Prefabricated Support Structure Of Underground Cross Passage And Its Engineering Application

In the early stage of urban underground tunnel excavation,a large number of reinforced grid and shotcrete composite structures are often used.This method has many problems,such as complex construction process,long construction period,poor working environment and so on.Prefabricated corrugated plate tunnel primary support is a new type of underground tunnel support structure,which has the technical characteristics of factory prefabricated modular construction,fast construction speed,simple process,green environmental protection and so on.In this paper,based on the corrugated plate test section of No.1 shaft underground cross passage of an underground station in Beijing,the stress and deformation characteristics and engineering application of corrugated steel are studied by using the methods of numerical simulation and field monitoring measurement:(1)Taking an underground cross passage project as an example,the influence factors of stress and deformation of corrugated steel were studied by numerical simulation.The results show that the vertical deformation of the vault decreases with the increase of the thickness of the corrugated plate,and the decreasing trend gradually slows down;The results show that the increase of corrugated plate size can effectively reduce the vertical deformation of vault,but its influence is small;The stratum strength and grouting reinforcement range are inversely proportional to the vault vertical deformation.The thickness and size of corrugated steel have an important influence on the lining and soil layer of underground cross passage,and they are important parameters in the design process.(2)Numerical simulation is used to study the supporting process of No.1 shaft underground cross passage.The simulation results show that the surface settlement is larger when the underground cross passage is supported by corrugated steel,and smaller when the reserved core soil is excavated.It shows that the cavity is closed to form a ring,which has a good resistance to deformation,and the corrugated plate support structure has an important impact on the soil;In a certain range,the excavation step is directly proportional to the surface settlement,and the grouting reinforcement range is inversely proportional to the surface settlement.Therefore,in actual construction,reasonable excavation step and grouting range can effectively control the lining and soil deformation of underground cross passage.(3)The fabricated support structure is applied to the supporting process of No.1 shaft construction cross passage.The monitoring data show that the settlement value and settlement rate of each monitoring point in the construction process are within the control range,and the monitoring value does not exceed the allowable value of monitoring measurement.The fabricated steel structure supporting structure based on corrugated steel plate is reasonable and feasible as the lining structure of underground cross passage.