Experiment Study Onthe Deformation Of Pile Foundation By Excavation In Thick Mucky Soft Soil

The thick mucky soft soil is widely distributed in the coastal and waterfront areas in China, the engineering properties mainly includes: high moisture content, high void ratio, low permeability, small anti-shearing intensity, high deformation value, long consolidation time, huge compression index, thixotropic, rheological and inhomogeneity, which are harmful to engineering constructions. At present there are many mucky soft soil foundation treatment methods in engineering constructions. But there is rare systematic study of the transverse deformation of pile foundation by excavation till now. The study is with the mucky soft soil of pile foundation excavation in coastal areas as research background. The factors about affecting of transverse deformation of pile foundation is analyzed through the locale test and geotechnical centrifuge model test. The main content and conclusion include:(1) The changes of soil pressure, pore water pressure, the stress of steel bars, the horizontal displacement of piles, the settlement and the displacement of soil conditions are analyzed through in-situ test. With the data of the test, we found the mainly factor about affecting of transverse deformation of pile foundation is the thickness of the mucky soft soil.(2) According to the requirement of the geotechnical centrifuge model test, a set of excavation device is designed. And this device has been used in the test successfully. The advantage of the device is that the equipment of the centrifuge model can no longer stop during the experiment process. It can avoid the experiment errors because of the shutdown.(3) The changing rules of the strain of pile, the horizontal displacement of pile, the settlement and displacement of soil has been gained through the geotechnical centrifuge model test. The maximal location of the stress of piles is found at the junction of the mucky soft soil and the other soil. The longer of the pile, the larger of displacement. The influence range of the soil is the roughly same as the thickness of the mucky soft soil. The strength of the soil that is the key factor is caused the displacement of the pile.