Search Results (473)

Dahua in Guangxi is an important soft jade mining area in southern China. Despite this, research on the nephrite from this region, particularly on the coloring mechanism of black nephrite, remains limited. This study systematically investigates the gemological, mineralogical, and geochemical properties of black nephrite from Dahua. Petrographic analysis reveals that tremolite is the primary mineral, with clinochlore and apatite as associated minerals. Tremolite (SiO₂: 58.00 wt%; MgO: 24.75 wt%; CaO: 12.46 wt%) in Dahua nephrite is close to the theoretical values of tremolite. Chlorite thermometry indicates formation temperatures of 240 °C and 328 °C. Geochemical analysis of the samples shows enrichment in light rare earth elements (LREEs), flat heavy rare earth element (HREEs) patterns, and Ce and Eu anomalies. The Mg²⁺/(Mg²⁺ + Fe²⁺) ratio was below 0.06. In the c(Ca²⁺), c(Mg²⁺), and c(Fe²⁺ + Fe³⁺) ternary diagram, the amphibole plots close to the Dahua green nephrite, suggesting a similar genetic environment and supporting a contact metasomatic origin for the amphibole. Combined with the geological setting, mineralization was driven by hydrothermal fluids from diabase magma, which introduced Si and heat, with Ca and Mg being mobilized from the dolomitic limestone host rocks. These findings contribute to the understanding of nephrite formation in Dahua, distinguishing it from nephrite from other regions and providing a foundation for future studies on the geochemical and mineralogical characteristics of nephrite. Full article

Active support systems are being increasingly applied in the control of large deformation in soft rock tunnels, and exploring the bearing characteristics of prestressed anchor bolts is of great engineering value for improving the long-term stability of tunnel structures. To address the problems of insufficient quantitative characterization of the bearing performance of prestressed anchor bolt support in soft rock tunnels and the difficulty of small-scale model tests in revealing the synergistic bearing law of support and surrounding rock, this study took a 350 km/h double-line high-speed railway tunnel as the prototype and established a large-scale tunnel structure model test system to conduct comparative tests under three working conditions: unsupported, ordinary bolt support, and prestressed anchor bolt support. By monitoring the tunnel failure process and mechanical response of the support structure throughout the test, the failure modes, bearing capacity, deformation characteristics, and axial force distribution of anchor bolts of tunnels under different support forms were systematically analyzed to quantitatively reveal the active support mechanism and bearing strengthening effect of prestressed anchor bolts. The results show that the design bearing capacity of the tunnel model with prestressed anchor bolt support is increased by 127.3% and 31.6% compared with that of the unsupported and ordinary bolt support models, and the ultimate bearing capacity is increased by 120.0% and 43.5%, respectively. Its secant stiffness in the initial loading stage reaches 80.0 kPa/mm, which is five times that of the ordinary bolt support and can effectively restrain the early plastic deformation of the surrounding rock. When the design bearing capacity is reached, the tensile stress of prestressed anchor bolts accounts for 40.2~69.8% of the ultimate tensile strength, with a more uniform axial force distribution and a much higher utilization rate of material mechanical properties than ordinary anchor bolts, which can fully mobilize the bearing potential of deep rock mass and realize the synergistic bearing of support and surrounding rock. This study accurately quantifies the bearing strengthening law of prestressed anchor bolts on tunnel support systems and clarifies the core mechanism of their active support. The research results provide important experimental basis and theoretical reference for the optimal design and engineering application of prestressed anchor bolts in soft rock tunnel engineering. Full article

Taking the Daliang Tunnel of the Lanzhou–Xinjiang High-speed Railway crossing a reverse strike-slip fault as the engineering background, seismic damage investigations of the Daliang Tunnel and other cross-fault tunnels under earthquake action were conducted. Using 1:50 meso-scale model tests, experimental analyses were carried out on the lining strain response, internal crack development and failure, and surrounding rock pressure variation during fault dislocation. The failure modes and mechanisms of tunnels crossing reverse strike-slip faults were thoroughly explored. Meanwhile, a three-dimensional numerical model of the Daliang Tunnel was established to investigate the influence of dislocation modes with structural zonation within the fault zone on the surrounding rock response. The results indicate that the damage and strain response of the tunnel lining are mainly distributed within the fracture zone, predominantly characterized by combined oblique shear and compression failure. Due to the displacement of the lining induced by strong surrounding rock movement, surrounding rock pressure exhibits considerable variation at the boundaries of the fracture zone, accompanied by certain void detachment phenomena. The overall deformation of the tunnel crossing the reverse strike-slip fault presents an “S”-shaped pattern, which is consistent with the numerical simulations. The compression and dislocation morphology of the sidewalls within the rupture surface is in good agreement with the point cloud plan view. The compressive deformation and strain of the surrounding rock are most significant within the rupture surface. Meanwhile, the soft-to-hard transition segments between the new fracture zone and the rupture surface, as well as between the rupture surface and the influence zone, exhibit a trend of first decreasing and then increasing. Full article

