报告人简介

张雄博士是密苏里科技大学（Missouri S&T）土木、建筑和环境工程系的詹姆斯-海德曼（James A. Heidman）教授。他在德克萨斯农工大学获得土木工程博士学位。在加入密苏里科技大学之前，他曾在阿拉斯加费尔班克斯大学和辛辛那提大学工作10年。自1992年以来，张博士一直从事岩土工程领域的教学和研究工作。他的研究重点是开发先进的实验室技术以快速表征岩土材料、非饱和土水-力耦合行为的本构模型、气候-土-结构相互作用的数值建模、边坡稳定性分析、土壤稳定和地基改良以及冻土工程。

张博士现任ASCE GI浅基础委员会主席、《Canadian Geotechnical Journal》编委、《ASCE Journal of Cold Region Engineering》副主编。他还是多个全国性技术委员会的委员，如ASCE GI膨胀土标准住宅结构设计委员会、ASCE GI路面委员会和 TRB AKG30 地质环境和气候对土工材料影响委员会。他获得了国际土力学和岩土工程学会非饱和土委员会 TC106 颁发的2016年非饱和土力学国际创新奖。

报告简介

Remarkably, after nearly six decades of study of unsaturated soil behavior, arguments still exist among researchers over some fundamental aspects of unsaturated soil behavior. Most points of debate arise from poor quality data associated with laboratory measurement difficulties for unsaturated soils. Because of these measurement difficulties, drained suction-controlled triaxial (SCTX) tests, which are the simplest to perform yet require lengthy test time, have become the standard in development of a database for unsaturated soil constitutive model development. All modern unsaturated soils constitutive models have been developed using SCTX test results. Our recent studies (Zhang 2016) indicated that data from the SCTX testing methods are inadequate and inappropriate for use in the development of theories for unsaturated soils, and there is no theoretically correct data that can be used for constitutive model development of unsaturated soils.

This presentation discusses the limitations of the SCTX tests in the characterization of unsaturated soils. A possible solution to the problem was proposed based on a newly developed modified state surface approach (MSSA). It is proposed that results from undrained (constant water content) tests be used to replace the SCTX tests for the constitutive modeling purpose. Not only can it produce theoretically more correct results with much simpler testing equipment, but also significantly reduce the testing time (from 2-3 months/test to 4-5 hours/test). This can potentially lead to extensive applications of unsaturated soil mechanics in routine engineering projects.