水泥胶凝砂土动力特性研究
Experimental study on dynamic properties of cemented sand
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摘要: 通过室内动三轴试验研究了砂土与水泥胶凝砂土在不同应力条件下的动力变形特性及抗液化特性,结果表明:胶凝材料的掺入显著提高了砂土在动荷载作用下抵抗变形的能力,在较低水泥掺加量条件下,胶凝砂土中砂土的动力特性仍占据主导地位,其动力特性仍可用沈珠江提出的砂土动力黏弹性模型来模拟;胶凝砂土的动模量比砂土大3倍以上,而抗液化动剪应力则为砂土的2倍以上,但初始变形量及累计动残余变形量值均较砂土大幅降低;胶凝作用对低应力状态更为敏感,应力水平越低,胶凝作用对砂土抵抗动力变形能力的提高越显著,随着胶凝材料掺入,浅层砂土已很难发生地震液化,深层砂土的液化破坏主要为变形破坏,但破坏时也累积了较大的动孔隙水压力。Abstract: The dynamic properties and anti-liquefaction characteristics of sands and cemented sand (CS) are comparatively studied by using lab dynamic triaxial shear tests. It is shown that the capability of sand to resist deformation under dynamic load is significantly improved by adding cementing materials. Under lower adding of cementing materials, the dynamic properties of sands still play a leading role in CS, and they can be calculated using the dynamic constitutive model proposed by Zhujiang Shen. The dynamic modulus of CS is increased by more than 3 times and the anti-liquefaction dynamic shear stress by over 2 times than those of sand, while the initial deformation and the cumulative dynamic permanent deformation significantly decrease. Compared with high confining pressure and consolidation stress, the cemented action is more sensitive to lower stress state. The lower the stress state, the more obvious the effect of the cemented action to improve the capability of sand to resist deformation under dynamic load. With the adding of cementing materials, earthquake liquefaction of the shallow sand hardly occurs, and the liquefaction failure of deep sand is mainly deformation one with more cumulative dynamic pore water pressure.