Development and application of a novel ring shear apparatus
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摘要: 研发一种测量并控制孔隙水压力的环剪仪能够获得试样受到的总应力、孔隙水压力和有效应力,从而有效地揭示试样应力—应变—孔压演化特征。本文采用自主研发的可以控制排水条件的全自动环剪仪,实现了环剪过程中控制孔隙水压力,测量孔隙水压力、试样排水体积、扭矩和轴向位移等参数。以黄土坡滑坡滑带土为例,分别开展了固结排水环剪试验、固结不排水环剪试验、变孔压环剪试验和环剪试样渗透试验。试验结果表明:采用侧边密封+顶底部设置三通阀门的方式,可以保证环剪室承受0~1000kPa的孔隙水压力;当下环剪盒底部进水阀打开并连接体积压力控制器时,可以控制孔隙水压力,测量某一孔压下试样排水或吸水体积,体积量程为0~200cm3;当上环剪盒顶部出水阀打开并连接孔隙水压力传感器时,可以测量不排水条件下试样内部的孔隙水压力,其量程为0~1000kPa。试验过程中,剪胀剪缩由轴向位移传感器来测量,其量程为0~10mm;环剪力由高精度扭矩传感器测量,其量程为0~300N·m。除了上述功能之外,结合新型环剪仪还可开展孔隙水压力动态变化对环剪强度的影响试验,固结或环剪过程中试样常水头渗透试验等。一种新型环剪仪可以精确地开展试样在大变形、不同孔压条件下的环剪试验,为揭示滑坡长距离滑动过程中孔隙水压力的演化机理提供技术支撑。Abstract: The total stress, pore water pressure and effective stress of the sample can be obtained by developing a new ring shear apparatus for measuring and controlling pore water pressure, and the stress-strain-pore water pressure characteristics of the sample can be effectively revealed. In this paper, the self-developed automatic ring shear apparatus can control the drainage conditions, and realize the control of pore water pressure during the ring shear process, and measure the pore water pressure, sample drainage volume, torque and axial displacement. Taking the slip zone soil of Huangtupo landslide as an example, the consolidated drainage ring shear test, consolidated undrained ring shear test, variable pore pressure ring shear test and constant head permeability test were carried out respectively. The test results show that the ring shear chamber can withstand 0~1000kPa pore water pressure by using side seal and top and bottom tee valve. When the inlet valve at the bottom of the lower ring shear box is opened and the volume pressure controller is connected, the pore water pressure can be controlled and the volume of drainage or absorption of the sample under a certain pore pressure can be measured with a measuring range of 0~200cm3. When the outlet valve at the top of the upper ring shear box is opened and the pore water pressure sensor is connected, the pore water pressure inside the sample under undrained conditions can be measured with a range of 0~1000kPa. During the test, the shear dilatancy or shear contraction was measured by the axial displacement sensor with a measuring range of 0~10mm. The ring shear force is measured by a torque sensor with a range of 0~300N·m. In addition, the influence of dynamic change of pore water pressure on ring shear strength and the change of sample permeability coefficient during consolidation or ring shear can also be tested with the new ring shear apparatus. A novel ring shear instrument can accurately carry out mechanical tests of specimens under large deformation and different pore pressure conditions to provide technical supports for revealing the evolution mechanism of pore water pressure during long distance landslide sliding.
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