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Copyright of Acta Universitatis Lodziensis: Folia Archaeologica is the property of Wydawnictwo Uniwersytetu Lodzkiego and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Potential of using a PSAS to improve the properties of sand for use as a backfill material. • Appropriate water content w of the PSAS-treated sand reduces the swelling potential of PSAS treated sand. • Significant lower strength development of PSAS-treated sand compared with OPC-treated sand under same mixing conditions. • PSAS-treated sand is a suitable replacement of OPC-treated sand. • XRD profiles show that the formation of CaCO 3 is dominant in the PSAS-treated. The aim of this study is to investigate the potential of using a paper sludge ash-based stabilizer (PSAS) to improve the properties of sand proposed to be used as a backfill material around underground pipes. The swelling potential and strength of the sand treated with PSAS are investigated by conducting a series of laboratory tests. Similar tests are conducted on sand treated with ordinary Portland cement (OPC). Swelling potential tests show that the PSAS-treated sand with a water content of 0% show significant expansion during soaking, similar to the OPC-treated sand. However, the test results reveal that an appropriate moisture content of the PSAS-treated sand reduces its potential for expansion, depending on the duration of its temporary placement at the construction site. Unconfined compression tests show that the compressive strength of the PSAS-treated sand is significantly lower than that of the OPC-treated sand under the same mixing conditions, even though the chemical composition of PSAS is relatively similar to that of OPC. The increase in compressive strength with the curing time is more gradual in the PSAS-treated sand than in the OPC-treated sand, suggesting that the former is easier to re-excavate. X-ray diffraction profiles showed that the formation of calcite is dominant in the PSAS-treated sand, and that berlinite may be an additional contributor to the increase in strength of PSAS-treated sand in the long term. [ABSTRACT FROM AUTHOR]

X. Li, D. Zhang, and Y. Hou [[21]] monitored ground deformation during the excavation process of shield tunnels in water-rich strata and verified the results using the numerical software FLAC 3D. Thus, secondary grouting of the existing tunnel should be carried out promptly before the tunnel underpass excavation. The first paper, authored by X. Li, Y. Yang, X. Li, and H. Liu [[14]], introduced three shield tunnel construction cases to acquire the main driving parameters for the evaluation of cutting head clogging. The second paper, prepared by J. Du, Q. Fang, J. Wang, and G. Wang [[2]], divided the process of a high-speed train passing through a railway tunnel into three stages, according to the spatial relationship between the train and the tunnel. [Extracted from the article]

This paper focuses on theoretical analytical models to calculate the limit support pressure and vertical earth pressure on the cutting face for tunnels. The failure zone is divided into two parts: a sliding failure zone and an upper loosen zone, and the limit support pressure calculation equation is derived. To verify the rationality of the theoretical model, it was compared with the existing theory, numerical simulation, and centrifugal test, and then the parameter analysis was carried out. The results show that the results of this paper agree well with the existing theory, numerical simulation, and centrifugal test. The inclination angle of the proposed mechanism is determined based on the results of the existing centrifuge test, and the recommended inclination angle is between 52° + u/2 and 54° + u/2. The method is proven to be safe and accurate. It can provide a theoretical basis for similar projects. [ABSTRACT FROM AUTHOR]

The article discusses contribution by Charles Willson Peale into the field of paleontology. Topics discussed include American naturalists who were researching on creatures that were becoming smaller, excavation of mastodons, and full skeletons that were mounted, wooden pieces that replace missing mastodon bones and analysis of elephant skeletons.

