Model Test Research About Influencing On Soil And Foundation When Groundwater Rising In Loess Area

As the increasing of global temperature which is induced by greenhouse effect, the glacier has been melting, the sea level has been rising, and consequently, the groundwater level in coastal area has been generally increased. And in some inland area, groundwater level has also increased because seasonal rainfall has increased and groundwater extraction has reduced. In addition, groundwater rising also exists after pit precipitation. Therefore, both in coastal and inland area, it is bound to affect the buildings and environment to a certain extent, especially in China, there are about 600,000 square kilometers loess of which three-quarters is collapsible; the impact on foundation caused by groundwater rising is not to be ignored.After accessing to lots of documents, systematically summing up domestic and international research status of unsaturated soils and pore water pressure and a detailed study about soil stress and seepage problems, some specific work has been done:1.The conventional model test of the interaction among loess-pile-raft and the test in the condition of groundwater rising have been done in the Geotechnical Engineering Laboratory of the Xi'an University of Architecture and Technology, and the parameters of the soil which is used in the model test have been menstruated by laboratory soil test;2.In the model test, based on the data measured by earth pressure cell and osmometer, which is planted along the center line under the raft in different depths and at interface of typical soils, the changes of soil mechanics are compared before and after groundwater rising and the impact on soil mechanics caused by groundwater rising is analyzed.3.In the model test, based on the data measured by dial indicators planted on the raft , difference of raft settlement is compared before and after groundwater rising, the characteristics of raft settlement under groundwater rising is revealed;4.In the model test, based on the data measured by earth pressure cell planted under the raft, the transfer process of load shared by piles and soil is analyzed under sustained load, the regulation of changes about ratio load-sharing after groundwater rising is studied.