Damage Zone Research Articles

Anchorage characteristics and their impacts on the seismic performance of HECC/RC composites external beam-column joint

In order to enhance the seismic performance and streamline the construction process, particularly in precast frame structures, steel-polyethylene hybrid fiber-reinforced engineered cementitious composites (HECC) is utilized to replace reinforced concrete (RC) in the external beam-column joint core area to form HECC/RC composite joints. In this study, to further alleviate rebar congestion, five no-stirrup reinforced HECC/RC composite external beam-column joints with reduced beam longitudinal rebar anchorage length (i.e., 6d-18d) in core area and one control RC specimen are designed and tested under cyclic loading. Experimental results indicate that anchorage failure occurs until the anchorage of the beam longitudinal rebar decreases to an extremely short length of 6d. In comparison with the control RC specimen, HECC/RC specimens display a reduced bond damage zone and superior bond behavior. Although relatively larger stress is transferred to the anchorage free end when anchorage length is 9d, the beam longitudinal rebar is still effectively anchored without significant slip, indicating that anchorage length of 9d in joint core area may be sufficient which needs further research. In addition, the ultimate bond strength of the rebar embedded in joint core area is lower than that observed in pullout test, underscoring the necessary of considering a safety factor in design anchorage length estimation. Lastly, the contribution of bonding condition on shear force transfer in joint core area is analyzed according to force transfer mechanism, which would promote the determination of the shear capacity of HECC joint. As the bonding damage expanded, the proportion of shear force resisted by truss mechanism decreases, emphasizing the crucial role of adequate anchoring in external joint.

The effects of precursory velocity changes on earthquake nucleation and stress evolution in dynamic earthquake cycle simulations

Seismic velocity changes in earthquake cycles have been observed over a wide range of timescales and may be a good indicator of the onset of future earthquakes. Understanding the effects of precursory velocity changes right before seismic and slow-slip events could potentially elucidate the onset and timing of fault failure. We use numerical models to simulate fully dynamic earthquake cycles in 2D strike-slip fault systems with antiplane geometry, surrounded by a narrow fault-parallel damage zone. By imposing S-wave velocity changes inside fault damage zones, we investigate the effects of these precursors on multiple stages of the seismic cycle, including nucleation, coseismic, postseismic, and interseismic stages. Our modeling results show a wide spectrum of fault slip behaviors including fast earthquakes, slow-slip events, and variable creep. One primary effect of the imposed velocity precursor is on the earthquake nucleation phase, and earlier onset of precursors causes earthquakes to nucleate sooner with a smaller nucleation size that is not predicted by theoretical equations. Furthermore, such precursors affect the nucleation of dynamic earthquakes and slow-slip events. Our results highlight the importance of short- and long-term monitoring of fault zone structures for better assessment of regional seismic hazard.

Comparison of Performance Analysis Results with Developed Site-Specific Response Spectra and Turkish Seismic Design Code: A Case Study from the SW Türkiye Region

On 6 February 2023, the Kahramanmaraş earthquakes clearly showed that the elastic spectrum curves in TBEC-2018 are insufficient to represent earthquake behavior. In this study, the effect of using a site-specific spectrum curve instead of the elastic spectrum given in TBEC-2018 on the earthquake safety of a building is investigated. For this purpose, the provinces in southwest Anatolia, Türkiye, which is one of the most tectonically complex regions with frequent seismic events, were selected. In the first stage of the study, spectrum curves were obtained for earthquakes with return periods of 2475, 475, and 72 years for each of the provinces in this region. These spectrum curves were obtained using probabilistic seismic hazard studies that take into account the active faults of the provinces and earthquake activity in both historical and instrumental periods. In the second stage of the study, analytical models of a selected model RC building were created according to each province, and static pushover analyses of these building models were performed both according to the elastic spectrum given in TBEC-2018 and according to the spectrum curve created specifically for the province. The results of the analyses show that the change in the spectrum changes the target displacement level of the buildings, and as a result, the cross-sectional damage zone of the structural elements under the earthquake effect is changed. So much so that using the site-specific instead of the elastic spectrum given in TBEC-2018 changed the damage zone of 43% of the beams and 26.4% of the columns in the İzmir model. The change in the section damage zones changed the performance level of some floors of the models and the performance level of the building. The study revealed the importance of using the most realistic elastic spectrum curves in order to determine the earthquake performance of buildings that is as close as possible to their behavior in a possible earthquake.

