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With the increase in mining depth and intensity, dynamic disasters such as rockburst in mines are becoming more severe. Deep resource extraction is characterized by a high in-situ stress geological environment, closely associated with geological dynamic disasters. However, there is currently no quantitative analysis method for the correlation between the two. In this study, an elastic energy density calculation method is employed, considering the dissipative effect of the self-weight stress field on the tectonic stress field. The remaining energy, referred to as impact energy, is used to classify the risk of coal seam impact, providing a computational method for rapid assessment of impact risk before mining production. The proposed calculation method is compared with 22 mine impact engineering practices in the literature, showing accurate predictions for 21 mines. Since measuring in-situ stress and coal seam physical and mechanical properties is a preliminary work in coal seam extraction, the comprehensive analysis of these data holds significant research and practical value.

Previous studies show that the adhesive strength can be expressed as a constant value of the critical ISSF (Intensity of Singular Stress Field) for several butt joints and lap joints. This study deals with the scarf joints where two distinct singular stress fields appear at the interface end. How to evaluate the scarf joint strength is described in comparison with the lap joint where two singular stress fields appear but the second singular stress field is weak. It is found that the adhesive strength of the scraf joints can also be expressed as a constant value of one of the ISSF like other joints. When two singular stress fields are comparable, the debonding strength of the scarf joints can be expressed at a certain point of the sum of the two singular stress fields as σ θ c ( 10 μ m ) = const.

Ultra‐deep bedrock gas exploration remains at a preliminary stage, where comprehensive in‐situ stress evaluation can provide crucial guidance for sweet spot prediction. Taking the bedrock reservoirs in Block K2 of the northern Qaidam Basin as an example, this study systematically assesses in‐situ stress by integrating drilling data, array acoustic logging, conventional well logging, fracturing tests, seismic interpretation, and numerical simulation. A novel in‐situ stress prediction method for ultra‐deep bedrock reservoirs is proposed, which is based on rock mechanical parameter fields and overcomes the limitations of conventional approaches regarding solution multiplicity and computational complexity. The results demonstrate that the bedrock reservoir follows a σv > σH > σh stress regime with significantly lower stress activity compared to shallower reservoirs, showing σH − σh differential stresses predominantly ranging 8–12 MPa. Borehole breakout and drilling‐induced fracture analysis reveals a NNW‐SSE orientation of the maximum horizontal stress. Building upon measured stress constraints, we first established a well‐log interpretation method. Subsequently, we developed a 3D stress field modeling approach through Poisson's ratio optimization, leveraging the positive correlation between wave impedance and Poisson's ratio. This was achieved by integrating Petrel‐based genetic inversion with spectral decomposition, CNN, and GA optimization techniques. The bedrock displays strong horizontal stress heterogeneity, featuring alternating high‐low stress zones. This stress distribution closely correlates with tectonic deformation and faulting patterns. Thrust faults typically create 200 m‐wide stress concentration zones, causing severe borehole instability. These zones also contain poorly‐connected mineralized fractures that reduce permeability and productivity. In contrast, peripheral stress‐relief zones show better reservoir quality, with effective open fractures and consequently higher gas productivity. These findings highlight in‐situ stress as a critical indicator for both well placement and productivity evaluation in ultra‐deep bedrock reservoirs. Log interpretation results diagram of rock mechanical parameters for ultra‐deep bedrock in Well k1‐1.

The inversion of the ground stress field in rock masses is critical for accurate tunnel and underground engineering design. This study addresses the challenge of accurately capturing both the primary and secondary stress field components in rock masses. The ground stress field consists of the primary stress field, generated by applied tectonic loads, and a secondary stress field, which cannot be fully explained by these loads and is attributed to long-term tectonic processes. This unexplained secondary stress field is often non-random in nature. To improve the accuracy of the ground stress field inversion, we propose prioritizing the use of a regression model with a constant term. This model better accounts for the secondary stress field by capturing long-term tectonic influences. The constant term in the regression model is shown to represent the non-random secondary stress field, which cannot be explained by applied tectonic loads. Furthermore, we define two key conditions for applying this regression model: (1) the constant term should not exceed the maximum measured stress and preferably should not surpass the minimum measured stress, and (2) the residual sum of squares of the regression model with a constant term should be smaller than that of the model without a constant term. By incorporating the constant term, the model improves the representation of both primary and secondary stress fields, offering a more accurate inversion of the ground stress field, especially when the stress field contribution from independent variables is incomplete.

