Tunneling Technology Research Articles

Performance-based analysis on fire behavior of shield tunnel joint with DDCI connector

In recent years, there has been significant advancement in large-diameter shield tunnel technology, with the continuous emergence of new joint types. To meet the different requirement of application, numerous studies have been done on the mechanical behavior of the various new joints. In this paper, a new DDCI connector for the shield tunnel joint was proposed. Simultaneously, a thermo-mechanical performance analysis was conducted on the new longitudinal joint combining inclined bolts and the DDCI connector. A refined finite element model of the new joint was established and various working conditions were designed to obtain a full understanding of the thermo-mechanical performance of the structure. This evaluation included the presence of initial loads and exposure to different fire curves, specifically the RABT and RWS fire curves. The validity of the numerical model and the indirect coupling analysis method were verified by physical experiments and previous research, respectively. The temperature distribution, joint opening and internal force of the connectors were analyzed in the study. According to the results, different fire curves and thermo-mechanical sequences both have a great impact on the mechanical response of the new joint under elevated temperature. Moreover, due to the involvement of the DDCI connector, the new joint shows clear advantages in strength and stiffness over the conventional joint. The results contribute to the fire-resistant design of the large-diameter shield tunnels adopting the scheme of the new joint with a DDCI connector.

The development, implementation principles and application of the endoscopic super minimally invasive surgery

Endoscopic therapy has gone through three stages of development: intraluminal treatment, endoscopic tunneling technology, and endoscopic super minimally invasive surgery (ESMIS). Compared to the drawbacks of traditional surgical methods"organ resection and anatomical reconstruction", super minimally invasive surgery (SMIS) emphasizes the surgical concept of"curing diseases while preserving organs and functions". SMIS conducts treatment through four channels: natural cavity channel, tunnel channel, puncture channel, and multi cavity channel. It offers dozens of surgical methods for diagnosing and treating gastrointestinal diseases. At present, relatively sound implementation principles for ESMIS treatment have been established to ensure the safety and effectiveness of surgery, and to continuously expand other diagnostic and therapeutic fields.

Study on Safety Tunneling Technology of Secondary Outburst Elimination by CO2 Gas Fracturing in High-Outburst Coal Seam

The No. 3 coal seam in the Yuxi Coal Mine has a measured maximum gas content of 25.59 m3/t, along with a maximum gas pressure of 2.9 MPa, indicating its high risk to gas and outbursts. To mitigate outburst risks of the coal seam, the 1301 working face has been implemented with gas pre-drainage measures by grid boreholes from underlying roadways. After one year of extraction, it was confirmed that the gas content at all 33 test sites was below 8 m3/t, meeting the outburst prevention standards. However, during subsequent coal tunnel excavation, the gas desorption index K1 value frequently exceeded the standard, resulting in numerous occurrences of abnormal gas emission or small-scale outbursts. To tackle the challenges associated with safe excavation following the first-round regional outburst prevention measures, a research and industrial trial of CO2 gas fracturing (CO2-Frac) technology for secondary outburst prevention and rapid excavation was completed. The results show that the dual-hole and high-pressure (185 MPa) CO2-Frac considerably contributes to outburst prevention. K1 exceedances per hundred meters of tunnel excavations were from an average of 2.54 without CO2-Frac to an average of 0.28 after the new technology was implemented, leading to an eight-fold reduction. Additionally, the monthly excavation footage increased from an average of 81.64 m without CO2-Frac to an average of 162.42 m with CO2-Frac, resulting in a two-fold improvement. The dual-hole and high-pressure CO2-Frac is an advanced technology for safe and efficient excavation for secondary outburst elimination in highly outburst-prone coal seams in the Yuxi Coal Mine, with potential for widespread application in similar coal seam conditions.