Carbonate reservoirs in the Shunbei area develop pronounced fracture networks after acidized hydraulic fracturing and thus have the potential to be repurposed as underground gas storage (UGS) after hydrocarbon depletion. Characterizing their mechanical behavior is essential for safe UGS operation; however, deep to ultra-deep natural cores are difficult to obtain, and conventional macroscopic tests often cannot provide parameters that meet engineering requirements. To address this issue, nanoindentation combined with QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) was employed to quantify microscale mineral distributions and the mechanical properties of the major constituents. The investigated rock is calcite-dominated (89.62%), with minor quartz (9.89%) and trace feldspar-group minerals (1.89%). Minerals are randomly embedded, and soft–hard phase boundaries are widely distributed. A finite–discrete element method (FDEM) model was then constructed and calibrated in ABAQUS. The discrepancies in uniaxial compressive strength and elastic modulus relative to laboratory results were 6.51% and 9.91%, respectively, indicating good agreement in both mechanical response and failure mode. Parametric analyses using three additional models with different mineral proportions show that damage preferentially initiates at mineral phase boundaries and stress concentration zones induced by end constraints. Microcracks then propagate and coalesce into a dominant compressive–shear band, and final failure is mainly governed by slip along the shear band with localized tensile cracking. With increasing quartz and feldspar contents, enhanced heterogeneity and a higher density of phase boundaries lead to a higher density of crack nucleation sites and increased crack branching, and the failure pattern transitions from a single shear-band–controlled mode to a more network-like fracture system. Moreover, macroscopic strength is not determined solely by the intrinsic strength of individual minerals; heterogeneity and phase-boundary characteristics strongly govern microcrack behavior, such that higher hard-phase contents may result in a lower peak strength. Full article

This study addresses the challenges posed by weakly cemented strata in mine tunnels, where surrounding rock softens and deforms upon water exposure, which promotes the development of seepage pathways, and exhibits insufficient stability in bolt (cable) support systems. This study conducts laboratory grouting tests using silica sol on typical weakly cemented sandstone from Xinjiang mining areas. The mineral composition and pore structure were characterized using XRD, SEM, and mercury porosimetry. The injectable mixing ratio parameters for silica sol and the catalyst were determined through viscosity-time evolution tests. Grouting was performed using a custom-built constant-pressure grouting apparatus. After curing, unconfined compressive strength (UCS) and porosity-permeability tests were conducted to evaluate the micro-mechanism of grouting effects on the mechanical and permeability properties of weakly cemented sandstone. The results indicate: (1) The sandstone exhibits a high clay mineral content of 39.8%, dominated by illite. Its pores are primarily small-scale (10–100 nm), accounting for 79.31% of the total pore volume. This scale matches that of silica sol nanoparticles (approximately 9–20 nm), facilitating slurry penetration into micro-pores; (2) microscopic analyses reveal that silica sol effectively reconstructs pore structures through permeation filling and surface coating. Compared to KCl-induced gelation (with approximately 8% gel coverage), NaCl-induced gelation forms a more continuous gel film with more complete pore filling, achieving coverage of around 22%. Furthermore, the larger surface area of the gel aggregates indicates a more thorough filling of micro- and nano-pores, effectively enhancing rock mass compactness. (3) Permeability decreased from 6.91 mD to 3.55 mD, a reduction of 48.6%, while porosity decreased from 16.94% to 13.55%, showing a phased reduction during the grouting process; (4) following pressure grouting stabilization, the uniaxial compressive strength of sandstone increased appropriately by approximately 7–14%, while the elastic modulus rose by about 18–28%. The failure mechanism shifted from shear brittleness to a shear-tension composite state, with enhanced post-peak bearing capacity. These findings provide support for optimizing silica sol grouting parameters in weakly cemented strata tunnels and for the synergistic reinforcement of rock mass permeability and strength. Full article

