based on the test results, a compaction technique was newly
developed to minimize the mechanical changes occurred during the thawing.
Based on the compaction test results at the sub-zero temperatures, due to the
reduction of the compaction effect caused by the development of the ice, it was confirmed
that the maximum dry unit weight of the soil decreased. It can be implied that it is
difficult to obtain a relative degree of compaction in accordance with the specification at
sub-zero temperature and compaction energy should be increased to obtain proper one.
Based on the unconfined compression test results, since the reduction of the strength and
change in volumetric strain between the freezing and thawing temperature obtained from the
sample compacted at -3℃ are negligible, earthwork at this temperature can be performed.
On the other hand, in the case of the test results at -8℃, since the strength reduction rate
of the samples presents distinctly by 50% compared to the room temperature ones, the
structural stability can be affected by the reduction of the strength. Based on the
unsaturated soil characteristics test results, the weathered soil shows that the suction force
decreases with increasing the number of freezing and thawing cycles for all water contents
and the suction force applied to the freezing and thawing at -8℃ presents more distinct
change than tests at -3℃
Since the suction force is increasing shear strength by making negative pore pressure,
the reduction of suction caused by repeated freezing and thawing cycles at -8℃ can
severely affect the stability of the superstructure. Based on the all the test results presented
in this research, the suitability of ground materials for construction in winter season is
evaluated and the compaction guidelines are proposed. The coarse grained soils are the
most suitable ground material for construction in winter season and the water contents of
the ground material should be kept under 7% to minimize influence of frost heave. Based
on the experimental research presented herein, it can be concluded that the earthwork can
be performed in the winter season where the temperature is greater than -3℃ but the
earthwork should not be performed at the temperature lower than -8℃.
Due to the guidelines presented in this research was made on the basis of the results
obtained from laboratory test, it was not taken into account the uncertain conditions of the
field. The manual should be adjusted prior to the direct application to the field based on
the model or field verification.

목차 Contents

• 표지 ... 1
• 제출문 ... 2
• 보고서 요약서 ... 3
• 요약문 ... 4
• SUMMARY ... 13
• CONTENTS ... 15
• 목차 ... 16
• 제1장 연구개발과제 개요 ... 17
• 1절 연구개발의 목적 및 필요성 ... 17
• 2절 연구내용 및 범위 ... 18
• 3절 관련분야의 국내외 기술개발 현황 ... 18
• 4절 연구개발결과가 관련분야에서 차지하는 위치 ... 19
• 제2장 연구개발 수행내용 및 결과 ... 20
• 1절 동절기 다짐특성에 관한 선행연구 분석 ... 20
• 2절 영하온도에 따른 불포화함수특성에 관한 선행연구 분석 ... 34
• 3절 연구수행과정 및 내용 ... 49
• 제3장 최종 연구성과 및 적용실적 ... 90
• 1절 주요연구 성과 ... 90
• 2절 연구 성과 검증 ... 93
• 제4장 연구성과의 활용 및 추가연구 필요성 ... 97
• 1절 연구성과의 활용방안 및 기대효과 ... 97
• 2절 추가연구의 필요성 ... 98
• 제5장 참고문헌 ... 99
• 끝페이지 ... 102