Research On Mechanical Properties Of Engineered Cementitious Composite Foamed Mixture Lightweight Soil

During the use of the tunnel,the surrounding rock pressure changes greatly due to the surrounding environment,which adversely affects the safe use of the tunnel.Therefore,the interlayer material should be added between the linings to offset the changes caused by the surrounding rock pressure.In recent years,the bubble mixed lightweight soil has been more and more widely used in engineering construction.The bubble mixed lightweight soil has the characteristics of low compressive strength and high porosity.It can absorb a large amount of pressure changes from surrounding rocks during compression The energy produced.Using air-blended lightweight soil as the interlayer material,the new air-blended lightweight soil has a certain compressive strength(6MPa-9MPa)and deformation(>25%).A small amount of fiber is added to the air-blended lightweight soil to change the mechanical properties of the air-blended lightweight soil,so that the bending toughness and ductility are greatly improved.The research content is as follows.The research content is as follows.。1)Research on the performance of blowing agentThe foam bubble density of the three foaming agents produced by animal protein foaming agent,vegetable protein foaming agent and AOS foaming agent at different concentrations were studied,1h bleeding volume,1h sedimentation distance,3h drainage volume,3h sedimentation distance Such foam performance.Add a small amount of AOS foaming agent and vegetable protein foaming agent to animal protein foaming agent to study the foam performance of compound foaming agent foam bubble group density,1h bleeding volume,1h settlement distance,3h drainage volume,3h settlement distance and other foam properties.For comprehensive consideration,choose 100g animal protein foaming agent+5g vegetable protein foaming agent with a concentration of 10%.2)Study on mechanical properties of high ductility cementThe load-displacement curves of flexural strength,compressive strength,brittleness coefficient,bending toughness and 28d compressive strength of high ductility cement and ordinary portland cement at 3d and 28d are studied.The conclusion is that high ductility cement has better flexural strength,ductility,and plasticity,and can be used as a new type of air-blended lightweight soil cement material.3)Effects of foam content and water-cement ratio on mechanical properties of high ductility cement bubble mixed lightweight soilStudy the influence of different foam content and water-cement ratio on the flexural strength,compressive strength,brittleness coefficient,bending toughness and compressive elastic modulus of bubble mixed light soil at 3d,7d,14d and 28d to determine the best Foam content and water-cement ratio.According to the best foam content and water-cement ratio,the compressive test blocks of high ductility cement bubble mixed light soil and ordinary Portland cement bubble mixed light soil were made,and the load-displacement curve of 28d compressive strength was studied.The optimal blending amount of foam is 513L/m~3 and the optimal water-cement ratio is 0.3.4)Effect of fiber content on the mechanical properties of high ductility cement fiber bubble mixed lightweight soilThe effects of different basalt fiber content on the 3d,7d,14d,28d flexural strength,compressive strength,brittleness coefficient,bending toughness,and compressive elastic modulus of the bubble mixed light soil were studied to determine the optimal fiber content.According to the best fiber content,make high ductility cement bubble mixed light soil,ordinary silicate cement fiber bubble mixed light soil(fiber content 0.5%),high ductility cement fiber bubble mixed light soil(fiber content 0.5%)Compression test block to study the load-displacement curve of its 28d compressive strength.The optimal volume blending of fibers was determined to be 0.5%.