Mineral resources serve as a critical foundation for China’s energy system, with the Ordos Basin’s Tarangole mining area being a key mineral production base in the central and western regions. To support the restoration, development, and productivity enhancement of the mining area, this research systematically investigates the geological and mechanical properties of the sandstone in the region. Herein the innovation lies in its comprehensive analysis of the influence mechanisms of multiple factors—such as geological groups, particle size, evaluation indicators, sampling depth, temperature, and creep rate—on the mechanical behavior of sandstone. The study, through engineering geological surveys and mechanical testing of frozen sandstone (including uniaxial and triaxial creep tests), led to the following key findings: (1) the sandstone in the area is prone to softening and disintegration, classified as soft to moderately soft rock (UCS range: 5.14–10.26 MPa in natural state), with a basic quality grade of IV–V. (2) The thermal conductivity and specific heat capacity of the rock vary significantly with temperature. The recommended freezing temperature is −5 °C, based on engineering experience and economic considerations. (3) Freezing can effectively enhance the strength of sandstone (e.g., the strength of medium- and coarse-grained sandstone increases by 5 MPa at −20 °C compared to −10 °C), although it still falls within the category of extremely soft rock. (4) The water-ice phase transition induced by low temperatures significantly enhances the overall strength, stiffness, and deformation resistance of saturated sandstone. Accordingly, freezing measures can effectively enhance rock mass strength under low-temperature conditions. It is recommended that mining operations be prioritized during winter or colder seasons to ensure construction safety and efficiency. Full article

To address the engineering challenges of frequent flexural deformation and instability of composite roadway roofs and the difficulty in accurately controlling the support strength range during deep coal mining, this study takes the soft–hard interbedded composite roof of the working face in the West No. 1 Mining Area of Shuangyang Coal Mine in Shuangyashan as the engineering background. Typical fine sandstone (hard rock) and tuff (soft rock) from the on-site roof were selected to prepare layered composite specimens, and indoor four-point bending tests were conducted. Combined with theoretical calculations, strain monitoring, and acoustic emission (AE) real-time localization technology, the regulatory mechanisms of three key factors—lithological combination, loading rate, and span—on the flexural mechanical properties, deformation and failure modes, and fracture evolution laws of layered composite rock masses were systematically investigated. The research results show the following: (1) The flexural performance of layered composite rock masses is dominated by the interlayer interface effect. Their flexural strength is 46.7% and 41.1% lower than that of single hard rock and soft rock specimens, respectively, and the competitive mechanism between interface slip and delamination fracture is the core inducement of strength deterioration. (2) The strength and deformation characteristics of layered composite rock masses exhibit a significant loading rate effect. When the loading rate increases from 0.002 mm/s to 0.02 mm/s, the flexural strength decreases by 51.8% and the mid-span deformation deflection reduces by 50.1%. High loading rates will exacerbate the deformation mismatch between soft and hard rock layers, trigger premature failure of interface bonding, and inhibit the full development of structural plastic deformation. (3) Increasing the span significantly optimizes the flexural bearing performance of layered composite rock masses. When the span increases from 170 mm to 190 mm, the flexural strength increases by 65.7% and the mid-span deformation deflection synchronously increases by 65.7%. A large span can extend the flexural deformation path, promote the coordinated deformation of rock layers, and suppress local stress concentration. (4) The flexural failure of layered composite rock masses is dominated by Mode II shear cracks, while single-lithology specimens are mainly dominated by Mode I tensile cracks. Loading rate and span significantly change the crack propagation mode and energy release law. This study establishes a calculation method for the equivalent flexural stiffness of layered composite rock masses and reveals the mesoscopic mechanism of flexural failure of heterogeneous layered rock masses. The research results can provide a theoretical basis and experimental support for the optimization of support schemes and the prevention and control of roof collapse hazards for composite roofs of deep coal mine roadways. Full article

