Application Study On Composite Ground With Rammed Cement-Soil Pile In Loessial Area

This paper summarized the characteristics and design calculation for composite ground, and the reasonable selection of wet & sinking loessial ground base. It gave an overall analysis on the characteristics of composite ground with rammed cement soil pile, and the design and calculation for rammed cement soil pile, etc..The ground treatment method for composite ground base with rammed cement soil pile is widely applied in north china in recent years, and there's no former confirmed theory on using this method through seal and extrusion to settle the problems of wet and sinking and bearing capacity for loessial soil. This paper focus on the feasibility study on combination of seal and extrusion to hole formation and rammed cement soil pile, and its application on wet and sinking loessial area; gave a research method of bounds replacement rate for eliminating the wet or sinking of loessial area; and study on value access method of bearing capacity parameter for technology calculation. This problem study way: study on the theories of composite ground and physical mechanics character of loessial soil, deduce a hypothesis and test it according to rules or regulations, analysis and prove the theory, design, test, application, examination, and summary. The new ideas from this paper: using mechanics principle study of soil, create a practical test to prove that it could change the physical mechanics character of base soil completely, reducing distortion, improving strength, and eliminating wet or sinking of base soil by seal extrusion during hole formation process at certain replacement rate; it could strengthen the loessial soil base to high bearing capacity to standard value of 300 to 400kPa through seal extrusion to hole formation technology together with rammed cement soil pile. Some value of the parameters adopted by bearing capacity calculation of the composite base of rammed cement soil pile with seal extrusion to hole formation exceeded the criteria of 'Technical Regulation on Building Ground Treatment'. (JGJ79-2002) This technology meet the design requirements and save investment. It provided an economic, high efficient, safe, and reliable method of ground treatment for building construction in wet and sinking loessial area. Key words: rammed cement soil pile, composite ground, wet and sinking loessial, replacement rate, seal & extrusion, bearing capacity...