基于动三轴试验的层间错动带动孔压特性及能量分析
Dynamic pore pressure of the bedding fault material within the basal layer and energy analysis based on the triaxial test
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摘要: 2008年汶川地震触发的大光包滑坡滑带形成背景是渗水层间错动带，该带强度变化是决定滑坡启动的主要因素，动孔压发展是土体材料强度劣化的根本原因，故基于系列室内动三轴试验研究该带材料孔压特性。结果表明，动载下层间错动带材料孔压快速增长，循环剪应力比越大，孔压增长越快，不同荷载条件下应变达到5%时动孔压比等于1，材料液化，根据动孔压比与振次比曲线的拟合关系提出幂函数应力模型。从能量角度描述层间错动带材料孔压增长特性，揭示出循环剪应力比对累积能量耗损与动孔压比曲线影响较小而围压对其影响较大，并进一步提出孔压增长的能量模型。Abstract: The Daguangbao landslide was triggered by the 2008 Wenchuan earthquake. The sliding zone formed in a bedding fault along which groundwater could be found to flow. The key factor of the landslide initiation is the strength change in the bedding fault under the earthquake effect, and the development of dynamic pore pressure is the root cause of the material strength of soil degradation. Therefore, a series of dynamic triaxial tests were conducted on the materials to examine the property of dynamic pore pressure. The results show that the dynamic pore pressure of the bedding fault material grows faster under the dynamic load, and the dynamic pore pressure increases faster when the cyclic shear stress ratio is greater. The dynamic pore pressure ratio is basically equal to the confining pressure when the strain reaches 5%, and the materials are liquefied. A stress model of a power function according to the relationship of the dynamic pore pressure ratio and cycle ratio is proposed. The response of pore water pressure can be described by using energy, revealing that the cyclic shear stress ratio has less effect on the relationship of the dynamic pore pressure ratio and cycle ratio. The confining pressure has a great influence on the relationship of the dynamic pore pressure ratio and cycle ratio. The theoretical energy model of dynamic pore pressure is further proposed.
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Keywords:
- bedding fault /
- dynamic pore pressure /
- stress model /
- energy model
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