Pre-yielding and necking process of double network hydrogels revealed by sample geometry effects

Understanding the yielding and necking mechanisms of double network (DN) materials is crucial for establishing structure-property correlations. While previous studies have primarily focused on how macro-yielding behavior changes with network structure and swelling, in this work, we study the local internal damage in the pre-yielding process to unveil the yielding and necking mechanisms for typical DN gels. Through birefringence retardation imaging during tensile deformation on DN gels of various sample geometries, our findings reveal the following key points: 1) Initiation and Growth of Damage Zones: Prior to macroscopic yielding, damage zones initiate from the sample edges and gradually grow towards the sample center with elongation. 2) Rapid Propagation and Yielding: Beyond a certain stress threshold, damage zones rapidly propagate under constant loading. Two damage zones eventually merge at the sample center, resulting in yielding. 3) Intrinsic Stress Determination: The stress at this point is intrinsic and determined by the structure of the two networks. 4) Pseudo Size-Dependency: Samples with insufficient width exhibit a pseudo size-dependency of yielding stress, as yielding occurs before reaching the critical stress. To explain the origin of intrinsic yielding stress, we introduce an intrinsic effective crack length (cI) as a measure of stress concentration around the internal crack tip of the damaged zone in the first network. Beyond this length, the influence on internal stress concentration around the damage zone is effectively screened by the load-bearing effect of the stretchable second network. The estimated cI, dependent on the microstructure of the two networks, was approximately 10 times the mesh size of the first network for typical DN gels.

A coupled finite difference‐spectral boundary integral method with applications to fluid diffusion in fault structures

AbstractFluid migration in geological materials, a subject of great interest in various geophysical applications, has been interpreted through multiple numerical methods. Taking advantage of both a volume‐based method and a boundary integral method, we innovate a hybrid spectral‐boundary‐integral and finite‐difference method (SBI‐FDM) to describe the fluid injection and propagation in the fault structure. The coupling of the two methods is established from the consistent exchange of the pressure gradient from the volume‐based method and the boundary flux applied in the SBI boundary. The hybrid method benefits from its capability to truncate the domain and capture the fluid‐induced pore pressure in geological systems without modeling the whole bulk. After establishing the numerical framework, we verify the SBI‐FDM under both homogeneous and heterogeneous mediums using an analytical solution and the FDM results, respectively. After model verification, a sensitivity test showcases the stability of the numerical scheme. A speedup comparison of the SBI‐FDM against the FDM is presented. We observe that the proposed method can achieve better computational efficiency with up to one thousand times speedup in our test. Utilizing the proposed hybrid method, we also perform parametric studies to reveal the significance of mobility contrast between the damage zone and host rock, as well as the role of fault width during fault injection.

Evolution of mining-induced water inrush disaster from a hidden fault in coal seam floor based on a coupled stress–seepage–damage model

Water inrush originating from hidden faults in the coal seam floor is challenging to prevent due to their concealed nature. This paper develops a coupled stress–seepage–damage model for simulating rock fracture, implemented using the finite element method. The model is validated against compression-seepage tests on rock samples, capturing realistic dynamics of shear and tensile damage as well as permeability. The model is applied to the 27305 working face of a coal mine in Shandong Province, China, revealing the evolution of water inrush caused by a hidden fault. The results indicate that as the working face progresses, both the floor damage and the internal damage within the hidden fault escalate gradually. When mining reaches 80 m, the hidden fault has been activated internally, and the depth of floor damage reaches 13 m, which still has a certain distance from the hidden fault. At 100 m, the depth of the floor damage has stabilized, while the stress concentration at the hidden fault's tip increases, and it begins to expand if conditions for tensile damage are met. By the time mining reaches 110 m, the hidden fault has expanded 9.2 m in length and connected with the floor damage zone, forming a water inrush channel that links the aquifer to the working face, presenting a significant water inrush risk. This work provides an intuitive approach to understanding the evolution of water inrush from a hidden fault, aiding in the prevention of water inrush disasters in practical engineering applications.

