• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.225-232
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• 1999

Construction case of PRD (Percussion Rotary Drill) pipe pile and matters to be attended in construction of PRD pile were reviewed. The compressive and uplifting static pile load tests for PRD piles were performed and, also, analysis by Pile Driving Analyzer was done. Based on these results, bearing components in each resisting part (that is: steel toe, external skin, and internal skin) were measured separately. The measured resisting force was compared to the value calculated by the estimated formula. The pile capacity was mobilized in steel toe area and the external skin friction and the internal friction were not produced. Thus, it could be considered that toe of PRD pile should be supported in hard bearing stratum (for example, the fresh soft rock).

• 한국지반공학회논문집
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• 제23권3호
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• pp.61-75
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• 2007

우리나라에서는 암반 및 자갈층과 같은 단단한 층 내에 깊은 기초를 매입하는 것이 일반적이다. 그러나 Chaophraya(Bangkok)와 Mississippi강 삼각주에서 실시되고 있는 것과 같이, 대심도 낙동강 삼각주 퇴적토에서도 말뚝의 지지층으로써 중간 깊이에 위치하는 모래 및 모래질 자갈층을 고려할 필요가 있다. 이 연구는 이 지역에서 PHC 말뚝을 요구하는 깊이까지 항타할 때, 말뚝의 지지력을 위한 적절한 평가법을 찾고자 하였다. 지반조사는 두 현장의 5개소에서 실시되었다. 말뚝의 지지력은 지반조사 결과를 이용하고 CPT에 근거한 평가법과 여러 다른 해석법을 적용하여 계산되었으며, 상호 비교가 이루어 졌다. 항타된 5개의 말뚝에 대해 매입된 전 깊이에 걸쳐 잘 알려진 PDA시험이 체계적으로 수행되었다. 여러 평가법에 의하여 계산된 지지력은 PDA 및 정재하 시험결과와 함께 비교되었다. 그 결과, 주면마찰력은 set-up 효과에 따라 지배적으로 영향을 받으며, 장시간 경과 후에는 $\beta$법에 의한 결과와 좋은 일치를 보였다. 선단 지지력은 과소평가되는 PDA시험 보다는 정재하시험결과에 근거하여 적절한 평가법을 선정하였다. 최종적으로, CPT결과를 이용하여 이 지역에 적합한 지지력의 평가법을 도출하였다.

• Geomechanics and Engineering
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• 제21권1호
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• pp.23-33
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• 2020

An advancing cutting roof for gob-side entry retaining with no-pillar mining under specific geological conditions is more conducive to the safe and efficient production in a coalmine. This method is being promoted for use in a large number of coalmines because it has many advantages compared to the retaining method with an artificial filling wall as the gateway side filling body. In order to observe the inner structure of the gateway cutting roof and understand its stability mechanism, an equivalent material simulation experiment for a coalmine with complex geological conditions was carried out in this study. The results show that a "self-stabilization bearing structure" equilibrium model was found after the cutting roof caving when the cut line deviation angle was unequal to zero and the cut height was greater than the mining height, and the caving roof rock was hard without damage. The model showed that its stability was mainly controlled by two key blocks. Furthermore, in order to determine the optimal parameters of the cut height and the cut line deviation angle for the cutting roof of the retaining gateway, an in-depth analysis with theoretical mechanics and mine rock mechanics of the model was performed, and the relationship between the roof balance control force and the cut height and cut line deviation angle was solved. It was found that the selection of the values of the cut height and the cut line deviation angle had to conform to a certain principle that it should not only utilize the support force provided by the coal wall and the contact surface of the two key blocks but also prevent the failure of the coal wall and the contact surface.