An overview of potential excavation compensation method for tunnelling in deep rock engineering

The complicated geological environment of deep rocks poses new challenges to tunnel and mining engineering. Some thorny disasters such as large deformation of soft rock and rockburst are becoming more and more prominent. However, the classic tunnelling methods represented by the mine tunnelling method and the new Austrian tunnelling method are generally unsatisfactory in addressing these issues due to the limited self-stability of surrounding rock mass. Therefore, the excavation compensation method (ECM) with the core of active stress compensation has been proposed and applied in practical engineering construction to solve the above problems. After extensive engineering practice, the theoretical foundation, key technologies, and construction system of ECM have been established and improved. This article provides a comprehensive overview of this novel tunnelling method. In addition, its controlling effects on surrounding rock are demonstrated by two typical engineering examples. It could provide some new ideas and references for the development of future tunnelling technology.

Design and Implementation of IPsec VPN IoT Gateway System in National Secret Algorithm

With the development of Internet of Things technology, the security threats faced by the industrial control field are increasing, and strengthening the security protection capabilities of intelligent systems on IoT highways is becoming increasingly important. IPSec VPN tunneling technology can achieve identity authentication and encrypted data transmission, and is an important means to achieve secure data transmission in intelligent systems on Expressway intelligent tunnel system. The commonly used IPSec VPN gateway uses a traditional Linux protocol stack-based approach for data capture, which requires multiple data copies and context switching, resulting in low efficiency of IPSec services. In addition, the commonly used IPSec VPN security gateway is implemented on the basis of the open-source IPSec framework, using internationally recognized algorithms for encryption and decryption, which poses security risks. This article is based on the IPSec protocol, and studies the high-speed network packet capture framework PFRING technology, the fusion technology of national secret algorithm and IPSec protocol. It designs and implements an IPSec VPN IoT security gateway based on national secret algorithm. After experimental verification, the IPSec VPN gateway system constructed in this article has complete functions and better performance than the common open-source IPSec frameworks OpenSwan and strongSwan, and can meet the application requirements of IoT data encryption transmission.

World Bank-Assisted Community-Based Development Project for High-Value Crop Production: Failures and Successes

The government of Punjab has recently implemented a World-Bank-assisted community-based development project for the enhancement of farm productivity in water deficit areas of the Punjab province for 11 years. This paper describes a case study from the Faisalabad division, wherein drip irrigation in conjunction with tunnel technology has improved crop and water productivity of fruits, vegetables and cash crops, optimizing farm incomes. Not only crop yields were optimized, but also there were savings on water (30-45%) and other inputs, reduced incidence of pests and diseases (15-20%), early spring production by 35 days and higher quality of produce, which substantially increased farm incomes (19-41%) along with some environmental benefits. A conservative estimate showed a reduction in unemployment by 5% in project areas. Despite these impressive achievements, a post-project survey showed that 93% of beneficiary farmers abandoned drip irrigation systems, soon after project closure. It emphasized that in the Thal area, only a 4% system rolled back, suggesting the better suitability of the high-efficiency irrigation system for water conservation and productivity enhancement in sandy areas. Post-project farmer-participatory rural appraisal (PRA) shows that drip irrigation was rolled back due to multiple constraints. For example, unsuitable/inefficient design, clogging of drippers/drip lines, non-availability of spare parts, poor response of troubleshooters and top-down approach of the project, prompting better planning and implementation, in the future, for similar projects.

Analysis of sensor parameters for ultra close range lateral penetration of subway tunnel full section sand layer soil pressure shield tunneling

In order to solve the problem of large disturbance to the stratum caused by shield tunneling in the full face sand layer geology by using the earth pressure balance full bin tunneling technology in the subway tunnel shield construction, this paper presents a parameter analysis of the ultra close side penetration of the full face sand layer earth pressure shield in the subway tunnel. By analyzing the monitoring data of surface settlement caused by subway shield construction, it is concluded that the law of surface horizontal settlement basically conforms to peak settlement theory, and the law of surface vertical settlement basically shows a steady downward trend. Through the mathematical modeling of the cumulative settlement data affected by the shield passing of the right line tunnel at the surface monitoring point, the influence of the shield passing of the left line tunnel on the surface settlement is predicted, and the prediction result is accurate. The experimental results show that the maximum deviation is 1.47 mm and the minimum deviation is 0.03 mm. The prediction accuracy is high and meets the accuracy requirements of practical engineering. Under the same geological conditions and construction parameters, the disturbance law of tunnel shield construction on the ground surface has important guiding significance in practical engineering.