Tolerated outlier prediction method of excavation damaged zone thickness of drift based on interpretable SOA-QRF ensemble learning

ABSTRACT Drift excavation induces excavation damaged zones (EDZ) due to stress redistribution, impacting drift stability and rock deformation support. Predicting EDZ thickness is crucial, but traditional machine learning models are susceptible to potential outliers in dataset. Directly eliminating outliers, however, impacts training effectiveness. This study introduces an EDZ thickness prediction model utilising quantile loss and random forest (RF) optimised by the seagull optimisation algorithm (SOA), enabling median regression with tolerated outlier performance. 209 sets of data sets containing 34 mine borehole data were used to establish the prediction model. Evaluation using R 2, explained variance score (EVS), mean absolute error (MAE), and mean square error (MSE) demonstrates the superior accuracy of the proposed SOA-QRF model compared to traditional models. Based on the discussion on the treatment of outliers, the outcomes indicate that the SOA-QRF model is more suitable for the dataset with outliers as well as being able to effectuate tolerated outlier prediction. Additionally, three interpretation methods were utilised to explain the SOA-QRF model and enhance the transparency of the model’s prediction process and facilitating the analysis of dispatcher regulation.

Numerical simulation of rock blasting under different in-situ stresses and joint conditions.

High primary rock stress can limit the generation of rock cracks caused by blasting, and blasting usually shows different rock breaking states under different primary rock stress conditions. There are a large number of naturally formed joints in rock mass, due to the limitations of laboratory tests, a numerical model of jointed rock mass was established using LS-DYNA software to investigate the evolution of blasting damage under various in-situ stresses and open joints. In this simulation, using the Lagrange-Euler (ALE) procedure and the equation of state (JWL) that defines explosive materials, the study considered different joint thicknesses (2cm, 4cm, and 6cm), joint angles (0°, 30°, 60°, and 90°), and in-situ stress conditions (lateral stress coefficients of 0.5, 1, and 2, with vertical in-situ stresses of 10MPa and 20MPa), through stress analysis and damage area comparison, the relationship between damage crack propagation and horizontal and vertical stress difference is explored. The research aimed to understand the mechanisms underlying crack initiation and propagation. The results show that: (1) The presence of joints exerts a barrier effect on the expansion and penetration of cracks. When explosion stress waves reach the joint surface, their propagation is impeded, leading to the diffusion of wing cracks at the joint ends. When the lateral stress coefficient and joint angle are the same, an increase in initial in-situ stress results in a reduction in the area of the blasting damage zone. (2) Under the same initial in-situ stress conditions, the area of the blasting damage zone initially increases and then decreases with an increasing joint angle. However, it remains larger than that without a joint, and there exists an optimal angle that maximizes the damage area. In the simulated conditions, the area of damage cracks is greatest when the joint angle is 60° dip angle. (3) The presence of initial in-situ stress has a certain impact on the initiation and expansion of blasting cracks. The degree and nature of this influence are not solely related to the lateral stress coefficient but also depend on the joint's angle and thickness. When in-situ stress is present, the initial in-situ stress field's pressure is not conducive to the initiation and propagation of blasting cracks. However, the existence of a joint has a noticeable guiding and promoting effect on crack propagation, and the pattern of crack propagation is influenced by both joint and in-situ stress conditions.

The Performance Analysis of Grouting Repair Effect on the Accuracy of Disturbance Stress Test in Damaged Surrounding Rock Mass.

