Three-dimensional laser scanning and numerical investigation on the influence of freeze-thaw and hang-wall mining on the instability of an open-pit slope

The instability of the open-pit slope and associated disasters of complex orebodies such as hanging-wall mining are the key problems to be solved urgently in the development of western resources. In this work, taking the hanging-wall mining in the open-pit mine of Hejing iron mine, for example, the disaster mechanism influenced by the coupling freeze-thaw and hanging-wall mining is systematically studied by 3D laser scanning and numerical simulation. Firstly, the rock mass structure information such as dip, dip angle, spacing, and equivalent trace length characteristics was obtained using 3D intelligent recognition technology. Then, numerical simulation is employed to reveal the influence of freeze-thaw and excavation sequences on the overall stability of the open-pit slope. The stress, displacement, plasticity zone, and maximum shear strain patterns are revealed in detail. The results show that the excavation engineering will lead to frequent increase and unloading of the internal stress of the rock mass, and the gradual increase of the goaf area will cause great damage to the rock mass. The slope failure mode is strongly impacted by freeze-thaw weathering and orebody excavation

On the effect of water content on fatigue mechanical behaviors of mud-shale under stress disturbance conditions

This paper aims to reveal the fatigue damage and instability behaviors of mud-shale under multistage increasing-amplitude fatigue loading. The fatigue loading tests combined with real-time acoustic emission (AE) monitoring technique were employed to investigate the influence of water content on the deformation, damage, and fracture characteristics. Testing results show that rock fatigue life decreases with the increase of water content, and the hysteresis curve changes regularly with time. The failure process can be divided into three stages: initial stage, stable development stage and acceleration stage. The acoustic emission output activities were also influenced by the water content. The acoustic emission ring count and acoustic emission energy both decrease with increasing water ratio and the accumulative count and energy are the least for a sample having high water ratio. The acoustic emission activity shows a sudden increase trend at the amplitude-increasing moment, indicating the occurrence of strong damage within rock sample. The damage propagation within a cyclic loading stage is relatively small compared to the stress-increasing moment. The results are helpful to understand the fatigue mechanical responses of water-sensitive soft rock, as well as the slope stability of the open-pit mine. The research results have important theoretical and practical significance for promoting slope treatment and disaster prevention

Insight into the Effect of Natural Fracture Density in a Shale Reservoir on Hydraulic Fracture Propagation: Physical Model Testing

Here, laboratory tests were conducted to examine the effects of natural fracture density (NFD) on the propagation of hydraulic fracture (HF), HF and natural fracture (NF) interaction, and the formation of the stimulated reservoir volume (SRV). Laboratory methods were proposed to prepare samples with dense, medium and spare discrete orthogonal fracture networks. After conducting a true triaxial hydraulic fracturing experiment on the synthetic blocks, the experimental results were analyzed by qualitative failure morphology descriptions, and the quantitative analysis used two proposed new indices. On the pump pressure profiles, it reflected the non-linear interactions between HFs and NFs well. For rock blocks with a dense DFN density, pump pressure curves present fluctuation shape and the degree of interaction between HF and NF is strong; however, for model blocks with a sparse DFN density, the pump pressure curves present a sudden drop shape. In addition, different propagation behaviors of NFs—offset, divert, branch, and cross NF—can be observed from the fractured model blocks. By using a proposed index of “P-SRV”, the relationship between NFD and the fracturing effectiveness was further confirmed. Furthermore, the most striking finding is that mixed mode I–II and I–III fracture types can be formed in the naturally fractured model blocks. The experimental results are beneficial for grasping the influential mechanism of NFD on the propagation of HF and for developing more accurate and full 3D-coupled simulation models for unconventional oil and gas development

Insight into the Effect of Natural Fracture Density in a Shale Reservoir on Hydraulic Fracture Propagation: Physical Model Testing

Here, laboratory tests were conducted to examine the effects of natural fracture density (NFD) on the propagation of hydraulic fracture (HF), HF and natural fracture (NF) interaction, and the formation of the stimulated reservoir volume (SRV). Laboratory methods were proposed to prepare samples with dense, medium and spare discrete orthogonal fracture networks. After conducting a true triaxial hydraulic fracturing experiment on the synthetic blocks, the experimental results were analyzed by qualitative failure morphology descriptions, and the quantitative analysis used two proposed new indices. On the pump pressure profiles, it reflected the non-linear interactions between HFs and NFs well. For rock blocks with a dense DFN density, pump pressure curves present fluctuation shape and the degree of interaction between HF and NF is strong; however, for model blocks with a sparse DFN density, the pump pressure curves present a sudden drop shape. In addition, different propagation behaviors of NFs—offset, divert, branch, and cross NF—can be observed from the fractured model blocks. By using a proposed index of “P-SRV”, the relationship between NFD and the fracturing effectiveness was further confirmed. Furthermore, the most striking finding is that mixed mode I–II and I–III fracture types can be formed in the naturally fractured model blocks. The experimental results are beneficial for grasping the influential mechanism of NFD on the propagation of HF and for developing more accurate and full 3D-coupled simulation models for unconventional oil and gas development

The Prognostic Value and the Oncogenic and Immunological Roles of Vacuolar Protein Sorting Associated Protein 26 A in Pancreatic Adenocarcinoma

The identification of the prognostic markers and therapeutic targets might benefit the diagnosis and treatment of pancreatic adenocarcinoma (PAAD), one of the most aggressive malignancies. Vacuolar protein sorting associated protein 26 A (VPS26A) is a candidate prognosis gene for hepatocellular carcinoma, but its expression and function in PAAD remain unknown. The mRNA and protein expression of VPS26A in PAAD was explored and validated by bioinformatics and immunohistochemical analysis. The correlation between VPS26A expression and various clinical parameters, genetic status, diagnostic and prognostic value, survival and immune infiltration were evaluated, and the co-expressed gene-set enrichment analysis for VPS26A was performed. Cytologic and molecular experiments were further carried out to investigate the role and potential mechanism of VPS26A in PAAD. The mRNA and protein levels of VPS26A were elevated in PAAD tissues. High VPS26A expression was associated with the advanced histological type, tumor stage simplified, smoking status and tumor mutational burden score, and the poor prognosis of PAAD patients. VPS26A expression was significantly correlated with immune infiltration and immunotherapy response. VPS26A-co-expressed genes were mainly enriched in the regulation of cell adhesion and actin cytoskeleton and the immune-response-regulating signaling pathway. Our experiments further demonstrated that VPS26A promoted the proliferation, migration and invasion potentials of PAAD cell lines through activating the EGFR/ERK signaling. Our study suggested that VPS26A could be a potential biomarker and a therapeutic target for PAAD through comprehensive regulation of its growth, migration and immune microenvironment