Seepage anomalies pose a major threat to earth-rock dam safety, necessitating advanced predictive tools. This study develops an improved rescaled range (R/S) analysis method for quantitative prediction of seepage failure. The practical feasibility of the method is confirmed through an engineering case study, where it successfully diagnosed an anomalous piezometric head rise. The results show that the proposed method discerns both randomness and trends in seepage time series, elucidating the fractal evolution of seepage from incubation to failure. During incubation, high randomness reflects fine particle mobilization, chaotic rearrangement, and Brownian motion, leading to slow pore channel formation. In the formation stage, both randomness and weak trends appear, with fractal characteristics undergoing a non-stationary transition due to directional fine particle loss. As the process advances from development to failure, the V(n)∼Ln(n) relationship exhibits a sharp transition: trend dominance intensifies while long-term memory vanishes. This evolution, driven by continuous channel expansion toward full connectivity, heralds a critical threat to dam safety. Numerical simulations confirm the predicted failure trend and clarify the governing mechanisms. These findings provide a theoretical basis for early-warning thresholds and practical guidance for emergency decision-making regarding seepage failure in earth-rock dams.

Microwave heating offers a promising technique for rock breakage. However, the constituent diagenetic minerals within geological formations are inherently heterogeneous, and such mesostructural variability significantly influences the mechanisms of microwave-induced fracturing. To clarify the effects of grain size on the microwave-induced fracturing behavior, this study conducts a comprehensive investigation of coarse-, medium-, and fine-grained granites under 9 GHz open-ended microwave irradiation. Acoustic emission (AE), infrared thermography, and P-wave velocity measurements are integrated to monitor the thermo-mechanical responses of granites. The results demonstrate that coarse-and medium-grained granites exhibit greater P-wave attenuation, larger crack scales, and higher AE counts than fine-grained granites. The earlier decrease in the b-value and the increased proportion of shear cracks in coarse-grained granite suggest its earlier transition to the macroscopic failure stage. The thermal-damage conversion efficiency index and the damage-energy correlation index of coarse-grained granites can reach more than twice those of fine-grained granites. Furthermore, a novel grain-- grain boundary rock modeling method based on discrete material matrix and structured mesh is proposed. Electromagnetic-thermal-mechanical-fracture simulation in rocks under microwave irradiation is performed. The simulation results reveal that the coefficient of variation (COV) and spatial correlation length of multiphysics fields is larger in coarse-grained structures. Biotite and quartz act respectively as strong localized heat sources and high thermal-expansion carriers. The multiphysics field localization and grain-boundary weakening jointly drive the larger fracture scale in coarse-grained granite under microwave irradiation. These findings highlight the engineering potential of microwave-assisted rock breakage in deep coarse-grained granitic formations.

Revealing the disaster-inducing mechanisms of fracturing instability and the evolution patterns of fracture fields in the overburden during the mining of deeply buried extra-thick coal seams serves as the theoretical foundation for preventing hazards such as water and sand inrushes in coal mine working faces. Based on the mining geological conditions of the 2301 working face in a mine in Shaanxi Province, China, this study investigated the fracture movement and dynamic distribution characteristics of the fracture field in the overburden through a combined approach of numerical simulation, fractal theory, fracture entropy theory, mechanical modeling, and field measurements. Firstly, the dynamic evolutions of fracture rate, fractal dimension, fracture length, and fracture entropy in the overburden were analyzed from the perspective of the mining-induced fracture field. Besides, the proportions of open and closed fractures, fracture length characteristics, and fractal evolution features in various sub-regions during mining were further revealed. Moreover, the anisotropy of spatial distribution of fractures in the overburden was quantified, and the equilibrium trajectory equation of the stress arch in the overburden was established. The following beneficial results were obtained. The overburden exhibits pronounced group-wise fracture movement behavior and periodic arching characteristics of the fracture arch, where the periodic arching fracture serves as the dominant fracture controlling the fracture field. The fractures within the fractured zone are distributed in an “arc shape”, and the average fracture rate and fractal dimension there are 2.40% and 0.81, respectively. The mining-induced fracture field evolves into a largely symmetrical “arc-shaped” topological structure. During mining, the fracture field successively experiences “stress field reconstruction, fracture initiation and propagation, structural instability and reorganization, and self-repair regulation”, while fractures in the overburden undergo a dynamic evolution process from “fracture opening” to “fracture closing”. In this process, dominant fracture groups merge to form interconnected fracture networks. Furthermore, the anisotropy of fracture spatial distribution in different regions of the fracture field was quantified in the light of the fracture entropy theory, and the evolution and distribution characteristics of fracture dip angles in various regions of the mining-affected overburden were statistically analyzed. Based on the three-hinged arch structure theory, the equilibrium trajectory equation of the stress arch in the overburden was established. Field measurement results disclose a water-conducting fracture zone height of 224 m and a fracture-to-mining ratio of 24.9, which closely align with the numerical simulation outcomes. The findings provide valuable insights for hazard prevention in working faces under similar geological conditions.

