Research Initiation: Insitu Pore Water Pressure PredictionsDuring Earthquakes

当饱含水的松散砂土受到强烈地震震动引起的循环荷载时，如果水不容易排出(不排水行为)，就会产生过高的孔压。这种过大的孔压会降低土的强度，如果产生足够的压力，将导致土的破坏，称为液化。目前预测循环荷载作用下产生的孔压的方法往往高估了产生的压力，也就是说，它们导致了保守的预测。这项研究项目正在调查目前用于预测地震产生的孔隙水压力的土壤模型的准确性，并特别注意地震期间和地震后这种压力消散的影响。这些预测正在与实验室测试数据以及使用日本东京湾Owi岛仪表站进行的现场测试数据进行比较。这些数据包括松散砂质地基中两个深度的地面运动时程以及动态孔压测量。

When loose sands saturated with water are subjected to the cyclic loads resulting from severe earthquake shaking, excess pore water pressures are generated if the water cannot easily drain away (undrained behavior). This excess pore pressure reduces the soil strength, and if sufficient pressure is generated, will lead to a failure of the soil referred to as liquefaction. Current methods for predicting the generation of pore water pressure during cyclic loading often overpredict the pressures generated, that is, they result in conservative predictions. This research project is investigating the accuracy of soil models currently used for the prediction of earthquake-generated pore water pressures, with special attention being given to the effect of the dissipation of this pressure during and after the earthquake. The predictions are being compared with laboratory test data as well as data obtained from field tests using an instrumented site at Owi Island, Tokyo Bay, Japan. This data includes ground motion time histories as well as dynamic pore water pressure measurements at two depths in the loose sandy subsoils.