Leakage Of Underground Pipelines Causes Seepage Damage Of Silt Foundation Mechanism Research

In recent years,urban pavement collapse accidents in silt soil areas have occurred frequently,which not only damages the urban pavement structure,but also poses a serious threat to the safety of surrounding buildings and residents’ lives and properties.In all road collapse accidents,the road collapse caused by the leakage of the pipeline caused the soil seepage damage and then the road collapse accounted for a large proportion.However,there are relatively few systematic experimental studies on soil seepage damage caused by pipeline leakage at this stage,and the seepage damage mechanism and key influencing factors of soil are still unclear.Therefore,it is of great significance to study the mechanism of the seepage failure of the silt layer caused by pipeline leakage.This paper takes the silt layer road collapse accident caused by pipeline leakage as the research background,takes Zhengzhou typical silt and its blended soil(adding mineral soil to change its plastic index)as the research object,and uses a self-developed pipeline leakage test device to carry out the silt soil analysis.In the seepage failure test,the effects of water content,compactness and plasticity index on the seepage failure of the soil are analyzed,and the mechanism of the seepage failure of the silt caused by pipeline leakage is deeply studied.The main work and research conclusions of this paper are as follows:(1)Through the particle test,liquid plastic limit test and compaction test,the basic physical property index parameters of Zhengzhou typical silt were determined;the particle shape and contact mode of the silt soil were clarified through the scanning electron microscope test;and the indoor penetration test proved The variation law of the permeability coefficient of Zhengzhou typical silt with the degree of compaction was verified,and the existing empirical formula of permeability coefficient was verified;the typical Zhengzhou silt was blended by adding mineral soil,and the blended soil samples with different plasticity indexes were obtained(Silt-silty clay range).(2)A static water disintegration test device was designed and a soil disintegration test was carried out.The average disintegration rate,disintegration rate and related influencing factors of the typical Zhengzhou silt and its blended soil were analyzed;the impact test was designed The device has also carried out an impact test to analyze the influence of different compaction degrees,moisture content and plasticity index on its impact resistance.The test results show that with the increase of soil compactness and plasticity index,the disintegration performance of the soil gradually weakens,and the impact resistance gradually increases;with the increase of water content,the disintegration property of the soil gradually decreases.,The impact resistance is also weakened.(3)A test device for soil seepage failure under the condition of indoor pipeline leakage is designed.Through experiments,the effects of soil compaction,water content and plasticity index on the critical conditions and failure rules of soil seepage failure are studied,and soil disintegration is analyzed.,The correlation between the impact resistance and the conditions of soil seepage failure.The test results show that:(1)The soil in the range of silt to silty clay mainly suffers from fluid soil damage;among them,silt generally suffers from partial fluid soil damage,while for silty clay,as the plasticity index increases,its seepage failure The form gradually changes from local fluid soil to overall fluid soil;(2)The critical hydraulic gradient of silt soil is closely related to the degree of compaction,water content,and plasticity index.The critical hydraulic gradient of silt increases with the increase of the degree of compaction and plasticity index.Larger,it decreases with the increase of water content;the higher the degree of compaction,water content and plasticity index,the greater the difference between the hydraulic gradient of the soil completely destroyed and the critical hydraulic gradient;(3)The critical hydraulic gradient of the soil varies with it The erosion resistance increases gradually.In actual engineering,the soil erosion resistance can be used to evaluate the anti-seepage damage ability of the soil;(4)The relationship between soil disintegration and the critical hydraulic gradient is more complicated: due to compaction and plasticity When the index change causes the disintegration of the soil to change,the critical hydraulic gradient decreases with the increase of the disintegration of the soil;when the disintegration of the soil changes due to the change of the water content,the critical hydraulic gradient of the soil changes with the disintegration of the soil.Increase and increase.