疏浚淤泥EPS颗粒轻质混合土本构模型研究

Study on the constitutive model of lightweight EPS-bead-treated soil made from silt

不同配比的EPS颗粒轻质混合土的等向压缩试验和固结排水剪切试验结果表明,轻质混合土的力学特性,取决于试样的胶结结构强度及试验所选择的围压.基于殷宗泽建立的双屈服面模型,通过引入能反映轻质混合土胶结结构强弱的参数β,及反映其胶结结构逐渐破损的参数ω,建立了考虑轻质混合土结构性的弹塑性本构模型.模型试验结果表明,改进模型能反映不同配比EPS颗粒轻质混合土变形的基本规律.

Due to the limit of resources and growing awareness of environmental protection, the technologies of re generating dredged silt into artificial geomaterials have received more and more attention. One of these methods is to change the dredged silt into lightweight treated soil （LWTS）. The LWTS technology is to regenerate new lightweight geotechnical materials by mixing dredged silt of high natural moisture content with solidification and lightweight materials. There are two types of lightweight treated soil made from dredged silt. One is a foam-treated soil （FTS） , and the other is a bead-treated soil （BTS）. These artificial geomaterials are light in self-weight, high in strength and therefore have the capacity of self-standing. Another advantage in the use of such materials is the reduction of construction time and the pollution of environment. These advantages make them a promising option in civil engineering projects. A series of laboratory tests were conducted to extensively investigate mechanical properties of the lightweight soil. Isotropic compression tests were carried out on both cement-mixed lightweight soils and non-cementmixed lightweight soil. Curves of volume strain vs confining pressure （ in half logarithm coordinate） of cement-additive lightweight soils were identified as two folding lines at the consolidation yield stress, while curves of non-cement-mixed lightweight soil were identified as straight line. Based on the consolidated drained triaxial tests （ CD）, two different types of stress strain relations were observed： Strain hardening behavior for high structural strength specimens and strain softening behavior for low structural strength specimens. Subjected to shear, two different types of volume strain relations were observed ： dilation for high structural strength specimens and contraction for low structural strength specimens. Results show that the mechanical properties of lightweight BTS were dependent to a great extent on the structural property. Based on the two yield surface constitutive models proposed by Yin Zong-ze, an improved elastic-plastic constitutive model was introduced, taking into consideration of the structural properties of the bead-treated specimens by using parameter β, which represents the extent of structural strength and parameter ω that represents the damage rate of structure. In the end, the calculated results by the improved model were compared with testing curves. The improved model was found to be in close agreement with the tests data.