Study on Bending and Shear Strength Setting of Full-scale Model Additional Walls for Additional Wall Test Bed Combined with PHC-W Pile Retaining Wall

PHC-W말뚝 흙막이와 결합된 지하증설벽체 테스트베드 구축을 위한 실대형 지하증설벽체의 휨강도 및 전단강도 설정 연구

Abstract

Test bed additional wall combined with PHC-W pile retaining wall has been constructed. To determine the dimensions of test bed additional wall, bending and shear tests of full scale core members of additional wall were tested. Basement additional walls utilizing PHC-W pile retaining wall, which were developed by modifying the cross-section of PHC piles, were classified into the composite additional wall and the non-composite additional wall. Their tests were conducted to obtain bending strength and shear strength of basement additional walls ultilizing PHC-W pile retaining wall. Since bending strengths and shear strengths of the composite additional wall and the non-composite additional wall were similar, it could be confirmed that the non-composite additional wall could be applied instead of the composite additional wall. Full-scale model additional wall was 200 mm thick, thus the thickness of additional wall combined with PHC-W pile retaining wall could be reduced by 100~200 mm.

PHC-W흙막이벽체와 결합된 지하증설벽체의 테스트베드를 구축중에 있다. 지하증설벽체의 제원을 결정하기 위하여 실대형 지하증설벽체의 핵심 부재를 제작하여 휨강도실험 및 전단강도실험을 실시하였다. 원형 PHC말뚝의 단면 형상을 개량하여 개발된 PHC-W 흙막이벽체를 건축물 지하벽체로 활용하기 위하여 합성증설벽체와 비합성증설벽체를 제작하여 휨강도 및 전단강도 실험을 수행하였다. 합성증설벽체와 비합성증설벽체에서 휨모멘트 강도 실험값 및 전단강도 실험값이 유사한 수준으로 나타났으므로 합성증설벽체 대신에 시공이 간편하고 비용이 절감될 수 있는 비합성증설벽체를 적용할 수 있다는 것을 확인하였다. 실대형 모형 증설벽체는 두께 200mm로 제작되었는데, PHC-W 흙막이벽체와 결합된 지하증설벽체의 경우 동등 지하실 규모의 통상적인 지하벽체보다 두께를 100~200mm 정도 절감할 수 있는 것을 확인할 수 있었다.

Fig. 1. PHC-W pile

Fig. 2. The conceptual diagram of basement wall method using PHC-W pile retaining wall

Fig. 3. Diagram of the additional wall

Fig. 4. Detail diagrams for calculation of bending and shear strength

Fig. 5. Schematic diagram of bending tests and shear tests

Fig. 6. Test results of Bending Moment of the composite additional wall

Photo 1. Cracks of composite additional wall during bending test

Fig. 7. Shear test results of the composite additional wall

Photo 2. Failures of composite additional wall during shear test

Fig. 8. Test results of bending moment for non-composite additional wall

Photo 3. Cracks of non-composite additional wall during bending test (N-B-3)

Fig. 9. Shear test results of non-composite additional wall

Photo 4. Failures of non-composite additional wall during shear test (N-S-1)

Table 1. Calculation formula and material’s properties(a) Calculation formula

Table 2. Summary of calculated values

Table 3. Test plan

Table 4. Summary of test results