Development of a New Pore Pressure Transducer, Installation and In-Situ Dynamic Testing Procedures

CMS-9811153 Ben Hushmand，Hushmand协会地震引起的强烈地面震动的严重后果是潜在的土壤破坏，称为液化。为了彻底了解这种现象，并制定和校准分析技术，以预测液化的发生及其影响，必须在已适当确定现场土壤特性的仪器场地测量数据，并记录地震的地面运动，地震强度足以产生孔隙水压力的显着增加。世界各地的几个站点（例如，加州的金银岛）装有加速度计和孔隙压力传感器。1987年帝国谷地震期间，在加州的Wildlife液化现场记录的孔隙压力，以及随后对孔隙压力传感器的现场动态行为的调查，证明了开发可靠的孔隙压力传感器设计的必要性。本研究计划的目标是：（1）完善和改进加州理工学院最近开发的压力计的设计和结构（称为“加州理工”压力计）;（2）改进压力计现场安装和现场校准方法，（3）提供标准方法和指南，确定压力计设计、准备、安装和后续现场校准和维护的最低要求;（4）研究饱和颗粒土中产生的孔隙压力与液化势之间的相关性。在成功测试之后，将在金银岛国家岩土实验场建造并安装两个原型压力计，靠近现有的孔隙压力传感器，以提供（1）额外的仪器，（2）“Caltech”传感器和现有传感器在未来地震震动中的直接性能比较。该项目正在与新罕布什尔州大学Pedro de Alba教授领导的一个补充研究计划协调。

CMS-9811153 Ben Hushmand, Hushmand AssociatesA serious consequence of earthquake-induced strong ground shaking is the potential soil failure known as liquefaction. In order to arrive at a thorough understanding of this phenomenon, and to formulate and calibrate analytical techniques to predict the occurrence of liquefaction and its effects, data has to be measured at instrumented sites where the in-place soil properties have been appropriately established, and where ground motions have been recorded for an earthquake strong enough to have generated significant increases in the pore-water pressures. Several sites around the world (e.g., Treasure Island in California) are instrumented with accelerometers and pore pressure transducers . The pore pressures recorded at the Wildlife liquefaction site in California during the 1987 Imperial Valley earthquake, and subsequent investigations into the in-situ dynamic behavior of pore pressure transducers, demonstrated the need to develop a reliable pore pressure transducer design.The goals of this research program are: (1) to refine and improve the design and construction of a piezometer recently developed at the California Institute of Technology (known as the "Caltech" piezometer); (2) to refine the piezometer field installation and in-situ calibration methods, (3) to provide standard methods and guidelines defining the minimum requirements for the design, preparation, installation, and follow-up in-situ calibration and maintenance of piezometers; and (4) study the correlation between pore pressures generated in a saturated granular soil and the liquefaction potential.Following successful testing, two prototype piezometers will be constructed and installed at the Treasure Island National Geotechnical Experimentation Site, close to the existing pore pressure transducers, to provide (1) additional instrumentation, and (2) a direct performancecomparison during future earthquake shaking of the "Caltech" transducer and the existing transducers.This project is being coordinated with a complementary research program headed by Prof. Pedro de Alba at the University of New Hampshire.