Modified calculation of the elastic fulcrum method for soil-rock combination deep excavation
Pile-anchor retaining and protection is the main form for soil-rock combination deep excavations.At present,the elastic fulcrum method of soil excavations is generally used for soil-rock combination deep excavations,considering rock mass as granular material according to the equivalent internal friction angle.Because there are structural planes in rock mass,and it is closely related to the space formed by slope strike.Therefore,this algorithm is very problematic.In this paper,considering the characteristics of soil-rock combination deep excavation,the calculation method is proposed.That is,the elastic foundation beam method is used to calculate the internal force and displacement of the retaining and protection structure,which is calculated according to the excavation surface in the pit at 4 depth ranges,considering the constraint under the piles and the reserved rock shoulder load respectively.Including:① 4 depth ranges of excavation are:the ground to soil-rock interface,the soil-rock interface to the top surface of rock shoulder,the top surface of rock shoulder to near pile toe,near pile toe to the pit base,and the change condition of constraints under the piles in each depth range;② The design and calculation flow of soil-rock combination deep excavation is proposed;③ The calculation method of rock shoulder resistance considering the structural plane of rock mass is proposed;④ The calculation method of wedge stability is analyzed when there are two groups of structural planes in the rock mass,sliding along the intersection line to the pit.A comparison of the two algorithms and reliable numerical simulations verified by real measurements is carried out,and the modified method is more reasonable and accurate.
soil-rock combination deep excavationpile-anchor supportelastic fulcrum methodcalculation method
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