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王体强, 王永志, 屈盅伶, 梁小丛, 陈平山. 宽级配饱和珊瑚土场地剪应力-剪应变非线性响应动力离心试验研究[J]. 岩土工程学报. DOI: 10.11779/CJGE20240908
引用本文: 王体强, 王永志, 屈盅伶, 梁小丛, 陈平山. 宽级配饱和珊瑚土场地剪应力-剪应变非线性响应动力离心试验研究[J]. 岩土工程学报. DOI: 10.11779/CJGE20240908
Study on shear stress - shear strain nonlinear response of wide-graded saturated coral soil site in dynamic centrifugal test[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240908
Citation: Study on shear stress - shear strain nonlinear response of wide-graded saturated coral soil site in dynamic centrifugal test[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240908

宽级配饱和珊瑚土场地剪应力-剪应变非线性响应动力离心试验研究

Study on shear stress - shear strain nonlinear response of wide-graded saturated coral soil site in dynamic centrifugal test

  • 摘要: 珊瑚土作为热带和亚热带地区港口工程及军事、民事设施建设场地的重要土体,其在接近真实场地条件和地震自下而上传递下的循环剪应力、剪应变行为尚缺乏认知。基于动力离心试验可较真实模拟场地应力分布、排水条件、地震传递等优势,开展了典型水平饱和珊瑚土场地模型试验,探讨了珊瑚土场地的循环剪应力、剪应变时空分布特征与演化规律,比较了循环剪应力、剪应变与超静孔压比发展的关联性,并求解分析了不同埋深珊瑚土动剪切模量、阻尼比随剪应变的变化关系和发展模式。结果表明:反演获得剪应力-剪应变滞回圈具有良好的光滑性、连续性和规律性,随着循环次数增加,滞回圈逐步向水平倾斜且面积逐步扩大,呈明显的强度软化特征;同一荷载下,剪应力随埋深增加而增大,剪应变随埋深增加而先增加后减小,并随荷载强度的增大而增大,基岩峰值加速度0.05g~0.3g正弦荷载下,剪应变主要集中于0.01%~2%范围内。荷载强度逐渐提高条件下,剪应力与超静孔压比随埋深变化的关联性不明显,但超静孔压比增加对剪应力随埋深的增长表现出一定约束作用;而剪应变与超静孔压比随埋深的分布具有显著的一致性,当孔压比超过0.6时,土层剪应变将显著增加。求解的动剪切模量随埋深增大而增大、随剪应变增大而减小,具有良好的规律性;而阻尼比随埋深增大而减小,相对离散性偏大,与计算方法和液化强非线性相关;最大剪切模量明显低于单元试验结果,且典型水平饱和场地的珊瑚土动剪切模量比更符合Martin-Davidenkov模型。

     

    Abstract: As an important soil for port engineering and military and civil facilities construction sites in tropical and subtropical areas, there is a lack of knowledge about the cyclic shear stress - shear strain behavior of coral soils under near-real site conditions and bottom-up transfer of earthquakes. Based on the advantages that the dynamic centrifugal test can simulate the site stress distribution, drainage conditions, and earthquake transmission of the site more realistically, a typical horizontal saturated coral soil site model test is carried out. The spatial and temporal distribution characteristics and evolution laws of cyclic shear and stress shear strain in coral soil sites are discussed. The correlation between cyclic shear stress, shear strain, and the development of excess pore water pressure ratio are compared, and the relationship between the dynamic shear modulus and damping ratio with shear strain and the development model of coral soils with different burial depths is solved and analyzed. The results show that the shear stress-shear strain hysteresis loops evaluated by inverse analysis have good smoothness, continuity, and regularity, and with the increase of the number of cycles, the hysteresis loops are gradually tilted to the horizontal and the area is enlarged, which is an obvious characteristic of strength softening. Under the same load, the shear stress increases with the increase of burial depth, and the shear strain increases firstly and then decreases with the increase of burial depth and increases with the increase of load intensity, and under the sinusoidal load of 0.05g~0.3g, the shear strain is mainly concentrated in 0.01%~2%. The correlation between the shear stress and the excess pore water pressure ratio with the burial depth is not obvious when the load strength increases gradually, but the increase of the excess pore water pressure ratio has a certain constraint on the increase of the shear stress with the burial depth. While the distribution of shear strain and excess pore water pressure ratio is remarkably consistent with the buried depth. When the pore pressure ratio exceeds 0.6, the shear strain will increase significantly. The dynamic shear modulus increases with the increase of buried depth and decreases with the increase of shear strain with good regularity. The damping ratio decreases with the increase of buried depth, and the relative dispersion is larger, which is related to the calculation method and the strong nonlinear liquefaction. The maximum shear modulus is significantly lower than that obtained by the unit test, and the dynamic shear modulus ratio of coral soils in a typical horizontal saturated site is more consistent with the Martin-Davidenkov model.

     

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