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Abstract This paper is based on the proximity engineering project of the Baishiyi tunnel group passing under the Chongqing West Station track group. Considering the train load and the spatial relationship of the tunnel and track groups, the settlement patterns, horizontal displacement, and differential settlement of the tunnel–strata–tracks system during the excavation process are studied through theoretical calculations and numerical simulation methods. The results indicate that the tunnel vault, strata, and track settlement deformation patterns are similar. Throughout the tunnel construction process, the tracks underwent uplift, settlement, and eventually stabilized. The settlement trough formed by the excavation of the three tunnels below the track group has an impact range of 25–145 m. Between 35 and 75 m, the differential settlement of the double track gradually increases with excavation. As the tunnel face reaches 75 m, the track differential settlement gradually converges and tends to stabilize. To minimize the impact of underpass tunnel construction on track groups, it is recommended to use a combination of full-section hole grouting and surface reinforcement grouting for ground reinforcement. Additionally, optimizing the construction parameters, including the step length and primary support closure time, and strengthening the locking anchor can further reduce the impact.

Abstract To solve the problem of freezing damage in cold-region tunnels, this study proposed a rubber airbag interlayered composite lining system, and tested its performance of buffering, pressure adjustment, waterproofing, and heat preservation by simulating a low-temperature environment in an artificial freezing chamber. The experiment results show that the frost-heaving force exerted on the lining can always be lower than 1.69 kPa by constantly adjusting the airbag pressure, and the maximum frost-heaving force can reach 28.25 kPa without the airbag. In addition, the airbag also has good waterproof performance. Finally, the airbag can significantly improve the temperature field of the surrounding rock and reduce the freezing depth (6.75 cm

Abstract Accurate estimation of concrete (including shotcrete) consumption plays a crucial role in tunnel construction. A novel method has been introduced to accurately estimate concrete consumption with terrestrial laser scanning (TLS). The estimation needs to capture TLS data of tunnel surfaces at different stages of construction. Unrolling point clouds, a novel two-stage algorithm consisting of noise removal and hole filling has been used to generate resampled points. Furthermore, resampled points from two scans (before and after lining construction) ultimately generate an innovative computation model composed of multiple hexahedral elements, which is used for calculating volumes. The proposed technique was applied to the Tiantaishan highway tunnel and Da Fang Shan high-speed railway tunnel. The calculation relative error of the rebound rate is 0.19%, and the average relative error in predicting the demand for secondary lining concrete is 0.15%. Compared with 3D Delaunay with curve fitting, the proposed technique offers a more straightforward operation and higher accuracy. Considering factors such as tunnel geometry, support design, and concrete properties, a computational model will provide valuable insights into optimizing resource allocation and reducing material waste during construction.

Abstract Understanding the adverse effects of tunnel crossing active faults on tunnel structures is crucial for ensuring their safe operation and construction. This paper presents the results of a series of model tests conducted at a scale of 1:40 using a fault sliding test box. Three sets of fault comparison tests were carried out, namely: (1) the tunnel does not cross the fault, (2) the spring stiffness is reduced, and (3) the model is not reinforced. The objective was to study the failure characteristics of tunnels crossing active faults. The findings reveal that when the hanging wall moves downwards, cracks appear on the surrounding rock surface of the hanging wall, specifically above the tunnel lining crossing the fault. The lining is significantly damaged within the range of − 30–+ 30 cm. All points of axial force exhibit an increasing compression trend. The section of axial force and bending moment near the fault fracture surface is notably larger than that far from the fault fracture surface. The safety factor of the entire structure decreases sharply after dislocation, making the tunnel more susceptible to cracking at various locations such as the vault, arch waist, left and right arch feet, and inverted arch. It has been proven that the shear compression of the fracture surface during fault dislocation is the main cause of longitudinal through cracks in the lining. The use of springs with higher stiffness effectively ensures the reciprocating dislocation of the upper and foot walls, with long duration and large displacement, providing a better simulation of the dislocation of active faults.

