Study On The Application Of Fiber Containing Foam Concrete In Anti Frost Heaving Of Water Conveyance Channel

There are many water conveyance channels in the seasonal frozen areas of northern China,which ensure the production,living and ecological water use in the area.However,the channels in the seasonal frozen areas are often accompanied by frost heaving damage,which brings certain pressure to the safe and efficient operation of water conveyance channels.The conventional method to solve the problem of frost heave resistance in channels is to lay insulation board materials on the lower part of the channel lining.However,such materials have complex construction processes and are prone to defects and damage leading to failure.At present,foam concrete is widely used in the construction field.Its construction process is simple,and it has good cohesion with ordinary concrete lining.It has good mechanical and thermodynamic properties,which makes it possible to apply it to the water conveyance channel.However,such research is less.In this paper,foam concrete with glass fiber as an additive is taken as the research object to carry out research,in order to provide a new solution to the frost heaving of water conveyance channels in seasonal frozen areas.In this paper,the foam concrete is taken as the research object to carry out experimental research,and the dry density,moisture content,mechanics,thermodynamics and other performance indicators of foam concrete under four glass fiber admixtures are compared and analyzed.The optimal fiber admixtures suitable for channel thermal insulation performance are obtained,and then the applicable characteristics of foam concrete in channel frost heaving resistance are analyzed by numerical simulation method.The main research results are as follows:(1)The basic properties and thermodynamic properties of foam concrete with different glass fiber content under normal temperature and freeze-thaw freeze-thaw cycles were studied experimentally.The results show that at room temperature,with the increase of fiber content,the dry density and water absorption of foam concrete gradually increase,and the thermal conductivity first decreases and then increases.The dry density of foam concrete is the smallest when the fiber content is 0.2%,the water absorption of foam concrete is the smallest when there is no fiber content,and the water absorption of foam concrete is the largest and the thermal conductivity is the smallest when the fiber content is 0.4%;When the fiber content is 0.6%,the thermal conductivity of foam concrete is the largest;After 50freeze-thaw cycles,the thermal conductivity of foam concrete decreases first and then increases with the increase of fiber content.When the fiber content is 0.4%,the thermal conductivity of foam concrete is the smallest,and when the fiber content is 0.6%,the thermal conductivity of foam concrete is the largest.(2)The mechanical properties of foam concrete with different fiber content under normal temperature and freeze-thaw cycles were studied experimentally.The results show that the compressive strength,flexural strength and elastic modulus of foam concrete increase with the increase of fiber content at room temperature;When there is no fiber,the compressive strength,flexural strength and elastic modulus of foam concrete are the smallest;when the fiber content is 0.6%,the compressive strength and elastic modulus of foam concrete are the largest;when the fiber content is 0.4%,the flexural strength of foam concrete is the largest;After 50 freeze-thaw cycles,with the increase of fiber content,the compressive strength,flexural strength and elastic modulus of foam concrete gradually increase.Without fiber content,the compressive strength,flexural strength and elastic modulus of foam concrete are the minimum.When the fiber content is 0.6%,the compressive strength and elastic modulus of foam concrete are the maximum.When the fiber content is 0.4%,the flexural strength of foam concrete is the maximum.Considering the thermal and mechanical properties,the applicability of foam concrete is the best when the content is 0.4%.(3)The numerical simulation results of the Zibo Yellow River Diversion Channel Project show that,under the same thickness of insulation material,only considering frost heave,the freezing depth line of the channel is that the sunny slope is smaller than the shady slope,and the freezing depth gradually deepens from the bottom of the channel to the top of the channel.The maximum freezing depth of the channel under the insulation board material is 0.139 m,and the maximum freezing depth under the foam concrete material is0.263m;The normal frost heaving amount of the channel is greater on the shady slope than on the sunny slope.The maximum normal frost heaving amount of the channel under the insulation board material is 0.0904 m,and the maximum frost heaving amount of the channel under the foam concrete material is 0.085m;The maximum normal frost heaving force and tangential freezing force of the channel surface lining structure at the foot of the sunny slope and the foot of the shady slope under the insulation board material are less than those of the surface lining structure of foam concrete material.In the channel section in the area with high groundwater level,under the same thickness of insulation material,the pore water pressure under the surface lining of the channel bottom is the largest,3828.1Pa,when all the check valves fail.Under the four check valve conditions that meet the requirements of anti floating stability,the thickness of the channel surface lining structure under foam concrete material is less than that under the insulation board material.When all the upper and lower check valves fail,the thickness of the channel surface lining structure under foam concrete material is 14.12 cm,and that under the insulation board material is 18.17 cm.Based on the above studies,it can be seen that foam concrete has good thermodynamic and mechanical properties,which can meet the basic requirements of channel frost heave resistance.It can also be poured integrally with the upper lining structure to save construction procedures.In areas with high groundwater level,the thickness of the surface lining structure can be further optimized,and has good application effect in channel frost heave resistance..