滑动测微管抗渗能力的测试装置及试验研究

使用滑动测微技术进行桩身内力测试，测管安装时的防渗处理是该技术实现高质量测试的关键，已有处理措施鲜有其防渗效果的定量研究。研发了一套滑动测微管抗渗能力测试装置，对3种常用防渗处理措施不同压差下的渗流量进行了测定，得到计算渗流量的公式，结合现场条件分析了测管安装的注意事项。结果表明，测管内压力大时的渗流量要远大于测管外压力大时的渗流量；涂胶是一种效果非常好的防渗措施，采用该措施后一般不会有超过0.005 mm粒径的颗粒进入测管；增加测管内水头有利于减少杂质进入测管，但测管内水头不能高出桩孔内液面太多；灌注混凝土后，若测管内有水溢出应封闭测管限制水的溢出，若测管内水位下降，则应开放测管允许气体进入测管。

Testing device and experimental study on anti-seepage ability of sliding micrometer tube

It is a way to measure the internal force of pile foundation by sliding micrometer, and the anti-seepage measures during the installation of sliding micrometer tube are the key to achieve high quality test, while quantitative research on anti-seepage effect of measures is rare. A set of device for testing the anti-seepage ability of sliding micrometer tube was developed. The seepage flow of three common anti-seepage measures under different pressure differences was tested, and a formula for calculating the seepage flow was developed. The matters needing attention in the installation of the sliding micrometer tube were analyzed according to the site conditions. Test results show that when the internal pressure is higher than the external pressure, the seepage flow rate is much larger than that when the external pressure is larger than the internal pressure. Glue coating is a very effective anti-seepage measure, and generally no particles with a diameter over 0.005 mm will enter the sliding micrometer tube after adopting this measure. Increasing the water head in the sliding micrometer tube is beneficial to reduce impurities entering it, but the water head in the sliding micrometer tube can not be too much higher than the liquid levels in the borehole of the pile. After pouring concrete, if water overflow in the sliding micrometer tube happens, the orifice of the sliding micrometer tube should be closed to limit water overflow, and if the water level in the sliding micrometer tube falls, the orifice of the sliding micrometer tube should be opened to allow gas to enter it.