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Cutter wear is one of the key factors influencing construction efficiency during shield tunnelling. Prediction of cutter wear can improve construction efficiency by reducing the times of cutter inspections in engineering practice. Evaluation of cutter life is vital for cutter wear prediction, however, existing cutter life indices can only estimate the health condition of all cutters on cutterhead on a holistic basis. A new index was proposed to evaluate cutter wear located at a specific installation position on cutterhead. A deep learning model integrating the index was developed for the estimation of accumulated cutter wear during real time shield tunnelling. The new index can be obtained by monitored field parameters and can predict cutter wear with historical wear patterns. The input and output data samples were reshaped for multi-step prediction. A shield tunnelling section in Guangzhou weathered granite was used for validation. The proposed method can help reduce the cost of cutter replacement by reducing the times of machine interventions. The method article is a companion paper to the original article [1]. • Proposed index for prediction of cutter wear rate. • Deep learning model of 1D-CNN and GRU. • Multi-step cutter wear prediction.

Tunneling-induced ground surface settlement is associated with many complex influencing factors. Beyond factors related to tunnel geometry and surrounding geological conditions, operational factors related to the shield machine are highly significant because of the complexity of shield-soil interactions. Distinguishing the most relevant factors can be very difficult, for all factors seem to affect tunneling-induced settlement to some degree, with none clearly the most influential. In this research, a machine learning method is adopted to intelligently select features related to tunneling-induced ground settlement based on measured data and form a robust non-parametric model with which to make a prediction. The recorded data from a real construction site were compiled and 12 features related to the operational factors were summarized. Using the intelligent method, two other features in addition to cover depth–pitching angle and rolling angle–were distinguished from among the 12 feature candidates as those most influencing the settlement trough. Another new finding is that advance rate does not emerge in the top 10 selected models from the observational data used. The generated non-parametric model was validated by comparing the measured data from the testing dataset and performance on a new dataset. Sensitivity analysis was conducted to evaluate the contribution of each factor. According to the results, engineers in general practice should attend closely to pitching angle during tunnel excavation in soft soil conditions.

Columnar inclusion is a versatile and cost-effective technique for improving weak soils. Currently, most approaches are based on the “equal strain” assumption to calculate the deformation of soft ground reinforced by columnar inclusions. In this study, a new model to simulate the behavior of column-reinforced soft soil under equal stress conditions based on the variational principles is proposed. The proposed model satisfies the force equilibrium and deformation compatibility simultaneously, which is seldom fulfilled in traditional empirical methods or other analytical models. The corresponding analytical solution is obtained and its accuracy is verified by comparing it with the numerical solutions using finite element analysis. The comparisons of the proposed solution with an existing solution show that the proposed solution can provide very close agreement over a wide range of parameters while the existing solution is only able to provide a reasonable agreement for a certain range of stiffness ratio of the column and soft ground. In addition, a parametric study is made to illustrate the influence of various parameters on ground settlement predictions. The parametric study indicated that, by increasing the ratio of elastic modulus between the stone column and surrounding soils and the ratio between the radius of the stone column and the space of the stone column, the load transfer effect has been significantly improved, and the ground settlement becomes smaller. Furthermore, the Poisson’s ratio of the surrounding soil also has a very significant effect on ground settlement, while the effect of the Poisson’s ratio of the stone column on ground settlement is less significant compared with that of the surrounding soil.

This paper presents the roof fall collapse of a coal mine that occurred, causing 20 deaths and 1 injury, in Qinghai Province, China, on 14 August 2021. After the primary investigation of this incident and a brief description of the rescue action undertaken, this report discussed the possible reasons behind this disaster. The fissure water and damaged rock mass are the dominant triggering factors of this incident. Little concern for risk assessment and monitoring systems is one of the main man-made mistakes. Consequently, the reflections and suggestions are put forward to reduce or prevent the occurrence of roof fall incidents in coal mines. The noteworthy actions that are necessary in coal mine projects are conducting risk assessments based on geological condition and building proper support systems for coal mines considering he situation in situ.

