Study On The Permeability Characteristic Of Turfy Soil And Its Application In The East Of Jilin Province

In recent years, the uneven settlement of roadbed during the construction of lineprojects occurs frequently in turfy soil region in northeast China, and as an importantparameter in the calculation of the consolidation settlement of soft soil, the researchabout the permeability of turfy soil is not mature.In terms of the permeabilitycharacteristic of turfy soil in the east of Jilin Province, this paper were studied onpermeability characteristics of turfy soil and its application under the support of theNational Natural Science Foundation of China ‘Study on the structural property andconstitutive relations for marsh peat of seasonally frozen region’, etc. severaltransportation construction projects in Jilin Province. The influencing factors and lawon permeability of peat soil has been studied to make a comprehensive analysisthrough indoor and field infiltration test. Meantime, the method of test and calculationof permeability parameter through seepage experiment on site is discussed. Finally,based on the roadbed filling engineering at Jiaohe city in Jilin Province and incombination with one-dimensional consolidation theory, the change and value ofpermeability coefficient is discussed. The result shows us the law on the roadbedsettlement with the influence of permeability of turfy soil. Through specific researchon the problems as stated above, the conclusions was show as following:1. Due to the orientation and semi-orientation distribution of organic in the process offormation of turfy soil, the permeability characteristic has obvious difference invertical and horizontal direction, and with the location of different layer and differentnatural plant, its difference is also different. But with the increase of the consolidationstress in test, permeability will be significantly reduced and when the consolidationstress increased to100kPa, the permeability coefficient will decline to10%-40%ofnatural condition.2. The natural density and buried depth of turfy soil have little influence on thepermeability of it and the degree of decomposition and organic content are the main factors influencing the peat soil permeability. With increase of the decompositiondegree, the permeability of turfy soil will be significantly reduced, but in the processof loading gradually, the decrease of the permeability coefficient amplitude decreaseswith the increase of decomposition degree; With the increase of organic mattercontent, the permeability also presents obvious weakening trend.3. Through the steady pumping test in turfy soil layer at Jiaohe city in Jilinprovince,the permeability coefficient of turfy soil in this district is to an average of4.49×10-5cm/s. And under the influence of environmental factors, the results of thelaboratory infiltration test of the natural state of peat soil and field pumping testresults have certain differences.4．In the same drainage consolidation mode, the better the permeability of layer is, thefaster the consolidation rate at the same stress. In roadbed filling engineering atHuang Songdian highway, the largest settlement occurred in the center of roadbed. Att=234days, the settlement is21.36cm and the degree of consolidation is0.90.