Deep-buried tunnels with weak surrounding rock are frequently encountered issues in traffic engineering. It plays an important role in the excavation process and the project operation. This paper applies the theoretical analysis and laboratory test related to four different conditions in terms of their thickness to determine the mechanical response of deep-buried tunnel lining. Then, the energy dissipative structure theory is employed to explain the experimental results. This paper has made the following achievements: firstly, it is found that the toughness of the secondary lining was found to be often the most important indicator of tunnel safety, with better-toughness linings having higher tensile strength and crack resistance. Secondly, it suggests that the inclusion of steel reinforcement in the concrete lining can effectively improve the secondary lining toughness. Finally, it proves that the more ductile liner had more energy, higher load-carrying capacity, and was better able to maintain the overall stability of the structure. [ABSTRACT FROM AUTHOR]

Solutions for unloading stress waves in the continuous medium are widely applied to analyze the transient effect of excavation unloading in deep-buried tunnel engineering. This paper explores a semianalytic model for studying dynamic stress adjustments during transient excavation unloading in deep underground tunnels. The model employs finite time steps and toroidal elements on temporal and spatial scales, utilizing an iterative algorithm for dynamic response calculation. Griffith and Mohr–Coulomb strength criteria are introduced to calculate the difference in the critical generalized additional stress. This difference classifies stress adjustment paths into crack–shear (crack first and then shear) and shear models (shear only). Updated discontinuous boundaries are considered in the cracked element. Investigating the effects of unloading duration and initial in situ stress on dynamic response, a stress release index is realized to quantify the dynamic stress adjustment. Shorter unloading durations lead to more pronounced stress fluctuations, and higher stress release aggregation results in smaller plastic zones. Positive correlations between initial in situ stress and response characteristics are observed, resembling triaxial unloading test results. The model proposed in this paper enhances the understanding of the failure mechanism in the unloading process for deep hard rocks in underground engineering. [ABSTRACT FROM AUTHOR]

In this paper, the effects of the cement content and excavation speed parameters on the improvement effect of the artificial freezing method and the characteristics of frozen walls are studied by means of a field test, numerical simulation and theoretical model. The optimization effect of the cement content in the artificial freezing method is studied. It is found that 10% is the best content, which can maximize the freezing wall thickness and grouting effect, and promote uniform distribution of the temperature field. At the same time, the influence of the excavation speed on the stress and settlement of the foundation soil is analyzed. It is pointed out that the increase of the excavation speed will aggravate the settlement and stress redistribution, which may threaten the building structure. The evaluation method proposed in this paper verifies that the construction deformation and settlement control are within the safety standards and provides theoretical support and construction guidance for tunnel engineering. [ABSTRACT FROM AUTHOR]

Discontinuity is critical for strength, deformability, and permeability of rock mass. Set information is one of the essential discontinuity characteristics and is usually accessed by orientation grouping. Traditional methods of identifying optimal discontinuity set numbers are usually achieved by clustering validity indexes, which mainly relies on the aggregation and dispersion of clusters and leads to the inaccuracy and instability of evaluation. This paper proposes a new method of Fisher mixed evaluation (FME) to identify optimal group numbers of rock mass discontinuity orientation. In FME, orientation distribution is regarded as the superposition of Fisher mixed distributions. Optimal grouping results are identified by considering the fitting accuracy of Fisher mixed distributions, the probability monopoly and central location significance of independent Fisher centers. A Halley-Expectation-Maximization (EM) algorithm is derived to achieve an automatic fitting of Fisher mixed distribution. Three real rock discontinuity models combined with three orientation clustering algorithms are adopted for discontinuity grouping. Four clustering validity indexes are used to automatically identify optimal group numbers for comparison. The results show that FME is more accurate and robust than the other clustering validity indexes in optimal discontinuity group number identification for different rock models and orientation clustering algorithms. [ABSTRACT FROM AUTHOR]

China, situated in the circum-Pacific seismic belt, experiences frequent seismic activity and faces diverse geological conditions, making structural stability of paramount importance, especially under seismic conditions. The majority of current earthquake generation methods do not consider the nonstationary nature of earthquakes. This paper introduces a spectral representation-random function model for generating nonstationary earthquakes, effectively simulating stochastic seismic ground motion. Furthermore, traditional slope stability analysis methods are deterministic and incapable of providing probabilistic assessments of slope instability. Therefore, this paper proposes a unified framework for static and dynamic structural reliability analysis based on the direct probability integration method, quantifying the impact of stochastic seismic ground motion on the dynamic reliability of slope stability. Finally, the proposed methods are applied to an excavation slope in Nanjing, using sliding displacement and safety factors as evaluation criteria to study the reliability of the slope under the influence of stochastic seismic events. [ABSTRACT FROM AUTHOR]