Large deformations can easily occur when tunneling through weak surrounding rock with high underground stresses. Under high-stress environments, the surrounding rock stores a large amount of strain energy, and the strain energy stored in the soft and weak surrounding rock enclosure is dissipated through the large traveling plastic deformation. Therefore, the effective use of the surrounding rock’s bearing capacity and energy dissipation is a feasible solution to the large deformation problem. Based on the energy principle, this study designs a high compressibility, large stroke energy-dissipation element, which transforms the traditional support into energy-dissipation support and solves the problem of large deformation by reasonably utilizing the “displacement” of the surrounding rock. The experimental results showed that the steel plate assembled structure had an initial peak value of about 15 MPa, a constant resistance of about 2 MPa with a large stroke, and a compression rate of more than 75%, with good post-compression flexural peak characteristics. Elastic–plastic buckling analyses of defective steel plate composite structures were carried out using finite element analysis software, and the deformation and force characteristics of a variety of steel plate composite structures after buckling under actual field conditions were investigated. Based on the 3D laser scanning system, the thickness of the upper and lower steel plates of the steel plate composite structure was set to 1 cm, the height of the vertical plate was set to 28 cm, and the thickness was set to 8 mm. The original rigid supporting method was converted into one of compression support by circumferentially embedding the steel plate composite structure into the initial support structure. The resulting support configuration offered a high safety factor because the pressure of the surrounding rock was released by the deformation of the steel plate composite structure.

In this paper, the performance of a high-pressure grouting material and consolidation body, the key parameters of tunnel surrounding rock reinforcement, and the field reinforcement effect are compared and studied. The results show that 1) the compressive strength, elastic modulus, and seepage resistance of the consolidation body are related to the water–cement ratio. The permeability of the consolidation body increases with increasing water–cement ratio under the constant head; under the condition of a certain water–cement ratio, the strength increases with an increase in cement content. To meet the construction requirements and the slurry stability, a small water–cement ratio is appropriate. 2) Slurry pressure, rotary spray speed, and lifting speed on the single pile static load bearing capacity have a significant impact. Under the same static load conditions, the greater the slurry pressure, the lower the cumulative settlement value of the single pile, the cumulative settlement value increases less, and the amount of change in rebound is the same; with the increase in the rotational speed of the rotary spray, the lower the cumulative settlement value of the single pile, and the rate of change of the cumulative settlement value of the single pile decreases; and with the increase in the lifting speed, the cumulative settlement value of the single pile increases and the rate of change of the cumulative settlement value decreases. 3) The pile body cement soil is more uniform, has high strength, and is brittle, and the stratum where the slurry part is located is a loose powder clay layer and sandy layer. 4) After high-pressure jet grouting pile reinforcement, the top surrounding rock is more stable after the excavation of an ultra-shallow buried tunnel, the fissures between the surrounding rocks are filled with cement soil consolidation, and the integrity is improved. Certain piles also play a certain role in stopping water; high-pressure jet grouting pile reinforcement to improve the integrity of the surrounding rock played a role in consolidating the weak soil layer above the tunnel vault, creating conditions for the safe excavation of the shallow buried section of the tunnel.

The Sichuan-Tibet Railway is faced with risks of active faults, unfavorable geological conditions, high in-situ stress levels, and a high potential for Traditional tunnel seismic measures that can no longer guarantee the safety of tunnel structures in high-intensity earthquake areas. The new shock absorption capacity layer with resistance-limiting is proposed in this paper and the resistance-limiting shock absorption principle. To study the safety of the new anti-shock lining structure, a large-scale quasi-static model test was carried out based on the improved static-dynamic coupling shear force. The test analyzes the response rules of strain, structural internal force, and lining failure form of tunnel lining, taking into consideration three influencing factors including layer layout position, layout density, and tunnel buried depth. The results showed that: 1) Under the action of low-cycle reciprocating shear strain, the failure mode of the shallow buried tunnel is mainly the tensile failure of the arch waist and the failure of the arch waist and the side wall, and the failure mode of the deeply buried tunnel is mainly the compression failure of the arch waist; 2) Compared with the case of no shock absorption layer, the lining tensile stress on the inner side of the arch waist position is significantly reduced. Under the high shear strain (0.20%), the increased tensile stress trend was slowed down on the inner side walls; 3) The main working area of the resistance-limiting layer can effectively improve the lining stress distribution underground vibration and protects the tensile damage on the arch waist to the side wall. The width and depth of the crack are weakened and the seismic bearing capacity of the width and depth of the crack is weakened and the seismic bearing capacity of the lining structure is greatly strengthened; 4) The lining cracks without the resistance limiting layer develop violently, and the crack at the arch waist runs The lining structure failure mode of the resistance limiting layer arranged at the arch waist is similar to The lining structure failure mode of the resistance limiting layer.

