Development and performance testing of in-flight miniature CPTu equipment on ZJU-400 centrifuge
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摘要: 孔压静力触探(CPTu)是一种重要的土体原位特性测试手段,在常重力环境下的实际工程中得到了良好应用。在超重力离心模型试验过程中,由于存在模型高倍缩尺、承受高倍离心加速度和高速旋转产生机械振动等因素,利用静力触探方法测试模型地基土体特性存在较大的技术难度。浙江大学研制了离心机机载微型孔压静力触探装置,在离心超重力环境下具备沿水平轨道移动定位,竖向触探测量锥尖阻力、侧摩阻力和孔隙水压力的能力。开展了饱和砂性土模型地基离心机模型试验,在30g离心超重力下检验了该装置的测试性能,并初步揭示模型地基触探指标随模型地基深度的变化规律。Abstract: The piezocone penetration test (CPTu) is an important in-situ soil testing method widely used in conventional 1g condition in engineering practices. Due to the highly scaled model ground, high centrifugal acceleration and rotation-induced vibration during centrifuge model tests, the in-flight testing of CPTu in model ground remains a challenging task. A miniature CPTu equipment is developed in Zhejiang University based on ZJU-400 centrifuge apparatus, which is capable of moving horizontally to locate the penetration spot, and then measuring the cone tip resistance, sleeve friction resistance and pore water pressure during penetration under centrifugal hypergravity condition. The testing performance of this CPTu equipment is preliminarily checked by the centrifugal model tests on saturated sandy soils under centrifugal acceleration of 30g, and the depth variation of penetration parameters are observed and analyzed.
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表 1 福建砂物理力学性质
Table 1 Physical and mechanical properties of Fujian sand
参数 Gs emax emin D50/mm D30/mm D10/mm Cu Cc φ/(°) 值 2.622 0.943 0.6 0.16 0.14 0.1 1.6 0.96 39 表 2 萧山黏土物理力学性质
Table 2 Physical and mechanical properties of Xiaoshan clay
参数 Gs w/% e wP/% wL/% IP/% IL ccu/kPa φcu/(°) St 值 2.734 60~65 1.72~1.74 26.5 53.0 26.5 1.6 15.5 15 13.7~15 -
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