Foundation Pit Hubizhuang Confined Expansion Of Sac Type Body Of Prestressed Anchor Method In The Experimental Study And Engineering Application Of Expansive Soil

With rapid economic growth,increasing building density in urban area promotes effective use of underground space,deepening building foundation pit,accelerating application of retaining pile due to limited disposable land. Architectural foundation pit projects should be improved and supported to ensure safety for adjacent buildings, structures and underground pipeline use as well as constructing project. At present, prestressed anchor cable as one of the technologies fastest developed and most widely used in avoiding slipping on slope is welcome in foundation pit excavation support system and projects reinforcing soft rock and soil slope with advantages of large construction operating surface, convenience for earthwork excavation, controlling deformation with prestress and forming a common force system with pile. But when expansive soil foundation pit excavation depth is deeper than the buried depth, expansive soil characterized by water expansion and shrinkage, tends to pose direct threat to slope or pit stability, damaging surrounding architectural structure, even causing landslip.In traditional sense, methods for foundation pill supporting on expansive soil are double row pile method and inner supporting method.However, these two exist some defects and construction difficulties in coping with deformation displacement and construction complexity. Moreover, in expansive soil layer,they are weak in resisting pulling force and easy to lose stability. Up till now, there have been numerous examples of the foundation pit safety accidents caused by failure of the anchor cable,Thus whose application is limited.Nowadays, bearing capsule expansion anchor cable method adopts advanced technology and abandons traditional anchor cable force mechanism. Experiments, implemented in state house and Olson special projects of expansive soil area, through third party measurement unit observing displacement and settlement of foundation pit, underpinned by a number of data, combining related theory and projects,systematically analyzes principle, process and effect of the technology. Practice shows that the supporting method with high safety grade, large anchoring force can bring good social benefit and economic benefit, which is worth popularizing.