뒷채움재의 역학적 특성에 관한 연구

Abstract

최근 산업의 발달과 더불어 지하 구조물의 과밀화로 인해 도시 터널의 경우 점점 대심도화되는 경향이 있다. 터널의 시공 중 불가피하게 발생하는 공극 즉 지반과 복공 사이에 존재하게 되는 테일보이드가 지반 변위의 가장 큰 요인으로 작용하게 된다. 그러므로 지반 변위를 최소화하기 위해서는 테일보이드에 대한 뒷채움 효과가 중요하다.

본 논문에서는 다양한 배합비로 구성된 뒷채움 주입재에 대한 각종 실내실험을 통하여 주입재에 대한 물리적, 역학적 특성을 규명하였다.

재료 실험을 통하여 얻은 결과는 다음과 같다.

1. 겔타임은 재료의 교반 정도 등 여러 요소의 영향을 받으나, 물시멘트가 작을수록, 규산비가 작을수록 빨라지는 경향을 보였다. 겔타임은 물시멘트비, 규산비 등에 따라 온도가 20-25℃ 인 경우 15초 -1분30초 정도로 나타났다.

2. 시멘트 함량이 클수록 일축압축강도는 크게 나타났으며, 반면 파괴시의 변형률은 감소하였다. 인장강도는 일축압축강도의 1/15-1/20정도로 나타났다.

3. 삼축압축실험 결과 구속응?쩜? 증가할 수록, 파괴시의 강도, 변형률 모두 증가하였다. 또한 양생기간이 길어질 수록 압축강도는 증가하였으며, 초기 3일간의 양생기간에 현저한 강도 증가를 보였다.

In recent years, urban tunnels have more deeply constructed due to congestion of buried structures. In shield tunnelling spaces called tail-void are usually created between the ground and the outer face of the primary lining. In order to reduce the ground deformation, it is important to backfill in tail-void.

In this paper, an experimental investigation was undertaken to evaluate the physical and mechanical properties of grouts composed of various mixtures of backfill materials.

1. The gel time depends primarily on the cement content. As the w/c ratio decreases from 5:1 to 2:1, the gel time decreases form about 1 minute 30 seconds to 15 seconds at room temperature.

2. With increases of cement content, the strength of cement - silicate grout increases, but, the strain at failure decreases. Tensile strength obtained from the Brazilian test is about one -fifteenth the unconfined compressive strength.

3. With increases of confined stresses, the strength and strain at failure are all increased. The compressive strength of cement - silicate grout increases with curing time; significant strength increases are obtained in three days.

In recent years, urban tunnels have more deeply constructed due to congestion of buried structures. In shield tunnelling spaces called tail-void are usually created between the ground and the outer face of the primary lining. In order to reduce the ground deformation, it is important to backfill in tail-void.

In this paper, an experimental investigation was undertaken to evaluate the physical and mechanical properties of grouts composed of various mixtures of backfill materials.

1. The gel time depends primarily on the cement content. As the w/c ratio decreases from 5:1 to 2:1, the gel time decreases form about 1 minute 30 seconds to 15 seconds at room temperature.

2. With increases of cement content, the strength of cement - silicate grout increases, but, the strain at failure decreases. Tensile strength obtained from the Brazilian test is about one -fifteenth the unconfined compressive strength.

3. With increases of confined stresses, the strength and strain at failure are all increased. The compressive strength of cement - silicate grout increases with curing time; significant strength increases are obtained in three days.