Large deformation and difficult support are common in soft-rock roadways under deep high-stress conditions. The 1232(3) gob-side roadway of Dingji Mine was taken as the engineering background. A combined approach was used. It included theoretical analysis, numerical simulation, field measurements, and underground tests. The catastrophe mechanisms of surrounding rock and the corresponding stability control technologies were investigated for high-stress soft-rock roadways. The results showed a strong Rp–Rw effect. When the variation coefficient of the maximum horizontal principal stress satisfied Rp > 0.8, the influence on the variation coefficient of roof buckling deflection (Rw) became pronounced. Under this condition, roof deformation increased markedly. As roadway drivage changed from solid-coal-side driving to gob-side driving, the surrounding-rock stress became progressively asymmetric. The peak stress on the coal-pillar side decreased from 25.3 MPa to 21.5 MPa. The plastic zone expanded continuously. Its dominant development also shifted from the roof and floor toward the two ribs. After entering the gob-side condition, plastic-zone development on the coal-pillar side generally exceeded 2.5 m. The original support bolts could no longer remain effective. Different stress states and failure characteristics were observed on the solid-coal side and the gob side. Based on these differences, an asymmetric coupled support and surrounding-rock control system was established. The system integrated “time effectiveness + regional zoning + targeted reinforcement.” A field trial was conducted in the 1232(3) haulage roadway. Surrounding-rock deformation was effectively controlled, and favorable engineering performance was achieved. Full article

Large deformations in deep soft rock roadways primarily stem from low rock strength under high in situ stress and intense mining disturbance. This renders stability control a critical challenge in tunneling support engineering. Utilizing Xinhe Coal Mine’s deep soft rock tunnel as a representative case, this study integrates field monitoring, laboratory experimentation, and numerical simulation to investigate how excavation and grouted rock bolting influence surrounding rock stability. Building upon field-observed deformation mechanisms and support failure patterns, constitutive models for FLAC^3D’s embedded cable and beam elements were modified to achieve high-fidelity simulation of grouted support systems. Numerical models simulating diverse support schemes were established to analyze roadway displacement fields, plastic failure development, and structural behavior of support components, ultimately identifying the optimal rehabilitation solution. The research results indicate that the numerical simulation outcomes of the original support scheme exhibit good agreement with field observations in terms of roadway deformation patterns, deformation magnitudes, and occurrences of bolt/cable fractures. This demonstrates that the adopted refined numerical simulation methodology and parameters are reasonable and exhibit high reliability. Considering both surrounding rock stability and cost control, Roadway Rehabilitation Scheme S1 was identified as the optimal support solution. Its specific parameters are pre-grouting + full-section rock bolts (diameter 22 mm, length 2.4 m, spacing 0.8 m, row spacing 1.6 m) + full-section grouted cables (diameter 22 mm, length 6.2 m, spacing 1.0 m, row spacing 1.6 m). Full article

Addressing the engineering challenge of creep instability in weakly cemented fractured sandstones within extremely soft coal-bearing formations under long-term loading in western mining areas, using weakly cemented sandstone from a coal mine in Xinjiang as the study subject. This research employs uniaxial graded loading creep tests combined with full-information acoustic emission technology and DIC high-speed strain field observation to investigate the creep deformation patterns (The full name of “DIC” is the three-dimensional high-speed dynamic and static stress–strain analysis system of the DIC strain field measurement and analysis system. For the convenience of expression, this system will be uniformly referred to as DIC in the following text), damage evolution characteristics, and failure mechanisms of sandstone under intact, pre-fabricated 30° fractures, and pre-fabricated 60° fractures. Results indicate: Fractures significantly weaken rock strength and long-term stability. Unfractured specimens primarily exhibit columnar splitting tensile failure, while pre-fractured specimens show pronounced shear failure. Shear cracks accounted for 83.67% of failures in 30° pre-fractured specimens and decreased to 63.44% in 60° pre-fractured specimens. Intact specimens exhibited acoustic emission ringing responses during accelerated creep stages, whereas fractured specimens showed ringing responses as early as the first loading stage. During graded loading, ringing counts in pre-fractured specimens continuously accumulated, with cumulative counts significantly exceeding those of intact specimens. Pre-fabricated cracks induced significant stress concentration effects at the ends, causing failure cracks to propagate preferentially along the crack direction and forming a non-uniform deformation field bounded by the crack. The study revealed the micro-macro evolution patterns of progressive damage during creep in extremely weak fractured rock, providing theoretical support for early warning and control technologies against creep instability in tunnel rock masses of weakly cemented strata in western regions. Full article

