Experimental Study On Mechanical Behavior Of Cement-stabilized Dredged Seabed Clays In Dalian Bay

As China attaches much importance to the marine ecological environment protection,further improvement of the recycling use of dredged marine sediments become an inevitable trend of development.The way of using cement solidified dredged seabed clays to build artificial island will be adopted in the project of Sea-crossing Traffic Engineering in Dalian Bay.This method,which is applied in China for the first time and provides an effective technology for large-scale recycling use of dredged marine clays,not only deals with the problem of disposal of dredged clays,but also solves the problem of the source of materials for artificial island.The construction technology on solidification of the project requires that the clay and clay-cement mixed soil have certain fluidity and the strength,compression and permeability of the cement stabilized clays should be satisfied.According to the actual requirements of the project above,the mechanical properties including strength,compression and permeability of cement-stabilized dredged clays with different clay moisture content,cement content and age are synthetically studied.Besides,the influence of salt on the mechanical behavior of solidified soil is considered.This research not only provides the theoretical basis and reference of design for the selection of the material prescription and construction technology and the field test of Dalian Bay Project,but also is of great significance for the further study on theory of cement solidified soil.The main research work and achievements are as follows:（1）The unconfined compressive strength test was carried out.The influence regularity of the clay moisture content and cement content,age and salt on the stress strain curves and unconfined compressive strength of cement solidified soil were analysised and got a normalized expression of strength change with age.What’s more,the strength of cement stabilized soil was evaluated with different parameters,it is concluded that the evaluation for the strength of cement solidified soil with high water content range and high change of the strength showed good effect with effective void ratio e_st,put forward the strength prediction formula under arbitrary age,and discussed the relationship between the secant modulus E₅₀ and unconfined compressive strength q_u.（2）A series of one-dimensional compression tests were carried out on cement-stabilized soils and reconstituted clays by low initial stress of consolidation.The effect of clay moisture content and cement content,age and salt on compression curve,consolidation yield stress,compression index of cement solidified soil and the relationship between the consolidation yield stress and strength were analyzed and investigated in this paper.The corresponding void ratio e₁ for 1kPa was used as the parameter to normalize the compression curves of the solidified soil after yield,and the normalized expression of the compression curve after yield was obtained.（3）Falling head hydraulic conductivity tests were performed on both dredged clays and cement-treated soils under different consolidation stress.With the analysis for the influence law of clay moisture content and cement content,age and salts of cement-stablilzed clays on e-logk permeability curves,and compared with remolded soil,the results showed that the linear relationship between e-logk is suitable for the larger scope of strain and void ratio for cement solidified soil,and has a smaller permeability index.