In order to reduce the noble metal palladium dosage in the preparation of CL-20 so as to reduce its production cost, several carbon supports were prepared successfully using the hydrothermal carbonization method in the absence or presence of urea using microcrystalline cellulose (MC) as the carbon source, and the corresponding Pd(OH)2/C catalysts were fabricated using the deposition–precipitation method, which showed high activity in the debenzylation reaction of hexabenzylhexaazaisowurtzitane (HBIW) and tetraacetyldibenzylhexaazaisowurtzitane (TADB). It was found that all the catalysts showed a high efficiency in the debenzylation of HBIW, indicating that the structure of the used carbon supports had a limited impact on the catalyst performance in this reaction. On the contrary, the activities of the catalysts in the debenzylation of TADB were quite different. The results of the nitrogen sorption isotherm measurement (BET), scanning electron microscope (SEM), scanning transmission electron microscopy (STEM), powder X-ray diffraction (XRD), element analysis and temperature programmed desorption (TPD), as well as X-ray photoelectron spectra (XPS) characterizations of the supports and catalysts, showed that the relatively high activity of Pd/HTC in the debenzylation of TADB was related to the high Pd dispersion and novel mesoporous structure, while the further higher activity and stability of Pd/HTC-N1:1 in the same reaction were related with its high Pd dispersion, high total oxidized Pd species, and high surface pyridinic N contents as well as the eggshell distribution of Pd species on the support.

Supported manganese vanadate catalysts for selective catalytic reduction of NOx by ammonia (NH3-SCR) with wide temperature window were fabricated by assistance of microwave. Vanadate dispersed well on the surface of TiO2, giving an enhanced activity in a wide temperature range. The activity over the catalyst at low temperatures enhanced as vanadate loading increased, deriving from the promoting redox property and the lowering stability of adsorbed NH3 species. The in situ DRIFT results indicated that NH3-SCR reaction over the well dispersed vanadate catalyst follow the “Eley-Rideal” (E-R) mechanism for the effective adsorption of NH3. The results showed the potential applications of this kind of catalyst for NOx elimination in some certain conditions.

The engineering technology of undercrossing an airport flight area is relatively mature; however, the use of shield tunnels crossing the operating airport flight area in high liquidity sandy cobble stratum has rarely been reported. To discuss the feasibility of a double-line shield tunnel undercrossing the airport flight area in a sandy cobble region. Based on the case of the Chengdu Metro Line 10 that undercrosses the Shuang-Liu Airport, which is located in sandy cobble region, the deformation and stress laws of airport runway pavement structures were investigated via a three-dimensional numerical model. Stratum displacement, ground settlement and pavement tensile stress under different tunnel depths were analysed. Then, the pavement tensile stress was taken as the safety evaluation index and the vulnerable area of the pavement structure was proposed. The results show that after excavation of the double-line tunnel, the maximum ground surface settlement occurred above the tunnel centreline and the ground settlement curves presented a V-type settlement trough instead of a W-type. The existence of a runway greatly limited the deformation of the surrounding soil; with increasing depth, the effect degree of the runway pavement on the soil settlement decreased. The most unfavourable region of the runway pavement structure under the influence of tunnel excavation was found. With increasing burial depth, the maximum settlement of the surface centre point decreased continuously. It is recommended that the tunnel burial depth not exceed 23.5 m in this project. According to the displacement and stress control limitation of the airport pavement, it can be judged that the shield construction method meets the structural stability requirements of the pavement. The calculated results provide a reference for the shield tunnel construction in the same geological condition areas.