Wake mode identification of rotating triangle with machine learning approaches

The moving body usually leaves different forms of wake trails in fluids, and these wake fields contain physical information such as the state and geometry of the moving body. Recognizing and extracting these information from the wake can provide new insights for non-acoustic detection technology. Traditional methods do not easily extract the flow state, geometry, and other information directly from the wake structure. This work mainly uses convolutional neural network algorithms for intelligent recognition of the wake types of rotating triangles. Based on the flow field visualization technology of the soap film tunnel, the wake types of the flow around a structure controlled by external excitation of sinusoidal rotation are studied. The winding characteristics of the rotating triangle and the variation rule of the wake with control parameters are analyzed. At last, the recognition rate of the wake types on the test set is above 90%. The recognition rates of the experimental data not involved in the training conditions are all above 80%, demonstrating the generalizability of the model. This method provides a reference for further utilizing artificial intelligence in extracting physical information from wakes, playing a crucial role in advancing wake detection technology.

Analytical model for calculating the soil pressure on inclined shield tunnels during construction phase

As a new tunneling technology for shallowly buried tunnels, ground penetration shield tunneling (GPST) penetrates the ground directly without launching or receiving shafts, thereby improving the construction efficiency and land-occupation economics. Unlike traditional shield tunnels, which have a leveled or approximately leveled route, the entrance and exit sections of GPST tunnels are inclined, and the external soil and water pressures acting on the latter vary along the route. This study proposes a new loading calculation model for the GPST during the construction phase, considering the dynamically varying stress state along the route. First, a comparison was conducted to delineate the advantages of the proposed model in contrast to the modified conventional method, followed by an analysis of the potential underlying reasons. Subsequently, a parametric study is conducted to evaluate the influence of the excavation slope on the soil pressures acting on the tunnel. The results indicate that the proposed method is better suited for calculating loads at shallow burial depths in GPST.

Enhancement Seismic Response of a Bored Tunnel Using Isolation for the Challenge of a Faulted Rock Crossing

The tunnel boring method (TBM) is a widely used and effective tunneling technology in various rock mass quality circumstances. A “faulted rock mass” can range from a highly fractured rock mass to a sheared weak rock mass, making the ground conditions challenging for tunneling, especially for TBMs. “Faulted rock” significantly affects hard rock TBMs, primarily due to the TBM’s high geological risk and poor flexibility. TBMs require careful planning and preparation, starting with preliminary assessments. This study investigates the impact of establishing an isolation material between a circular tunnel and the adjacent faulting rock on seismic response. The two parts of the parametric analysis for the isolation material utilized in the model look at how changes in the mechanical characteristics of the material, such as the shear modulus of the rock and the fault, affect the stresses created in the tunnel. The second section examines how changes in the isolation width concerning the fault width affect the stresses and displacements produced in the tunnel. Additionally, the effectiveness of isolating the tunnel during sudden changes in the characteristics of the rock was investigated under seismic loading perpendicular to the tunnel and parallel to the tunnel. The finite element approach was utilized to model the TBM tunnel and the neighboring rock with a fault or sudden change in the rock using Midas/GTS-NX, simulating the interactions between the rock and the tunnel. Time-history analysis using the El Centro earthquake was conducted to calculate the stresses in the tunnels during seismic events. Peak ground accelerations between 0.10 g and 0.30 g were utilized for excitation. A time step of 0.02 s and a length of 10 s for the seismic event were used in the analysis, with traditional grout pea gravel vs. the isolation layer. Comparisons were made between the absolute stresses (the greatest possible values) in the normal tunnel section (Sxx) and those induced in the tunnel with traditional grout and with isolation. Furthermore, the study of vertical displacement was taken into consideration. The seismic isolation method is highly effective in improving the seismic safety of bored tunnels. The results show that the significant values of the ratio between the shear modulus of isolation and the surrounding soil should be between 0.2% and 0.4%. Where parts of the tunnel run through a fault, the effective length of isolation should be between one and two times the fault width. The dynamic behavior of the tunnel with isolation is better than that with traditional grout. Generally, when isolation is used for any length, it reduces the stresses at the area of sudden change. Consequently, engineering assessments from both structural and geotechnical engineering viewpoints are now required for these unique constructions. An underground structure’s safety should be evaluated by the designer to ensure that it can sustain various applied loads, taking into account seismic loads in addition to construction and permanent static loads. Tunnels may be especially vulnerable in areas where the composition of the soil or rock varies.

