Test Research On Earth Pressure And Displacement Of Row Pile Retaining And Protecting In Deep Foundation Pit Engineering

Because deep foundation pit engineering in urban involved many factors, its accident ratio is very high, which indicates that foundation pit engineering design theory isn't perfect and needs improve. But due to time limit and fund factor of foundation pit project and because test condition is hard to control, and due to test needs much fund and takes effect slowly, field in-situ test that is important to information design and construction is difficult to do .As effective research means, laboratory model test is used due to the following reasons: low cost, short test period, easy to do, test parameter flexible selected and easily to control. Some researchers at home and aboard apply model test to deep foundation pit simulation study, most of them are sheeting pile timbering deep foundation pit simulation which is stuffed with sand.In the paper, other research results are summarized, and a big test model indoor of row pile retaining and protecting deep foundation pit is designed. For homogeneous soil or samdwich soil structure three different retaining and protecting kinds: dense pile, thin pile and without pile are designed, using excavation simulation and loading on the top of slope,the model test is divided into two stages: foundation pit excavation simulation stage and destroy test stage. In this paper, for three different retaining and protecting kinds, the relation between soil pressure and displacement of piles, the relation between soil stress and strain, interaction of pile and soil and retaining and protecting loss-stability destroy are systemic studied.Research results show that foundation pit slope soil structure destroy characteristic is subgrade shear strain destroy, namely, it is gradually destroy. Lateral displacement of retaining and protecting piles has relations with embed depth, load grade and strength index parameter. Soil displacement and timbering pile displacement are in harmony with deformation. At the same time, some change regularity about earth pressure, soil stress distribution and dynamic changing are obtained. In a word, research result is useful to instruct foundation pit project's design and construction.