Disturbance stress assessment is crucial for ensuring the safety of deep engineering projects. Currently, the primary technique for continuously monitoring three-dimensional disturbance stress is the stress relief method, but its accuracy can be compromised by rock damage that occurs after excavation. To mitigate this issue, grouting is employed to repair damaged rock masses and enhance their mechanical properties. However, the impact of grouting techniques on improving the accuracy of disturbance stress testing is challenging to evaluate through laboratory and in situ experiments. To address this problem, numerical simulation technology is employed to investigate disturbance stress testing after the repair of damaged surrounding rock through grouting. The simulation results indicate that grouting repair significantly enhances the accuracy of stress testing. As the depth of damaged rock mass repair increases, the error in stress testing decreases. Achieving complete repair of the initial damage zone during grouting is essential to eliminate errors in stress testing. Expanding on the positive effects of grouting repair on stress testing, a segmented testing method for disturbance stress is proposed. The method involves separately testing the initial stress and stress changes, thereby reducing the stress level within the rock, minimizing rock failure, and enhancing the accuracy of disturbance stress testing. This study provides valuable reference methods, and the outcomes of this research will serve as a foundation for enhancing the accuracy of disturbance stress testing in deep hard rock engineering.

Fracture analysis and low-temperature thermochronology of faulted Jurassic igneous rocks in the Southern Colombian Andes: Reservoir and tectonic implications

Fractured basement hydrocarbon reservoirs are widely distributed worldwide in more than 30 basins, where volcanic and plutonic rocks have produced significant quantities of oil and gas. The Upper Magdalena Valley Basin (UMVB) is a mature and productive hydrocarbon basin located in the Colombian Andes. In this basin, plutonic and volcaniclastic Jurassic rocks are thrusted on top of Cretaceous to Cenozoic sedimentary rocks, which constitute the petroleum system. Multi-scale fracture analysis together with petrography, petrophysics, and low-temperature thermochronology were conducted in and outcrop analogue of this basement to assess the structural evolution and investigate the main factors controlling the development of fracture properties in igneous basements. Thermochronological data indicate the occurrence of three exhumation events between the Early Cretaceous and Miocene, suggesting that most of the fracture networks within the Agrado-Betania hanging-wall were likely formed before hydrocarbon migration. Structural analysis has identified a fault damage zone with a width of approximately 746 m. Volcanic breccias and ash tuffs exhibit slightly higher areal fracture intensities (P21 > 30 m/m2) compared to plutonic and clastic rocks (P21 < 20 m/m2). Furthermore, the fracture networks exhibit good connectivity, with connection per branch (CB) values exceeding the 1.5 percolation threshold. Petrophysical calculations of matrix-fracture properties indicate high permeabilities (ranging from 1000mD to 10000000mD) and low porosities (<10%). The structural position and the diagenetic transformation of the volcanic rocks are the primary factors controlling fracture intensity in the igneous rocks within the Agrado-Betania fault. Results from this outcrop analogue also show that polyphasic structural histories and the burial history positively influence the quality of fractured basement reservoirs.

Integrating Microseismic Monitoring for Predicting Water Inrush Hazards in Coal Mines

The essence of roof water inrush in coal mines fundamentally stems from the development of water-bearing fracture zones, facilitating the intrusion of overlying aquifers and thereby leading to water hazard incidents. Monitoring rock-fracturing conditions through the analysis of microseismic data can, to a certain extent, facilitate the prediction and early warning of water hazards. The water inflow volume stands as the most characteristic type of data in mine water inrush accidents. Hence, we investigated the feasibility of predicting water inrush events through anomalies in microseismic data from the perspective of water inflow volume variations. The data collected from the microseismic monitoring system at the 208 working face were utilized to compute localization information and source parameters. Based on the hydrogeological conditions of the working face, the energy screening range and its calculation grid characteristics were determined, followed by the generation of kernel density cloud maps at different depths. By observing these microseismic kernel density cloud maps, probabilities of roof water-conducting channel formation and potential locations were inferred. Subsequently, based on the positions of these roof water-conducting channels on the planar domain, the extension depth and expansion direction of the water-conducting channels were determined. Utilizing microseismic monitoring data, a quantitative assessment of water inrush risk was conducted, thereby establishing a linkage between microseismic data and water (inrush) data, which are two indirectly related datasets. The height of microseismic events was directly proportional to the trend of water inflow in the working face. In contrast, the occurrence of water inflow events and microseismic events exhibited a specific lag effect, with microseismic events occurring prior to water inrush events. Abnormalities in microseismic monitoring data partially reflect changes in water-conducting channel patterns. When connected with coal seam damage zones, water inrush hazards may occur. Therefore, abnormalities in microseismic monitoring data can be regarded as one of the precursor signals indicating potential floor water inrushes in coal seams.