Aloperine is an alkaloid found in the seeds and leaves of the medicinal plant Sophora alopecuroides L. It has been used as herbal medicine in China for centuries due to its potent anti-inflammatory, antioxidant, antibacterial, and antiviral properties. Recently, aloperine has been widely investigated for its therapeutic activities. Aloperine is proven to be an effective therapeutic agent against many human pathological conditions, including cancer, viral diseases, and cardiovascular and inflammatory disorders. Aloperine is reported to exert therapeutic effects through triggering various biological processes, including cell cycle arrest, apoptosis, autophagy, suppressing cell migration, and invasion. It has also been found to be associated with the modulation of various signaling pathways in different diseases. In this review, we summarize the most recent knowledge on the modulatory effects of aloperine on various critical biological processes and signaling mechanisms, including the PI3K, Akt, NF-κB, Ras, and Nrf2 pathways. These data demonstrate that aloperine is a promising therapeutic candidate. Being a potent modulator of signaling mechanisms, aloperine can be employed in clinical settings to treat various human disorders in the future.

The current geological sketch in tunnel engineering is mainly based on sketches of workers. However, geological sketch drawn by workers always offers fundamental data purely due to its drawing mode. A novel drawing method for geological sketch has been introduced using multiview photos in this process. The images of tunnel faces are taken from multiple angles, and every two pictures have overlaps. By measuring the distance between the camera and the tunnel face using a laser range finder, the photographic scale of each photo can be confirmed. SpeededUp Robust Features (SURF) is a good practice for detecting feature points, and the sparse point cloud is reconstructed from multiview photos by structure from motion (SFM). However, the sparse point cloud is not suitable for analysis for structural planes due to its sparsity. Therefore, patch-based multiview stereo (PMVS) is used to reconstruct dense point cloud from the sparse point cloud. After 3D reconstruction, the details of the tunnel face are recorded. The proposed technique was applied to multiview photos acquired in the Xiaosanxia railway tunnel and Fengjie tunnel in Chongqing, China. In order to record the geological conditions of the tunnel face quickly and accurately, Chengdu Tianyou Tunnelkey has developed a set of software and hardware integration system called CameraPad. Besides, CameraPad was used to collect the multiview photos of the tunnel face in the No. 1 Xinan railway tunnel in Jilin, China. By comparing with traditional and existing methods, the proposed method offers a more reductive model for geological conditions of the tunnel face.

In order to better realize the rockburst disaster control mechanism and approach, the rockburst response of concrete blocks with different energy absorption levels under different energy storage conditions was observed and analyzed by loading tests. The occurrence and control mechanism of rockburst were explored from the perspective of energy aggregation and energy dissipation. On this basis, a combined energy absorption support system of concrete-filled steel tube frames and hollow steel pipes for rockburst disaster control was designed, and the effectiveness of the system was verified by numerical simulation and field tests. The results of loading tests show that the failure mode of the specimens changes from static failure to dynamic burst under energy storage loading. The occurrence of rockburst is inevitable when the energy supply is sufficient, but the disaster can be reduced or eliminated by strengthening constraints and improving energy-absorbing capacity to transform rockburst into large deformation. The combined structure consists of the hollow steel pipes being energy-absorbing part and the concrete-filled steel tube frames being strong confinement part was proposed to control rockburst disaster in tunnel support. The numerical analysis on the dynamic response of the support under strong rockburst impact shows that the hollow steel pipes effectively reduced the impact force on the concrete-filled tube frames, and accordingly, the deformation of the entire support system decreased. Given the condition that the hollow steel pipes be able to absorb all the impact energy during deformation, the smaller the strength of the hollow steel pipe is, the smaller the impact force and the displacement is. The combined energy absorption support provides an effective solution for rockburst disaster management in tunnels with strict clearance requirements.

The effectiveness of the use of waste fly ash (FA) and cement (OPC) in the stabilization of subgrade soils and the reasons likely to influence the degree of stabilization were investigated. Incorporating waste fly ash (FA) and cement (OPC) as additives leads to significant environmental and economic contributions to soil stabilization. This study involves laboratory tests to obtain the Atterberg limit, free swell index (FSI), the unconfined compressive strength (UCS), the California bearing ratio (CBR), and the scanning electron microscope (SEM). The test results for the subgrade soil illustrate that the Atterberg limit, plasticity index, and free swell index are decreasing with the addition of different proportions of fly ash and cement, i.e., 0%, 5%, 10%, 15%, and 20% and 0%, 2%, 4%, 6%, and 8%, respectively. The CBR value of untreated soil is 2.91%, while the best CBR value of fly ash and cement mixture treated soil is 10.12% (20% FA+8% OPC), which increases 71.34% from the initial value. The UCS of untreated soil is 86.88 kPa and treated soil with fly ash and cement attains a maximum value of 167.75 kPa (20% FA+8% OPC), i.e., increases by 48.20% from the initial value. The tests result show that the stability of a subgrade soil can be improved by adding fly ash and cement. While effectiveness and usability of waste FA and cement are cost-effective and environmentally friendly alternatives to expansive soil for pavement and any other foundation work in the future.

