Effect Of Organic Matter Content On Static And Dynamic Triaxial Strength Of Peatsoil In Kunming,Yunnan Province

Peat soil(including peat and peat soil)is a kind of special soil formed under specific environment and geological action,which contains organic components such as cellulose,humus and minerals.Because the content of organic matter determines the classification of peat soil types and indirectly affects the physical and mechanical properties of peat soil,the engineering properties of peat soil are quite different from those of general soft clay.Peat soil has the characteristics of high water content,large void ratio and high pressure shrinkage,which leads to large settlement and easily causes foundation deformation or even cracking The low bearing capacity,low shear strength and strong rheological properties often lead to the loss of strength and extrusion failure of the foundation.In recent years,as the communication window and transportation hub between the two Asia,Kunming has been increasing its efforts to develop urban construction.As the core area of Kunming’s development,the surrounding area of Dianchi Lake has many major projects,such as rail transit,underground civil air defense,ring expressway,etc.,which will inevitably encounter engineering problems brought by peat soil during the construction process.Through the static and dynamic characteristics test and research of peat soil Therefore,it has important theoretical research value and practical significance to provide reference basis for relevant engineering design and construction.Based on the test results,the effects of organic matter content,consolidation pressure and vibration frequency on the static and dynamic strength of peat soil are analyzed.The main research work and conclusions are as follows:(1)The content of organic matter in soil samples was measured and the results were sorted out.The content of organic matter,consolidation pressure and vibration frequency were selected as control variables.(2)The dynamic triaxial consolidation undrained shear test is used to analyze the relationship between the principal stress difference and the axial strain under different consolidation pressure control conditions and different organic matter content control conditions.The static strength index and value are obtained by drawing the shear strength envelope,and the influence of organic matter content on the static strength index is analyzed.(3)By dynamic triaxial dynamic strength test,the relationship curves between dynamic shear stress and failure vibration number and between dynamic stress ratio and failure vibration number under the control of consolidation pressure,vibration frequency and organic matter content are obtained,and the test results are sorted out and analyzed.(4)Through fitting the data in the sum curve,different cyclic vibration times are used to simulate different levels of earthquake action,dynamic strength index and value are obtained by drawing shear strength envelope,and the influence of organic matter content,vibration frequency and cyclic vibration times on dynamic strength index is analyzed.(5)The static strength and dynamic strength are compared and analyzed.The static strength is used to normalize the dynamic strength.The relationship curve between the normalized cyclic strength and the failure vibration number is analyzed and fitted.The expression of the normalized dynamic strength curve is obtained.The dynamic strength of peat soil under different failure vibration number can be estimated from the static strength of peat soil.