Combination of a Failure Index and a Dilatancy-Dependent Permeability Model in Hydro-Mechanically-Coupled Numerical Simulations of Argillaceous Rock Formations of the Callovo-Oxfordian (COx)

Hydraulic-mechanical coupling in claystone is of great importance for repository research, as claystone is considered a possible host rock and hydraulic-mechanical coupled processes can affect the integrity of the barrier. Of particular importance in this context are excavation damage zones and hydraulically-induced microcracks and fractures. In this work, two constitutive equations developed for these hydraulic-mechanical coupled processes are combined in a novel way. The approach exploits the different dominant stress states that prevail in the respective processes. This approach is applied in several numerical simulations for validation and compared with experimental data. The measured data were obtained during gas-injection tests in the scope of the PGZ experiment in the underground laboratory of Bure, France, where the hydraulic-mechanical coupling of the is the Nabla operator claystone was investigated. Five numerical models were calculated, each with a different model configuration, to simulate the excavation damage zone and dilatancy-controlled flow during gas-injection tests. The numerical results show that the developed approach can first satisfactorily predict the extent and behaviour of the excavation damage zone under different stress conditions and the subsequent dilatancy-dependent permeability due to the increased gas pressure.

Effect of wet-dry history on performances of dense asphalt mixture: Experimental investigation and predicting model

Asphalt pavement experiences various wet-dry histories in the service stage. However, the influence of wet-dry history on asphalt mixture is unknown. Therefore, to clarify the performance degradation mechanism and predict the performance of asphalt mixture under the action of wet-dry history, the creep-recovery test, indirect tensile stiffness modulus test and indirect tensile strength test were conducted at different temperatures. The finite element method was adopted to analyze the moisture diffusing profile inside the specimen after wet-dry cycles. A moisture damage model considering the soaking time and repeated characteristics was developed to predict the damaged properties. Results show that wet-dry cycles cause a slight mass loss of asphalt mixture. Wet-dry cycling action leads to the increment in high-temperature deformation, and reductions in stiffness modulus and tensile strength. The increase of high-temperature deformation is primarily caused by viscoplastic component. Even if the soaking time is short, high moisture damage occurs while the wet-dry cycle is sufficient. Numerical simulations show that the moisture concentration profiles inside asphalt mixture vary under different wet-dry histories, leading to variations in the damage zone. The degree of damage is also closely related to the acting time of moisture. The critical immersion time of the dense asphalt mixture (about 43 hours) was determined in this study. When the immersion period is shorter than the critical immersion time, the strength loss is greater than the modulus. On the contrary, the degree of modulus damage is higher than that of strength. Considering the actual rainfall climate in China, the strength damage of the on-site asphalt mixture in the field predominates. The proposed model could reflect the weakening trends of modulus and strength. It has good universal applicability in predicting the damaged Marshall stability, modulus, and strength at different temperatures.

A thermo-hydromechanical damage model and its application to a deep geological radioactive repository

This study conducts a numerical analysis of long-term thermo-hydromechanical (THM) processes, with a particular focus on deep geological disposal of radioactive waste. It emphasizes the modeling of damage zones resulting from excavation activities, as well as changes in pore pressure and temperature. The numerical model presented in this paper delineates the fundamental relations of thermo-poro-elasticity. It also introduces a double phase field model specifically formulated for rock materials under compressive stress, taking into account THM coupling and time-dependent behavior. The proposed model has been implemented in a finite element code and applied to numerical analysis of short and long terms responses around a horizontal borehole in the context of the French High-Level Waste (HLW) disposal concept. In particular, displacements, temperature changes, pore fluid pressure variations as well as evolution of induced damage zones are presented and analyzed for different periods including excavation, operation and post-closure. It is found that the occurrence of damage zones is clearly related to the spacing distance between two neighboring disposal boreholes. The time-dependent deformation of host rock plays an significant role in the long-term responses.