Soft–hard composite strata are widely distributed in the surrounding rock of deep tunnels, which severely reduces TBM excavation efficiency. To elucidate the rock-breaking mechanism of TBM disc cutters in composite strata and to address unresolved issues related to cutter force evolution, a self-developed rotary cutting test platform was employed, and three types of large-scale samples (red sandstone, granite, and red sandstone–granite composites) were prepared, on which systematic rotary rock-cutting experiments were conducted under varying confining pressures, rotational speeds, and penetration depths. The results indicate that rock failure in composite strata exhibits pronounced heterogeneity, with significant stress concentration occurring at soft–hard rock interfaces, leading to abrupt increases in normal force and torque. Penetration depth is the most sensitive factor influencing cutting force and specific energy, followed by confining pressure and rotational speed. The minimum specific energy and maximum rock-breaking efficiency are achieved at a penetration depth of 2.5 mm, a confining pressure of 7 MPa, and a rotational speed of 2.5–3 r/min. Furthermore, a dynamic model describing the evolution of disc cutter normal force and torque at soft–hard rock interfaces was derived based on the CSM theoretical framework, and its validity was verified using the experimental results. Integrating experimental observations with theoretical analysis reveals that rock fragmentation in composite strata is dominated by radial tensile cracking in hard rock and shear-dominated crushing in soft rock, while strong stress perturbations and coupled failure occur at the composite interface. This study clarifies the force evolution and fracture mechanisms of disc cutters operating in composite strata and establishes a reliable dynamic prediction model for cutter loads, providing theoretical support and engineering guidance for TBM parameter optimization and cutterhead design. Full article

The large deformation of soft rock within tunnels not only induces cracking in the initial supports and distortion of steel arches but also compromises the structural integrity of the secondary lining. In this study, we first examined the cracking characteristics of the secondary lining on both sides of the Baoligang Tunnel situated in a strong tectonic zone. A total of 257 cracks were identified, with 118 located on the left side of the tunnel and 139 on the right side. The triaxial compression test revealed that the failure characteristics of carbonaceous slate are mainly caused by shear slip failure due to the presence of weak bedding planes. Subsequently, a tailored blasting charge structure was designed to demolish the reinforced concrete secondary lining. This design incorporated a dense arrangement of blasting holes and interval charging techniques applied to the arch shoulders and sidewalls of the blasting zone, effectively fracturing the secondary lining in the left tunnel of the Baoligang Tunnel. Finally, an analysis was conducted based on vibration signals recorded during the dismantling process from three representative sections. The recorded vibration velocities from Case 1 indicate that the explosive charge has a relatively minor impact on the lining of the right tunnel. The peak particle velocity (PPV) recorded from the damaged lining closest to the blast center on the left side is 31.48 cm/s, exceeding the allowable vibration standard. Thereafter, the Hilbert–Huang Transform (HHT) was employed to identify the dominant frequency of the recorded vibration signals, which was determined to be 64 Hz. In Case 2, the PPVs at all monitoring points are below the vibration control standard for traffic tunnels. In Case 3, the PPVs suggest that the vibration has a minimal effect on the newly installed initial support. Full article

When a tunnel traverses an inclined coal seam, the coal-tunnel angle α of the seam significantly alters the stress distribution in the surrounding rock, its failure mode, and the loading conditions on the support structure. This study investigates the influence of coal-tunnel angle α on surrounding rock stability and support structure loads, with the No. 1 Meijiaxiang Tunnel on the Wengma Railway in Guizhou Province serving as the engineering case. An integrated approach combining laboratory tests, numerical simulations, and engineering verification is employed. Laboratory tests were conducted to determine the basic mechanical properties of the limestone and coal. A refined 3D finite element model was developed in MIDAS GTS NX to analyze the effects of coal-tunnel angle α (α = 30°, 45°, 60°, 75°, 90°) and different construction methods on surrounding rock deformation, plastic zone development, and the stress state of the initial support. The results indicate that the coal-tunnel angle α significantly influences tunnel stability. Both crown settlement and the plastic zone extent decrease notably as α increases. Among the construction methods, the reserved core soil method most effectively controls surrounding rock deformation, but induces greater stress concentration in the initial support. Furthermore, for the most unfavorable case (α = 30°), an optimization analysis of the cyclic advanced length for the reserved core soil method was conducted. It is shown that using an 8 m advanced length can effectively control settlement while significantly reducing support stress and bolt axial forces. With its integrated methodology and detailed parameter analysis, this study provides a valuable theoretical and practical reference for optimizing the design and ensuring the safe construction of similar tunnels traversing inclined coal seams in complex soft–hard interbedded strata. Full article