The methane deflagration fracturing technology impacts and fractures the reservoirs and generates the complicated fracture network by the high-pressure and high-temperature gas, which is generated from the deflagrations of methane desorbed from in-situ reservoirs with the aid of combustion improver. It is important for improving the methane deflagration construction technology to realize the fracturing characteristics of rocks under the effect of deflagration loading. To overcome the difficulties of singularity and meshing-dependence in traditional numerical calculation methods for calculating the crack propagation problems of deflagration fracturing, based on the assumption of small deformation, the bond force vector in the ordinary state-based peridynamic model is rebuilt by using the peridynamic differential operator. The surface effect and volume correction in the classical ordinary state-based peridynamic model are avoided. Then the ordinary state-based peridynamic model of the rock fracturing under the effect of methane deflagration loading is built. The effects of the increase rate, decrease rate of deflagration loading, and the geo-stress distribution on the failure pattern are analyzed. The results show that, the distribution of geo-stress has a significant impact on the crack propagation characteristics of deflagration fracturing. The direction of the initial maximum stress is the dominating direction of crack propagation for the methane deflagration fracturing. With the decrease of the lateral pressure coefficient, the maximum fracturing radius of methane deflagration also increases, but the crack number and the total damage value decrease obviously. With the increase of the methane deflagration pressure increase rate, more initial cracks were generated around the wellbore and the formed initial radial cracks bifurcate and form circumferential secondary cracks, but the fracturing range of methane deflagration decreases. The initial cracks for methane deflagration fracturing mainly be formed during the pressure increase stage. The pressure in the decrease stage is mainly used for propagating the formed initial cracks. The fracturing range of methane deflagration increases with the decrease of the pressure decrease rate. The research results have a good guiding role in optimizing the boreholes layout and improving the fracturing effects for methane in-situ deflagration fracturing.

Local deformation around cracks within rock masses critically influences rock mass deformation and instability. However, correlation between internal and surface deformation at cracks remains poorly studied. This study prepared rock-like models to analyze the feasibility of using local strain direction deflection as a precursor to surface cracking, and examined the modulating effect of compressive strength on this precursor phenomenon. It discusses the feasibility of using internal strain direction deflection as a precursor to model instability and the influence of strength on this effect. Before instability, strain values on both sides of the internal fracture increases significantly, accompanied by abrupt changes in the deflection angle. Relative slip progressed through three stages: minor deformation, stable deformation, and rapid deformation. During the stable deformation stage, the deflection angle within the compression quadrant was strongly correlated with the sliding velocity. Higher compressive strength resulted in greater internal deformation before instability, more pronounced growth, lower relative sliding velocity, as well as a larger time and stress range over which surface deformation occurred. Lower compressive strength corresponded to a smaller ratio of the recovery stress to the peak strength.

