负压环境下新型地下水位测试装置研发

Development of a new apparatus for measurement of groundwater level under vacuum pre-loading

现行负压环境下的地下水位测试方法均不能正确反映真空预压条件下地基中的地下水位变化情况。鉴于此,先深入分析了现行负压环境下地下水位测试方法的局限性,然后详细地介绍了一种负压环境下新型地下水位测试技术,即闭口测压管法-激光测试法,最后依托实际工程进行了现场试验研究并验证了其合理性。研究结果表明:现行闭口测压管测试法均存在一定的局限性,主要体现在两方面:(1)测试装置均非常复杂,不便于现场安装埋设;(2)测试结果的影响因素较多,测试结果均不能代表真空预压条件下地基土体中地下水位的真实值。文中提出的新型测试技术,即闭口测压管测试法-激光测试法是基于激光测距原理进行测试的,其方法简便、成本低、结果直观。现场试验结果表明:真空预压条件下,地基中的地下水位总体上随地基的沉降而下降,且总的下降幅度稍大于真空预压期间地基的固结沉降值;激光测试法能正确反映真空预压条件下地基中的地下水位变化情况,有助于对真空预压加固效果进行正确评价和分析。

Current methods for groundwater level testing could not accurately reflect the actual variation of the groundwater level under vacuum pre-loading, and thus their limitations were comprehensively analyzed in this paper. A new testing method, namely closed piezometric testing method-laser testing method, was described in detail. Moreover, field tests were conducted to verify the rationality of the developed method. The results show that some restrictions are found in the existing closed piezometric testing method. On the one hand, the employed devices are very complex and challenging to install. On the other hand, experimental results are affected by many factors, which indicates that the results could not truly represent the ground level under vacuum pre-loading condition. However, the proposed new testing method has merits of easy, low-cost and intuitive results, owning to its principle of laser ranging. The field testing results show that during vacuum pre-loading, the groundwater level falls with the subsidence of ground foundation. In addition, the overall decline is slightly greater than the consolidation settlement of the foundation. Therefore, the new method can accurately reflect the actual variation of the groundwater level, and is useful to evaluate and analyse the effect of vacuum pre-loading.