Circular opening is commonly encountered in wellbore drilling of petroleum engineering, boring for cast-in situ pile installation, and tunneling excavation. This paper presents a rigorous solution for the elastoplastic responses of the anisotropic soft soil mass around a circular opening excavated under undrained and drained conditions. Both the anisotropic elastoplastic behavior and the 3D strength of the soft clay are incorporated in the present solutions. The well-established anisotropic critical state elastoplastic model S-CLAY1, which can represent the initial fabric anisotropy and stress-induced anisotropy of soft soil, is further modified by the Spatially Mobilized Plane criterion to consider the 3D strength of geomaterials. Then, the investigated problems, excavation of a circular opening under both short-term (undrained) and long-term (drained) conditions, are formulated as a system of first-order differential equations and are solved as initial value problems. The distributions of stress components and anisotropy parameters around the opening, the stress trajectory of a soil particle at the opening wall, as well as the stress–displacement curve at the opening wall are presented to investigate the elastoplastic responses of the opening. Extensive parameters show that the overconsolidated ratio and coefficient of earth pressure at rest (K0) have remarkable effects on the elastoplastic responses around a circular opening.
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Acta Geotechnica - In this paper, a simple but feasible approach is proposed to predict the time-dependent load carrying behaviours of jacked piles from CPTu measurements. The corrected cone... 相似文献
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Wei Shao Bora Cetin Yadong Li Jingpei Li Lin Li 《Geotechnical and Geological Engineering》2014,32(4):901-910
The addition of cementitious admixtures and/or inclusion of fibers are frequently used in practice to stabilize soils and to improve their mechanical properties. In this study, ring shear tests were conducted to investigate mechanical properties such as shear strength, angle of friction and cohesion values of randomly distributed discrete fiber-reinforced sand mixtures. The length and aspect ratio of the fibers used in the current study were 12 mm and 120, respectively. Specimens were prepared at four different fiber ratios (0.1, 0.3, 0.6, and 0.9 % by weight of sand). A series of ring shear tests were carried out on sand alone and fiber-reinforced sand mixtures at different normal stresses. The test results indicated that the addition of fiber had a significant effect on the shear strength of the sand. Shear stress of the unreinforced sand increases 1.29–2.32, 1.16–1.39, and 1.07–1.5 times at a normal stress of 50, 150, and 250 kPa, respectively with fiber inclusion. Fiber content had positive effects on improving the shear strength parameters (angle of internal friction and cohesion) of the mixtures. The cohesion and angle of internal friction of fiber-reinforced sand prepared at different ratios of fiber increased by 5.3–27.4 kPa and 2.0°–7.3° respectively. The inclusion of fibers improves the ductility of the soil by preventing the loss of post-peak strength. 相似文献
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采用理论分析的方法,首先基于半无限土体中改进的球孔扩张理论,求解新桩沉桩挤土效应引起的土体位移场。然后将其作为已知条件施加于邻近既有桩,分析既有桩变形和内力变化规律,探讨既有桩桩端约束条件、桩身刚度及土体模量对既有桩响应的影响;同时结合数值分析,对本文理论方法进行验证。最后分析了新旧桩之间距离和新桩半径对挤土效应引起的既有桩变形和内力的影响。结果表明：桩端约束形式仅影响桩端附近桩身变形;随着新旧桩之间距离的增加,既有桩变形和内力显著减小;随着桩径的增加,既有桩变形和内力均逐渐增大。最后提出采用远离既有桩和采用长细桩的措施来降低新桩施工对既有桩的影响。 相似文献
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