This study investigates the creep behavior and acoustic emission (AE) characteristics of bedded coal samples under acidic water environments. Uniaxial graded creep tests coupled with AE monitoring were conducted on samples with bedding angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees, respectively. The anisotropic mechanical behavior and acoustic emission characteristics in terms of stress-strain, deformation, AE count, AE energy, and spectrum characteristics were revealed. The experimental results show that the strength of the coal samples gradually decreases as the saturation duration increases. At the same axial stress level, the axial deformation of the coal samples becomes larger with increasing saturation duration. The mechanical strength exhibits a distinct "U-shaped" relationship with the bedding angle, initially decreasing and then increasing. Correspondingly, axial deformation at a given stress level first increases and then decreases as the bedding angle increases. AE activity, particularly the AE ring count and energy, peaks at specimen failure, indicating significant fracture development. Spectral analysis revealed that under conditions of severe strength degradation (e.g., 0 degrees bedding after 60-day saturation or 60 degrees bedding after 30-day saturation), high-frequency, high-amplitude AE signals were absent. This suggests a shift in the dominant fracture mechanism from small-scale cracking to larger-scale fracture propagation in weakened samples. These findings offer valuable theoretical insights for the prevention and early warning of coal mine disasters.

To investigate the dynamic response mechanism of deep mine surrounding rock under complex stress and cyclic impact loading, this study takes granite as the research object and systematically conducts dynamic mechanical tests on samples with different aspect ratios (0.5 and 1) under three-dimensional cyclic impact loading using a Split Hopkinson Pressure Bar system. The study considers different impact air pressures (0.4, 0.5, and 0.6 MPa) and combinations of pre-applied axial and confining pressures (simulating in situ stress conditions at depths of 400 and 600 m). The dynamic stress-strain behavior, energy dissipation patterns, damage evolution characteristics, and failure modes of the samples are analyzed. The results indicate that aspect ratio and impact air pressure significantly affect the dynamic peak stress, peak strain, and elastic modulus of the samples. The dissipated energy density increases linearly with the number of impacts, with samples of smaller aspect ratios exhibiting higher dissipated energy. The damage variable increases with the number of impacts, and high confining pressure can inhibit damage development. The failure mode transitions from "tensile-dominated" to "shear-composite," with aspect ratio influencing the crack distribution morphology. Based on energy and strain characteristics, a rockburst propensity index D r is proposed, which comprehensively considers peak stress, peak strain, and energy ratio, and its normalized relationship with the number of impacts is established, providing a theoretical basis for rockburst risk assessment in deep mines.

The evolution height and distribution pattern of mining-induced fractures beneath the hard roof of a deep ultra-thick coal seam are important parameters for the prevention and control of roof water hazards. This study took the 2303 working face of a coal mine as the engineering background. By integrating DEM numerical simulation, image processing technology, and field measurements, the typical failure structures of the mining-induced overburden and the evolution of the fracture field were quantitatively characterized from the perspectives of fracture count, fracture length, fracture area, fracture porosity, fracture density, fractal dimension, fracture entropy, fracture inclination angle, and permeability. On this basis, the mining-induced failure and movement characteristics of the overburden structure and the evolution of the fracture field beneath the hard roof of a deep ultra-thick coal seam were elucidated. The following beneficial findings were yielded: 1) The mining-induced overburden at different stratigraphic levels undergoes the transition from intact suspended structures to fractured and collapsed ones and from stable suspension to fracturing and rotational subsidence, and ultimately to bending subsidence. The water-conducting fracture zone was observed to sequentially go through five stages and reach a peak height of 224.0 m, with a fracture-to-mining ratio of 18.7. The simulation results are in good agreement with the field observations. 2) The evolution of fracture porosity and fractal characteristics associated with the upward propagation of fracture “opening, closure, and compaction” in different sub-regions of the mining-induced fracture field was revealed. The fractal dimension of the fracture field successively undergoes a dimension-rising stage, a dimension-stable stage, a dimension-falling stage, and another dimension-stable stage, and the fracture field displays a trapezoidal distribution along the mining direction. 3) The anisotropy of the spatial distribution of mining-induced fractures was quantified based on the fracture entropy index. When secondary fractures propagate along the main fracture path, the fracture entropy evolves nonlinearly. The compaction effect in the goaf causes partial fracture closure, leading to dynamic convergence of fracture entropy. In addition, the distribution and evolution characteristics of fracture inclination angle types in different regions and at different mining distances were statistically analyzed. 4) Considering the structural characteristics of the mining-induced overburden, a seepage model comprising a weak-seepage zone, an intermediate seepage transition zone, and a strong-seepage zone was constructed. Moreover, the evolution of mining-induced overburden seepage fractures was concluded, and the overburden damage and hazard-causing mechanism of ultra-thick coal seam mining was explained from both macroscopic and microscopic perspectives.