Seismic isolation technology of shallow buried large section utility tunnel with soft soils in seismically vulnerable area

Shallow utility tunnels with exceptionally large cross-sections in weak soil can face significantly more severe seismic risks compared to conventional deep tunnels in seismic hazard areas. This study investigates the seismic response and isolation technologies applied to a large section utility tunnel with 4 compartments in one layer, employing seismic simulations. The engineering context, dynamic motions, and measuring points of the numerical simulation were introduced. Subsequently, the finite element method was employed to explore the seismic behaviors of the large section utility tunnel when subjected to strong earthquake excitations under four conditions. The study explored and comparatively evaluated the seismic isolation effectiveness of three proposed schemes: the grouting scheme, the buffer layer, and the assembly of three-quarters buffer layer, cushion and grouting. The analysis included various indexes such as the deformation, the principal and shear stress, and the safety factor. The finding reveals that the assembly seismic scheme exhibits the most significant seismic effect (95.39%), followed by the buffer layer (38.82%), and the grouting scheme (25.66%). The assembly seismic scheme is recommended for the seismic design in the current large-section utility tunnels. These conclusions provide valuable scientific guidance for the seismic design of large-section utility tunnels, aiding in enhancing earthquake resilience.

Research on piezoelectric vibration energy harvester for cutting part of roadheader

At present, coal mine tunneling technology is developing in the direction of intelligence and unmanned. The piezoelectric vibration energy harvester can convert the vibration energy generated by the cutting part of roadheader into electrical energy and realize the energy self-sufficiency of the low-power wireless sensor. In practical applications, the vibration frequency of the cutting part of roadheader is different, and the working condition is complex, resulting in the energy recovery efficiency of the vibration energy harvester is not ideal. In order to improve its adaptability and reliability, a separated excitation broadband piezoelectric vibration energy harvester is proposed in this paper.

Predicting Model of Dual-Mode Shield Tunneling Parameters in Complex Ground Using Recurrent Neural Networks and Multiple Optimization Algorithms

Based on the left tunnel of the Liuxiandong Station to Baimang Station section of Shenzhen Metro Line 13 (China), a prediction model for the advanced rate of dual-mode shield tunneling in complex strata was established to explore intelligent tunneling technology in complex ground. Firstly, geological parameters of the complex strata and on-site monitoring parameters of EPB/TBM dual-mode shield tunneling were collected, with tunneling parameters, shield tunneling mode, and strata parameters selected as input features. Subsequently, the Isolation Forest algorithm was employed to remove outliers from the original advance parameters, and an improved mean filtering algorithm was applied to eliminate data noise, resulting in the steady-state phase parameters of the shield tunneling process. The base model was chosen as the Long-Short Term Memory (LSTM) recurrent neural network. During the model training process, particle swarm optimization (PSO), genetic algorithm (GA), differential evolution (DE), and Bayesian optimization (BO) algorithms were, respectively, combined to optimize the model’s hyperparameters. Via rank analysis based on evaluation metrics, the BO-LSTM model was found to have the shortest runtime and highest accuracy. Finally, the dropout algorithm and five-fold time series cross-validation were incorporated into the BO-LSTM model, creating a multi-algorithm-optimized recurrent neural network model for predicting tunneling speed. The results indicate that (1) the Isolation Forest algorithm can conveniently identify outliers while considering the relationship between tunneling speed and other parameters; (2) the improved mean filtering algorithm exhibits better denoising effects on cutterhead speed and tunneling speed; and (3) the multi-algorithm optimized LSTM model exhibits high prediction accuracy and operational efficiency under various geological parameters and different excavation modes. The minimum Mean Absolute Percentage Error (MAPE) prediction result is 8.3%, with an average MAPE prediction result below 15%.

