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The continuous mechanical mining technology represents the development trend and significant transformation in excavation techniques for non-coal mines. It embodies a systematic and integrated innovation encompassing rock breaking methods, rock-breaking equipment, excavation methods, and excavation processes. Based on the current status of continuous mechanical mining technology in non-coal mines, this paper firstly outlines the technical characteristics of mechanical mining and summarizes the key scientific and technological challenges to be addressed. It provides an overview of various mechanical cutter-based rock-breaking methods, rock mass cuttability, and the development and application of continuous mechanical excavation technology. In response to the problems and challenges facing continuous mechanical mining technology in non-coal mines, this paper proposes a four-tier approach for technological breakthroughs; "process needs-technological breakthroughs-equipment research and development-engineering application." Research will be conducted across multiple aspects, including rock-breaking theory, key technologies, mining equipment, mining methods, and complete sets of processes, aiming to promote the development and advancement of safe, efficient, green, continuous, and intelligent non-explosive mechanical mining technologies and equipment for non-coal mines in China. [ABSTRACT FROM AUTHOR]

The rock mass deformation modulus is one of the most important design parameters in a range of rock engineering applications. Its value is usually obtained directly through in situ testing or estimated indirectly on the basis of a rock mass quality classification system. Because in situ testing is generally costly, time-consuming, and presents operational difficulties, it cannot be carried out extensively, and many researchers have concentrated on developing indirect procedures to obtain information on the modulus of deformation, such as the RMR method, Q method, and GSI method. The purpose of this paper is to present a new system for estimating the rock mass deformation modulus called the BQ method, which is based on the BQ (basic quality) system. In this paper, the BQ system is first briefly reviewed, and then more than 60 in situ measurements from three large hydropower stations in China are used to develop a new relationship between BQ and the deformation modulus, based on a power function relationship. The paper also derives correlations based on the existing estimation formula and the relationship between BQ and other classification schemes, resulting in several recommended formulas for estimating the deformation modulus of a rock mass using the BQ method. [ABSTRACT FROM AUTHOR]

Following invasion, insects can become adapted to conditions experienced in their invasive range, but there are few studies on the speed of adaptation and its genomic basis. Here, we examine a small insect pest, Thrips palmi , following its contemporary range expansion across a sharp climate gradient from the subtropics to temperate areas. We first found a geographically associated population genetic structure and inferred a stepping-stone dispersal pattern in this pest from the open fields of southern China to greenhouse environments of northern regions, with limited gene flow after colonization. In common garden experiments, both the field and greenhouse groups exhibited clinal patterns in thermal tolerance as measured by critical thermal maximum (CTmax) closely linked with latitude and temperature variables. A selection experiment reinforced the evolutionary potential of CTmax with an estimated h 2 of 6.8% for the trait. We identified 3 inversions in the genome that were closely associated with CTmax, accounting for 49.9%, 19.6%, and 8.6% of the variance in CTmax among populations. Other genomic variations in CTmax outside the inversion region were specific to certain populations but functionally conserved. These findings highlight rapid adaptation to CTmax in both open field and greenhouse populations and reiterate the importance of inversions behaving as large-effect alleles in climate adaptation. [ABSTRACT FROM AUTHOR]

The soil-bedrock interface is a common form of contact, which is widely distributed in various geological environments and involves many fields. Moreover, the stress history, geomaterial properties, and morphological differences of the soil-bedrock interface make it obvious regional characteristics, which greatly increases the complexity of the study. A series of laboratory direct shear experiments were carried out to study the anisotropic shear properties of loess-bedrock interface on the loess plateau in Shanxi Province, China. The results show that (1) the morphology of the shear plane is an important reason for the anisotropy of the loess-bedrock interface, which is mainly manifested by undulations. (2) The shear modes of the interface are mainly constituted by four forms: cutting, climbing, friction, and pushing, which together affect the anisotropy. (3) Based on the Mohr-Coulomb strength criterion, the influence of shear angle is considered, the expression of strength criterion for anisotropy of soil-rock interface and the strength envelope plane are obtained, which extends to three-dimensional state. [ABSTRACT FROM AUTHOR]

Underground coal mining leads to land subsidence, which, in turn, results in damage to buildings and infrastructure, disturbs the original ecological environment, and hinders the sustainable development of coal mining cities. A reasonable estimation of land subsidence, on the other hand, is the foundation for building protection, land reclamation, and ecological environment reconstruction. However, when we applied the existing land subsidence estimation theory to the deep mining areas of the Ordos coalfield in western China, there was a significant deviation between the estimations and the measurements. To explain such unusual case, we propose using the overburden's average GSI (Geological Strength Index) value instead of the compressive strength (UCS) of rock specimens for a better representation of the overburden's overall properties. By using on-site subsidence monitoring results and historical data, we provided evidence which supports that the overburden's average GSI value has a much greater impact on subsidence rates than the UCS. Subsequently, we investigated the relationship between three typical overburden's GSI values and the subsidence rates via a calibrated numerical model, revealing the variation patterns of maximum surface subsidence when the overburden's average GSI value is set at 30, 50, and 75, respectively. Finally, on the basis of the measured and simulated results, we discussed a non-conventional strip mining method for mining subsidence control in the deep mining areas of the Ordos coalfield in western China, and explained why it is possible and what are the significant advantages behind. The proposed methods, findings, and suggestions in this paper are therefore quite helpful for researchers and engineers who wish to estimate and control the mining-induced land subsidence, as well as for those who are particularly interested in the study of environment science related to land subsidence. [ABSTRACT FROM AUTHOR]

Rock Quality Designation (RQD) is among the widely used measures of the quality of rock masses and can be derived through Monte Carlo stochastic process-based fracture network simulations. However, repeated simulations can yield variable RQD results. Here, we introduce a four-step approach that incorporates class ratio analysis to estimate the representative RQD, which includes (1) extracting the mean and confidence interval of the RQD sample, in terms of the Confidence Neutrosophic Number Cubic Value (CNNCV), (2) employing class ratio analysis to determine the thresholds of the number of virtual boreholes and that of the number of models for a given size D, beyond which the CNNCV remains substantially unchanged, (3) accepting the CNNCV at the thresholds of the number of models as the representative RQD for the model of size D (RQD(D)) and (4) determining the representative RQD (rRQD), defined as the specific value which, once D exceeds, the RQD(D) does not change significantly. The introduced approach is illustrated with a case study of an open-pit slope in China, and it was tested for its performance. The RQD calculation results of the proposed method and the traditional single-model approach exhibit differences, which diminish with increasing model sizes. At the 95% confidence level, the stable size of the RQD determined by the proposed method is 13 m, compared to 25 m for the single-model approach. This method enhances the accuracy of representative elementary volume predictions by accounting for the diversity in the simulation results of RQDs for the same size. Overall, the introduced approach offers a reliable method for obtaining RQD estimates. [ABSTRACT FROM AUTHOR]

