Engineering Characters Of Miscellaneous Fill And Stability Analvsis Of Foundation Pit Slope

With the old city reconstruction and the city scale expanding unceasingly, many new buildings are often planed and designed in the engineering site which covers miscellaneous fill stratum. The analysis and research of the miscellaneous fill foundation pit slope gradually becomes hot and difficult topics in geotechnical engineering. Combining with the foundation pit engineering project of Hainan Broadcasting Group residential buildings, this paper is based on the geotechnical experimental study of miscellaneous fill in this site. According to the engineering project of foundation pit monitoring data, there is an analysis of the stability of foundation pit and its influencing factors. This paper applies ANSYS software to analyzing the foundation pit slope stability, which compares the results of finite element simulation with foundation pit monitoring and proposes the deformation and stress distribution rules of foundation pit slope.(1) There is a larger variability and discreteness on thickness, moisture content, dry density and density of miscellaneous fill. The miscellaneous fill is soft soil which has engineering properties of unconsolidated soil, low bearing capacity, low mechanical properties and low shear strength. The miscellaneous fill is slightly corrosive to the concrete structures and the rebar in reinforced concrete structures. The miscellaneous fill subsoil can’t be used as the bearing stratum of a project. If the miscellaneous fill subsoil is used as foundation pit slope, the designers should take proper reinforcement measures.(2) The miscellaneous fill is the surface of stratum which consolidation time is short. Because of self-weight consolidation, the variation of vertical deformation is large and the variation of horizontal deformation is relatively small at the top of foundation pit slope,. After excavation, foundation pit supporting and reinforcement measures should be taken to ensure the stability of foundation pit slope as soon as possible.(3) The engineering site should clearly indicate the area where the lorry should be forbad driving, to prevent vehicle load causing shear damage of foundation pit slope soil and the creep of foundation pit slope soil. Heavy rainfall and continued rainfall will lead to part of the internal foundation pit slope soil being in saturated condition, which causes the soil softening and deformation.If one monitoring point has abnormally increasing deformation, monitoring and patrolling near the monitoring point are a constant assignment which needs intensify. Judging the stability of foundation pit based on the monitoring data of foundation pit.(4) As the characteristic tree species in Hainan, casurina equisetifolia has the characteristic of stronger viability, shorter growing duration and better mechanical properties, it is widely used in Hainan foundation pit supporting project. The foundation pit slope adopt the supporting reinforcement of casurina equisetifolia timber piles, which play an important role on the whole skeleton structure of foundation pit slope and improve the shearing strength of the foundation pit slope as a whole. The timber piles dominate the foundation pit slope deformation and stress concentration and ensure the stability of foundation pit slope.(5) The linear load pressed on the top of foundation pit slope which adopts the supporting reinforcement of timber piles. With the linear load increasing, the risk of the foundation pit slope deformation creasing. According to the deformation and damage of timber piles in the finite element model, the stability of foundation pit slope can be effectively evaluated to prevent the failure of foundation pit slope.(6) Contrast the composite support and the timber pile support in the finite element model, the foundation pit slope which adopts the composite support has a better global stability.