Study And Engineering Application Of Soil Mixing Cutter(SMC) Deep Mixing Wall

The soil mixed wall constructed by SMC(Soil Mixing Cutter)method is a new type of deep mixing wall.It has a wide application prospect in foundation pit engineering and water conservancy project.At present,the domestic application of this technology has just strated,and the technical specification for its construction process,design parameters and quality control method are not found..Relying on a foundation pit engineering in Suzhou and an irrigation engineering in Yanggu,and summarizing the existing engineering achievements,the effect of construction,engineering characteristics and application of SMC method are studied.The main results are as follows:(1)By collecting engineering cases,the theory of construction,process of construction,equipment and materials of SMC method are introduced in detail.The analysis shows that SMC method has characteristics of strong mixing ability,high quality of mixing wall,wide application and high construction efficiency.SMC method can be used as cutoff drains in foundation pit and irrigation engineering,partition walls in contaminated site and special ground treatment method in soft soil,pebbles,strong weathered siltstone and mediun weathered siltstone.(2)Relying on actual engineerings in Suzhou and Yanggu,through core sampling drilling and labortatory test,the effect of deep mixing wall constructed by SMC method is analyzed.The results show that the UCS of deep mixing wall contructed by SMC method is more than 0.5 MPa and the permeability coefficient is below 10-6cm/s.The construction effect is better than triaxial mixed piles and TRD method.The core samples which are collected at bottom of wall are better than collected at top of wall.The deep mixing contructed in sand and silt is better than clay.The qualities of samples in the overlap of walls are as same as inside of walls and a uniform cement-soil wall can be formed.(3)The influence of bentonite on SMC deep mixing wall is studied by UCS test,permeability test and MIP test.The results show that bentonite can effectively improve strength and impermeability of cement soil by reduce the void ratio of sample and changing the distribution of pore size.The optimum content of bentonite is 2.5-5%.(4)The feasibility of using GGBS as the adding material of SMC method is studied by labortatory test.The results show that GGBS can improve the engineering performance of soil mixing wall constructed by SMC method combine with bentonite.The economic and social benefits of using GGBS as material are analysed.The optimum replacement ratio of GGBS is 30%.