The Study and Application of Overlength Impact Bored Pile with Small Diameter Through Ultra Deep Soft Soil Layer

Sludge and mucky soil belong to soft soil,which have properties of high water content,small internal friction angle,low cohesion and low shear strength.These properties go against the construction of impact bored pile in soil.Hole collapse and shrinkage are two common quality problems in the construction of impact bored piles in soft soil.In this paper,the construction of overlength impact bored pile with small diameter in Dongfang Dianqi workshop project is considered.By using the principle of soil mechanics,the factors that impact the hole wall stability are analyzed;the reasonable range of gravity of mud is determined which provides the technical support for construction;reasonable technical measures such as controlling technical parameters,selecting reasonable driving hammer,adopting small stroke and big weight mud etc.are taken and it proves successful to construct overlength impact bored pile with small diameter through ultra deep soft soil layer.