初始条件对砂含水率测试精度的影响

Influence of Initial Conditions on Test Accuracy of Sand Moisture Content

采用微波法含水率测定仪在传感器安装角度10°～90°,砂含泥量0. 5%～3. 5%,细度模数2. 2～3. 2以及松散堆积和紧密堆积2种堆积状态下测试了砂的含水率。结果表明:微波法含水率测定仪传感器的安装角度介于30°～60°时测量值相对集中,误差偏小,测试精度高,最佳安装角度为40°～50°;含泥量波动对含水率测试精度影响较小,测试结果均未超出0. 3%的误差限值;砂细度模数在2. 4～2. 8波动对测试精度的影响基本可以忽略,太细或者太粗的砂则难以保证含水率的测试精度;初始含水率越高,砂的堆积状态对测试精度的影响越大。因此,微波法含水率测定仪使用前应选择与现场堆积状态相一致的砂料进行基线校准。

The moisture content of sand was measured by microwave moisture meter at the sensor installation angle of 10°~90°,sand mud content of 0.5 %~3.5 %, f ineness modulus of 2.2~3.2 under two packing states of loose and tight accumulation.The results show that when the sensor installation angle of microwave moisture meter is between 30°~60°,the measurement value is relatively concentrated,the error is small,the measurement accuracy is high,and the optimum installation angle is 40°~50°.The f luctuation of mud content has little inf luence on the accuracy of moisture content measurement and the test results do not exceed the error limit of 0.3 %.The inf luence of sand f ineness modulus f luctuating between 2.4 and 2.8 on test accuracy can be neglected,while it is diff icult for too f ine or too coarse sand to guarantee the test accuracy of moisture content.The higher the initial moisture content,the greater the effect of sand packing state on test accuracy is.Therefore,we should select sand material,which state is consistent with the packing state in the f ield ,for baseline calibration before by using the microwave moisture meter.