In the fragile mining areas of western China, the contradiction between coal mining and water resource protection coexists prominently. Facing this issue, it is necessary to understand the dynamic relationship between mining-induced shear stress and groundwater seepage, as well as the fracture morphology of the overlying strata. In this study, the seepage characteristics of rough fractures within the rock mass are thoroughly investigated, with an emphasis on studying the effects of shear stress and seepage erosion. This research is carried out through seepage experiments and 3D fracture morphology scanning, and the research results are mainly as follows: (a) Rocks with higher shear strengths show less fluctuation in changes in fracture morphology and seepage velocity. (b) The permeability of sandstone and concrete fractures is inversely proportional to the shear stress. The layering of coal greatly limits seepage through the fractures and the permeability of coal is about one-tenth of the permeability of sandstone and concrete under the same conditions. (c) The mechanism of erosion damage to the rock by water-force coupling is the result of the shear and extrusion generated by rock fractures and the transport of rock particles. Changes in fracture erosion and seepage characteristics brought about by the damage will mutually promote and intensify the erosive effect of water force. (d) The degree of change in fracture morphology (fracture damage) under the same conditions is coal > concrete > sandstone. There are differences in the response of different types of rock to the shear stress–seepage erosion, but all show obvious changes in fracture damage and seepage characteristics. [ABSTRACT FROM AUTHOR]

The staggered distribution of joints and fissures in space constitutes the weak part of any rock mass. The identification of rock mass structural planes and the extraction of characteristic parameters are the basis of rock-mass integrity evaluation, which is very important for analysis of slope stability. The laser scanning technique can be used to acquire the coordinate information pertaining to each point of the structural plane, but large amount of point cloud data, uneven density distribution, and noise point interference make the identification efficiency and accuracy of different types of structural planes limited by point cloud data analysis technology. A new point cloud identification and segmentation algorithm for rock mass structural surfaces is proposed. Based on the distribution states of the original point cloud in different neighborhoods in space, the point clouds are characterized by multi-dimensional eigenvalues and calculated by the robust randomized Hough transform (RRHT). The normal vector difference and the final eigenvalue are proposed for characteristic distinction, and the identification of rock mass structural surfaces is completed through regional growth, which strengthens the difference expression of point clouds. In addition, nearest Voxel downsampling is also introduced in the RRHT calculation, which further reduces the number of sources of neighborhood noises, thereby improving the accuracy and stability of the calculation. The advantages of the method have been verified by laboratory models. The results showed that the proposed method can better achieve the segmentation and statistics of structural planes with interfaces and sharp boundaries. The method works well in the identification of joints, fissures, and other structural planes on Mangshezhai slope in the Three Gorges Reservoir area, China. It can provide a stable and effective technique for the identification and segmentation of rock mass structural planes, which is beneficial in engineering practice. [ABSTRACT FROM AUTHOR]

The shear constitutive model of soils plays a key role in the stability analysis of slopes. In this work, a statistical damage-based shear constitutive model for soils and its parameter determination method are proposed. An improved Weibull distribution function is introduced to calculate the damage variable. The shear test results of the slip band soils of the three gorges reservoir area in China are used to validate the proposed model. Quantitative indexes such as coefficient of determination, mean absolute percentage error and mean square error confirm that the accuracy of the proposed model is higher than that of an existing model. Compared with the existing model, the proposed model can better describe the experimental curve of shear stress vs. shear displacement in the post-peak stage. To analyze slope stability, a displacement-dependent transfer coefficient method is proposed by combining the proposed shear constitutive model with limit equilibrium theory. A case study demonstrates that the soil deformation at both ends of the slide mass is in the strain softening state first as the external load increases, and the resisting segment of the slide mass is located in its middle position. For a specified factor of safety, by considering the strain softening behavior in the proposed method, the computed allowable displacement of the slope is reduced at most by approximately 27% to that using the existing method neglecting the characteristics. The displacement-dependent transfer coefficient method reflects the progressive failure mode of the slope and can easily determine the displacement mapped to a factor of safety varied with the slope stress state. [ABSTRACT FROM AUTHOR]

In response to the significant soft rock deformation challenges encountered during the construction of the Minxian Tunnel along the Lanzhou-Haikou Expressway (G75), this study conducted a comprehensive analysis of soft rock types and the underlying mechanical mechanisms governing the deformation of the surrounding rock. It presented tailored mechanical transformation strategies to address diverse mechanical mechanisms. Also, it introduced the application of anchor cable with high pre-tightening force, constant resistance and large deformation, a proven solution widely employed in mining and rock engineering. Furthermore, the research proposed a highprestress and active and passive combined support technique, encompassing pre-reinforced retaining structure, optimally arranged active retaining structure with long and short NPR anchor cables, steel arches, and permanent retaining structure of shotcrete. By implementing numerical simulations and on-site monitoring, the results demonstrated a remarkable reduction in the maximum deformation of the surrounding rock in the test section to only 73 mm, and the pre-tightening forces applied to the anchor cable with constant resistance and large deformation ranged from 280 to 300 kN, underscoring the effectiveness of the optimized retaining technique in controlling surrounding rock deformation. This research highlights the pivotal role of retaining structure with constant resistance and yielding support, which significantly improves deformation control. [ABSTRACT FROM AUTHOR]

The green odorous frog (Odorrana margaretae) displays a circular distribution around the Sichuan Basin of western China and possesses multiple replicate hybrid zones between lineages with high levels of divergence. To gain an understanding of the speciation process, we obtained 1540 SNPs from 29 populations and 227 individuals using ddRAD sequencing. Population structure analysis revealed three groups within the species: the West, North & South, and East groups. Demographic inference showed that they were initially isolated at ~2 million years ago, and subsequent post-glacial expansion produced the current circular distribution with four secondary contact zones. Hybridization in those zones involved lineages with various levels of divergence and produced greatly different patterns of introgression. Contact zones between the East and North & South groups (E-S and E-N) had contrast admixture levels but both showed a general lack of potential barrier loci. Meanwhile, the reconnection of the West and North & South groups produced two contact zones along the rim of the Basin. The S-W zone had extensive admixture while the N-W zone had limited admixture within a narrow geographic distance. Both showed substantial barrier effects, and a large number of potential barrier loci were shared. We also detected strong coupling among these loci. The N-W hybrid zone involved two highly-diverged lineages (F ST = 0.704) and many loci have reached fixation around the hybrid zone. This study system offers a unique opportunity to understand the dynamics of introgression in contact zones and the architecture of reproductive isolation at different stages of speciation., (© 2021 John Wiley & Sons Ltd.)

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office 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.)