An analytical–numerical method for the hydraulic–mechanical coupling analysis of time-dependent behavior of pressurized tunnels: Impact of an excavation damaged zone

The issue of pressurized tunnels has been sufficiently investigated in the literature; nevertheless, the long-term behavior of the problem, which is the case in very squeezing conditions, remains unexplored. From a practical standpoint, the development of a damaged zone around the tunnel, due to the poor quality of blasting for excavation, imposes an additional challenge in predicting tunnel responses. This paper introduces an analytical approach addressing both water seepage and the excavation damaged zone (EDZ) concerning the long-term behavior of lined circular pressurized tunnels. To achieve this goal, the rheological behaviors of the initial rock mass and damaged zone are modeled using the Burgers model, along with considering the time-dependent variation in the rock mass hydraulic conductivity. After the validation of the model, the conducted parametric studies reveal that rock mass and lining hydraulic conductivities, EDZ radius, and the Burger shear modulus are the most influential parameters.

Practical Methodology for Evaluating Mining Front Stability Based on the Diametrical Core Deformation Technique

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.

Experimental and numerical analysis of tunnel primary support using recycled, and hybrid fiber reinforced shotcrete

Shotcrete plays a pivotal role in the construction of tunnels and underground structures; however, its inherent brittleness necessitates reinforcement to enhance ductility. This research explores the use of fiber-reinforced shotcrete as primary tunnel support to enhance ductility and reduce brittleness. Traditional steel mesh reinforcement complexities have led to the investigation of alternative materials. The research evaluates different fiber mix designs, including industrial steel, recycled steel fibers from tires, and Forta fibers, examining their strength parameters and deformation performance. A 3D finite element model is used to simulate a horseshoe-shaped tunnel with optimal mix design and plain shotcrete in a soil environment. The study finds that hybrid industrial and recycled fibers are more effective than single fibers, enhancing compressive, tensile, and flexural strength and reducing ground surface settlement and tensile damage. The optimal mix design of this study has increased compressive, tensile, and flexural strength, as well as flexural toughness, compared to plain shotcrete. Numerical modeling reveals that utilizing fiber reinforced shotcrete made out of optimal fiber mix design as primary support results in a significant reduction in ground surface settlement and tensile damage value. Furthermore, the study shows a significant reduction in the damaged zone area under tensile stresses. The results of the study highlight the potential of fiber reinforced shotcrete as a primary support for tunnels, leading to improved performance and sustainability in tunnel construction.

Development a novel empirical approach to control overbreak, surface quality and slope angle of benches following blasting

Overbreak, slope angle and quality of a bench behind the boundary of excavation as attractive subjects for mining and civil engineers are the most crucial consequences of the post-blast. But the breakage mechanism of blasting has not originally been well clarified how a desirable slope angle and quality of a bench can be obtained by common drilling and blasting operations and what parameters can affect such blasting consequences? The breakage mechanism and influence of the blasthole parameters such as hole diameters, explosive weight per hole, burden, spacing, stemming, bench height, powder factor and blastability index on the depth of the overbreak zone (L&lt;sub&gt;OZ&lt;/sub&gt;), the difference between hole and bench slope angles (α°-β°) and the width of damaged zone (L&lt;sub&gt;DZ&lt;/sub&gt;) in fifteen zones of Sun gun open pit copper mine, Golgohar open pit iron ore mine, Khoy limestone, Rashakan limestone, Bonab silica mine and Evoghli gypsum mine were investigated. New multivariable nonlinear relations between each of L&lt;sub&gt;OZ&lt;/sub&gt;, (α°-β°) and L&lt;sub&gt;DZ&lt;/sub&gt; with the combination of Φ&lt;sub&gt;h&lt;/sub&gt;, Q, B, S, S&lt;sub&gt;t&lt;/sub&gt; and K were developed. The new achievements in this study can be new guides to obtain the desirable bench slope angle and bench faces.