This study addresses the major engineering challenges of leaving roadways along the goaf in shallow-buried coal seam tunnels through water-bearing soft rock. It focuses on three core issues: the mechanism of rock mass softening upon water exposure, large-deformation control, and directional pressure relief technology. By integrating laboratory testing, theoretical analysis, numerical simulation, and field testing methods, the evolution of macro- and micro-mechanical properties of rock under water–rock interaction can be studied. The research developed constant-resistance large-deformation rock bolts with “yielding within resistance and resisting within yielding” characteristics, revealed the mechanism of directional fracturing through shaped charge blasting, and proposed a synergistic control technology for along-the-goal rib retention: “shaped charge blasting for roof fracturing and pressure relief + reinforced rib support + debris retention devices.” Research findings indicate: increased sandstone water content triggers dissolution of calcareous cement and expansion of clay minerals, leading to rock strength degradation and accelerated deformation, yet the failure mode remains uniaxial shear failure. The developed constant-resistance large-deformation anchor core device maintains a stable working resistance of approximately 350 kN within a 396–405 mm tensile deformation range, significantly enhancing the support system’s crack-resistant capacity under pressure. The focused jet directs cracks to penetrate along predetermined paths, forming planar damage zones and effectively suppressing vertical damage to the surrounding rock. Based on field monitoring, the tunnel was divided into advance support zones, temporary support zones, and stable tunnel sections, enabling a differentiated support scheme. The engineering application achieved stable tunnel retention and safe reuse. This study provides key theoretical foundations and technical approaches for controlling rock mass stability in similar tunnel conditions. Full article

As a cornerstone of China’s energy infrastructure, the coal mining industry relies heavily on the stability of its underground roadways, where the support of soft rock formations presents a critical and persistent technological challenge. This challenge arises primarily from the high content of expansive clay minerals and well-developed micro-fractures within soft rock, which collectively undermine the effectiveness of conventional support methods. To address the soft rock control problem in China’s Longdong Mining Area, an integrated material–structure control approach is developed and validated in this study. Based on the engineering context of the 3205 material gateway in Xin’an Coal Mine, the research employs a combined methodology of micro-mesoscopic characterization (SEM, XRD), theoretical analysis, and field testing. The results identify the intrinsic instability mechanism, which stems from micron-scale fractures (0.89–20.41 μm) and a high clay mineral content (kaolinite and illite totaling 58.1%) that promote water infiltration, swelling, and strength degradation. In response, a novel synergistic technology was developed, featuring a high-performance grouting material modified with redispersible latex powder and a tiered thick anchoring system. This technology achieves microscale fracture sealing and self-stress cementation while constructing a continuous macroscopic load-bearing structure. Field verification confirms its superior performance: roof subsidence and rib convergence in the test section were reduced to approximately 10 mm and 52 mm, respectively, with grouting effectively sealing fractures to depths of 1.71–3.92 m, as validated by multi-parameter monitoring. By integrating microscale material modification with macroscale structural optimization, this study provides a systematic and replicable solution for enhancing the stability of soft rock roadways under demanding geo-environmental conditions. Soft rock roadways, due to their characteristics of being rich in expansive clay minerals and having well-developed microfractures, make traditional support difficult to ensure roadway stability, so there is an urgent need to develop new active control technologies. This paper takes the 3205 Material Drift in Xin’an Coal Mine as the engineering background and adopts an integrated method combining micro-mesoscopic experiments, theoretical analysis, and field tests. The soft rock instability mechanism is revealed through micro-mesoscopic experiments; a high-performance grouting material added with redispersible latex powder is developed, and a “material–structure” synergistic tiered thick anchoring reinforced load-bearing technology is proposed; the technical effectiveness is verified through roadway surface displacement monitoring, anchor cable axial force monitoring, and borehole televiewer. The study found that micron-scale fractures of 0.89–20.41 μm develop inside the soft rock, and the total content of kaolinite and illite reaches 58.1%, which is the intrinsic root cause of macroscopic instability. In the test area of the new support scheme, the roof subsidence is about 10 mm and the rib convergence is about 52 mm, which are significantly reduced compared with traditional support; grouting effectively seals rock mass fractures in the range of 1.71–3.92 m. This synergistic control technology achieves systematic control from micro-mesoscopic improvement to macroscopic stability by actively modifying the surrounding rock and optimizing the support structure, significantly improving the stability of soft rock roadways. Full article