In recent years, low-temperature SCR (Selective Catalytic Reduction) denitrification technology has been popularized in non-power industries and has played an important role in the control of industrial flue gas NOx emissions in China. Currently, the most commonly used catalysts in industry are V2O5-WO3(MoO3)/TiO2, MnO2-based catalysts, CeO2-based catalysts, MnO2-CeO2 catalysts and zeolite SCR catalysts. The flue gas emitted during industrial combustion usually contains SO2, moisture and alkali metals, which can affect the service life of SCR catalysts. This paper summarizes the mechanism of catalyst poisoning and aims to reduce the negative effect of NH4HSO4 on the activity of the SCR catalyst at low temperatures in industrial applications. It also presents the outstanding achievements of domestic companies in denitrification in the non-power industry in recent years. Much progress has been made in the research and application of low-temperature NH3-SCR, and with the renewed demand for deeper NOx treatments, new technologies with lower energy consumption and more functions need to be developed.

The commonly used strength design concept of tunnel support structures is inadequate to address the large deformation of soft rock. This study designed a series of energy-absorbing dampers (EDs) with low stiffness and high deformation capacity based on the energy principle. The ED was directly installed on the steel arch, which used its compression deformation to release the surrounding rock pressure and absorb the surrounding rock deformation to ensure the stability of the initial support structure. A compression test analyzed the ED’s mechanical properties, optimizing the structural parameters. The preliminary test results showed that the arc energy-absorbing damper’s (AED-I) peak strength (15.33 Mpa) was lower than the standard compressive strength of C25 shotcrete, with a safety factor of 1.63. The AED-I’s maximum compression ratio was 73.20%. To further improve the AED-I’s reliability and ability to absorb the deformation of surrounding rock, the bending radius of the AED-I’s energy-absorbing steel plate was reduced from 1800 mm to 1300 mm. After optimization, the AED-IO’s peak strength was reduced to 10.5 Mpa, and the safety factor increased to 2.38. The maximum compression ratio of the AED-IO also increased to 75.79%. The AED-IO has been applied to treat the large deformation of soft rock in the Zhongshao Tunnel on the Yuchu Expressway. Compared with a traditional support method, the maximum surrounding rock pressure was only 0.13 Mpa in the section where the AED-IO was applied. The maximum steel arch stress was 122.26 Mpa, far less than its uniaxial compressive strength. The application of the AED-IO ensures the stability of the initial support structure. Meanwhile, using an AED-IO saves CNY 24,323.85 per meter and reduces waste emissions by 20 tons.

Developing a catalyst with high SO2 and H2O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO2/H2O-DRIFTS, XPS, TEM, SEM, NH3/SO2-TPD, H2-TPR, and ICP techniques revealed that the high SO2 and H2O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO2 adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.

The influence of the surface chemical properties of the carbon support on the Pd dispersion, activity and stability of Pd(OH)2/C catalyst for the hydrogenolytic debenzylation of tetraacetyldibenzylhexaazaisowurtzitane (TADB) was studied in detail. The flowerlike nanosheet carbon material (NSC) was chosen as the pristine support, meanwhile chemical oxidation with nitric acid and physical calcination at 600 °C treatments were used to modify its surface properties, which were denoted as NSCox-2 (treated with 20 wt% HNO3) and NSC-600, respectively. The three carbon supports and the corresponding catalysts of Pd/NSC, Pd/NSC-600, and Pd/NSCox-2 were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), nitrogen sorption isotherm measurement (BET), powder X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectra (XPS), temperature-programmed desorption (TPD), temperature-programmed reduction (H2-TPR), thermogravimetric analysis (TG), and element analysis. The debenzylation activities of Pd/NSC, Pd/NSC-600, and Pd/NSCox-2, as well as the three catalysts after pre-reduction treatment were also evaluated. It was found that the activity and stability of the Pd(OH)2/C catalysts in the debenzylation reaction highly depended on the content of surface oxygen-containing groups of the carbon support.