The dominant pests (Coleoptera) of cereal crops, and population forecast for this

Goal. Create a forecast of the development of harmful organisms in cereal crops, to determine the economic feasibility of applying plant protection measures.&#x0D; Methods. Analysis of the phytosanitary state of cereal crops in Ukraine, where the main attention is paid to the dominant pest species. Analysis of the areas of distribution of these pests, population dynamics, their phenology and the state of populations in the context of natural and climatic zones (Steppe, Forest-steppe and Polissya). To assess the phytosanitary state of crops, and its dynamic changes, the following are used: — the results of phytosanitary monitoring of crops (according to generally accepted methods), which were carried out directly by the staff of the forecast laboratory of the Institute of Plant Protection of NAAS; — current reports of researchers from other laboratories of the Institute of Plant Protection of NAAS from the places of business trips; — materials of decadal reports of regional plant protection stations, as well as signaling and forecasting points; — information on the phytosanitary situation from regional state research stations and institutes of NAAS.&#x0D; Results. A study of the phytosanitary state of cereal crops on the territory of Ukraine was carried out, the dominant species of pests were identified, materials were prepared regarding the peculiarities of the phytosanitary state in the conditions of the year, and a long-term (annual) forecast of the development of pests for the next year was drawn up, based on the appropriate analysis of the data obtained.&#x0D; Conclusions. In recent years, climate change in Ukraine has manifested itself through an increase in the average annual temperature, and an increase in the sum of effective temperatures. A decrease in the zone of sufficient soil moisture was noted, its line shifted to the north. Under the influence of abiotic factors, pests constantly change the boundaries of their habitat and zones of damage, therefore reliable protection of crops is impossible without constant monitoring, constant clarification of the species composition of phytophages, and phytosanitary forecast. Improved methodological approaches for assessing the phytosanitary state of acrocyanoses and the promptness of obtaining relevant data will allow agricultural producers to make timely decisions on the economic feasibility of using certain plant protection products.

Impact and implications of hydrothermal fluids migration in the Frolov hydrocarbon province in West Siberia

Both the prolific source rocks of the Bazhenov Formation and the reservoir-prone units of the Abalak Formation cover most of the West Siberian region. Hydrothermal fluids circulation has been suggested to affect hydrocarbon potential and reservoir properties at some localities of this vast hydrocarbon province. However, integrated studies are currently lacking. Here we present an extensive multidisciplinary study combining regional studies with core logging properties and sample analyses (i.e. geochemistry, petrography, organic geochemistry) to reveal processes related to the hydrothermal activity that affected both formations. We also focus on the factors and implications for secondary unconventional reservoir formation within the deposits from the Kamennaya summit of the Frolov oil and gas region. Three boreholes corresponding to type sections located in different parts of the study area (elevated, transitional and deep) were investigated. The elevated and transitional parts of the basin are adjacent to the weakened contact zones of a granite massif. These tectonic discontinuities acted as conductors for hydrothermal fluids circulation on the area. Lithological and stable isotope studies revealed the presence of intensive hydrothermal secondary alterations in various types in rocks, including massive metasomatic carbonatization, sulfatization, sulfide mineralization and leaching processes. This hydrothermal fluid activity resulted in reservoir formation within siliceous radiolarite layers, while in the deep part of the basin potential reservoirs were completely healed. Organic matter maturity varies in different parts of the basin. We identify several mechanisms related to the various hydrothermal processes that influenced rocks composition, structure and organic matter maturity: (1) A weakened zone located on the periphery of the granite massif in the basin basement is characterized by extensive fault damage zones facilitating the migration of high temperature fluids along deposits during post-sedimentation stages; (2) The thickness, mineral composition of the rocks overlying the basement control fault attenuation and fluid workflow; (3) The fluids composition, their acidity/alkalinity, prompted various changes in rock structure, especially in secondary porosity formation. The identification of various hydrothermal processes and their influence on pore space allowed to determine the approach for the spatial distribution prediction of unconventional reservoirs in the studied formations, and subsequently improve the efficiency and effectivity of the exploration process not only at the Kamennaya summit, but also on the other similar West Siberian basin areas.