砂土介质中多类型土压力盒标定试验

Experimental study on calibration tests of earth pressure cells in sand soil

针对厂家给出的土压力盒标定系数K值与实际岩土工程中土压力盒K值之间存在误差的问题,进行了多类型土压力盒标定试验,并结合各类型土压力盒工作原理分析其在相同埋设环境下的差异及其产生原因。选取3类具有代表性的土压力盒(振弦式单膜土压力盒、振弦式双膜土压力盒、电阻应变式土压力盒),采用砂标法对其进行标定试验,将试验所得K值和厂家给定的K值做对比分析,并依据试验结果提出线性拟合公式,给出砂土介质中各类土压力盒的标定系数。结果表明:振弦式土压力盒砂标K值小于厂家提供K值,差值在50%左右;电阻应变式土压力盒砂标K值大于厂家提供K值,差值在3倍左右。

Compared with the calibration coefficient K of earth pressure cells in practical application in civil engineering, K values provided by manufacturers have certain errors. To solve this problem, calibration tests were performed on different kinds of earth pressure cells, and differences between K values of different kinds of earth pressure cells obtained from calibration tests under the same embedded conditions, as well as the reasons, were analyzed based on their operating principles. Three kinds of typical earth pressure cells （single-film vibrating wire, double-film vibrating wire, and resistance strain gauge earth pressure cells） were selected for calibration tests in sand soil. The test results were compared with the values provided by manufacturers, and a linearly fitting formula based on test results was used to calculate the calibration parameter of different kinds of earth pressure cells in sand soil. Test results show that the K values are 50% smaller than those provided by manufactures for vibrating wire earth pressure cells, however the K values are four times those provided by manufactures for resistance strain gauge earth pressure cells.