Virtual Private Network—Firewall Integration for Wireless Local Area Network Improvement against Jammers

Wireless networks are susceptible to many security problems since the wireless medium is open. Jammer (jamming attack) is the most important problems in wireless networks. It is denial-of-service attack in which attackers send malicious signals or messages on a channel that is intended for normal traffic by intentionally interfering with the network. One of the solutions is the development of tunneling technology as an attempt to secure communication networks. Virtual Private Network (VPN) tunneling technology when integrated with firewall would provide a suitable security. In this study, number of Jammers would interfere with the normal operation of the network resulting in performance degradation of network. These Jammers decrease throughput and increase delay and data dropped. The aim of this study is to improve the performance of Wireless Local Area Network (WLAN) by integrating Firewall with VPN in number of different Riverbed Modeler simulation scenarios which it is utilized in this study for video and data applications. Firewall is a technology employed to regulate the level of network connectivity. It can block unauthorized access from an external network to an internal network’s resources. In this study, the tunneling technology of VPN was integrated with firewall to improve the performance by increasing the throughput and decreasing delay and data dropped. The firewall would block any access to the server from the workstations and the VPN would filter the packets to allow a specific access to the specific server. The results showed that VPN when integrated with firewall increased the throughput from 1,350,000 to 1,500,000 bits/sec and decreased the delay from 0.0054 sec to 0.0047 sec and data dropped from 7,800 to 5,000 bits/sec so that this study proved that VPN incorporated with firewall provides a good throughput and delay improvement for wireless local area network.

Моделирование процесса вибрационного обезвоживания угольной мелочи в технологических системах гидромеханизированных шахт

Introduction. The article discusses the issues of modeling various variants of flow line tunneling technologies based on an analysis of the structure of the tunneling cycle. Materials and methods. As research methods, the authors used: analysis of the structures of the tunneling cycle of continuous mining technologies, mathematical modeling of processes and operations, and industrial testing of options for implementing the proposed technological tunneling systems. Results. Obtained during the implementation of a mathematical model of a high-frequency, low-amplitude process of vibration dehydration of mineral raw materials of small fractions, using fine coal (sludge) as an example, made it possible to determine the optimal parameters of the kinematics of the working body in accordance with the parameters of the source material. Innovative solutions have been proposed for the design of vibration dewatering devices with mechanical and hydraulic high-frequency flexibly adjustable drives. Conclusion. The article summarizes the results of research in the field of modeling and optimization of fine coal dewatering parameters in technological systems of mining enterprises. Options for implementing innovative technical devices for high-frequency, low-amplitude effects on the source material are proposed to increase the efficiency of dehydration. Resume. An analysis of existing means and methods for dewatering rock mass has shown that in relation to the technology of hydromechanized coal mining with its underground dewatering and recycling of process water, the most promising is the use of high-frequency vibration dewatering devices with a mechanical or hydraulic drive. The study of the kinematics of movement of the dewatered rock mass made it possible to determine the optimal values of vibration parameters

Study on waterproof and drainage technology of mountain tunnel in high-pressure and water-rich region

High-pressure groundwater brings great challenges to the construction of mountain tunnels. Hence, controlling and discharging groundwater are two key problems that must be addressed before constructing tunnels in high-pressure and water-rich region. Fluid–solid coupling seepage analysis method is used to analyze the variation of displacement, stress and pore water pressure of the tunnel. A waterproof and drainage method suitable for tunnels in high-pressure and water-rich region is proposed. Curtain grouting plays a dual role in waterproof and reinforcing surrounding rock. Decompression drainage holes are designed in order to further reduce the pore water pressure acting on the initial lining. The thickness of grouting circle, the permeability coefficient ratio and the decompression drainage holes distribution rate of the initial lining are the main factors that affect the waterproof and drainage effect of tunnels in high-pressure and water-rich region. Suggested parameters on waterproof and drainage measures for tunnels in high-pressure and water-rich region are given after comprehensive analysis, which can provide basis for the technology on high-pressure groundwater treatments and constructions of underground engineering under complex geological conditions.

