王学滨, 张博闻, 董伟, 余斌. 2019: 位移控制加载、内压及侧压作用下平面应变含孔洞土样应变场观测. 工程地质学报, 27(6): 1270-1280. DOI: 10.13544/j.cnki.jeg.2018-269
    引用本文: 王学滨, 张博闻, 董伟, 余斌. 2019: 位移控制加载、内压及侧压作用下平面应变含孔洞土样应变场观测. 工程地质学报, 27(6): 1270-1280. DOI: 10.13544/j.cnki.jeg.2018-269
    WANG Xuebin, ZHANG Bowen, DONG Wei, YU Bin. 2019: DIGITAL IMAGE MEASUREMENTS OF STRAIN FIELDS OF CLAY SPECIMENS WITH HOLES UNDER INTERNAL AND LATERAL PRESSURES IN PLANE STRAIN CONDITION. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1270-1280. DOI: 10.13544/j.cnki.jeg.2018-269
    Citation: WANG Xuebin, ZHANG Bowen, DONG Wei, YU Bin. 2019: DIGITAL IMAGE MEASUREMENTS OF STRAIN FIELDS OF CLAY SPECIMENS WITH HOLES UNDER INTERNAL AND LATERAL PRESSURES IN PLANE STRAIN CONDITION. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1270-1280. DOI: 10.13544/j.cnki.jeg.2018-269

    位移控制加载、内压及侧压作用下平面应变含孔洞土样应变场观测

    DIGITAL IMAGE MEASUREMENTS OF STRAIN FIELDS OF CLAY SPECIMENS WITH HOLES UNDER INTERNAL AND LATERAL PRESSURES IN PLANE STRAIN CONDITION

    • 摘要: 利用研制的平面应变模型加载及观测系统,研究了位移控制加载条件下含孔洞土样的破坏过程。孔洞内压及侧压由气囊施加。利用数字图像相关方法,获得应变场。通过布置测线的方式,研究了剪切带内外最大剪切应变及主应变轴偏转角的分布及演变规律。得到了下列结果。随着纵向应变的增加,含孔洞土样的最大剪切应变的分布经历由均匀变形向局部化变形的转化过程。对于剪切带外的测点,随着远离孔洞表面,最大剪切应变有增加的趋势,这与剪切带内损伤导致带外弹性应变降低(卸荷)有关。在孔洞表面附近,最大剪切应变变化复杂,这与应变弹性成分的下降与塑性成分的增加的博弈有关。对于剪切带尖端的测点,其和前后测点相比,水平线应变发生突增(剧烈膨胀),垂直线应变的值发生突降(挤压程度剧烈降低),剪切应变的值发生突增(剪切变形剧烈增加),由此导致主应变轴偏转角的值发生突增,达到30°。当纵向应变相同时,侧压或内压的增加对含孔洞土样的纵向应力有增强作用。

       

      Abstract: We use a home-developed loading and measuring system to study failure processes of clay specimens with holes under displacement-controlled loading and in plane strain condition. We use gasbags to apply the internal and lateral pressures for the displacement-controlled loading. We further use the digital image correlation method to obtain the strain fields. We arrange the monitored lines to investigate distributions and evolution of the maximum shear strains and principal strain axis rotational angles inside shear bands and outside. We find the following results. With an increase of the vertical strain, clay specimens undergo uniform deformations and subsequent localized deformation, as found from spatiotemporal distributions of the maximum shear strains. For monitored points outside shear bands, the maximum shear strains have an increasing tendency when they are far away from the hole, which is due to unloading, i.e., the decrease of the elastic strain resulting from damages inside shear bands. For monitored points in the vicinity of the hole surface, changes of the maximum shear strains are complex, which is related to competition between the decrease of the elastic part and the increase of the plastic part. For the monitored point at the shear band tip, in comparison with monitored points in its forward and backward directions, the horizontal linear strain rapidly increases, the value of the vertical linear strain rapidly decreases, and the value of the shear strain rapidly increases, leading to a rapid increase of the value(about 30 degrees) of the principal strain axis rotational angle. At the same vertical strain, the vertical stress of the clay specimen with a hole increases as internal and lateral pressures increase.

       

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