Ensuring the stability of surrounding rock is crucial for the safety of underground engineering projects. In this study, an improved fuzzy comprehensive evaluation method is proposed to accurately predict the stability of surrounding rock. Five key factors, namely, rock quality designation, uniaxial compressive strength, integrality coefficient of the rock mass, strength coefficient of the structural surface, and groundwater seepage, are selected as evaluation indicators, and a five-grade evaluation system is established. An improved analytic hierarchy process (IAHP) is proposed to enhance the accuracy of the evaluation. Using interval numbers rather than real numbers in constructing an interval judgment matrix can better account for the subjective fuzziness and uncertainty of expert judgment. Subjective and objective weights are obtained through IAHP and coefficient of variation, and the comprehensive weight is calculated on the basis of game theory principles. In addition, trapezoidal and triangular membership functions are employed to determine the membership degree, and an improved fuzzy comprehensive evaluation model is constructed. The model is then used to determine the stability of the surrounding rock based on the improved criterion. It is applied to six samples from an actual underground project in China to validate its effectiveness. Results show that the proposed model accurately and effectively predicts the stability of surrounding rock, which aligns with the findings from field investigations. The proposed method provides a valuable reference for evaluating surrounding rock stability and controlling construction risks. [ABSTRACT FROM AUTHOR]

The mechanical behavior of host rock for a deep geological repository of high-level radioactive waste plays a key role in ensuring the isolation function of host rock as a natural barrier under the multi-field coupling environment. For a better understanding of granite in China's Beishan pre-selected area for geological disposal of high-level radioactive waste, a series of investigations were carried out on in-situ stress field of rock mass at depth, strength and deformation characteristics of rocks under different stress and temperature conditions, and rock boreability and adaptability to Tunnel Boring Machine (TBM) technology. The results indicate that Beishan granite shows typical characteristics as a hard and brittle rock with a quite low permeability, and it is favorable to geological disposal. Meanwhile, a new rock mass suitability evaluation system was proposed, and the rock mass mainly composed of Beishan granite was proven to be suitable for geological disposal. Besides, the constructability of Beishan granite at engineering scale was tested and verified through field tests in the Beishan Exploration Tunnel (BET). Here, we summarize the main outcomes of rock mechanics research on Beishan granite in the past years and introduced the current progress of Beishan underground research laboratory (URL) for geological disposal. [ABSTRACT FROM AUTHOR]

Rock mass conditions are extremely sensitive to tunnel boring machine (TBM) tunneling. Therefore, establishing a surrounding rock excavatability (SRE) classification system applicable to TBM tunnels. Accurately and intelligently identifying excavatability grades can also facilitate efficient TBM tunneling and intelligent construction. Specific excavation and penetration rates were used to evaluate SRE. Their correlations with geological and tunneling parameters were explored using the field data from two water conveyance tunnels in China with different lithologies. A high-precision empirical SRE classification system was constructed using TOPSIS for multi-objective decision-making, and it was verified using engineering cases. An intelligent identification model for SRE grades in the stable phase of a TBM excavation cycle was established using 12,382 TBM rock-breaking datasets and deep forest models. Ten characteristic parameters, e.g., total thrust, were selected as model input features. Hyperparameter optimization was achieved using the grid search method. Deep forest was compared with decision tree, random forest, support vector classifier, and deep neural network. The contribution of the model's features was measured using random forest. The main conclusions are as follows: the proposed SRE classification method is feasible and matches well with the actual excavation. In the intelligent identification of SRE classification, the accuracy and F1 scores when using deep forest were 96.33% and 0.9581, respectively. Deep forest exhibited better grade identification performance than the four models. Among the ten input features, penetration is the most important feature for the model's input, while the top shield cylinder rod's chamber pressure is the least important. The findings can provide some references for SRE classification and prediction and intelligent TBM control. [ABSTRACT FROM AUTHOR]

Taxa are traditionally identified using morphological proxies for groups of evolutionarily isolated populations. These proxies are common characters deemed by taxonomists as significant. However, there is no general rule on which character or sets of characters are appropriate to circumscribe taxa, leading to discussions and uncertainty. Birch species are notoriously hard to identify due to strong morphological variability and factors such as hybridization and the existence of several ploidy levels. Here, we present evidence for an evolutionarily isolated line of birches from China that are not distinguishable by traditionally assumed taxon recognition proxies, such as fruit or leaf characters. We have discovered that some wild material in China and some cultivated in the Royal Botanic Gardens Edinburgh, formerly recognized as Betula luminifera, differ from other individuals by having a peeling bark and a lack of cambial fragrance. We use restriction site-associated DNA sequencing and flow cytometry to study the evolutionary status of the unidentified Betula samples to assess the extent of hybridization between the unidentified Betula samples and typical B. luminifera in natural populations. Molecular analyses show the unidentified Betula samples as a distinct lineage and reveal very little genetic admixture between the unidentified samples and B. luminifera. This may also be facilitated by the finding that B. luminifera is tetraploid, while the unidentified samples turned out to be diploid. We therefore conclude that the samples represent a yet unrecognized species, which is here described as Betula mcallisteri. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to test the effects of a novel diabetes self‐management education (DSME) programme focused on multilevel social resources utilization on improving self‐management behaviour, social resources utilization and haemoglobin Alc (HbA1c) in patients with type 2 diabetes mellitus (T2DM). Methods: A randomized controlled design was used. A total of 118 participants with T2DM from two communities were recruited through randomized sampling, and randomly assigned to the novel DSME group or the traditional DSME group. DSME focusing on multilevel social resources utilization was implemented in the novel DSME group. Data were collected at baseline (T0), at the end of the intervention (T1) and 3 months after the end of intervention (T2) from 3 March to 16 November 2014. Results: Comparing these two groups, the participants in the novel DSME group reported significantly better improvement in self‐management behaviour and social resources utilization at T1 and T2 (all p < 0.01). A significant difference was found in the mean improvement of HbA1c level between the two groups at T2 (p < 0.05). Conclusions: The novel DSME programme focused on multilevel social resources utilization can effectively enhance T2DM patients' self‐management behaviour and social resource utilization and lower HbA1c levels. More importantly, the effects could last longer. Summary statement: What is already known about this topic? Traditional diabetes self‐management education does not guarantee lifelong effective diabetes self‐management behaviour.The utilization of multilevel social resources has been found to be positively associated with self‐management behaviour and health outcomes of patients with chronic diseases. What this paper adds? The novel diabetes self‐management education programme is beneficial to community patients with type 2 diabetes mellitus as it shows significantly better effects in improving diabetes self‐management behaviour, social resources utilization and HbA1c level, and the effects last longer.Due to the large diabetes patient population and the relative shortage of medical resources in China, focusing on inspiring patients' initiative to actively tap and utilize existing and potential social resources for self‐management is indicated when developing education protocols for diabetes patients. The implications of this paper In addition to traditional self‐management education, community health‐care professionals should pay attention to the education of social resources utilization to further improve and solidify diabetes patients' self‐management behaviour.Especially in places with large population and limited medical resources, it is economical and effective to inspire patients to actively tap and utilize existing and potential social resources for self‐management. [ABSTRACT FROM AUTHOR]

The presence of water in sandstone joints affects the shear characteristics of the joints, which is of considerable importance to the stability evaluations of rock slopes or tunnels subjected to water fluctuations. A series of direct shear tests with three immersion durations (30, 180, and 360 d) in water were conducted on the sandstone joint specimens collected from the reservoir area of the Three Gorges hydropower station, China. To perform duplicate tests, three-dimensional (3D) optical scanning and 3D rigid engraving were coupled to produce sandstone joints with the same surface morphology. The shear curves of the dry and immersed sandstone joints were divided into the three stages of sliding, shear-breaking, and post-peak wearing. The damaged area of the immersed joints decreased with the increased immersion duration under the same normal loading. The immersion duration did not affect the shear mode of the joints, and the peak and residual shear strengths of the sandstone joints decreased by approximately 10–28% and 2.9–26.4%, respectively, after the 360-d immersion. Experimental results pointed to the lubricant effect as the dominant mechanism for a water-induced reduction in the shear strength of the joints, followed by the chemical dissolution effect. Given the lubricant and chemical dissolution effects, a semi-empirical shear strength criterion was proposed to predict the peak shear strength of the rock joints subjected to the immersion durations. Validation against experimental shear data obtained in this study and from related literature indicated satisfactory accuracy of the proposed criterion for predicting the peak shear strength after the immersion. An engineering example of the Jianchuandong unstable rock mass located in the Three Gorges reservoir was used to demonstrate the function of wetting in lowering its safety factor. Highlights: 3D scanning and 3D engraving were coupled to produce sandstone joints. Direct shear tests with different immersion durations were conducted on joints. A novel shear strength criterion was developed considering immersion duration. [ABSTRACT FROM AUTHOR]

