水泥砂浆体中三向压力传感器的测量特性

 确定三向压力传感器实测应力与其周围待测介质初始应力的关系是实现其应力测量的必要条件。为了解三向压力传感器在实际应用中的测量特性，利用RMT岩石力学试验系统对自行研发的三向压力传感器进行标定，研究各个传感面的重复性和线性度，得到各个传感面的标定系数。以水泥砂浆为材料，浇筑制成嵌入三向压力传感器的立方体试样(边长：600 mm)，并利用自行研制的真三轴试验加载装置，研究重复荷载作用下水泥砂浆体中三向压力传感器实测应力随外部加载应力状态的变化规律。水泥砂浆体的孔隙结构使得三向压力传感器的实测应力存在滞后现象，但在重复荷载作用下，水泥砂浆体中的孔隙结构逐渐被压密，三向压力传感器的实测应力曲线逐渐趋于稳定。静水应力状态加载条件下，三向压力传感器的实测应力与其对应方向的加载应力呈线性相关关系；非静水应力条件下，三向压力传感器的实测应力不仅与其对应方向的加载应力呈线性相关关系，而且与其对应方向的加载应力与其它两个方向的加载应力之差，也成线性相关关系。在此基础之上，提出了用于描述介质初始应力状态对三向压力传感器实测应力影响规律的数学关系。

MEASURING PERFORMANCE OF THREE-DIMENSIONAL PRESSURE SENOSR IN CEMENT MORTAR BODY

The relation between measured stress of three-dimension pressure sensor(3DPS) and initial stress of surrounding medium plays an important role in rock stress measurement. In order to know the measuring performance of 3DPS for practical applications，calibration test is performed in rock mechanics testing system to investigate the repeatability and linearity of 3DPS and corresponding calibration coefficients are obtained. A cubic cement mortar sample，which side length is 600mm，with 3DPS embedded in the center is poured. It is loaded under different repeated stress states by the developed true-triaxial loading system. Due to pore structure of the cement mortar body，the measured stress curves of 3DPS show a hysteresis phenomenon when loads are applied for the first time. As a result of the pore structures are pressed compact under repeated loads，the measured stress curves tend to be stable. For hydrostatic stress loading，the measured stresses of 3DPS are linear to the loading stresses. For non-hydrostatic stress state loading，the measured stresses of 3DPS are not only linear related to the loading stresses in the same direction but also related to the differential stresses that related to the other two directions. Then，an equation for describing the influence of loading stress on the measured stress of 3DPS in cement mortar body is proposed.