张雄教授1992年毕业于同济大学，1995年在中国水利水电科学研究院获得硕士学位， 2004年获美国德州农工大学博士学位。现任密苏里科技大学（终身）教授，博士生导师。兼任Canadian Geotechnical Journal 编委,《Geomechanics and Engineering, An International Journal》期刊副主编。研究领域包括岩土材料测试方法、非饱和土的水-力学本构模拟、环境-土体结构相互作用的数值模拟、边坡稳定性分析、基础加固和冻土工程。曾先后主持并参与美国国家自然科学基金、美国交通部等多个重点研究项目。

ABSTRACT:When an infrastructure is built, for example, a pavement structure, it is often built with soils compacted at their optimum moisture contents. The surface soils are exposed to the surrounding atmospheric environment with relative humidity of less than 90%. Such a relative humidity corresponds to a suction value of 140 MPa. All soils become air-dry under such high suction and have very low permeability (nearly impermeable) to transport water from inside to outside. In the meantime, the soils inside the pavement structure tend to reach equilibrium with the ground water table through capillary rise.

When surface soils are air-dry and have cracks, they have high permeability for water infiltration. As a result, the soils inside the pavement structure are often wet or have tendency to become wet with time. Increase in soil moisture content often means deteriorating performance. Research indicates when moisture contents of the soil increase from 3.3% to 6%, the resilient moduli for Alaska D-1 materials are at least reduced 50%. Therefore keeping moisture content low in the pavement structure is very important for pavement performance.

Conventional drainage system relies on gravity to drain water out of soils, which cannot help prevent the above scenarios from happening. A new type of wicking fabric is recently developed to drain the water under unsaturated conditions and potentially maintain good performance. By installing a layer of wicking fabric in the pavement, the water in the pavement structure can be transported along the wicking fabric to the shoulder and vaporized to the surrounding atmosphere which has much higher suction. It is likely to generate a relatively dry zone in the pavement structure which not only can help improve pavement structure, but also help prevent the frost heave and subsequent thaw-weakening in cold regions.This seminar discusses the application of the wicking fabric to prevent the frost heave and thaw-weakening at the Beaver Slide of the Dalton Highway by dehydrating the water in the pavement structure under unsaturated conditions