Responding to severe surrounding rock deformation failures and other problems in roadways in western China with large mining heights and intense mining, the work presented in this paper studied the mechanism of surrounding rock deformation failures in roadways with dynamic pressure through field investigations, theoretical analysis, and numerical simulation. According to the research findings, mining roadway deformation failures are affected by roadway layout orientation, working face mining intensity, and dynamic load disturbances from roof breakage. Coal pillars, as bridges connecting the roof and floor, constitute the energy transfer path near roadways surrounding rock, and an unreasonable coal pillar size and lateral overhanging roof structure may aggravate static load energy accumulation in the roadway surrounding rock. Roadway protection with small or large coal pillars may increase elastic energy loss in the energy transfer path; a reasonable size of small and large coal pillars is 15 m and 35 m, respectively. Using roof cutting for pressure relief may reduce the elastic energy of roadway surrounding rock by 14.35-26.33% during primary mining and 21.57-29.31% during secondary mining, thereby reducing the static load elastic energy in the surrounding rock and improving the stability of roadway surrounding rock. [ABSTRACT FROM AUTHOR]

Understanding the evolutionary processes that shape the landscape of genetic variation and influence the response of species to future climate change is critical for biodiversity conservation. Here, we sampled 27 populations across the distribution range of a dominant forest tree, Quercus acutissima, in East Asia, and applied genome‐wide analyses to track the evolutionary history and predict the fate of populations under future climate. We found two genetic groups (East and West) in Q. acutissima that diverged during Pliocene. We also found a heterogeneous landscape of genomic variation in this species, which may have been shaped by population demography and linked selections. Using genotype‐environment association analyses, we identified climate‐associated SNPs in a diverse set of genes and functional categories, indicating a model of polygenic adaptation in Q. acutissima. We further estimated three genetic offset metrics to quantify genomic vulnerability of this species to climate change due to the complex interplay between local adaptation and migration. We found that marginal populations are under higher risk of local extinction because of future climate change, and may not be able to track suitable habitats to maintain the gene–environment relationships observed under the current climate. We also detected higher reverse genetic offsets in northern China, indicating that genetic variation currently present in the whole range of Q. acutissima may not adapt to future climate conditions in this area. Overall, this study illustrates how evolutionary processes have shaped the landscape of genomic variation, and provides a comprehensive genome‐wide view of climate maladaptation in Q. acutissima. [ABSTRACT FROM AUTHOR]

Excessive deformation has been observed during the construction of large-section (over 100 m2) tunnels in soft rock all over the world. A case study of deformation control for large-section tunnel construction in fractured carbonaceous slate was conducted. Xingzishan tunnel, China, was first excavated using the three-step reserved core soil excavation method (TRCSEM); however, this resulted in serious rockfalls at the tunnel arch and local collapse. To enhance the stability of the tunnel face, three different tunnel support systems with relatively stiff structures were proposed and tested along the tunnel chainage in the same rock condition, but all of them failed. The mechanism of the TRCSEM was revealed by field measurements, highlighting the significance of the stability of the upper bench of the tunnel face. In view of this, the three-step temporary inverted arch method (TTIAM) was employed and used with advance support. With this new method, the upper bench of the tunnel face was reinforced with fibreglass bolts to mitigate the deformation. Compared with the TRCSEM, the TTIAM effectively controlled large deformation at the tunnel face during the excavation in fractured carbonaceous slate with an acceptable construction cost. [ABSTRACT FROM AUTHOR]

With the increase of mining depth, disaster degree of rock burst in fault-controlled area is becoming more and more serious. To analyze mechanism and control method of fault rock burst, No. 3316 mining face controlled by No. 3DF56 fault in Jining mine, China, is selected as case study. First, by analysis of general situation of the mining face, mechanical characteristics of coal rock, and micro-seismic events, it is determined that the coal seam has the possibility of rock burst in the process of the face mining towards the fault. Second, based on strength theory of rock, criterion of fault shear instability is obtained, and influence of cohesion and friction angle on the stability of fault is analyzed, and it is concluded that improving the cohesion of rock can control the fault slip. Third, by borehole detection recorder, it is determined that fracture areas of fault surrounding rock distribute in the range of 0–4 m from the surface of roadway surrounding rock and 0–5.0 m from the fault. Finally, control method of "precise grouting to couple shallow and deep boreholes" is introduced, and the grouting borehole scheme is optimized. Field test results show that the method can improve the compressive strength of coal rock and distribution laws of micro-seismic events, weaken the possibility of fault slip, effectively control the deformation of roadway surrounding rock and improve the control effect of rock burst. It can provide a reference for other coal mines with similar geological conditions. [ABSTRACT FROM AUTHOR]

The variation in Tunnelling boring machine (TBM) equipment and geological information of tunnels result in substantial differences in real-time TBM tunnelling data. This variation makes it difficult to apply machine learning models trained by historical engineering data on new projects. To overcome this challenge, a novel data conversion approach from a mechanical analysis perspective has been proposed to normalise TBM tunnelling data, such as cutterhead torque and cutterhead thrust, which help to unify data from different projects under the same framework. Furthermore, the effectiveness of this approach has been verified through analogy analysis and machine learning applications. With the application of these conversion relationships, the machine learning model trained on a completed Yin-Song project with big data (12,501 boring cycles) is applied to the on-going Yin-Chao Water Diversion Project in China with limited data (777 boring cycles) and gives reliable predictions for each performance parameter (with R2 for the cutterhead thrust of 0.81 and R2 for the cutterhead torque of 0.70). This approach enhances the usefulness of TBM intelligence for cross-engineering geophysical prospecting in different geological conditions. [ABSTRACT FROM AUTHOR]

Real-time and accurate prediction of surrounding rock grade is crucial for tunnel dynamic construction and design. However, the internationally accepted semi-quantitative methods (e.g. rock mass rating (RMR), Q, and basic quality (BQ)) cannot provide fast and accurate classification in construction. This study proposed an intelligent surrounding rock classification method and a tunnel information management system, which can predict the surrounding rock grade in real-time and accurately. A database is collected with 286 cases in China, including seven geological parameters and surrounding rock grades. Based on different training parameters, 12 classification models are established using VGGNet, ResNet, and support vector machine (SVM) algorithms. The accuracy of the SVM classifier is 93.02%, which performs better than the VGGNet and ResNet classifiers. Moreover, precision, recall, F-measure, receiver operating characteristic (ROC), and 20-case verification show that the SVM classification model has greater robustness in learning and generalising for small and imbalanced samples. Additionally, a tunnel information management system is developed with cloud technology, which can accurately predict the surrounding rock grade within 10 s. Overall, the achievements of this study can provide valuable references for real-time rock mass classification in traffic tunnels and underground powerhouses. [ABSTRACT FROM AUTHOR]

