结构界面单膜电阻式微型土压力盒室内砂土标定方法研究

Laboratory Sand Calibration Method of Single Membrane Resistance Miniature Earth Pressure Cell Set on the Structural Surface

微型土压力盒室内砂土标定试验是提高相关地下结构模型试验精度的主要方法.本研究探讨了土压力盒的埋设方式、上部填砂厚度、标定桶尺寸对结构界面单膜电阻式微型土压力盒室内砂土标定试验结果的影响.研究结果表明,将土压力盒嵌入底板内的埋设方式能够降低标定误差,同时若想提高模型试验中土压力盒的量测精度,需采用与模型试验一致的埋设方式进行室内砂土标定试验;随着上部填砂厚度和标定桶尺寸的增加,标定误差呈现先减小后增大的趋势;为了降低微型土压力盒室内砂土标定试验的标定误差,建议土压力盒的埋设方式为嵌入底板内,上部填砂厚度为所用土压力盒直径的3~4倍,标定桶直径为所用土压力盒直径的8.6~10倍.

The laboratory sand calibration test of the miniature earth pressure cell is the main method to improve the accuracy of the underground structure model test. In this research,the influence of the embedding method of the earth pressure cell,the upper sand filling thickness,and the size of the calibration bucket on the results of the calibration test of single membrane resistance type miniature earth pressure cell set on the structural surface is discussed. The results show that the method of inserting the earth pressure cell into the plate can reduce the calibration error. At the same time,it is necessary to use the embedding method consistent with the model test for laboratory sand calibration test to improve the measurement accuracy of the earth pressure cell in the model test. With the increase of the upper sand filling thickness and the size of the calibration bucket,the calibration errors first decrease and then increase. In order to reduce the calibration error of the laboratory sand calibration test,it is recommended to insert the earth pressure cell into the plate.At the same time,the upper sand filling thickness should be 3 to 4 times of the diameter of the earth pressure cell used,and the diameter of the calibration bucket should be 8.6 to 10 times of the diameter of the earth pressure cell used.