A lateral loading model box was used to carry out model tests under two cases: the tunnel was located in loess(case 1)and penetrated by potential sliding surface in loess(case 2). The stress characteristics of tunnel lining in the process of slope deformation were studied, and the laws of slope deformation, pressure change of tunnel surrounding rock and lining moment change were analyzed. Results showed that the surrounding rock near the slope side of the tunnel lining was easy to form a void zone under the two cases. The maximum width of the void zone was about 1 cm in case 1 and close to 2 cm in case 2. The void zone in case 2 was much larger than that in case 1, with a relative increase of 100%; Compared with case 1, the peak value of lining bending moment in case 2 increased significantly, with a relative increase of 159.33%, and the maximum increase was located in the area near the side arch foot of the slope. The slide of the potential sliding surface in the slope significantly increased the possibility of tunnel lining damage.

PFC^3Dwas used to simulate the rock fragmentation of five kinds of rocks with different strength under different lateral pressure coefficient, cutter spacing and penetration. In the numerical simulation, the crack propagation diagram of the rock fragmentation process was recorded and the normal force, rolling force and the number of particles damaged in the rock fragmentation process of the disc cutter under different working conditions were monitored. Through the crack propagation analysis and the calculation of the rock fragmentation specific energy of the disc cutter under different working conditions, the following conclusions were obtained: the crack propagation diagram showed that there was an optimal s/p in the rock fragmentation process of the disc cutter(s and p were the cutter spacing and penetration, respectively); With the increase of lateral pressure coefficient, the efficiency of rock fragmentation decreased; When the lateral pressure coefficient was 0.8, 1.0, 1.2 and 1.6, the rock fragmentation efficiency of disc cutter was high when s/p=10; When the lateral pressure coefficient was 1.4, the rock fragmentation efficiency was high at s/p=12.5.

On the basis of theoretical analysis in the framework of specific energy, the main factors of such an interaction were summarized as: the size and the spacing distance of cutters, mechanical properties of stratum, and penetration. A method for design of scaled model tests of tunneling process, by means of shield boring machines, was proposed. The diameter of cutterhead was reduced, while the size and the spacing distance of cutters, the stratum, and the penetration were kept as the same as they were on site. Such a method was applied to a model test of the tunneling of the Cancer Hospital Metro Station of Shenzhen Line 14. This station was the first application of a new construction method which was characterized by that the station was firstly excavated by a small shield boring machine and then re-excavated by a larger one. The results of the model test allowed for predictions of the axial forces and the torque moments of the prototype cutterhead. The predicted values agree well with the monitored ones on site. This underlines the reliability of the proposed method for design of the model test. The originality of this work was highlighted by the quantitative relations between the quantities of the model and the prototype shield boring machines, which provides a reliable method for design of a model test of tunneling by means of shield boring machines.

Taking the Muzhailing Highway Tunnel of Weiwu Expressway as the engineering background, the characteristics and mechanism of the large deformation of the high-stress carbonaceous slate tunnel were analyzed through the records of typical large-deformation disasters and rock mass characteristics. The results of the study showed that the carbonaceous slate tunnel mainly had two large deformation modes, namely conventional type and sudden type; for different lithological sections, the deformation of the surrounding rock was generally expressed as “corrugated developed carbonaceous slate section> thin monoclinic structural carbonaceous slate section> layered carbonaceous slate interbedded with sandy slate section(interbedded section)”; the deformation mechanism of carbonaceous slate mainly included “slab beam” bending deformation, interlayered structure bedding-slip and plastic flow. The corrugated development section was dominated by plastic flow, the thin monoclinic structure section was dominated by “slab beam” bending deformation, and the interbedded section was dominated by bedding-slip.

The evolution process of water and mud inrush disaster in fault tunnel under the effect of rainfall was discussed under the self-developed multifunctional tunnel model test device. Based on the momentum equation of porous media with apparent velocity, the pressure loss in porous media area was simulated. The influence laws on rainfall intensity, fault dip angle, fault orientation and surrounding rock classification for water and mud inrush was also analyzed. The results showed that the greater the rainfall intensity was, the stronger the softening effect of rainfall on the surrounding rock and the greater the damage to the surrounding rock of fault tunnel was; under the same rainfall intensity, the greater the dip angle of the fault was, the greater the damage to the tunnel health was; under the same rainfall intensity, when the fault passes through the tunnel, the stability of tunnel surrounding rock could not be guaranteed; under the same rainfall intensity, the greater the permeability coefficient was, the more unstable the surrounding rock and the higher incidences of water inrush and collapse disasters was. Moreover,the experimental results were in correspondence with the numerical simulation results. The research provides some insights and references for deepening the understanding of water and mud inrush in fault tunnel and proposing effective control measures.

