| With the rapid economic development,the problem of soil and groundwater pollution in China is becoming increasingly serious.The prevention and treatment of underground soil and groundwater pollution has deeply affected urban construction and residents' lives.The Soil-bentonite cutoff wall technology is an isolation measure that effectively blocks the movement of groundwater and pollutants developed in recent years.The performance and economy are significantly better than the existing plastic cutoff wall,and it has a good application prospect.However,people's understanding of its mechanical properties and consolidation behaviors is still insufficient.Most of the practical operations in design,construction and testing rely on experience,and no systematic design guidelines have been formed.In this regard,this paper conducts an in-depth analysis of the consolidation behavior of Soil-bentonite by numerical calculation methods from different working conditions and different soil layers of the cutoff wall.Furthermore,the results of actual engineering calculation models are compared with the field measurements.The results can provide valuable reference for the design of the cutoff wall.(1)The characteristics of consolidation behavior of the Soil-bentonite cutoff wall in uniform cohesive soil layer are analyzed.The horizontal and vertical deformation of the soil-bentonite separation wall mainly occurs in the range of 3 meters below the ground,and continues to increase within 5 days to 3 months after backfilling,and tends to stabilize after 3 months.Therefore,the design of the cutoff wall should mainly control the deformation within 3 months after the backfilling.(2)The consolidation characteristics of the soil-bentonite cutoff wall under the additional load are compared with those without the additional load.With the additional load,it has a greater influence on the cutoff wall,both displacement of the upper part and the increase of vertical stress.Instead,the vertical deformation of the wall is restrained,so that the settlement deformation in the shallow part becomes less.However,the relationship between consolidation behavior and time is not affected by the additional load,and all tend to stabilize after the cutoff wall is completed for 3 months.With additional load,the design of the soil-bentonite cutoff wall should focus on the control of the horizontal displacement of the upper part.(3)Analyze the consolidation behavior characteristics of the soil-bentonite cutoff wall with or without soft soil.It shows that in the presence of a soft soil layer,It has a great influence on the vertical settlement of the wall.The reduction of vertical stress and pore water pressure of the soil increases the total settlement,and the point of maximum settlement occurs about 2 meters below the ground.But it has little effect on horizontal stress and horizontal deformation.When there is a soft soil layer,the design should focus on controlling the wall settlement of the soil-bentonite cutoff wall.(4)Propose the trend of the consolidation behavior characteristics of the Soil-bentonite cutoff wall.Through comparing the gap between the field measurements and the numerical simulation in a landfill project,which is in Jinjiang China.The design should consider additional loads.When there is equipment loads,material stacking,and vehicle loads on the site.If the measurements of the vertical settlement deformation of the wall is much larger than the calculation result,it may be related to the disturbance of the wall material construction on site.The disturbance caused the settlement of the wall to increase rapidly.Therefore,in the design and construction of soil-bentonite cutoff wall,the impact of construction on the wall should be fully considered.Considering the influence of weather,sensor elements,construction and other unfavorable factors,comparing the reasonably revised test results with the numerical calculation results,the trend is basically consistent.It is shows that,numerical simulation analysis is an effective method for analysis,design,and construction of the consolidation of soil-bentonite cutoff wall in project with fully considering the various influencing factors. |
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