Scientific prediction of the penetration rate (PR) of tunnel boring machines (TBMs) is of great significance to the selection of tunnel construction methods, the prediction of construction progress, and the evaluation of benefits. In view of the high nonlinearity, fuzziness, and complexity of the TBM excavation process, this paper attempts to present a new algorithm that integrates partial least squares regression (PLSR) with boosted regression trees (BRT) for predicting the PR of TBMs. For this purpose, 150 datasets were obtained from the Lanzhou water conveyance tunnel project in China. Six impact factors were selected as the input layers of the proposed model by single-factor correlation analysis. To develop the PLSR-BRT model, two principal components of the influencing parameters were extracted via the PLSR method, and the BRT algorithm was employed to establish the predictive model. In addition, other models such as PLSR back propagation neural network (BPNN), BRT, PLSR, support vector regression (SVR), and artificial neural network (ANN) were adapted for use in this problem to verify the predictive accuracy of the proposed model. The results demonstrated that the PLSR-BRT model achieved the best predictive performance compared with the other models, with coefficient of determination value (R2) and root mean square error (RMSE) of 0.96 and 1.78, respectively, for the testing set. The PLSR-BRT model can maximally avoid both overfitting and inadequate fitting. In view of engineering applications, the complexity and redundancy of the field dataset can be solved via reducing the dimensionality of input parameters, and the training samples could be expanded by a boosted method so that the discontinuously acquired geological parameters are unable to restrain the model performance. This method serves as an effective approach for TBM PR prediction and has excellent potential for a variety of scientific and engineering applications. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature 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.)

The fast and accurate classification of surrounding rock mass is the basis for tunnel design and construction and has significant value in engineering applications. Therefore, this paper proposes a method for classifying and predicting surrounding rock mass based on particle swarm optimization (PSO)–least squares support vector machine (LSSVM). The premise of the research is that the data acquired from digital drilling technology are divided into a training group and a test group; the training group continuously optimizes the algorithm for the particle swarm optimization least squares support vector machine, and then the test group is used for verification. Moreover, the fast searching abilities of the particle swarm significantly accelerate the computational power and computational accuracy of the least squares support vector machine, making it a high-speed analog search tool. Taking the Jiaozhou Bay undersea tunnel in China as an example, a comparison of the evaluation results of PSO-LSSVM and QGA-RBF (quantum genetic algorithm-radical basis function neural network) is undertaken. The results show that PSO-LSSVM matches well with the field-measured surrounding rock grade. Applying the method in an engineering context proves that it has good self-learning abilities, even when the sample size is small and the prediction accuracy is high; as such, it meets the engineering requirements. The technique has the advantages of small sample prediction, pattern recognition, and nonlinear prediction. [ABSTRACT FROM AUTHOR]

The influence of saturation on the Poisson's ratio v of reservoir sediments has an engineering significance in the field of oil and nature gas exploration. Based on a self-developed combined (BE-EE-RC) test system, under the dehydration path, the Poisson's ratio variation of reservoir silty-fine sand in Hangzhou Bay, China, was investigated. Results show that the P- and S-wave velocities vary non-monotonically with decreasing saturation at different net stresses, and reach a maximum at the optimum saturation Sr(opt); Biot's theory with respect to variation in Vp with Sr matches well with the measured e data. With a small amount of gas intrusion, Poisson's ratio of saturated sand shows a sudden drop and gradually stabilizes; then, it attenuates slowly and reaches the minimum value at Sr(opt). Once the saturation degree decreases to the level lower than Sr(opt), it rapidly increases. Based on the soil–water characteristic curve (SWCC) and mesoscopic evolution of internal pore water morphology, the variation in Poisson's ratio v can be divided into four segments of saturation: the boundary effect stage, the primary transition stage, the secondary transition stage, and the unsaturated residual stage. Ultimately, a prediction model for Poisson ratio's v of the silty-fine sand was proposed to consider the saturation variation. [ABSTRACT FROM AUTHOR]

Gentle slopes with large amounts of granite blocks are widespread in granitic areas with warm and humid climate. These blocks pose a potential risk to the existing and planned infrastructure. The instability type and geometry of these blocks will influence their motility and destructive power to some extent. This study aims at creating a classification system that can indicate both the shape and the instability type of these blocks and then developing a block removal scheme. The classification system was constructed based on the mechanical stability analysis of blocks on an inclined surface. This analysis identified key factors affecting stability, including block shape, block weathering roundness, the existing state of a block on a slope, and the friction between the block and the slope. The achieved work allowed the establishment of a direct correlation between block geometry and their instability types. The availability of this classification system was validated by field data and experimental data in the literature. The proposal to remove blocks identified as the toppling types, such as cylindrical-toppling types, cuboid-toppling types, cube-toppling types, was put forward to avoid the uneconomical problem of a complete clearance. Meanwhile, this classification provides a foundation for further research on the instability probability of each type of block and the development of a more refined blocks' removal scheme. The classification approach adopted in this paper can provide a reference for the classification of other lithological blocks under similar engineering geological conditions. [ABSTRACT FROM AUTHOR]

Massive rockslides are recognized as one of the most catastrophic hazards due to their rapid sliding velocity and high destructiveness. This study focuses on the progressive failure analysis of translational rockslides (PFTRs) on a cataclinal dip slope, whose shear failure develops mainly along the bedding plane of the underlying strata from the head to the toe of the rockslide. A force and energy equilibrium-based analytical method (FEE) is proposed, combining shear failure propagation and strength degradation, to analyse the stability based on static equilibrium and displacement based on energy equilibrium. A representative translational rockslide, the Shanshucao landslide in the Three Gorges Reservoir, China, is used as a case study. The results of the FEE are validated by comparison with the revised rigid limit equilibrium method (RLEM) and numerical simulation (NS). According to the RLEM and NS, when the shear failure of the slide surface develops to a position with a horizontal distance of approximately 225 m, the rockslide steps into the critical state from partial progressive deformation to failure of the entire rockslide. The FEE obtains a similar result, and the corresponding horizontal distance is 200 m. The rockslide displacement calculated by the FEE agrees well with the results of the NS. Before the critical state, the rockslide displacement is less than 0.05 m; afterwards, the displacement of the entire rockslide obviously increases. In addition, it is proven that the hydrostatic pressure in subvertical tension cracks and the post-failure shear surfaces are the primary impetus for accelerated deformation of rockslides and further development of failure surfaces. The validated results indicate that the FEE is a straightforward and effective method to analyse both the stability and displacement of PFTR, which is significant for rockslide early warning and risk mitigation. In addition, the FEE still has limitations with regard to generalization of the landslide geo-mechanical model and the method validation with observational data of historical events. [ABSTRACT FROM AUTHOR]