This short communication reports a water inrush hazard during the construction of the Shijingshan Tunnel in Zhuhai, Guangdong, China. On 15 July 2021, a water inrush accident occurred at the construction site 1.16 km away from the tunnel entrance, resulting in 14 casualties. The purpose of this study is to investigate and discuss the water inrush process in this atypical case. The principal causes of this tunneling accident include the special geological conditions at the construction site, high hydraulic conductivity at the part that connects the underground water system and the overlying water body (the Jida Reservoir), and the impact of heavy rainfall. Moreover, four significant suggestions are proposed to prevent the possible occurrence of water inrush disaster: (1) assessing the risk level in areas prone to water inrush; (2) getting a comprehensive geological prediction based on borehole data and artificial intelligent methods; (3) establishing a monitoring system during the tunneling process; (4) strengthening the self-protection skills of construction workers.

The collapse of a 30-year-old hotel building in Suzhou, Jiangsu Province on 12 July 2021 raised legitimate questions about the identification of old buildings’ condition and risks stemming from remedial operations. This short communication reports and investigates the causes of this accident, which led to 17 deaths and 5 injuries. Subsequently, it describes the rescue actions undertaken, including logistic means, operational strategies, and procedure sequencing. The causes of the accident were attributed to: (i) the poor quality and fragility of the building, (ii) illegal renovations and extensions, as well as (iii) the laxism of relevant departments that failed to timely check the risk level of the building before these renovations. Thanks to efficient organization and management, the rescue operations were completed within 42 h. Based on this preliminary analysis, some recommendations are proposed to prevent similar incidents in the future.

A huge gas explosion occurred on 13 June 2021 in Shiyan City, China, resulting in 25 casualties and serious injuries to 37 people. The main victims of this explosion were stall keepers and customers buying breakfast and fresh vegetables in the food market. There is a continuous need to enhance the understanding of such unfortunate events, given the dangers they pose. This study analyzes the causes of this accident considering the general background and scenes of the explosion, and then describes the rescue operations undertaken. The investigation results revealed that the explosion was caused by the poor maintenance of gas facilities and negligence of safety regulations. It is, therefore, recommended that the control of these two main aspects be strengthened to reduce the recurrence of such unfortunate accidents.

The title compound, CH5N6+·Cl−, crystallized with two indepedent 1,5-diaminotetrazolium cations and two independent chloride anions in the asymmetric unit. In the crystal, there are a number of N—H...Cl hydrogen-bonding interactions, which generate a three-dimensional network.

Diabetic nephropathy is a major complication of diabetes mellitus (DM). Recent studies suggest that immunological mechanisms have a key role in the pathogenesis of DM, therefore these mechanisms may be important targets for diabetes therapy. The present study evaluated the effects of anti-α1-adrenergic receptor antibody (α1-R Ab) mediation and doxazosin treatment in a rat model of DM. It was observed that levels of 24-h urinary protein, serum creatinine and transforming growth factor-β1 in DM were significantly increased after α1-R Ab mediation (all P<0.05). In addition, electron microscopy identified severe damage in the renal tissue microstructures of DM rats following α1-R Ab mediation, while only mild abnormalities were observed in that of healthy rats mediated with α1-R Ab and of untreated DM rats. No marked abnormalities were observed in the renal tissue of healthy blank controls. Furthermore, in DM rats treated with α1-R Ab mediation + doxazosin intervention, the expression of TGF-β1 significantly decreased, and renal functions and renal matrix remodeling were significantly improved, relative to untreated DM controls (P<0.01). These results suggest that α1-R Ab may be involved in renal matrix remodeling during DM, and that kidney protection during DM may be achieved through treatment with corresponding receptor antagonists. [ABSTRACT FROM AUTHOR]

Previous studies have usually idealized the boundary conditions of unsaturated soil as absolutely permeable or impermeable. However, this assumption is not sound for the majority of cases where the boundary is partially permeable. In this study, partially permeable conditions are described using exponential functions for the excess pore-air and pore-water pressures at the boundaries. A generalized analytical solution for the consolidation of unsaturated soil under these proposed boundary conditions and constant initial excess pore-air and pore-water pressure conditions were obtained. The results of the proposed solution agreed with an analytical solution available in the literature, which verifies the feasibility of this study. The proposed solutions were subsequently tested and compared to published experimental data. Furthermore, a new concept, degree of drainage, was developed to characterize the partial-drainage conditions at the boundaries. Finally, a parametric study was carried out to show the consolidation characteristics under different degrees of drainage and ratios of hydraulic conductivities of air and water phases. The excess pore-pressure dissipation processes at the boundaries and the average degrees of consolidation for both the air and water phases are presented and discussed. [ABSTRACT FROM AUTHOR]