It is essential to establish a digital twin scene, which helps to depict the dynamically changing geographical environment accurately. Digital twins could improve the refined management level of intelligent tunnel construction; however, research on geographical twin models primarily focuses on modeling and visual description, which has low analysis efficiency. This paper proposes a knowledge-guided intelligent analysis method for the geometric deformation of tunnel excavation profile twins. Firstly, a dynamic data-driven knowledge graph of tunnel excavation twin scenes was constructed to describe tunnel excavation profile twin scenes accurately. Secondly, an intelligent diagnosis algorithm for geometric deformation of tunnel excavation contour twins was designed by knowledge guidance. Thirdly, multiple visual variables were jointly used to support scene fusion visualization of tunnel excavation profile twin scenes. Finally, a case was selected to implement the experimental analysis. The experimental results demonstrate that the method in this article can achieve an accurate description of objects and their relationships in tunnel excavation twin scenes, which supports rapid geometric deformation analysis of the tunnel excavation profile twin. The speed of geometric deformation diagnosis is increased by more than 90% and the cognitive efficiency is improved by 70%. The complexity and difficulty of the deformation analysis operation are reduced, and the diagnostic analysis ability and standardization of the geographic digital twin model are effectively improved. [ABSTRACT FROM AUTHOR]

The complex construction process of the metro shield method often leads to safety accidents. The various construction stages of shield tunnel construction comprise different construction activities and are accompanied by different safety risk factors. However, traditional risk assessment often evaluates the risk factors as a whole before shield tunnel construction and does not evaluate the risk factors dynamically by construction stages and by construction activities. To fill this gap, this paper aims to construct a dynamic Bayesian-based safety risk assessment model for shield tunnel construction from the perspective of changing construction stages and activities. First, safety risk factors were identified using the work breakdown structure-risk breakdown structure (WBS-RBS) method. Then, a three-stage dynamic assessment model of safety risks was constructed to depict the shield launch, shield tunnel, and shield reach. The dynamic Bayesian network (DBN) was improved to address the model with triangular fuzzy numbers and the leaky noisy-or-gate extension model. Finally, a case study was conducted. The model proposed in this paper is able to reveal the dynamic evolution of safety risks triggered by different construction activities. It offers a new simulated model for the prevention of safety accidents in the construction of metro shields. [ABSTRACT FROM AUTHOR]

This document is a discussion of a research paper titled "Numerical Study of the Effect of Ground Improvement on Basal Heave Stability for Deep Excavations in Normally Consolidated Clays" by Ari Surya Abdi and Chang-Yu Ou. The authors conducted a three-dimensional finite-element method analysis to investigate the impact of ground improvement on the stability of deep excavations in soft clays. They proposed a modified Terzaghi's method based on their findings. However, the discussion raises concerns about the reliability of the authors' numerical simulation results and suggests the need for validation through field or experimental data. It also questions the use of an elastic-perfectly plastic Mohr-Coulomb model and the absence of mention of dewatering in the original paper. The discussion further examines the displacement patterns and deflection profiles of retaining walls during excavation. The author requests a response from the original authors. [Extracted from the article]