To address the damage evolution of rock salt in Qianjiang, uniaxial compression tests were carried out by using the MTS815 rock mechanics test system. The specimens were collected from the target formation. The results showed that there was no obvious compaction stage in the uniaxial compression of rock salt. The stress-strain curve could be divided into three stages: initial non-damage elastic stage(very short); plastic platform stage, where the damage accumulated rapidly(very long); failure stage, where damage continued to develop. Based on the deformation and failure process of rock salt under uniaxial compression, a mathematical model of damage evolution was established. The reliability of the model was verified by the experiment, which could well reflect the stress-strain process and the damage evolution of ultra-deep rock salt in Qianjiang. In view of the splitting failure of the ultra-deep rock salt under uniaxial compression, the mechanical explanation was given. The research results have a certain guiding significance for the construction of underground salt cavern gas storage.

In order to efficiently treat the suspended solids with small size in the wastewater discharged during tunnel construction in karst area, the pollutants in the tunnel construction wastewater from Guilin to Liucheng Expressway were analyzed. Based on the concept of micro-flocculation filtration method, suspended solids with small size in wastewater were treated by coagulation-filtration process.The results showed that the main pollutants in the tunnel sewage were suspended solids and hydrogen ion concentration. Polymericferric sulfate silicatewas used as green flocculant, the flocculated wastewater was directly filtered, which could effectively remove at least 65% of the suspended solids with small size in water. For the wastewater with suspended solids content of 25, 50, 100 mg/L, the removal rates of suspended solids are 65.52%~68.47%, 79.06%~80.91%, and 85.19%~88.85%, when the precipitation time in 0~5 minutes, respectively.It can be seen that the precipitation process has little effect on the removal of suspended solids with small size. Therefore, it is suggested to cancel the precipitation process in wastewater treatment and directly adopt the flocculation-filtration process to efficiently treat the suspended solids with small size in the tunnel sewage.

Based on a power pipe tunnel project in Xiasha, Hangzhou, 3D finite element software ABAQUS was used to conduct numerical simulation of parallel pipe jacking process, the effects of successive pipe jacking staggered distance and mud-water pressure on soil settlement were studied.The maximum settlement was located directly above the center line of parallel pipe jacking and deviates from the leading pipe. The settlement caused by the descending pipe was 1.5 times that of the leading pipe; when the mud pressure was close to the static earth pressure, the settlement was the smallest; with the increasing of the staggered distance between the leading pipe and the descending tube, the soil settlement generally decreased. Meanwhile, the soil settlement generated by jacking was about 2 times as much as that generated by separate jacking. After the cross distance exceeded 4.31 times of the outside diameter of the pipe joint, the settlement had little change.

The large diameter(13.46 m)shield was used to undercross the existing metro tunnel on the North Ring Road-Tianmu Mountain Expressway. This paper started with the long-term monitoring results of the existing metro tunnel, and combined the distribution characteristics of the upper and soft and hard complex strata and the spatial position relationship between the large shield and the subway tunnel, the feasibility of short distance underpass was analyzed, the MJS(Metro Jet System)columns was used to reinforce the surrounding strata of the existing subway tunnel and grouting reinforcement in the tunnel from the ground was proposed. The effectiveness of the overall response measures was verified by the finite difference software FLAC^3D, and the field implementation and the actual monitoring results were analyzed. The practice showed that the scheme of large diameter shield tunneling under the existing subway tunnel with small clear distance in the upper soft and lower hard stratum was feasible, and the measures of MJS ground reinforcement of the surrounding stratum of the existing tunnel and grouting reinforcement in the tunnel were effective, which could provide reference for similar engineering construction.

The subway tunnel disaster recognition based on image processing is affected by the occlusion on the surface of the subway tunnel segment, which leads to inaccurate disaster feature recognition. In order to reduce the influence of occlusion on disaster recognition, according to the characteristics of various occlusions on the surface of the subway tunnel, the Mean-shift target tracking algorithm was used to determine the center position of the occlusion and then determine its area. The cascade classifier was used to quickly identify the occlusion and mark all the occlusions. This method could quickly identify and mark the occluded objects in the subway tunnel segment image. When there was no accurate identification, the algorithm would intelligently prompt and record the unidentified image for subsequent artificial auxiliary marking. Experiments showed that this method could quickly batch process subway tunnel segment image. In the disaster identification of subway tunnel, the influence of shelter area can be avoided, and it has certain engineering practicability.