Deep hard rock tunnels are prone to fatigue-induced instability and rockburst-like failure under high in-situ stress, excavation unloading, and cyclic disturbance. However, the understanding of the failure process, energy precursors, and three-dimensional (3D) damage morphology remains insufficient. This paper takes granite from Shandong Linglong Gold Mine as the research object. Through true triaxial fatigue loading (TTFL) tests simulating field-derived stress states and excavation disturbance effects, combined with CT 3D reconstruction, scanning electron microscopy (SEM), and energy analysis, the mechanical response, axial energy evolution, and macro–meso–micro failure characteristics of hard rock are systematically investigated. The results show that under TTFL, the stress–strain curves exhibit obvious hysteresis characteristics, and peak strain and residual strain increase nonlinearly with cyclic loading, reflecting progressive fatigue damage accumulation and accelerated deformation before instability. Axial input energy and dissipated energy increase stepwise with stress amplitude, while the dissipated energy ratio evolves in a “U” shape; its sharp rise from the stable fluctuation stage can serve as an energy-based precursor to instability. The joint energy coordinate system can distinguish the transition from compaction and stable damage accumulation to critical failure. Macroscopic failure manifests as symmetric “V”-shaped rockburst pits and conjugate crack networks, with a maximum pit depth of approximately 14 mm. SEM observations reveal sliding cracks, intergranular fractures, transgranular fractures, and longitudinal through-fractures, showing cross-scale failure characteristics. This study reveals the damage-instability mechanism of hard rock under TTFL, providing experimental support for fatigue damage assessment and instability warning in deep hard rock tunnels.

Research on CO2 phase change blasting has historically fallen behind field practice as a powerful alternative to explosive rock-breaking technology. The jet generated by CO2 phase change blasting serves as the primary force behind the fracturing of rock mass. A comprehensive CO2 blasting jet test system was developed, utilizing high-speed infrared and standard high-speed cameras, based on the principle of rock splitting in CO2 fracturing technology and the ultra-high under-expansion jet of CO2. The research explored the characteristics of blasting jets as they evolved from various types of fracturing devices across different shear thicknesses. The results show that the initial jet of CO2 blasting represents a typical ultra-high under-expansion jet, characterized by significant instability and varying morphological features at different stages. The shape of the initial blast jet of the Type 95 fracturing device is notably influenced by the expansion wave, transforming from an oval to an approximately spherical shape. The evolution of the jet encompasses intricate phase changes. The CO2 phase change blasting jet experiences injection initiation, dynamic expansion, and stable development, resulting in a complex flow of a gas-solid two-phase mixture. As the thickness of the shear slice increases, the diffusion length of the visible cloud axis also expands, whereas the boundary gain of the diffusion capacity diminishes. Furthermore, the maximum diffusion velocity along the jet axis increases. In the high-temperature expansion phase, the core temperature of the jet rises dramatically, surpassing the temperature measurement limit by 184.133 ℃, resulting in the jet angle approaching nearly 180°. As the shear slice thickness increases, both the duration of the over-temperature region and the proportion of “over-temperature pixels” in the CO2 blasting jet rise accordingly. This study offers essential data and experimental backing for additional exploration of the rock-breaking mechanisms associated with CO2 blasting jets.

