Stress-Strain Analysis On The Immersion Strength Of The Lime-soil Foundation

Lime-soil is used on improving ground bearing capacity and diminishing collapse of soil. Lime is a kind of low-priced construction material, using lime-soil cushion and lime-soil compaction pile to treat foundations can gain good economy effect. A lot of research for reinforcement mechanism by lime and microscopic reaction mechanism between lime and soil by domestic and foreign scholars, but the analysis of immersion strength was not enough. However lime-soil immersed, regardless of its strength and deformation and elastic modulus are quite different, and failure mode will be different. Based on indoor triaxial test, research on mechanical properties of lime-soil in immersion could more actually consider work situation. Thus, study on the mechanical properties of lime-soil by using traxial compression tests has very important practical significance.The subject through about a lot of samples triaxial tests which samples was immersed in water. According to the stress-strain law, we can get a series of soaking strength application characteristics. The curing age, moisture content, confining pressure and other factors, which can affect the mechanical properties of lime-soil, are mainly considered in the test. According to the stress-strain law, using finite element analysis software simulates lime-soil of the stress and deformation. Compare with the experimental results. The main achievement and conclusions can be given as follows:1. Testing lime-soil samples in different curing ages, different moisture content, different confining pressure and wet-dry two different states by triaxial compression tests. Analyzing the effect of various factors on stress-strain relationship of lime-soil systematically.2. Axial strain corresponding to extremism strength of ages short lime-soil is bigger. When the specimens destroyed, strength is close to the extremism value, ages longer lime-soil presents brittle failure. The longer of the ages, the higher of the extremism strength value when the specimens which are under same confining pressure destroyed. Lime-soil strength increases with the increase of the water content when water content is less than optimal water content, the closer to the optimum moisture content, the smaller of the growth margin. Lime-soil strength decreases with the increase of the water content when water content is more than optimal water content, and down significantly. With the increase of confining pressure, both the initial elastic modulus and shear strength value of lime-soil samples are improved.3. The early strength of lime-soil increased rapidly in curing; the relationship between shear strength and curing period increased logarithmically; moisture content on the lime-soil strength value has obvious effect, maximum appeared in optimum water content; in the situation of shorter curing, confining pressure was significantly affected the growth of shear strength.4. The deformation modulus of lime-soil growth with the increasing of confining pressure and curing period. While the curing age T=30d, the deformation modulus of sample can reach to74.4-86.7%of T=90d’s. Average can reach to about81.6%of T=90d’s. So the deformation modulus of lime-soil growth trend has slowed more than90days.5. Value c increased ten times than before;there is also a large growth in valueΦ.6. Samples damage in the form of brittle shear failure, brittle crack failure and plastic shear failure.7. The FEM calculation results show that the vertical stress and the distance to foundation are proportional relations, that is, along with the depth increasing, the stress increase constantly. There appears stress-focus phenomenon at the bottom of the cushion layer with the surrounding soil contacting surface. The higher values of composite foundation vertical displacement appeared in the lime-soil cushion. And the freestone cushion under the settlement will happen relatively minor. The increase of vertical strain with depth and continuously decreased. It is close to the actual situation.8. Using the triaxial compression test results of lime-soil as the parameters during the FEM calculation. The simulated results are very close to the measured results. It can reflect the actual project and provide practical reference for engineering analysis.