•Simulate the slot-shaped breakout based on a 3D DEM-continuum coupled model.•Reveal the formation of slot-shaped breakout due to particle crushing and removal.•Reveal the formation of compaction ...band after the breakout length ceases to grow.•Study the effects of different parameters on the length of slot-shaped breakout.
Mechanism for slot-shaped borehole breakouts observed from drilling experiments in high-porosity sandstone is investigated using the hybrid DEM-continuum mechanics modeling approach. The rock material in DEM is modeled as an assembly of particles with flat joints at contacts. The failure mechanism for the slot-shaped breakout is mainly attributed to particle crushing, which is different from the conventional dilatant V-shaped breakout where shear failure plays the primary role. The damage evolution of the slot-shaped breakout can be divided into three stages, i.e., breakout initiation induced by the stress concentration near the excavated borehole, formation and propagation of the slot-shaped borehole breakout as a result of particle crushing and removal, and formation of a compaction band at the tip of the breakout when the breakout length ceases to grow. The dynamic change of stress during the breakout slot extension is modeled. The continuous particle breakage at the tip of the breakout maintains the same level of stress concentration as the breakout propagates. The majority of the particle loss is caused by the particle crushing and subsequent removal. The evolution of microcrack strike suggests change of the preferential failure orientation from approximately parallel to the maximum horizontal stress direction to forming a small angle to the minimum horizontal stress direction. Parametric studies show that increasing the horizontal stress anisotropy, broadening the range of particle size, and increasing the rock porosity will all increase the length of the slot-shaped breakout. The normalized breakout length tends to increase with the increase of borehole size before reaching a stable value.
Based on the engineering prototype of new Jinjishan Tunnel in Fuzhou 2nd ring road, the 1/30 downscale ground-lining model was fabricated. Then the earthquake-simulating tests were carried out on the ...shaking table apparatus to explore the seismic responses and seismic properties of large section mountain tunnel. The time-domain analyses on the test results show that the PHA (peak horizontal acceleration) amplification coefficients of ground increase non-linearly with elevation. The elevation effect of ground takes “S” form, which distinguishes itself from other regular ones. The PCP (peak contact pressure) oscillation coefficients at the sidewall and the arch of lining increase almost linearly with the seismic intensity, which implies that the sidewall and arch carry a majority of seismic loading under large ground motion excitation. The frequency-domain analyses on the test results show that the existence of large section tunnel changes the seismic property of original ground significantly. The 1st and 2nd dominant frequencies reflect the seismic properties of original ground and lining structure respectively, and both of them decrease gradually with the repeated excitations. Meanwhile the frequency components around the 2nd dominant frequency are augmented significantly when the seismic wave passing through the model from bottom to surface.
A novel series of alkali and alkaline earth metal combined fluorine beryllium borates NaCaBe2B2O6F, KCaBe2B2O6F, and KSrBe2B2O6F were successfully synthesized through molecular engineering design and ...grown in crystals by spontaneous nucleation technique from self-flux systems. The idea, introduction of relatively small alkali and alkaline earth metal cations and the fluorine anion, successfully resulted in the novel UV NLO crystal NaCaBe2B2O6F, the following substitution of cations directed to two centrosymmetric compounds KCaBe2B2O6F and KSrBe2B2O6F. In all of their structures, the a–b plane is the infinite lattice layer (Be3B3O6F3)∞ made up of BO3 and BeO3F anionic groups, and for the first time, it was found that the adjacent layers are connected with fluorine bridge atoms to form (Be6B6O12F3)∞ double layers, instead of oxygen bridge atoms usually occurred in other oxides. This structural characteristic is greatly beneficial to improve the layering-growth habit and eliminate polymorphism of a crystal. Optical measurements on the nonlinear optical crystal of NaCaBe2B2O6F reveal that this crystal is phase-matchable and its short-wavelength absorption edge is down to deep UV (below 190 nm). Theoretical calculations on electronic structure were carried out to explain the experimental results. Our preliminary results indicate that NaCaBe2B2O6F has promising applications in the UV spectrum region.
