Study On Cut-off Wall Of Foundation Pit And Materials Compounding

To a Certain depth in the pit, the support structure requires sufficient strength and stability to resist the earth pressure and the seepage pressure of head difference along with the foundation excavation. Diaphragm walls, mainly made of concrete or reinforced concrete, only serves as cut-off wall down to a certain depth of pit, of which the intensity requirements is lowered accordingly; Influenced by the high head pressured rigidity cut-off wall and the surrounding soil does not have good deformation compatibility, which makes cracks a usual happening. Unfortunately the common seepage curtain can barely meet water-proof requirements of foundation pit, thus applicable materials compounding and structures are in demand to ensure the safety of foundation pit.It is known to all that different soil mixed with cement can reflect different mechanics, deformation and permeability. And with different ratio of cement, even the same soil can demonstrate different physical and mechanical properties. In this paper, strength and permeability test of soil-cement are carried out between different soil cement with different cement ratio to obtain a comprehensive understanding of the characteristics of soil cement and the inherent law among these indicators reflecting these properties. It is hoped that this paper can provide a reference when selecting the appropriate ratio in actual projects.This essay takes for example the excavation of South Tower of the building in Tianjin Binhai New Area. The sealing effect of high-pressure jet grouting pile seepage curtain is tested through coring test of high pressure jet grouting pile and impervious well test of anti-seepage curtain made of the high pressure jet grouting pile, the sealing effect of high-pressure jet grouting pile seepage curtain is tested. Numerical simulation and field test show that in the enclosure structure and seepage prevention of deep foundation pit, the use of reinforced concrete diaphragm wall and anti-seepage curtain made of the high pressure jet grouting pile structure is of the economy, the safety and the feasibility.