The issue of uneven ground settlement caused by the excavation of subway tunnels represents a significant challenge in the design and construction of subway projects. This paper examined the fractal characteristics of surface settlement caused by subway excavation, employing wavelet transform and fractal theory. Firstly, the noise reduction effects of different wavelet functions, decomposition levels, threshold functions, and threshold selection rules were evaluated using the SNR and RMSE. Subsequently, 291 data points were derived from 18 interpolation points through fractal interpolation, representing a utilization of only 18% of the original data, to enhance the original monitoring data information by a factor of 2.94. The average relative error between the fractal interpolation results and the monitoring data was approximately 13%, which was indicative of a high degree of accuracy. Finally, the fractal dimension of the monitoring curves under different monitoring frequencies was calculated using the box-counting method. The denoising effect of the dbN wavelet function was found to be superior to that of the symN wavelet function in the denoising process of subway construction surface deformation monitoring data. Furthermore, the hard threshold method was observed to be more effective than the soft threshold method. As the monitoring frequency decreased, the fractal dimension of the deformation curves showed an overall decreasing trend. This indicated that high-frequency monitoring could capture more details and complexity of the surface settlement, while low-frequency monitoring led to a gradual flattening of the curves and a decrease in details. [ABSTRACT FROM AUTHOR]

This study employs scientometric analysis to investigate the current trajectory of research on tunnel boring machine (TBM) performance and collaborative efforts. Utilizing software tools like Pajek 5.16 and VOSviewer 1.6.18, it scrutinizes literature from 2000 to 2021 sourced from the Web of Science (WOS). The findings illuminate TBM research as an interdisciplinary and intersectoral field attracting increasing national and institutional attention. Notable contributions from China, Iran, the United States, Turkey, and Australia underscore the global significance of TBM research. The recent upsurge in annual publications, primarily driven by Chinese research initiatives, reflects a renewed vigor in TBM exploration. Additionally, the paper presents a succinct evaluation of TBM advantages and drawbacks compared to conventional drill and blast methods, discussing key considerations in excavation methodology selection. Moreover, the study comprehensively reviews TBM performance prediction models, categorizing them into theoretical, empirical, and artificial intelligence-driven approaches. Finally, rooted in metaverse theory, the discourse delves into the immersive learning model and the architecture of a TBM metaverse. In the future, the immersive training and learning model diagram can be employed in scenarios such as employee training and the promotion of safety knowledge. Additionally, the TBM metaverse architecture can simulate, monitor, diagnose, predict, and control the organization, management, and service processes and behaviors of TBMs. This will enhance efficient collaboration across various aspects of the project production cycle. This forward-looking perspective anticipates future trends in TBM technology, emphasizing societal impact and enhancement of economic benefits. [ABSTRACT FROM AUTHOR]

Rockburst is a kind of common geological disaster in deep tunnel engineering. It has the characteristics of causing great harm and occurring at random locations and times. These characteristics seriously affect tunnel construction and threaten the physical and mental health and safety of workers. Therefore, it is of great significance to study the tendency of rockburst in the early stage of tunnel survey, design and construction. At present, there is no unified method and selected parameters for rockburst prediction. In view of the large difference of different rockburst criteria and the imbalance of rockburst database categories, this paper presents a two-step rockburst prediction method based on multiple factors and the stacking ensemble algorithm. Considering the influence of rock physical and mechanical parameters, tunnel face conditions and excavation disturbance, multiple rockburst criteria are predicted by integrating multiple machine learning algorithms. A combined prediction model of rockburst criteria is established, and the results of each rockburst criterion index are weighted and combined, with the weight updated using the field rockburst record. The dynamic weight is combined with the cloud model to comprehensively evaluate the regional rockburst risk. Field results from applying the model in the Grand Canyon tunnel show that the rockburst prediction method proposed in this paper has better applicability and higher accuracy than the single rockburst criterion. [ABSTRACT FROM AUTHOR]