Deep roadway excavation in water-rich shale formations faces coupled challenges of long-term water saturation and cyclic blasting dynamic disturbance, yet the true triaxial mechanical behavior and coupled damage mechanisms of water-saturated shale under such conditions remain unclear. This study converts field blasting loads into laboratory stress paths via on-site monitoring, Fourier transform processing, and Miner's rule derivation, and conducts true triaxial fluid-structure coupling tests on shale specimens with varying saturation durations and pore water pressures, integrated with acoustic emission (AE) monitoring, post-test computed tomography (CT) scanning, 3DEC numerical simulation, analytical modeling, and neural network verification. The results show that pore water pressure acts as a damage amplifier, accelerating strain accumulation and damage evolution, while water saturation preconditions the microstructure: it transforms failure modes from localized brittle fracture to distributed ductile shear damage, and suppresses the permeability threshold of natural specimens via clay swelling-induced fracture network modification. Notably, a maximum damage point is identified at 24 h of water saturation, where the synergistic degradation of saturation-induced weakening and disturbance-induced damage peaks across all pore water pressure conditions. The developed neural network model achieves high accuracy in predicting post-disturbance mechanical properties. This work provides critical theoretical support for stability control and support design of water-rich shale roadways during blasting excavation.

Hydraulic fracturing technology leads to the development of lots of fractures in the surrounding rock reservoir, forming a three-dimensional fracture network, which plays a role in hindering the transfer of high stress. Under temporal-spatial influence, however, the fracture networks of different media will appear, mainly including water medium fractures and air medium fractures. Clarifying the influence of different medium fractures on the stress transfer is quite important for the layout of the three-dimensional fracture network. In this study, the effects of air and water medium fractures on stress transfer were explored through fracture mechanics theory, and Split Hopkinson Pressure Bar (SHPB) test. Under the joint action of fractures and stresses, the rock mass will form an undamaged zone, a damaged zone around the fracture, a damaged zone under the primary action of stress wave, and the damaged zone under repeated action of reflected stress wave, a model of dynamic load stress transfer hindered by fractures is established, through SHPB test study on dynamic load stress transfer hindered by air/water medium fracture, composite sized fractures, and different impact velocity, the correctness of the model is verified by comparing the theoretical data and experimental data. The results show that air medium fractures can hinder the transfer of stress wave and form a large number of reflected waves to damage the rock mass. The water medium fracture can gather energy, act on the surrounding broken rock mass, form confining pressure, and increase the strength of rock mass, making it difficult to destroy the rock mass under stress action. With the increase of impact energy, the energy absorbed by fractures in water medium is limited, and a large number of stress waves damage rock mass.

This research aims to examine the damage and failure behaviour of red sandstone under multistage-stage amplitude increasing cyclic (MS-AIC) loading, with three different increasing stress amplitudes (ISA). By combining macroscopic mechanical testing and acoustic emission (AE) monitoring techniques, the impacts exerted by three distinct ISA schemes are comprehensively analysed. The investigation focuses on the stress-strain behaviour, energy evolution, AE activity, and damage development in red sandstone. The results demonstrate that (1) Under MS-AIC loading, both the axial strain and damage accumulated progressively with cycle number. According to the irreversible axial strain produced during cyclic loading, a model which can describe the process damage of red sandstone was proposed. (2) The energy evolution analysis showed that under the effect of different ISA, the input energy accumulated, and the dissipated energy exhibited an initial decrease followed by an increase. (3) The cumulative AE counts rose steadily with cycles; AE counts and energy release rate increase sharply when the stress increases. As ISA increased, the tensile cracks ecrease gradually, with the growth in the shear cracks. The final failure mode was a composite tensile-shear fracture. The results support further understanding of the stability of rock mass under MS-AIC loading.

