Experimental Research On The Bearing Capacity Of Super-long Large Diameter Excavated Pile In Yudong Chongqing

Nowadays, Super-long and Large-diameter Excavated Piles are widely used in bridges with super-long spans in west complex geologic mountain, the characteristic of the pile and the interaction between the pile and soil are very complex,so the investigation of theory is very important. Its design method is according to that of common pile yet. Socketed length of the pile is too long. So it is necessary to study the Bearing Behavior of Super-long and Large-diameter Bored Piles.Based on the tests of several piles of 2 bridges, which are being constructed in the area of Yudong Chongqing, the mechanism of load transfer and the characteristic of bearing capacity are analyzed,and it was simulated with ANSYS. Self-balanced Testing Method was performed to several piles of the bridge. Combined with the engineering geological feature of mudstone of the Badong group of middle Tertiary,The relevant factors influencing the characteristics of bearing capacity of pile foundation,the findings may provid reliable evidence to the design and construction of pile foundation in the area.The experiments show that the bearing capacity of Super-long and Large-diameter Excavated Piles is mainly contributed by side friction, especially by their upper and middle parts, even under the bearing limitation, the ratio of base resistance to the total load is very low, so this type of piles is friction ones. Considering these features of Super-long and Large-diameter Excavated Piles, bearing capacity design for common pile is not applicable to this kind of piles. It is suggested that the design of vertical bearing capacity should be in terms of permissible settlement of piles, or according to the real side friction distribution of piles.The pile of bridge in Yudong must be shorten.In addition, the value of side friction by test in-site is large than that by surveying. That is to say, these designs are conservative.Self-balanced Testing Method has advantages over conventional testing method in safety, economy,high load capacity and easily. It fit more than surcharge method in pile foundation detection of bridge in west complex geologic mountain. What's more, it is effective way to study the negative friction, the side friction of pile-soil, because its O-Cell can be placed any part of the pile.