The Applied Research In Silty Clay Of Composite Soil-nailing Wall Retaining Structure

The text is based on the tunnel excavation rebuild project of zhengzhou part in107StateLine Road, compared selections used in the more common methods of deep foundation pit.and in allusion to engineering geology, hydrology, environment, construction requirementsand other conditions of the practical engineering, intended to adopt the composite nailingsupported by micro-steel piles. This article carries on the three-dimensional model analyzingby the MIDAS/GTS finite element software, to the composite nailing retaining structuresupported by micro-steel piles. And verified the validity and raeionality of MIDAS/GTSthrough the practical engineering example to analysis the structural’s internal force anddeformation of the supporting structure used of conposite soil-nailing rataining by micro-steelpiles. On that basis, Through simplifying model to research the influencing factors about thecomposite nailing supported by micro-steel piles, and the influence of micro-pile, soil nailing,surface layer and overload for the deformation control of the composite soil-nailing support.At the same time, this article provided the optimum design parameters for the designers andconstruction workers to reference. The main work includes:1. The combination of the slope excavation and composite soil nailing support bymicro-steel piles could control the deformation effectiveness of the foundation pit. Thehorizontal displacement curve of the foundation pit presented "Drum-shaped" distribution,which was small in both ends and big in the middle; moreover, the farther from the foundationpit, the smaller and the more stable the sedimentation at the top of the foundation pit. And thebase heave was gradually leveled off and up to maximum value in the2times the width of theoutside from the foundation pit wall. The shearing force and the bending moment of themicro-steel piles were the largest at the ends of platform, and in the deep bottom of thefoundation pit, with the process of excavation, the internal force was decreased graduallyalong the depth and reduced to0in the embedded depth of the micro-steel piles. the axialforce of the soil nail gradually increased with the process of excavation, the axial force wasthe biggest in the cutters and lugs of the soil nail, the closer to the bottom of the foundation pitthe soil nail was, the closer to the bottom of the foundation pit the soil nail was proximity tothe biggest axial force. The results obtained from the finite element method were inaccordance with the measured value, but it was bigger than the measured value. 2. By simplifying model, the text was researched the deformation control of thecomposite soil-nailing support by micro-steel piles. The addition of micro-steel piles impacton the deformation of the foundation pit and the axial force of soil nail was very obvious, andchanges in the diameter and spacing of micro-steel piles impact on the horizontaldisplacement, was more obvious than on the vertical displacement.3. The diameter、spacing、dip angle and length of soil nailing impact on the deformationof the foundation pit, was mainly influence on the horizontal displacement. Basically thethickness of surface layer impact on the deformation of the foundation pit could be ignored.The deformation of foundation pit was influenced by overload was more obvious.4. In consideration of influencing factors of composite soil nailing support by themicro-steel piles, the influence on the deformation of foundation pit, and taking into accountthe safety and economics of foundation pit, the text gave optimum design parameters.