In order to study the influence of excavation sequence of three-hole parallel shield tunnel on surface settlement and segment convergence, an improved "three-stage analysis method" was proposed to calculate the surface settlement of three-hole parallel shield tunnel. Based on Peck's existing theory, this method deduced the ground settlement formula under the three-hole parallel condition, and can calculate the ground settlement more accurately. Based on the engineering background of a shield tunnel section in Jiangsu Province, a three-dimensional model of a three-hole parallel shield tunnel was established by using Flac3d software, and the three-hole parallel shield tunnel was simulated under four working conditions: right–center–left, right–left–center, right–left–right and right–center (reverse)–left. This paper analyzed the influence of tunnel excavation sequence on surface settlement, soil displacement and deformation of tunnel segments. The construction sequence was optimized based on the above influencing factors. It was found that Case 4, S-type sequential excavation, produced the least ground settlement. The surface settlement value caused by S-type excavation sequence was only 11.41 mm, and the convergence value of the segments generated by S-type excavation sequence was relatively small. Considering the economic factors such as construction efficiency and benefit, the S-shaped excavation sequence was better. The new calculation method of tunnel surface settlement and the optimal sequence of tunnel construction proposed in this paper can provide reference for actual construction. [ABSTRACT FROM AUTHOR]

Rockburst is a phenomenon inwhich free surfaces are formed during excavation, which subsequently causes the sudden release of energy in the construction of mines and tunnels. Light rockburst only peels off rock slices without ejection, while severe rockburst causes casualties and property loss. The frequency and degree of rockburst damage increases with the excavation depth. Moreover, rockburst is the leading engineering geological hazard in the excavation process, and thus the prediction of its intensity grade is of great significance to the development of geotechnical engineering. Therefore, the prediction of rockburst intensity grade is one problem that needs to be solved urgently. By comprehensively considering the occurrence mechanism of rockburst, this paper selects the stress index (σθ/σc), brittleness index (σc/σt), and rock elastic energy index (Wet) as the rockburst evaluation indexes through the Spearman coefficient method. This overcomes the low accuracy problem of a single evaluation index prediction method. Following this, the BGD-MSR-DNN rockburst intensity grade prediction model based on batch gradient descent and a multi-scale residual deep neural network is proposed. The batch gradient descent (BGD) module is used to replace the gradient descent algorithm, which effectively improves the efficiency of the network and reduces the model training time. Moreover, the multi-scale residual (MSR) module solves the problem of network degradation when there are too many hidden layers of the deep neural network (DNN), thus improving the model prediction accuracy. The experimental results reveal the BGDMSR-DNNmodel accuracy to reach 97.1%, outperforming other comparable models. Finally, actual projects such as Qinling Tunnel and Daxiangling Tunnel, reached an accuracy of 100%. The model can be applied in mines and tunnel engineering to realize the accurate and rapid prediction of rockburst intensity grade. [ABSTRACT FROM AUTHOR]

The deformation behavior of deep excavations is affected by many factors, among which the geological conditions are greatly affected. Hangzhou Bay is affected by marine siltation and river alluvium, and the geological conditions within the urban area of Hangzhou are quite different. In this paper, the geological and deformation data of 79 deep excavation cases in the Hangzhou urban area were collected, and the statistical analysis showed that the deformation control of excavations in the silt area was poor. The average maximum lateral wall displacement of deep excavations of the Hangzhou urban area was 0.41%H (H was the depth of the excavation), the average value of the alluvial area was 0.22%H, and the average value of the silted area was 0.55%H. The influence of geological conditions, wall type, and construction period on the deformation of excavations was compared, and the deformation behavior of excavations in the silted area was clearly affected by various factors. [ABSTRACT FROM AUTHOR]

This paper provides a historical analysis of the peak and demise of the international view on cultural heritage. In the 1980s, cultural internationalism emerged as a conservative reaction against the adoption of the 1970 UNESCO Convention, which organises the restitution and return of stolen cultural properties. Internationalist and cosmopolitan scholars who have claimed that cultural heritage 'belongs to humanity', generally condemned restitution, and pushed back against the ratification of the Convention. The international view on cultural property became traditionally dominant in milieus such as universal museums, antiquity markets and some academic disciplines. However, over the past half-decade, the growing importance of research on provenance has challenged cultural internationalism in two areas. Firstly, research on provenance focused on art and archaeological crime has shown that artefacts allegedly excavated in the past are often the proceeds of recent looting, especially in conflict zones. Secondly, recent studies on historical provenance have revealed that many objects were collected using colonial violence. As a result, developments in criminology, postcolonial history, and indigenous peoples' rights have generally led to the retreat of cosmopolitan narratives on cultural property. Ultimately, this paper highlights that cosmopolitanism in cultural heritage has historically hinged on the imperialist past. [ABSTRACT FROM AUTHOR]