Kidney clear cell carcinoma (KIRC) is the most common subtype of renal cell carcinoma. Peroxisomes play a role in the regulation of tumorigenesis and cancer progression, yet the prognostic ...significance of peroxisome-related genes (PRGs) remains rarely studied. The study aimed to establish a novel prognostic risk model and identify potential biomarkers in KIRC.
The significant prognostic PRGs were screened through differential and Cox regression analyses, and LASSO Cox regression analysis was performed to establish a prognostic risk model in the training cohort, which was validated internally in the testing and entire cohorts, and further assessed in the GSE22541 cohort. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to explore the function and pathway differences between the high-risk and low-risk groups. The relationship between risk score and immune cell infiltration levels was evaluated in the CIBERSORT, ESTIMATE and TIMER databases. Finally, potential biomarkers were identified and validated from model genes, using immunohistochemistry.
Fourteen significant prognostic PRGs were identified using multiple analyses, and 9 genes (ABCD1, ACAD11, ACAT1, AGXT, DAO, EPHX2, FNDC5, HAO1, and HNGCLL1) were obtained to establish a prognostic model via LASSO Cox regression analysis. Combining the risk score with clinical factors to construct a nomogram, which provided support for personalized treatment protocols for KIRC patients. GO and KEGG analyses highlighted associations with substance metabolism, transport, and the PPAR signaling pathways. Tumor immune infiltration indicated immune suppression in the high-risk group, accompanied by higher tumor purity and the expression of 9 model genes was positively correlated with the level of immune cell infiltration. ACAT1 has superior prognostic capabilities in predicting the outcomes of KIRC patients.
The peroxisome-related prognostic risk model could better predict prognosis in KIRC patients.
An analysis of tunnel face stability generally assumes a single homogeneous rock mass. However, most rock tunnel projects are excavated in stratified rock masses. This paper presents a ...two-dimensional (2D) analytical model for estimating the face stability of a rock tunnel in the presence of rock mass stratification. The model uses the kinematical limit analysis approach combined with the block calculation technique. A virtual support force is applied to the tunnel face, and then solved using an optimization method based on the upper limit theorem of limit analysis and the nonlinear Hoek–Brown yield criterion. Several design charts are provided to analyze the effects of rock layer thickness on tunnel face stability, tunnel diameter, the arrangement sequence of weak and strong rock layers, and the variation in rock layer parameters at different positions. The results indicate that the thickness of the rock layer, tunnel diameter, and arrangement sequence of weak and strong rock layers significantly affect the tunnel face stability. Variations in the parameters of the lower layer of the tunnel face have a greater effect on tunnel stability than those of the upper layer.
► The flattening effect on tunnel lining is proposed for the first time. ► Flattening effect is significant when bending radius is smaller than 5000m. ► Ground resistance reduces the moment and shear ...force due to flattening effect. ► Moment and shear force due to flattening effect are comparable to earth pressure.
Longitudinal differential settlement of shield-driven tunnel may cause longitudinal bending of the structure, which may further introduce flattening of the tunnel. The flattening of a tunnel as well as the additional internal forces and deformations it causes is seldom studied in the literature. In this paper, analytical solutions are first developed for estimating the additional forces and deformations caused by flattening of a jointed shield-driven tunnel. The effects of tunnel joints, tunnel diameter, lining thickness, ground resistance and original tunnel curvature on the flattening effect of the tunnel are discussed. An application example of a tunnel in Shanghai is adopted to illustrate the flattening of the tunnel. It is found that the flattening effect is significant if the bending radius of tunnel is smaller than 5000m, and that the deformations and internal forces induced by the flattening effect is comparable with those induce by the earth pressure. Thus, if the flattening effect is ignored, the design may be unsafe. It is important to consider the additional internal forces due to tunnel flattening in tunnel design when differential settlements are expected.
•Different tunnels with different void behind the liner are investigated numerically.•The changes of liner stresses and deformation induced by the voids are studied.•Liner stresses and deformation ...will change which may result in liner damage.•Effect of void size, location, depth on liner stresses is studied.•Tunnel shapes, lateral stress ratio and rock type are also examined.
