Research on Standard Value of Ultimate Shaft Resistance for Fragile Intermediary Weathered Bedrock

This paper presents a calculation formula and puts forward the value range of standard value of shaft resistance for fragile intermediary weathered bedrock because it needs to be provided when the pile was placed at the fragile intermediary weathered bedrock, but there was no value recommended of it in technical code of building pile foundations.And the value range of standard value of shaft resistance for fragile intermediary weathered bedrock was validated by engineering practice.The results show that the value range of standard value of shaft resistance was 1 400~5 400 kPa for soft rock and it was 5 400~21 700 kPa for hard rock under dry drilling, and it was 1 200~4 600 kPa for soft rock and it was 4 600~18 500 kPa for hard rock under mechanical hole building.And the engineering property of fragile intermediary weathered extremely soft rock is similar to strong weathered soft rock, the fragile intermediary weathered soft rock is inferior to compacting gravel, the fragile intermediary weathered relatively soft rock is similar to compacting gravel, the fragile intermediary weathered relatively hard rock is better than compacting gravel.