The technical challenges associated with deep underground space activities have become increasingly significant. Among these challenges, one major concern is the assessment of rockburst risks and the instability of rock masses. Extensive research has been conducted by numerous scholars to mitigate the risks and prevent occurrences of rockburst through various assessment methods. Rockburst incidents commonly occur during the excavation of hard rock in underground environments, posing severe threats to personnel safety, equipment integrity, and operational continuity. Thus, it is crucial to systematically document real cases of rockburst, allowing for a comprehensive understanding of the underlying mechanisms and triggering conditions. This understanding will contribute to the advancement of rockburst prediction and prevention methods. Proper selection of an appropriate rockburst assessment method is a fundamental aspect in underground operations. However, there is a limited number of studies that summarize and compare different prediction and prevention methods of rockburst. This paper aims to address this gap by analyzing global trends using CiteSpace software since 1990. It discusses rockburst classification and characteristics, comprehensively reviews research findings related to rockburst prediction, including empirical, simulation, mathematical modeling, and microseismic monitoring methods. Additionally, the paper presents a compilation of current rockburst prevention measures. Notably, the paper emphasizes the significance of control strategies, which provide key insights into the effective utilization of stored energy within rock. Finally, the paper concludes by suggesting six directions for implementing intelligent management techniques to mitigate hazards during underground operations and reduce the probability of rockburst incidents. [ABSTRACT FROM AUTHOR]

This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling. Laboratory tests were conducted to determine the soil parameters used in the modified Cam-Clay (MCC) model. Intelligent field monitoring means were adopted and a three-dimensional model was established. Spatial and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft soil. Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented. The behaviors of diaphragm walls, columns, the maximum wall deflection rate, ground surface settlement, and utility pipelines were focused on and investigated during the whole excavation process. Besides, the axial forces of the internal supports are analyzed. Based on the measured and simulated data, the following main conclusions were obtained: the numerical simulation results are in good agreement with the measured values, which proves the accuracy of the model parameters; the wall and the ground surface showed the maximum displacement increment at stage 9, which was a coupled product of the "creep effect" of the soft soil in Nanjing, China and the "depth effect" of the excavation; as the excavation progressed, the ground settlement changed from a "rising" to a "spoon-shaped" trend, dvm was measured between dvm = 0.0686%H and dvm = 0.1488%H; the rebound deformation curve of the pit bottom was corrugated, and the depth of disturbance of the pit bottom after the completion of soil unloading was 2-3 times the excavation depth; the closer the pipeline is to the corner of the pit, the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur; the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation. [ABSTRACT FROM AUTHOR]

In the western mining region, weakly cemented rock layers above the coal seams often lead to frequent catastrophic accidents during mining due to their instability. To address this, this paper analyzes the movement characteristics of surrounding rock in the recovery roadway and the effectiveness of from nearby large coal pillar roadways. A mechanical model for the failure of weakly cemented roadways was established, and numerical simulations were used to verify the feasibility of leaving small coal pillars along soft, thick coal seams. Additionally, existing measurements were used to evaluate the impact of leaving small coal pillars on the deformation of the surrounding rock in the recovery roadway. The results show that after changing the coal pillar retention to 5 m in the 130,205 working face of the Yangchangwan mining area, the roadway is in a low-stress zone, with minimal surrounding rock deformation, meeting safety requirements for production. [ABSTRACT FROM AUTHOR]

