Laboratory Qualification and Field Behavior Studies of Piezometers for Measuring Earthquake-Induced Pore Pressures

摘要：美国新罕布什尔大学的Pedro deAlba和Jean Benoit，当饱和砂土被地震震动时，孔隙水压力会显著增加，从而导致土壤的刚度和强度下降，最终往往导致砂土的液化，并对结构造成重大破坏。虽然孔隙压力的积累已经在实验室实验中进行了模拟，但目前只有一种情况是在地震诱发的强震作用下，在现场沉积物中测量了这些孔隙压力到液化点的发展。不幸的是，在这种情况下获得的孔隙压力记录具有某些不寻常的特征，这导致一些研究人员质疑其有效性。因此，对于岩土地震工程师来说，获得更多的记录是至关重要的，以便为在实验室和离心机试验基础上建立的数学模型提供最终验证。该研究项目包括对当前使用的压电计设计进行广泛的实验室和实地研究。在实验室中，将在试验箱中模拟压电计的安装，并测量压电计在单独水中和饱和土壤中对动孔隙压力增加的响应。因此，将确定压电计的设计、饱和和安装的可接受程序。在第二阶段，将开发用于定期检查压电计响应的现场装置。这些第二阶段的试验将深入了解由于与周围土壤的长期生物或化学相互作用而引起的反应变化问题。该项目的结果将是一套设计、制造、安装和长期监测压力表阵列的指导方针，旨在获得地震期间孔隙压力发展的急需的现场数据。该项目正在与加利福尼亚州Hushmand协会的Behnam Hushmand博士领导的一个互补研究项目进行协调。

Abstract: CMS-9709334, Pedro deAlba & Jean Benoit, University of New Hampshire When a saturated sand deposit is shaken by an earthquake, there can be a significant build-up of pore-water pressure, with consequent loss of rigidity and strength of the soil, often ending in actual liquefaction of the deposit, and major damage to structures. While pore-pressure buildup has been simulated in laboratory experiments, there is only one case currently available in which the development of these pore pressures to the point of liquefaction was measured in a field deposit under earthquake-induced strong-ground shaking. Unfortunately, the pore pressure records obtained in this case have certain unusual features, which has led some researchers to question their validity. Consequently, it is of primary importance to geotechnical earthquake engineers to obtain more records, in order to provide a final verification of mathematical models developed on the basis of laboratory and centrifuge testing. This research project involves an extensive laboratory and field study of piezometer designs in current use. In the laboratory, piezometer installation will be simulated in a test chamber, and piezometer response to dynamic pore pressure increases will be measured both in water alone and in saturated soil. Acceptable procedures for design, saturation and installation of piezometers will thus be identified. In the second phase, a field installation for periodically checking piezometer response will be developed. These second-phase tests will provide insight into the problem of response changes, if any, due to long-term biological or chemical interaction with the surrounding soil. The outcome of this project will be a set of guidelines for the design, manufacture, installation and long-term monitoring of piezometer arrays designed to obtain much-needed field data on pore pressure development during earthquakes. This project is being coordinated with a complementa ry research program headed by Dr. Behnam Hushmand of Hushmand Associates, California.