| In recent years,China has seen a rapid increase in tunnel routes and urban underpasses becoming gradually more popular,which has led to a greater tendency for ground loading and even overloading around tunnels.Ground loading can cause soil deformation and settlement,which can affect the force and deformation of the lining structure and pose a serious threat to tunnel safety.In addition,the full-section tunnel boring machine(TBM),which is a major tool for tunnel construction,uses disk-cutters for rotary rock breaking.As the core component of rock breaking,the disk-cutters are prone to various kinds of failures during construction due to the non-uniformity of rocks in nature,which can affect the rock-breaking efficiency.In order to ensure the safety and stability of the TBM tunneling process and improve tunneling efficiency,this thesis designed a physical scaling model and conducted ground stacking tests to comparatively study the effect of TBM lining support.Additionally,using the rotary cutting finite element method,dynamic simulations of the rock breaking effect of the disk-cutters were performed,with a simulation study of the changes in the rock breaking force of the disk-cutters.Furthermore,the influence of rock on the rock breaking effect and the rock breaking force of the disk-cutters were summarized.The main research results of this paper are as follows:(1)The lining support effect of a full-section tunnel boring machine was studied by conducting physical scale down model tests.A physical test model was designed according to the actual tunnel size of 1:60,a tunnel rotary boring system was established for tunnel excavation,and a settlement observation system was designed to monitor and measure soil settlement.Loading tests were carried out for the gross tunnel and lined tunnel respectively to summarize the tunnel deformation and soil settlement laws and to quantify the lining support effect.Compared with the gross tunnel model,the lined tunnel model is significantly more capable of withstanding the ground stacking load,with 34.3% reduction in total soil settlement and 61.7% reduction in soil surface collapse pit depth.(2)The study investigated the stress change,strain change,and energy curve of different rocks during the simulation of rock breaking using disk-cutters.The study utilized elasticplastic intrinsic models,as well as plastic and elastic intrinsic models,as rock material for rock breaking simulation.The goal was to determine the resistance and deformation abilities of different rocks during TBM tunneling.The plastic model was found to be highly susceptible to deformation and damage.The elastic model,on the other hand,requires significant stresses to produce small strains,and releases stress more quickly as disk-cutting continues.The elastic model also exhibits the most intense energy curve fluctuations.(3)The study found significant lateral force magnitude in the simulation of the elastic and plastic models,particularly in disk-cutter lateral force,which exceeded the vertical force.Using the elastic model,the relationship between rock elastic modulus and disk-cutter depth of cut on rock-breaking force was studied,with the findings demonstrating a linear relationship that can be fitted as a linear function.Conversely,the relationship between diskcutter depth of cut and rock-breaking force is more complex,with optimal points existing between them.In actual excavation processes,the balance between disk-cutter depth of cut and excavation efficiency must be considered to ensure that disk-cutters maintain a suitable depth of cut to break the rock efficiently. |
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