Experimental Study On Mechanical Properties Of Solidified Soft Loose Soil

There are a lot of peat strata and gravel soil slopes in Yunnan,Guizhou and other places in China,which cause great hidden trouble to the quality and safety of geotechnical engineering.Grouting reinforcement is a common means to deal with soft and loose soil in engineering,but the design of grout proportion is always a difficult problem.Therefore,it is necessary to design the grouting proportion of peat and gravel soil and study the mechanical properties of solidified soil.In this thesis,taking Xiaobaiyan tunnel project in Guizhou as the engineering background,indoor geotechnical tests are carried out on the physical properties of peat soil and gravel soil,and appropriate grouting materials and reasonable grout ratio are selected to study the grout properties,and the grout of two kinds of soil is obtained respectively.Then,conventional triaxial tests were carried out on the cured soil to study its mechanical properties,explore the curing effect,and establish the stress and strain constitutive model of the cured soil,in order to provide a reference for similar projects.The main research work and conclusions are as follows :(1)Indoor geotechnical tests were conducted on peat soil and gravel soil to test their physical indexes such as water content,density,specific gravity,organic matter content and liquid-plastic limit.Among them,the peat soil has high water content,low density,high organic matter content,and low shear strength;the gravel soil has strong inhomogeneity,good particle gradation,high compactness,and shear strength is affected by the stone content.(2)Based on orthogonal test,cement-dominated grouting materials were selected to prepare two kinds of grouting grout,and the viscosity,specific gravity,water extraction rate,gelling time,stone rate and uniaxial compressive strength of stone body were tested.According to the test results,regression analysis and grey model prediction are carried out to select a better mix plan to prepare for the reinforcement of the two soils.(3)With good slurry curing peat soil and gravel soil,that has made to conventional triaxial test of solidified soil,according to the test results of analysis of failure form,the stress-strain curve,the normalized analysis was carried out on the stress strain curve and normalized equation is obtained,including curing peat soil stress-strain relationship in strain hardening model,curing of gravel soil stress-strain relationship in strain softening model,The linear fitting of the two normalized equations is good and conforms to hyperbolic form.(4)Based on Duncan-Chang model,set up two kinds of stress strain constitutive model of stabilized soil,according to the test results,the correction model of the eight parameters,are suitable for the elastic constants of peat soil and solidifying of gravel soil,using the model of two kinds of solidified soil stress-strain relationship curve fitting,and compared with the actual test curve analysis,the results show that the model is in good agreement with the experimental results and can reflect the stress-strain relationship of the two solidified soils.