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通过三轴试验系统研究了新型土工材料——轻量砂的变形及强度特性。结果表明,不同的配比、龄期使轻量砂具有不同的原生结构强度,围压使不同原生结构强度的土样处于剪胀或剪缩状态,导致发生应变硬化、应变软化以及相应状态下孔压的3种对应形态变化。变形模量随EPS(发泡聚苯乙烯)球粒掺入比的增大而线性减小,随水泥掺入比、龄期增大而线性增大,相同配比的土样变形模量与围压关系不大;三轴抗压强度随EPS球粒掺入比增大而呈负指数关系减小,随水泥掺入比、龄期、围压增大而线性增大,存在水泥掺入比阀值;土骨架转换效应对于土样强度的影响很大,造成了土体单轴、三轴抗压强度分带,高水泥掺入比能够大大弱化EPS颗粒的土骨架效应。结合前人成果,系统地研究了轻量砂密度、无侧限抗压强度的影响因素,引入材料学中比强的概念,提出了单价比强图结合配方公式的方法,对轻量土砂进行配方优化。分析了轻量土砂应力-应变关系转型问题,提出采用无侧限抗压强度来表征不同配比、龄期轻量土砂的原生结构强度。通过试验与数理统计,建立临界围压与原生结构强度的关系,为数值模拟计算与建立本构模型奠定了基础。
The deformation and strength characteristics of a new type of geotextile, lightweight sand, were studied by a triaxial test system. The results show that different ratios and ages make the light-weight sand have different primary structural strength. The confining pressure makes the soil samples with different primary structural strengths dilatational or sheared, resulting in strain hardening, strain softening and corresponding states Pore pressure of the three corresponding morphological changes. The deformation modulus decreases linearly with the increasing of EPS (expanded polystyrene) spherulites, and increases linearly with the cement incorporation ratio and age. The deformation modulus of the same proportion The compressive strength of triaxial axis decreases with the increase of EPS pellet incorporation ratio, and decreases with the increase of EPS mixing ratio, the age and confining pressure increase linearly, and the cement incorporation Compared with the threshold value, the soil framework conversion effect has a great influence on the strength of soil samples, resulting in the uniaxial and triaxial compressive strength banding of soil, which can greatly weaken the soil skeleton effect of EPS particles. Based on the previous achievements, the influencing factors of lightweight sand density and unconfined compressive strength are systematically studied, and the concept of stronger ratio in material science is introduced. The formula of unit price / Formulation optimization. This paper analyzes the problem of stress-strain transition in light soil sand, and proposes to use unconfined compressive strength to characterize the primary structural strength of sand with different proportions and ages. Through the experiment and mathematical statistics, the relationship between the critical confining pressure and the strength of the primary structure is established, which lays the foundation for the numerical simulation and the establishment of the constitutive model.