Multi-seam repeated mining in gully terrain readily induces overburden structural reconfiguration, reconnection of fracture networks, and renewed surface damage, thereby posing a serious threat to the ecological environment and safe mining in coalfields. To investigate the pronounced fracture reactivation of the overburden and the associated surface failure response under upward repeated mining in gully terrain, this study combines physical similarity simulation, particulate flow numerical simulation, and field displacement monitoring to systematically examine overburden stress evolution, fracture network development, and surface movement and deformation. The results show that, during lower-seam extraction, the overburden stress flow is deflected and a macroscopic stress-arch structure is formed; by contrast, upward repeated mining causes this macroscopic stress arch to gradually dissipate and reorganise into a multi-level stress-arch system, indicating a transition in the overburden load-bearing path from a single dominant arch to multilevel load sharing. On this basis, a dynamic identification method for the caving zone and waterconducting fractured zone was developed by integrating the overburden bulking coefficient, contact damage degree, and dominant fracture dip angle. Combined with porosity, fracture orientation entropy, fractal dimension, and connectivity coefficient, the fracture network was quantitatively characterised by zoning, and four typical zones were identified, namely the macroscopic fracture zone, the caving-compaction zone, the fracture reactivation zone, and the gully damage zone. Field monitoring and numerical results consistently indicate that upward repeated mining induces a second episode of intense surface subsidence, with the subsidence process exhibiting a staged evolution of rapid increase-slow increase-stabilisation. After repeated mining, the ground surface subsided by a further 2.65 m, and the maximum horizontal displacement of the slopes on both sides of the goaf reached 3.20 m. Comparative analysis further demonstrates that upward repeated mining results in stronger overall overburden damage and fracture reactivation than downward repeated mining, whereas downward repeated mining triggers surface damage at an earlier stage. These differences are fundamentally governed by the inheritance of pre-existing structural damage, stress-arch reconfiguration induced by repeated mining, and the asymmetric constraints imposed by gully topography. The findings provide a theoretical basis for failure-risk identification and hazard prevention under repeated mining in gully terrain.

The regulatory effects of dynamic loading frequency on grouted reinforcement specimens (GRSs), particularly under complex underground disturbances, remain insufficiently explored. To address this gap, we conducted increasing-amplitude fatigue tests at various frequencies. This study investigates the consequent evolution of fatigue damage, acoustic emission (AE) characteristics, and macroscopic failure modes. Findings demonstrate that increasing the loading frequency leads to progressive enhancements in both the fatigue strength and life of GRSs. By contrast, a consistent decrease is observed in the peak axial, radial, and volumetric strains and their respective strain rates, indicative of significant frequency sensitivity and viscoelastic behavior in the material. Based on irreversible axial strain, the fatigue damage model exhibits a three-stage evolution characterized by initial, stable, and accelerated growth phases under increasing-amplitude loading. This process is marked by a strong sensitivity to loading frequency. AE monitoring reveals that both cumulative ring count and energy count decrease markedly at higher loading frequencies. Analysis of frequency spectrum characteristics, the b-value, and RA-AF crack evolution indicates that loading frequency substantially influences crack propagation modes and failure mechanisms by modulating the time scale of crack expansion and the rate of strain accumulation per cycle. Under high frequency fatigue loading, shear crack activity becomes more prominent, whereas low frequency fatigue loading tends to induce macroscopic tensile failure. These insights establish a theoretical basis for assessing the longtime stability of grouted reinforcement structures in underground metal mines, supporting their safety design during complex dynamic disturbances.