Copyright of Praehistorische Zeitschrift is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate prediction of excavation deformation and stress affects the safety of excavation engineering and the surrounding environment. However, the traditional calculation method ignores the influence of soil shear action and its nonlinear deformation characteristics. Therefore, this paper proposed a coupled analytical method for braced excavation considering the continuity of soil deformation and nonlinear pile–soil interaction. A nonlinear Pasternak two-parameter foundation model was developed based on the Pasternak foundation model and nonlinear p–y curves. The control differential equations for the excavation in the critical and embedded sections were derived. Also, the numerical solutions of excavation deformation and force under different boundary conditions were obtained by the finite difference method and Newton's iteration method. Further, the excavation calculation procedure considering the construction process and nonhomogeneity of soil was suggested. Through finite-element (FE) and engineering case analyses, the traditional calculation method overestimated the excavation deformation and internal force, while the proposed methods were consistent with the measured results. Finally, the effects of soil shear stiffness and initial foundation reaction modulus on the excavation were discussed, and we found that the two parameters had more significant impact on the wall bending moment than displacement. The results provide some reference for the design calculation of braced excavation. [ABSTRACT FROM AUTHOR]

With the continuous development of the geological engineering field, high-voltage electric pulse plasma rock-fracturing technology has become a research hotspot in recent years. It is now widely recognized that this fracturing technology has many application prospects and great economic benefits. Through the research process of this technology, it has proven to be an efficient and new type of rock-fracturing technology, which overcomes the problems of high cost, low efficiency, high safety risk, and serious pollution associated with traditional rock-fracturing technology. Also, it has unique advantages in terms of protecting the environment and reducing damage to the surrounding buildings. This paper reviews the research history of plasma shock wave influencing factors and pulsed discharge plasma rock-fracturing technology, summarizes the research on this technology from the perspectives of the mechanism of high-voltage electric pulse plasma rock fracturing and practical application, and discusses the feasibility of this technology when applied to the field of tunnel boring as well as the future development direction. This technology can be better used in the tunnel-boring field, which can greatly improve the tunnel-boring efficiency, but at present, the research on plasma rock-fracturing-assisted tunnel boring is still in the laboratory research stage, which lacks systematic research equipment and judging indexes, and the follow-up should focus on improving the systematic research capabilities of the plasma rock-fracturing-assisted tunnel-boring equipment, and systematically and comprehensively carry out research on rock-fracturing by plasma-assisted excavation equipment. [ABSTRACT FROM AUTHOR]

The Qinling water conveyance tunnel has a large buried depth and high in-situ stress level, and rockburst disasters frequently occurred during excavation. In order to find out the mechanical mechanism of rockburst, the research work in this paper is as follows: (1) In-situ three-dimensional hydraulic fracturing method was used to measure the in-situ stress of the deep buried tunnel crossing the ridge. (2) Based on the measured in-situ stress results, the stress distribution characteristics of the tunnel crossing the ridge were obtained by the multiple linear regression method, and the rockburst tendency during construction was predicted. (3) A three-dimensional numerical model of tunnel excavation was established to analyze the dynamic adjustment characteristics of the surrounding rock stress and elastic strain energy during TBM excavation, and to clarify the mechanical mechanism of rockburst. The research results show that the maximum principal stress of the deep-buried tunnel crossing the ridge of Qinling is 40–66 MPa, which belongs to extremely high in-situ stress level, and medium-strong rockburst may occur during excavation. In the process of TBM excavation, the stress of the surrounding rock in the range of 2.6 times the diameter of the tunnel before and after the working face is adjusted violently, and the concentrated zones after the stress redistribution are mainly distributed in the arch roof and arch bottom, and the stress concentration coefficient can reach 2.06. The arch roof, arch waist, and arch bottom are susceptible to immediate rockburst due to stress transient unloading at the moment of excavation. After the elastic strain energy of the surrounding rock at the arch roof and the arch bottom is released and accumulated, it is easy to cause time delayed rockburst, and the depth of the rockburst pit can reach 3.5 m, which is consistent with the rockburst phenomenon in the field. [ABSTRACT FROM AUTHOR]