超静孔隙水压下软土卸荷蠕变特性试验研究
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TU431

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重庆市教育委员会科学技术研究项目(KJ1713327);重庆科技学院校内科研基金(ck2017zkyb013);重庆科技学院建工学院院内基金(JG201703)


Experimental study on unloading creep properties of soft soils under excess pore-water pressure
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    摘要:

    考虑超静孔隙水压作用的软土卸荷力学特性对富水软土地区地下空间开挖变形和稳定性分析具有重要作用。以深圳地区淤泥质软土为研究对象,开展不同初始超静孔隙水压作用下的K0固结不排水三轴卸荷强度试验和卸荷蠕变试验。试验结果表明:初始超静孔隙水压越大,固结围压越小,软土卸荷破坏越具有突然性;软土卸荷强度应力-应变曲线大致呈双曲线型,其双曲线函数拟合结果表明,卸荷强度随着初始超静孔隙水压的增大而大致线性减小。卸荷蠕变对初始超静孔隙水压敏感性很大,卸荷蠕变破坏时的偏应力约为卸荷强度试验中偏应力的90%。UU0.5应力路径相对于UU0.0应力路径更容易发生卸荷强度破坏和卸荷蠕变破坏,在实际工程中,应尽可能控制软土侧向卸荷比和超静孔隙水压的大小。

    Abstract:

    The unloading creep properties of soft soil under the excess pore water pressure are important for analysis of the deformation and stability of underground excavation in water-rich soft soil region. In this paper, the silty soft soil in Shenzhen was investigated via conducting unloading K0 consolidation undrained triaxial test and unloading creep test under different initial static pore water pressures. Results show that a higher initial excess pore water pressure and a smaller consolidation confining pressure will cause more abrupt unloading failure of the soft soil. The stress-strain curve of the unloading strength of soft soil is in the form of hyperbola. The results of hyperbolic function fitting show that the unloading strength decreases linearly with increase of initial excess pore water pressure. The unloading creep deformation is found to be sensitive to the initial excess pore water pressure. The failure deviatoric stress in unloading creep test is about 90% of the deviatoric stress in unloading strength test. The unloading failure and creep failure are more likely to occur under stress path with UU0.5 compared with UU0.0. Therefore, the confining unloading rate and the excess pore water pressure should be cautiously controlled in engineering practice.

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刘东燕,邓晓佳,黄伟,李东升,蒋海飞.超静孔隙水压下软土卸荷蠕变特性试验研究[J].土木与环境工程学报(中英文),2019,41(4):1-9.

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  • 收稿日期:2018-10-29
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  • 在线发布日期: 2019-07-27
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