To investigate the effect of prazosin on patients with diabetic nephropathy (DN), α1-adrenergic receptor (α1-R) autoantibodies and refractory hypertension, a total of 126 patients with DN and hypertension were recruited. The patients were divided into a refractory hypertension group, (n=76) and a non-refractory hypertension group (n=50). The epitope of the second extracellular loop of the α1-R (192-218) was synthesized and an enzyme-linked immunosorbent assay (ELISA) was performed to detect serum autoantibodies. In the group with DN-associated refractory hypertension, the positive rate of autoantibodies against the α1-R was 80.3% (n=61). The 61 patients who were positive for α1-R autoantibodies were randomly divided into a treatment group (n=31) and a control group (n=30). The patients were given drugs at the same dosage and administration, with the exception of prazosin, which was provided only to the patients in the treatment group [1 mg, three times a day (tid)] for a duration of six weeks. Subsequently, prazosin was added (1 mg, tid) to the therapeutic schedule of the patients in the control group and the α1-R autoantibody-negative group for another six weeks. The analysis was carried out on an intention-to-treat basis. The prazosin treatment resulted in significant improvements in hypertension in the treatment group (P<0.05), while there was no marked improvement in the control group. The total effective rate of hypertension improvement was 90.3% in the treatment group, which was higher compared with that of the control group (33.3%). In conclusion, α1-R autoantibodies may play an important role in the pathogenesis of DN with refractory hypertension. Prazosin was demonstrated to be effective and safe in the treatment of DN with refractory hypertension. [ABSTRACT FROM AUTHOR]

Objective Impaired glucose tolerance (IGT) is considered a transitional phase in the development of type 2 diabetes, and is also independently associated with the occurrence of cardiovascular disease. Endothelial dysfunction (ED) represents a very early step in the development of atherosclerosis. The aim of the present study was to examine ED in the fasting state and after a glucose challenge as well as after administration of an antioxidant agent. Patients and methods The study subjects included 42 IGT patients and 26 healthy individuals (control group). The IGT patients were randomly divided into two groups, 21 in each group (the alpha-lipoic acid group and the placebo group). In the alpha-lipoic acid group, 300 mg of alpha-lipoic acid was administrated before an oral glucose tolerance test (OGTT); in the placebo group, 250 ml of 0·9% sodium chloride was administrated before the OGTT. In addition, 250 ml of 0·9% sodium chloride was also administrated to the control subjects before the OGTT (control group), and then vascular function was examined in the fasting state and repeated 1 and 2 h after the glucose load. High-resolution ultrasound was used to measure flow-mediated endothelium-dependent arterial dilation (FMD) and glyceryltrinitrate (GTN)-induced endothelium-independent arterial dilation. Results In the fasting state, and at 60 and 120 min, FMD in both the placebo and alpha-lipoic acid groups was significantly lower than in the controls ( P < 0·01). In the control group, FMD tended to decrease at 60 min after glucose loading and returned to the baseline levels at 120 min ( P > 0·05). In the placebo group, FMD decreased significantly at 60 min after glucose loading ( P < 0·01) and increased markedly from 60 to 120 min ( P < 0·01). The alpha-lipoic acid-treated patients showed FMD values intermediate between the control subjects and the IGT patients treated with placebo, at both 60 and 120 min, and the differences were significant ( P < 0·01). In multiple regression analysis, FMD was significantly correlated to fasting blood glucose (FBG), low density lipoprotein cholesterol (LDL-C), lipoprotein (a) [Lp(a)], C-reactive protein (CRP), thiobarbituric acid reactive substances (TBARS) and age in IGT patients at baseline ( P < 0·01). Spearman's analysis showed a significant negative correlation between FMD and plasma glucose levels, and between FMD and TBARS during the OGTT in IGT patients (placebo group) ( P < 0·01). There was also a significant correlation between FMD and plasma glucose levels, and between FMD and TBARS during the OGTT in IGT patients treated with alpha-lipoic acid ( P < 0·05), although the power of association decreased. Conclusion In subjects with IGT, FMD was impaired both in the fasting state and after a glucose challenge, probably through increased production of oxygen-derived free radicals. The ED observed after a glucose challenge is related to the extent of hyperglycaemia and TBARS, and an antioxidant agent can improve the impairment of endothelial function induced by acute hyperglycaemia. [ABSTRACT FROM AUTHOR]