Experimental Study On Permeability Characteristics Of Peat Soil In Yunnan Province

Peat soil has the characteristics of high organic matter content,high moisture content,high compressibility and low bearing capacity,which makes it a bad soil in engineering construction.In recent years,with the rapid economic and social development of southwestern China,the cracks and damages of roads,bridges,houses and other infrastructure in peat land areas have become more and more serious.It is very important to study the consolidation settlement of peat soil foundation and understand its permeability characteristics.In view of this,this paper takes the shallow peat soil in Dali area and the deep peat soil in Kunming area as the research object,and studies the permeability characteristics and influencing factors of peat soil through the consolidation and seepage test and permeability test,and draws relevant conclusions.First of all,explores under the load step by step through osmotic pressure test the influence of consolidation pressure on same peat soil infiltration characteristics,and the permeability coefficient and the loading time,consolidation stress and void ratio as well as the relationship between primary and secondary consolidation stage summary analysis the change rule of permeability coefficient,the results showed that the low load conditions(P < 200 k Pa),primary consolidation phase permeability attenuation by more than 90%.Under high load(P?200k Pa),with the increase of pressure,the attenuation of permeability coefficient in the main consolidation stage decreases,while that in the secondary consolidation stage increases to 30%.Under high load,the compression of peat soil in the main consolidation stage is 60% of the total compression of this stage.The permeability coefficient decreases exponentially with the loading time.The stability time of the permeability coefficient of west lake peat soil in Dali is about 1d(day),and that of deep peat soil in Dali and Kunming is about 7h(hour).Secondly,through the permeability test to explore the permeability anisotropy of the original peat soil,it is found that the horizontal permeability coefficient of the peat soil in the West Lake area of Dali is 2-17 times of its vertical permeability coefficient,while the mud shows isotropy.In the relationship between permeability coefficient and depth,the horizontal permeability coefficient of deep peat soil in Kunming decreases linearly with the increase of depth,while the vertical permeability coefficient decreases exponentially with the burial depth of soil sample,and the burial depth of soil sample has greater influence on the horizontal permeability.At the same time,the permeabilityanisotropy of peat soil decreases with the increase of soil depth.Finally,in order to eliminate the influence of water content,density and structure on the permeability of peat soil,the relationship between the permeability characteristics,organic matter content and fiber content of remolded peat soil was discussed by means of permeability test through controlling the water content and density of remolded peat soil.The results show that when the fiber content is the same,the permeability coefficient of peat soil has a negative correlation with the organic matter content,that is,the permeability coefficient decreases with the increase of organic matter content;when the organic matter content is the same,the permeability coefficient of peat soil increases with the increase of fiber content.