Methane in situ explosive fracturing (MISEF) aims to create efficient fracture channels in perforations by utilizing detonation loading to facilitate methane migration, yet the confined propagation of methane–oxygen explosive loading and its control on through-going fracture formation in bedding shale remain insufficiently understood. In this study, core-scale methane–oxygen explosive fracturing experiments were combined with high-fidelity numerical simulations to investigate the multiscale fracture evolution and dynamic failure mechanism of bedding shale. Post-fracturing fracture networks were quantitatively characterized using μ-CT three-dimensional reconstruction, fracture surface morphology analysis, multifractal characterization, and seepage evaluation. A physically consistent explosive-loading model was further established by coupling a modified JWL equation of state with a bedding-resolved shale constitutive model, enabling the reproduction of explosive-wave propagation, reflection, superposition, and stress evolution within the explosion tube–shale borehole system. The results indicate that, under low confining pressure, explosive loading induces a three-dimensional fracture network dominated by a bedding-controlled through-going main fracture and supplemented by secondary bedding-parallel fractures, whereas elevated confining pressure markedly suppresses fracture propagation and connectivity. Increasing explosion intensity enhances fracture volume, connectivity, and spatial complexity, while the pore–throat system within the through-going fracture evolves from fine short-range channels to a composite network with multiscale apertures and flow pathways. Multifractal and seepage analyses reveal that fracture complexity is mainly intensified in localized high-damage zones rather than through uniform spatial expansion, and that through-going fractures serve as preferential flow conduits. Numerical results further show that confined explosive waves sustain energy transmission through reflection-induced amplification, generating coupled radial compressive and hoop tensile stresses perpendicular to bedding, while fracture initiation and coalescence along bedding planes are governed by short-duration, high-amplitude hoop tensile stress pulses. This study clarifies the dynamic mechanism of bedding-controlled through-going fracture formation and provides a mechanistic basis for optimizing MISEF in bedding shale.

Blockage during the pipeline transport of cemented paste backfill (CPB) causes significant economic losses to mining operations. Suspending agent (SA) addition has been proposed as an easily implementable and low-cost method to mitigate the risk of pipeline blockage caused by sedimentation during the transportation of CPB. However, the effects of SAs on the rheological and sedimentation properties of CPB are not yet fully understood. This study investigated the rheological and sedimentation characteristics of CPB with different types of SAs. CPB mixtures were prepared with three types of SAs (hydroxypropyl methylcellulose (HPMC), polyacrylamide (PAM), and xanthan gum (XG)) at concentrations of 1.5, 3.0, and 6.0 g/L. The rheological properties (yield stress and viscosity) and sedimentation characteristics (bleeding and monitored via layered electrical conductivity) were measured over 0-2 h. Additionally, zeta potential and microstructural analyses were conducted. SA addition increased the yield stress and viscosity of CPB. Concurrently, the SAs inhibited bleeding and sedimentation. Furthermore, the SAs appeared to significantly inhibit the sedimentation of cement particles. The findings develop CPB technology utilizing SAs and provide important guidance for ensuring smooth pipeline transportation.

富水隧道围岩中孔洞缺陷会加剧软岩时效劣化，其应力松弛损伤机制及长期力学行为预测仍有待深入研究。以郑万高铁巴东段某隧洞泥岩为对象，开展水–岩作用下含不同孔深泥岩应力松弛及加载破坏试验，结合溶液pH值、离子浓度、扫描电镜和数字图像相关技术，研究孔洞深度对泥岩松弛特性、细观结构及破裂演化的影响；融合一维卷积神经网络的局部时间特征提取能力与长短期记忆神经网络的长期依赖表征能力构建CNN-LSTM应力松弛预测模型。结果表明：随孔洞深度增加，泥岩应力松弛量和稳定时间均增大，剩余应力比及峰值强度降低、破坏程度加剧；水–岩作用导致矿物颗粒胶结弱化、黏土矿物水化及孔隙裂隙扩展，且深孔试样的细观结构劣化更显著；松弛阶段孔周形成环状应变集中区，加载破坏阶段张拉裂纹多由孔洞附近应变集中区域起裂并逐渐贯通。CNN-LSTM融合模型能够在本文室内试验数据范围内较好表征应力松弛曲线的非线性时序变化特征，均方根误差（RMSE）降至0.001 7，决定系数（R²）增至0.995 7。研究结果可为富水软岩应力松弛行为分析及数据驱动预测方法建立提供试验参考。本文所建模型适用范围受室内试验参数限制尚不能直接外推至实际隧洞围岩长期稳定性评价，仍需结合现场监测数据、原位应力条件、裂隙网络特征和地下水化学环境进一步校准与验证。