A highly porous metal-organic framework (Cu-TDPAT), constructed from a paddle-wheel type dinuclear copper cluster and 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine (H6TDPAT), has been tested in Ullmann and Goldberg type C–N coupling reactions of a wide range of primary and secondary amines with halobenzenes, affording the corresponding N-arylation compounds in moderate to excellent yields. The Cu-TDPAT catalyst could be easily separated from the reaction mixtures by simple filtration, and could be reused at least five times without any significant degradation in catalytic activity.

The reasonable buried depth of metro station should be investigated for Qingdao with the upper-soft and lower-hard stratum. Strength reduction method has been utilized to study FOS of metro station under different buried depths. As the buried depth increases, the curve of FOS can be divided into three parts as the slowly changed part, the rapidly-increased part, and the gradually-decreased part. Taking FOS = 1 as limitation, the formula of least rock cover thickness has been derived. Based upon the formula, the characteristics of safety distribution changing with buried depth for metro station which behaves as three zones (DI, E, DII) have been discovered. Two typical metro stations have been used to verify the research results.

In the present study, a series of CeO2/TiO2 catalysts were fabricated by dry ball milling method in the absence and presence of organic assistants, and their catalytic performances for the selective catalytic reduction (SCR) of NO by NH3 were investigated. It was found that the addition of organic assistants in the ball milling process and the calcining ambience exerted a significant influence on the catalytic performances of CeO2/TiO2 catalysts. The nitrogen sorption isotherm measurement (BET), powder X-ray diffraction (XRD), Raman spectra, high-resolution transmission electron microscopy (HR-TEM), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), sulfur dioxide temperature-programmed desorption (SO2-TPD), thermogravimetric analysis (TG), Fourier transform infrared (FT-IR) and X-ray photoelectron spectra (XPS) characterizations showed that the introduction of citric acid in the ball milling process could significantly change the decomposition process of the precursor mixture, which can lead to improved dispersion and reducibility of cerium species, surface acidity as well as the surface microstructure, all which were responsible for the high low temperature activity of CeTi-C-N in an NH3-SCR reaction. In contrast, the addition of sucrose in the milling process showed an inhibitory effect on the catalytic performance of CeO2/TiO2 catalyst in an NH3-SCR reaction, possibly due to the decrease of the crystallinity of the TiO2 support and the carbon residue covering the active sites.

Heteropoly acids (HPAs) with the Keggin structure have been widely used in NOx removal. Two kinds of catalysts (those with and without the Keggin structure) are prepared for studying the effect of the Keggin structure on the NH3-SCR reaction. A series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analyses are conducted to investigate the surface-adsorbed species on the catalysts during the SCR reaction. The mechanism for enhancing low-temperature activity of the catalysts is proposed. Furthermore, the effect of NH4+ in the Keggin structure is also investigated. Results indicate that both the Langmuir–Hinshelwood (L-H) and Eley–Rideal (E-R) mechanisms occurred in the NH3-SCR reaction over the catalyst with the Keggin structure (Cat-A); in addition, when more acid sites are provided, NOx species activity is improved and more NH4+ ions participate in reaction over Cat-A, thus promoting SCR activity.

Tunnel lining (bare-lining) cross-sections play an important role in analyzing deformations of tunnel linings. The goal of this paper is to develop an automatic method for extracting bare-lining cross-sections from terrestrial laser scanning (TLS) point clouds. First, the combination of a 2D projection strategy and angle criterion is used for tunnel boundary point detection, from which we estimate the two boundary lines in the X-Y plane. The initial direction of the cross-sectional plane is defined to be orthogonal to one of the two boundary lines. In order to compute the final cross-sectional plane, the direction is adjusted twice with the total least squares method and Rodrigues' rotation formula, respectively. The projection of nearby points is made onto the adjusted plane to generate tunnel cross-sections. Finally, we present a filtering algorithm (similar to the idea of the morphological erosion) to remove the non-lining points in the cross-section. The proposed method was implemented on railway tunnel data collected in Sichuan, China. Compared with an existing method of cross-sectional extraction, the proposed method can offer high accuracy and more reliable cross-sectional modeling. We also evaluated Type I and Type II errors of the proposed filter, at the same time, which gave suggestions on the parameter selection of the filter.