Rock joints in faulted zones are usually filled with large amounts of fault gouge, in which clay-rich fillings are very common. Fault water can significantly influence the mechanical parameters of clay-rich fillings and affect the shear mechanical behaviour of rock joints. Based on a tunnelling project passing through a faulted zone in Yunnan Province of China, this paper investigates the mechanical behaviour of rock joints with clay-rich fillings. A series of direct shear tests are conducted on rock joint samples made from rock blocks and fillings collected from a fault zone. The shear stress‒displacement curves and shear failure characteristics of rock joints are obtained, and several key factors of the fillings are considered, such as particle size, mineral composition, clay content, and water content. Furthermore, the peak and residual shear strengths are analysed by considering the influence of the water content and normal loading pressure. The test results show that water content of fillings has a great influence on shear strength of clay-filling rock joints; there is a trend to a negative correlation between the shear strength of rock joints when water content (w) exceeds the plastic limit (wp). Finally, a shear strength model for rock joints with clay-rich fillings is proposed based on the JRC-JCS strength criterion. Influence of water content on the shear strength of rock joints with clay-rich fillings is studied. A series of direct shear tests are conducted on rock joint samples based on a tunnelling project. The shear stress–displacement curves of rock joints with clay-rich filling are obtained. A shear strength weakening model of clay-filled joints is proposed. Highlights: Influence of water content on the shear strength of rock joints with clay-rich fillings is studied. A series of direct shear tests are conducted on rock joint samples based on a tunnelling project. The shear stress-displacement curves of rock joints with clay-rich filling are obtained. A shear strength weakening model of clay-filled joints is proposed. [ABSTRACT FROM AUTHOR]

The geology of Tamusu site candidate for high-level radioactive waste (HLW) in Inner Mongolia in China was characterized by large size, moderate burial, good integrity, strong nuclide adsorption, very low permeability, high stress strength, and a relatively stable regional tectonic environment. An evaluation system of QCHLW for the suitability of clay rock strata for HLW geological disposal was proposed and applied to Tamusu site candidate. The result shows that the geological factors meet the requirements of China for a clay rock site for an HLW geological repository. [ABSTRACT FROM AUTHOR]

As the weak structure of geotechnical engineering, frozen rock joints determine the stability of geotechnical engineering in frozen region. To study the influencing factors of the peak shear displacement of frozen rock joints, three groups of tuff coupling joints (upper and lower joints completely coincide) are selected in Jiangluling Tunnel, Qinghai Province, China. The joint surface morphology is obtained by three-dimensional scanning technology. The joints are frozen at – 35 ℃ for 12 h before direct shear test. The test results show that there are three main shear failure patterns of frozen rock joints, which are mainly determined by the opening degree of joints. The peak shear displacement decreases with the increase in joints surface roughness and opening degree, and increases with the increase in normal stress. By analyzing the characteristics of peak shear displacement under different opening degrees and normal stress, the influencing factors of peak shear displacement and shear strength of frozen rock joints are discussed. On this basis, the expression of peak shear displacement of frozen rock joints is proposed. It provides a theoretical basis for quantitative study on shear deformation of frozen rock joints. The study provides technical support for geotechnical engineering construction and rock slope instability prevention in frozen region. [ABSTRACT FROM AUTHOR]

To explore the stability analyses and control methods for surrounding rocks in deep hard rock shafts, this paper is based on field engineering geological surveys and laboratory rock mechanics tests and relies on the main shaft being constructed in the Shaling Gold Mine of China as the engineering background. The quality of the rock mass is evaluated by the Q system, rock mass rating (RMR) and geological strength index (GSI). The mechanical parameters of the surrounding rock mass of the shaft are calculated by using the generalized Hoek–Brown failure criterion, and the main support system is determined based on the rock mass classification system. Based on the finite element method, a two-dimensional plane strain model is constructed to analyze and evaluate the deformation and plastic region range of surrounding rocks for different support systems. On this basis, considering the dilatancy and plastic softening characteristics of hard rock masses, an analytical solution of the stress, strain and plastic region radius of hard rock around shafts in homogeneous media is proposed. Finally, the plastic region of the surrounding rock is measured by the P-wave velocity test method. The results show that after considering the dilatancy and plastic softening characteristics of the rock mass, the numerical simulation, theoretical analytical solution and measured results are basically consistent, and the proposed support system can effectively ensure the stability of the shaft. [ABSTRACT FROM AUTHOR]

Aim: Amphibians require both terrestrial and aquatic environments to complete their life cycles. Thus, they are subject to complex selection pressures stemming from different environments, and these selection pressures are likely to vary geographically with variation in temperature and precipitation. Studies of genetic differentiation along geographical clines allow identification of footprints of these selection pressures. Location: China. Methods: To identify possible signatures of local adaptation to particular environmental conditions, we conducted a genome‐scan with 20,572 single‐nucleotide polymorphisms (SNPs) obtained with restriction site‐associated DNA sequencing of pooled samples from 10 Microhyla fissipes populations spanning a 1,398 km long latitudinal gradient in China. Results: The results revealed significant genetic differentiation among populations (FST =0.090). Numerous outlier SNPs associated with variation in both annual average temperature (n = 69) and precipitation (n = 248) were detected. Main conclusions: The degree and pattern of population differentiation in the SNPs supported the hypothesis that these SNPs have been subject to directional natural selection associated with temperature and precipitation and, hence, are reflective of geographically varying local adaptation. Hence, conservation and management plans for Microhyla fissipes should take into account this heterogeneity in genetic constitution in its populations. [ABSTRACT FROM AUTHOR]

Geotechnical issues due to inappropriate support designs of underground drift will affect mining developments and production. The aim of this study was to provide a systematic support design method for deep hard-rock drifts in China. Field investigations and laboratory studies were carried out on the engineering geological properties of the rock masses along drifts in the Sanshandao Gold Mine. Potential wedge analysis and safety factors were determined using Unwedge software. The rock mass properties and support requirements were analyzed accordingly using different rock mass classification systems; then, an updated combined support system including rock bolts, wire mesh, and shotcrete was proposed. Numerical methods were used to quantify the plastic zone and principal stress of the drift, the plastic zone was reduced, and the rock stress state was improved after installing the support systems. Field monitoring data also confirmed that the updated support system prevented excessive rock mass deformation in drift. This study provides a reliable method for deep hard-rock drift support at Sanshandao Gold Mine and will also be helpful for the optimization of subsequent support. [ABSTRACT FROM AUTHOR]

Species range shift is one of the most significant consequences of climate change in the Anthropocene. A comprehensive study, including demographic, physiological and genetic factors linked to poleward range expansion, is crucial for understanding how the expanding population occupies the new habitat. In the present study, we investigated the demographic, physiological and genetic features of the intertidal gastropod Nerita yoldii, which has extended its northern limit by ~200 km over the former biogeographical break of the Yangtze River Estuary in recent decades. Data from neutral single nucleotide polymorphisms (SNPs) showed that the new marginal populations formed a distinct cluster established by a few founders. Demographic modelling analysis revealed that the new marginal populations experienced a strong genetic bottleneck followed by recent demographic expansion. Successful expansion that overcame the founder effect might be attributed to its high capacity for rapid population growth and multiple introductions. According to the non‐neutral SNPs under diversifying selection, there were high levels of heterozygosity in the new marginal populations, which might be beneficial for adapting to the novel thermal conditions. The common garden experiment showed that the new marginal populations have evolved divergent transcriptomic and physiological responses to heat stress, allowing them to occupy and survive in the novel environment. Lower transcriptional plasticity was observed in the new marginal populations. These results suggest a new biogeographical pattern of N. yoldii has formed with the occurrence of demographic, physiological and genetic changes, and emphasize the roles of adaptation of marginal populations during range expansion. [ABSTRACT FROM AUTHOR]