The direction of the main compressional stress, at the origin of the orthoenstatite (Oen) inversion to low-clinoenstatite (LCen) lamellae observed in partially dehydrated antigorite-serpentinites, has been inferred based on the crystallographic orientation relationship between Oen host crystals and the LCen lamellae by means of electron backscattered diffraction (EBSD) combined with optical microscopy. This technique was applied to two samples: a transitional lithology (Atg-Chl-Ol-Opx) and a metaperidotite (Chl-Ol-Opx), both collected within 3 m from the serpentinite dehydration front exposed in Cerro del Almirez (Betic cordillera, South Spain). The metaperidotite displays a clear crystal-preferred orientation (CPO) of both Oen and LCen. The transitional lithology shows weaker CPOs. The meta-peridotite contains LCen crystals representative of two possible variants of the Oen to LCen martensitic transformation with distinct orientations, which are consistent with a unique compression direction at ca. 45° to the normal to the foliation and to the lineation of the precursor serpentinite. In contrast, in the transitional sample, calculated compressional stresses display an almost random orientation. The observation of such a variation in the stress field recorded by two samples separated by <3 m rules out a tectonic origin for the stresses producing the LCen in these metaperidotites. We interpret therefore these stresses as resulting from compaction during dehydration. The present analysis implies that compaction-related stresses, though variable at the meter scale, may be organized at the centimeter scale during dehydration reactions of serpentinite.

Die-forging structural parts are widely used in the main load-bearing components of aircrafts because of their excellent mechanical properties and fatigue resistance. However, the forming and heat treatment processes of die-forging structural parts are complex, leading to high levels of internal stress and a complex distribution of residual stress fields (RSFs), which affect the deformation, fatigue life, and failure of structural parts throughout their lifecycles. Hence, the global RSF can provide the basis for process control. The existing RSF inference method based on deformation force data can utilize monitoring data to infer the global RSF of a regular part. However, owing to the irregular geometry of die-forging structural parts and the complexity of the RSF, it is challenging to solve ill-conditioned problems during the inference process, which makes it difficult to obtain the RSF accurately. This paper presents a global RSF inference method for the die-forging structural parts based on the fusion of monitoring data and distribution prior. Prior knowledge was derived from the RSF distribution trends obtained through finite element analysis. This enables the low-dimensional characterization of the RSF, reducing the number of parameters required to solve the equations. The effectiveness of this method was validated in both simulation and actual environments.

Heterogeneous membrane structures with rigid elements are often used in flexible electronic and aerospace structures. In heterogeneous membrane structures under tension, the disturbance stress caused by the rigid element changes the stress distribution of the membrane, and it is difficult to calculate the stress distribution of the heterogeneous membrane structure using the traditional stress functions method. In this article, we propose a method for calculating the non-uniform stress field based on the Eshelby elastic inclusion theory, which states that tension membrane structures contain square rigid elements. The wrinkle distribution of the rigid element at different positions is predicted by a stress analysis, and the influence of the position and size of the rigid element on the wrinkle distribution of the membrane is studied by a finite-element simulation. The research results show that the wrinkle pattern of the stretched membrane can be controlled by changing the position of the rigid element to meet some special needs.

Depending on boundary conditions, welding parameters and plate thickness, high residual tresses may arise near the weld toe of a welded joint. Compressive or tensile residual stresses significantly influence the fatigue strength of the joints in the high-cycle regime. If the weld toe is modelled as a sharp, zero-radius V-shaped notch, the residual stress fields can be expressed in terms of residual notch stress intensity factors (R–NSIFs) calculated in the elastic or elastic-plastic fields. The possibility to quantify the intensity of the residual singular stress field by means of the R–NSIFs allows the designer to estimate the influence of residual stresses on the fatigue life of welded joints. In this work, the influence of residual stresses on the fatigue resistance of Al-alloy butt-welded joints is estimated by using the local stain energy density approach. Values predicted by the proposed method show a good agreement with experimental data taken from literature.

In this study, the fatigue fracture criterion of the adhesively bonded joint is discussed. The singular stress field is formed at the interface end in the butt joint and causes the debonding fracture. The singular stress field is represented with the intensity of singular stress field (ISSF). The static debonding strength of the adhesively bonded joints is expressed with a constant value of critical ISSF. The rotating-bending fatigue tests are carried out on the butt joints of 15mm in diameter with four different adhesive thicknesses of 109 - 159μm, 209 - 265μm, 393 - 432μm and 754 - 841μm. The evaluation method by the ISSF is applied to the experimental results. It is found that the fatigue strength of the butt joint can be expressed with the constant value of critical ISSF.

The state of stress in a mining front constantly changes with mining activities. In a recent study, the authors developed and verified with laboratory measurements an analytical model for the calculation of mining-induced stresses based on measuring the deformations of a diamond drill rock core extracted perpendicular to the mining front or face. The method is called diametrical core deformation technique (DCDT). In this study, the DCDT is used in combination with 3D numerical modelling to develop a practical methodology for the assessment of mining face stability. To demonstrate the methodology, a diamond drill rock core was retrieved from an access drift face 530 m below the surface of an underground mine in northern Quebec. The state of stress in the mining front is estimated from the DCDT and used to adjust the orientation and principal stress magnitudes in the local area around the access drift in a 3D linear-elastic numerical model using an iterative approach. As the rock core is partially fractured due to previous face advance blasting, the numerical model is further adjusted to model the observed damage zone. The 3D model after adjustments is used to examine the mining front stability with the Hoek–Brown failure criterion. It is postulated that the proposed methodology is suitable for the stability assessment of any mining front with or without an observed damage zone.