Vertical Bearing Capacity of Mixing Implanted Pile Foundation in Coastal Typical Soil Layer in Fujian Province
Mixing implanted tubular pile is a new type of pile foundation that implanting tubular pile into cement soil mixing piles by joint load carrying.At present,it is widely used in clay and silt layers,but there is no practical experience in the strongly weathered rock strata under coastal soft soil in Fujian province.To further explore the influence of pile tip penetration into rock on the vertical bearing capacity of mixing implanted tubular piles,relying on the highway project of China national highway G324(road section from Fuqing Xincuo Shuangyu to Dawo),the on-site vertical load tests are conducted for 3 mixing implanted tubular piles.The slow speed load method is adopted to study the bearing capacity of mixing implanted tubular piles,which shows the working characteristics of friction end bearing pile.The test result indicates that the load-settlement curve of mixing implanted tubular pile changes slowly,and shows the working characteristics of friction tip bearing pile in the typical offshore strata.The side friction resistance of upper part of pile body,which has obvious asynchrony,develops before the lower part.At different depths of same soil layer,the variation of pile side friction with relative displacement of pile and soil is basically the same,but the ultimate side friction increases slightly with the increase of depth.When the mixing implanted tubular pile tip enters the strongly weathered tuff,the measured value of pile side friction resistance at silty clay layer is generally consistent with the recommended value of specification,while the pile side friction resistance in the strongly weathered tuff stratum is 35%-44%higher than that of specification.In the calculation of pile tip resistance,the characteristic value of pile end bearing capacity is suggested to adopt half of the standard value of ultimate pile end resistance of concrete precast pile in the relevant standard code,in order to make up for lack of evidence for calculation of end resistance of deep mixing tubular pile when the pile end enters rock.
bridge engineeringmixing implanted pilefield testbearing capacityside frictionpile tip resistance
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