The engineering quality of rock mass is a key factor to evaluate the long-term stability and safety of high-level radioactive waste (HLW) geological disposal engineering and is also the important basis for disposal site selection. Traditional rock mass quality classification methods, such as RMR and Q , can meet underground engineering but still should be studied further for the site evaluation in the HLW disposal engineering. In this study, rock mass structure rating (RMSG) was proposed based on the quantitative control index of rock mass structure which was from the rock mass quality classification methods. Based on the statistical results of rock mass structure, the relationship between the number of RMSG and the modified RMR ( F RMR ) and Q ( F Q ) was established, China, as a case study. Results from this study show that RMSG is linearly related to F RMR and negatively exponential to F Q . The research results can solve the evaluation of rock mass quality for HLW geological disposal engineering, and the addition of more engineering examples over time will enable further verification. [ABSTRACT FROM AUTHOR]

Discontinuities with different joint wall compressive strengths (DDJCS) are common in the Three Gorges Reservoir Area, China. Accurate estimation of the peak shear strength of DDJCS is essential for evaluating the stability of rock slope in the area. However, the coupling effects of strength difference in rock types and matching degree in rock blocks on the peak shear strength of such a discontinuity have not been well investigated. In this study, DDJCS with different matching degrees are used to conduct direct shear tests, modelled by applying horizontal dislocations between the two rock blocks along shearing direction. Experimental results illustrate that the joint peak shear strengths decrease linearly as the horizontal dislocation increases, while the ratio of peak shear strength for the unmatched DDJCS to the matched DDJCS is almost unaffected by the joint wall strength difference when the imposed lateral dislocation is equal. An empirical criterion is proposed by multivariate regression analysis to account for the above-mentioned coupling effects, which can be degraded into available criterion as the horizontal dislocation is zero. Several natural discontinuities with different joint wall compressive strengths are then collected from the Three Gorges Reservoir Area to verify the proposed criterion. Due to the low overall estimation error (about 6.20% for the unmatched rock-like discontinuities, and 12.4% for the unmatched natural discontinuities), the proposed criterion can be used to evaluate the peak shear strengths of unmatched DDJCS to some extent. Highlights: Peak shear strength of discontinuity with different joint wall compressive strengths linearly decreases as initial horizontal dislocation between the two rock blocks increases. New failure criterion is developed to evaluate the peak shear strength of unmatched discontinuity with different joint wall compressive strengths. Three factors are mainly considered by the proposed criterion: matching condition, joint wall strength difference, and three-dimensional roughness metric. [ABSTRACT FROM AUTHOR]

Reconstructing diet can offer an improved understanding toward the origin and evolution of modern humans. However, the diet of early modern humans in East Asia is poorly understood. Starch analysis of dental calculus is harmless to precious fossil hominins and provides the most direct evidence of plant food sources in early modern human dietary records. In this paper, we examined the starch grains in dental calculus from Fuyan Cave hominins in Daoxian (South China), which were the earliest modern humans in East Asia. Our results reveal the earliest direct evidence of a hominin diet made of acorns, roots, tubers, grass seeds, and other yet-unidentified plants in marine isotope stage 5 between 120 and 80 ka. Our study also provides the earliest evidence that acorns may have played an important role in subsistence strategies. There may have been a long-lasting tradition of using these plants during the Late Pleistocene in China. Plant foods would have been a plentiful source of carbohydrates that greatly increased energy availability to human tissues with high glucose demands. Our study provides the earliest direct consumption of carbohydrates-rich plant resources from modern humans in China for the first time. In addition, it also helps elucidate the evolutionary advantages of early modern humans in the late Middle and early Upper Pleistocene. [ABSTRACT FROM AUTHOR]

During underground excavations for civil and mining engineering purposes, the variations in mechanical properties of jointed rock mass are important, especially for the design of underground structures. The unreasonable evaluation of strength properties for rock masses can lead to the structure instability of underground construct, which subsequently causes collapse accidents in underground engineering and poses a serious threat to the structures safety. Rock mass classification system is an effective method for determining the strength parameters for rock masses. Firstly, the existing approaches for determining the strength parameters of rock masses are reviewed using classification systems such as the joint factor, jointing index methods, rock mass rating (RMR), Q-system (Q), geological strength index (GSI), and rock quality designation (RQD). Since in some cases, rock quality designation (RQD) is the only information available, a comparative study with other methods then is conducted to verify the limitation and deficiencies of RQD method. On this basis, a newly developed method from RQD classification system based on drilling special energy is established to estimate the rock mass strength. Finally, the developed method is applied in the tunnel engineering in the Daheba hydropower station in Hanjiang to the Weihe River project of China, and the results are compared with those from the previous works. The in situ test results show that the developed method can give appropriate values compared to various suggested relationships from RMR, Q, and GSI. The results can be treated as an important design reference for the prevention and treatment of surrounding rock instability and underground excavations in the Daheba hydropower station. [ABSTRACT FROM AUTHOR]

Premise: The enemy release hypothesis predicts that release from natural enemies, including soil‐borne pathogens, liberates invasive plants from a negative regulating force. Nevertheless, invasive plants may acquire novel enemies and mutualists in the introduced range, which may cause variable effects on invader growth. However, how soil microorganisms may influence competitive ability of invasive plants along invasion chronosequences has been little explored. Methods: Using the invasive plant Solidago canadensis, we tested whether longer residence times are associated with stronger negative plant‐soil feedbacks and thus weaker competitive abilities at the individual level. We grew S. canadensis individuals from 36 populations with different residence times across southeastern China in competition versus no competition and in three different types of soils: (1) conspecific rhizospheric soils; (2) soils from uninvaded patches; and (3) sterilized soil. For our competitor treatments, we constructed synthetic communities of four native species (Bidens parviflora, Solanum nigrum, Kalimeris indica, and Mosla scabra), which naturally co‐occur with Solidago canadensis in the field. Results: Solidago canadensis populations with longer residence times experienced stronger positive plant‐soil feedbacks and had greater competitive responses (i.e., produced greater above‐ground biomass and grew taller) in conspecific rhizospheric soils than in sterilized or uninvaded soils. Moreover, S. canadensis from older populations significantly suppressed above‐ground biomass of the native communities in rhizospheric and uninvaded soils but not in sterilized soil. Conclusions: The present results suggest that older populations of S. canadensis experience stronger positive plant‐soil feedbacks, which may enhance their competitive ability against native plant communities. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience 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.)