Voids behind the liner may be created during or after construction of the tunnel liner because of insufficient backfilling, poor workmanship, water erosion or gravity. Survey on a number of tunnels that suffered collapse while in service showed that voids behind the liner were the main factors for the failure. The paper provides a better understanding of the stress redistribution that occurs in the rock mass around a void and quantifies the stresses induced in the liner due to the voids. The effects of cavities or voids due to different size, location and depth are explored numerically through an elasto-plastic finite element analyses. Other factors such as lining flexibility, in situ stresses and tunnel shape are also investigated. The analyses show that voids can induce a large change of the thrust and bending moment in the liner with respect to the case of a liner without a void. The bending moment can even reverse sign, which may result in cracks in the lining or even failure. The voids also change the distribution of the rock stresses around the tunnel, which may result in progressive failure of the rock and rock falls that can lead to additional damage to the liner. Because the void forms behind the liner, it may not be readily detected until significant damage to the liner has been produced, generally in the form of severe cracking, spalling or even failure.
It is essential to cast light on the construction risks in tunnel excavations through the fault-fracture zone (FFZ). This study adopts the material point method (MPM) to simulate the failure ...responses of a rock tunnel face during excavation through the FFZ. A numerical study was conducted to compare a physical model test and validate the feasibility of using the MPM in simulating tunnel face failure. One hundred ninety numerical simulation cases were constructed to represent a rock tunnel excavation project with different site configurations. The simulation results suggest that the cohesion and the friction angle significantly influence failure responses. The tunnel cover depth can magnify the failure responses, and the FFZ thickness significantly affects the mobilized rock mass volume when the FFZ consists of a weak rock mass. The numerical simulation results suggest three deformation patterns: face bulge, partial failure, and slide collapse. The failure responses can be characterized by stress arch, slip surface, angle of reposing, and influence range. The insights suggested by the face failure responses during excavation through the FFZ can aid field engineers in determining the scope of possible damage, and in establishing emergency measures to minimize losses if such failure occurs.
The recent outbreaks of mpox have raised concerns over the need for effective vaccines. However, the current approved vaccines have either been associated with safety concerns or are in limited ...supply. mRNA vaccines, which have shown high efficacy and safety against SARS-CoV-2 infection, are a promising alternative. In this study, three mRNA vaccines are developed that encode monkeypox virus (MPXV) proteins A35R and M1R, including A35R extracellular domain -M1R fusions (VGPox 1 and VGPox 2) and a mixture of encapsulated full-length mRNAs for A35R and M1R (VGPox 3). All three vaccines induce early anti-A35R antibodies in female Balb/c mice, but only VGPox 1 and 2 generate detectable levels of anti-M1R antibodies at day 7 after vaccination. However, all three mRNA vaccine groups completely protect mice from a lethal dose of vaccinia virus (VACV) challenge. A single dose of VGPox 1, 2, and 3 provide protection against the lethal viral challenge within 7 days post-vaccination. Long-term immunity and protection were also observed in all three candidates. Additionally, VGPox 2 provided better passive protection. These results suggest that the VGPox series vaccines enhance immunogenicity and can be a viable alternative to current whole-virus vaccines to defend against mpox.
For a tunnel driven by a shield machine, the posture of the driving machine is essential to the construction quality and environmental impact. However, the machine posture is controlled by the ...experienced driver of shield machine by setting hundreds of tunneling parameters empirically. Machine learning (ML) algorithm is an alternative method that can let the computer to learn from the driver's operation and try to model the relationship between parameters automatically. Thus, in this paper, three ML algorithms, i.e. multi-layer perception (MLP), support vector machine (SVM) and gradient boosting regression (GBR), are improved by genetic algorithm (GA) and principal component analysis (PCA) to predict the tunneling posture of the shield machine. A set of the parameters for shield tunneling is extracted from the construction site of a Shanghai metro. In total, 53,785 pairwise data points are collected for about 373 d and the ratio between training set, validation set and test set is 3:1:1. Each pairwise data point includes 83 types of parameters covering the shield posture, construction parameters, and soil stratum properties at the same time. The test results show that the averaged R2 of MLP, SVM and GBR based models are 0.942, 0.935 and 0.6, respectively. Then the automatic control for the posture of shield tunnel is illustrated with an application example of the proposed models. The proposed method is proved to be helpful in controlling the construction quality with optimized construction parameters.
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