Clinical analysis of the results of recessions elimination using tunnel technology

In modern plastic surgery of soft tissues of the oral cavity, there is a wide variety of ways to close recessions of the gingival margin and increase the keratinized gum zone, but only a few of them give a well-predicted and effective result. So, one of the most popular techniques is the tunneling technique using a de-epithelized free gingival graft. The prevalence of this method is primarily due to its minimally invasive nature, which allows for accelerated regeneration of the gingival margin and reduces the likelihood of postoperative complications. The analysis of 20 clinical cases of closure of recessions of the gingival margin of the teeth on the upper and lower jaws according to the Miller classification of class I and II, subclasses A and B and the Francesco Cairo classification type 1 and type 2 with the use of tunnel technology according to Zuhr. The high efficiency of this method of closing recessions has been revealed, including in terms of achieving an optimal long-term forecast and aesthetic result.

Research and Practice of Full Plugging Groundwater Technology in Water-Rich TBM Diversion Tunnel

To solve the problem of water discharge in the tunnel when the tunnel passes through the low-pressure water-rich fractured stratum, the grouting plugging technology of the low-pressure water-rich tunnel is studied. The grouting plugging scheme is optimized through the field test. The post-validation research is numerically simulated and the parameters of the complete sealing grouting ring are analyzed. The results show that: 1) Full plugging grouting can effectively improve the funnel effect of precipitation with good water plugging effect. With the decrease of the permeability coefficient and the increase of the thickness of the grouting ring, the flow velocity around the tunnel and the water discharge in the tunnel both decreased significantly, with a trend of “rapidly decreasing-slowly decreasing”. Considering various factors, an optimal grouting ring thickness between 1.5 m and 2.5 m and a reasonable range for permeability coefficient between 2.07 × 10−6 cm/s and 4.14 × 10−6 cm/s are considered appropriate. 2) The use of cement-water glass system full plugging grouting for water plugging, can significantly reduce the discharge of water, only partial dripping or even dripping state. Using polyurethane foam single point method to systematically block grouting and water plugging can only changes the discharge path and hardly attenuates water discharge.

Геоходная технология строительства подземных выработок: необходимость создания

The article discusses the need to create geokhod-based technologies for construction of underground workings. It reviews the main drawbacks of the current tunneling technologies. A new approach is emphasized to driving underground workings and shaping of underground space, where tunneling is initially considered as the movement process of a solid body, i.e. the tunneling machine, through the surrounding rocks (the geologic environment). The main structural elements of the technological mode to shape, i.e. to develop, the underground space are considered based on the priority development of new approaches to construction geotechnology and geotechnics. In the process of shaping one of the structural elements of the technological mode, i.e. the design and technological tools, the first priority is to create a range of technologies to drive underground workings for various purposes and location within the subsurface space and for different geological environments. The authors have formed the concept of Geokhod tunneling technologies and defined their application areas. The need for the development of new design and technological solutions related to rock support with the perimeter support and, especially, to the challenges of driving tunnels of variable cross-section is identified.

Case study on shield steering along a sharp curve

Due to ongoing development of shield tunnelling technologies, usage of more complicated tunnel alignments is increasing. Therefore, more proper steering of shield machines is expected. Shield behaviour is controlled mainly by copy cutter, articulation mechanism, and jack force, but these three shield steering parameters are not easy to be determined, because of their high co-linearity and varying geological conditions. A discharging tunnel with a sharp curve was planned by an articulated EPB type shield. Therefore, as a preliminary analysis, the required shield steering parameters for the planned tunnel were calculated by shield behaviour simulation, and the obtained shield steering parameters were compared with the shield equipped capacity. Furthermore, as a post-analysis, the shield behaviour simulation was carried out by using the site measured data, and the input parameters at the preliminary analysis were examined. Through this research, the followings were found: 1) in the preliminary analysis, the shield equipped capacity is enough to construct the tunnel; 2) in the post-analysis, it was required to increase the face resistance parameter and to decrease the effective rates of overcut and copy cutter length, to match the analysis shield behaviour to the measured one; and 3) the shield kinematic model can simulate shield behaviour reasonably.