The construction of 1500 m depth shaft in Xincheng Gold Mine, China, faces complex stress conditions such as high geostress (>50 MPa), high ground temperature (>50 °C), high water-pressure (>9 MPa), and highly corrosive. Traditional deep shafts excavated by the sinking and lining method cannot adapt to high geostress problems, such as rock bursts and large deformations, etc., in the deep shaft construction process. To avoid and adjust the high geostress induced the rockburst and large deformations, the mechanism of the advanced sequential geopressure release (ASGR) has been proposed for the ground control in deep shaft construction. In this paper, the safe distance between the concrete lining and the shaft excavation face is determined based on the ASGR mechanism, which can provide the space for geopressure release, and primary support based on rock mass quality and numerical simulation was employed to control the geopressure and deformation. A new support scheme for the deep shaft is proposed, using long bolts to restrain severe deformations, metal mesh, and a double reinforcement bar to improve the induced stress distribution. According to the results, the construction scheme of deep shaft has been improved, and the safe support distance of the proposed scheme is determined to be 12 m, with an interval of three excavation cycles. Compared to the original scheme of shaft lining after excavation, the proposed scheme based on the ASGR mechanism can effectively improve the geopressure release and benefit from controlling the rockburst and large deformation of deep shaft induced by high geostress conditions. The stress distribution in the lining is more uniform, and safety factor of the lining is increased to 2.0, which is benefit the long-term stability of deep shaft. [ABSTRACT FROM AUTHOR]

The classification and real-time identification of surrounding rock grades are of great significance to guide tunnel boring machine (TBM) construction. Taking a water diversion project in China as the background, this study evaluates the relationship between tunneling parameters, surrounding rock grades, and tunneling performance (TP) using actual TBM tunneling and geological data with the aim to create a novel surrounding rock classification method that is based on tunneling performance. The advance rate and specific energy of excavation are used as the measurement indexes of TBM TP to carry out the surrounding rock classification. The rationality of TP classification is verified by statistical analysis of the distribution of the thrust, torque, rotational speed, penetration, penetration rate, and utilization of surrounding rocks at all TP grades. Furthermore, a cross-validation support vector machine model based on mean interval value backpropagation is used to realize the real-time identification of TP grades, achieving an accuracy of 95%. Finally, the correlation between thrust and penetration rate under the basic quality index (BQ) and TP classification systems is analyzed, respectively. It is found that there is a positive correlation under the TP classification system and a negative correlation under the BQ classification system, indicating that the TP classification system is more suitable for guiding TBM construction than the BQ classification system. The proposed tunneling performance classification method and real-time identification model of TBM tunnel surrounding rocks provide a reference for guiding the safe and efficient tunneling of TBMs. [ABSTRACT FROM AUTHOR]

Highlights: A novel BAS-DNN model for prediction of TBM advance rate is developed. A database involving geotechnical and operating risks (RMR, TWCR, and RI) is set up. Quadratic relationships exist between RMR, TWCR, and AR. AR decreases while the descending rate gradually increases with RI increasing. The BAS-DNN model shows good performance in the tunnel section with a jamming event. [ABSTRACT FROM AUTHOR]

As an important part of a double-layer shaft lining in China, a polyethylene sandwich can reduce or even eliminate the constraint effect on the inner shaft lining, which is confined by the outer shaft lining, thus improving the integrity of the inner shaft lining concrete. To reveal the interface shear mechanism of the concrete-high density polyethylene (HDPE) material, a series of 16 direct shear tests were performed under high normal loads (0.6~4 MPa) with four different surface morphologies. The experimental results showed that the interfaces exhibit a clear strain-softening property during shear, and the shear strength increases linearly with increasing normal stress. Three shearing mechanisms, plowing, localized plastic deformation, and dilatancy, were observed in these experiments. The research results are of great theoretical and practical value for understanding the shear mechanism and predicting the shear strength of a shaft lining concrete-HDPE interface under high normal stress. [ABSTRACT FROM AUTHOR]

Underground water-sealed storage cavern is an important way for petroleum strategic reserve in China, which owns lots of outstanding advantages, such as low operating costs, high safety, and land resource conservation. As the major structure in underground water-sealed storage cavern, its layout parameters and excavation scheme will have significant impact on rock stability and overall project quality. A method is put forward to optimize layout and excavation scheme of main caverns. In this method, the Q system and Hoek–Brown strength criterion is utilized to estimate equivalent mechanical parameters of rock mass based on field survey data. Numerical test analysis is carried out by 3 Dimensions Distinct Element Code (3DEC). Displacement, maximum displacement and plastic zone volume are selected as three indicators for quantitative assessment. Besides, it is applied into a proposed large-scale underground water-sealed storage cavern project in China. Results show that axial direction should adopt NW325°, buried depth of cavern crown should locate at − 100 m, and spacing should be 1.5 times the span (36 m). Scheme two and "jump excavation" mode is recommended in construction, which can effectively reduce the interaction effect between adjacent caverns. This method has the characteristics of easy data acquisition, strong operability and common applicability. The achieved results can not only provide reference for related projects, but also further enrich the research content in this field, which has a certain engineering value and theoretical significance. [ABSTRACT FROM AUTHOR]

The Cyclophyllidea comprises the most species-rich order of tapeworms (Platyhelminthes, Cestoda) and includes species with some of the most severe health impact on wildlife, livestock, and humans. We collected seven Cyclophyllidea specimens from rodents in Qinghai-Tibet Plateau (QTP) and its surrounding mountain systems, of which four specimens in QTP were unsequenced, representing "putative new species." Their complete mitochondrial (mt) genomes were sequenced and annotated. Phylogenetic reconstruction of partial 28S rDNA, cox 1 and nad 1 datasets provided high bootstrap frequency support for the categorization of three "putative new species," assigning each, respectively, to the genera Mesocestoides , Paranoplocephala , and Mosgovoyia , and revealing that some species and families in these three datasets, which contain 291 species from nine families, may require taxonomic revision. The partial 18S rDNA phylogeny of 29 species from Taeniidae provided high bootstrap frequency support for the categorization of the "putative new species" in the genus Hydatigera. Combined with the current investigation, the other three known Taeniidae species found in this study were Taenia caixuepengi , T. crassiceps , and Versteria mustelae and may be widely distributed in western China. Estimates of divergence time based on cox 1 + nad 1 fragment and mt protein-coding genes (PCGs) showed that the differentiation rate of Cyclophyllidea species was strongly associated with the rate of change in the biogeographic scenarios, likely caused by the uplift of the QTP; i.e., species differentiation of Cyclophyllidea might be driven by host-parasite co-evolution caused by the uplift of QTP. We propose an "out of QTP" hypothesis for the radiation of these cyclophyllidean tapeworms. [ABSTRACT FROM AUTHOR]

The slope stability has already become one of the most important factors directly related to the safety production and development of a mine, which is principally controlled by the properties of geological discontinuities of slope, such as bedding planes, faults, cleavage and joints. In this study, a new approach for the evaluation of slope stability in large open-pit mines was presented based on a comprehensive investigation of the geometry and shear strength of the geological discontinuities. This approach follows three steps: (1) graded kinematic analysis using stereographic projection techniques; (2) field estimation of shear strength of discontinuities with the consideration of the impact of uncertainty and scale dependency; and (3) slope stability assessment based on deterministic analysis by FoS and the probabilistic analysis by PoF. A case study, namely, the Yangtaowu Slope in the Dexing Copper Mine, was selected for the application of this approach. The stability assessment result shows good agreement with field observation, illustrating the ability of the proposed method in effectively predicting the stability of open-pit mine slopes. Furthermore, the comparison of the calculated results based on the precise and generalized calculation models demonstrated that the accuracy of the geometric model has a high influence on the stability assessment. [ABSTRACT FROM AUTHOR]