Deformation Increment Research Articles

Methodology for Determining the Optimal Support Control Distance Based on the Deformation Increment Rate of Surrounding Rock and Its Engineering Application

Methodology for Determining the Optimal Support Control Distance Based on the Deformation Increment Rate of Surrounding Rock and Its Engineering Application

Experimental study on seismic damage of SRC-RC vertical hybrid structure

In order to analyze the seismic performance of the SRC-RC vertical hybrid structure, three substructure models were designed, and the key data of structural performance, such as hysteresis curve, skeleton curve, bearing capacity, energy dissipation of structure, residual deformation and damage degree were obtained by carrying out low cyclic loading tests. According to the tests, the plastic development at the column base was delayed because of the reinforcement of section steel, and the plastic development at beam end was much more sufficient, which benefited the beam hinge mechanism in the transition area, so that the transition area has better energy dissipation capacity and deformation capacity. Based on the more sufficient lateral displacement of beam hinge, the beams suffered bending deformation obviously, and interaction between the beams and the infilled wall was significant, which led to a more complex interface force transmission, so the bending cracks and the shearing cracks were densely distributed along the full length of the beam. Meanwhile, the reinforcement of section steel not only improved the deformation capacity of the models but also resulted in more significant damage difference in positive and negative loading. To quantitatively evaluate the damage level, a seismic damage index system was proposed, including displacement damage degree, bearing capacity damage degree and residual deformation index, which reflect the increment of deformation caused by structural damage, the deterioration of bearing capacity and the residual deformation, respectively. It is suggested that the structural failure should be defined respectively under different modes: For the strength degradation behavior mode and ductility behavior mode, structural failure should be confirmed if the load reduces to 0.90 and 0.85 times of the peak load, respectively; and for the brittle behavior mode, the frame is considered to fail when the load reaches the peak without considering the structural performance after the peak load.

Numerical study on the mechanical and deformation behavior of a shield tunnel under different geological conditions

Investigating the mechanical and deformation response of a shield tunnel to nearby cavities has a significant importance on the structural safety assessment and protection. Limited to the laborious modelling and analysis barriers, the refined structural model including lining segments and connecting bolts are proposed by the BIM-based parametric modelling technology, using which the geometric properties can be adjusted through one-click operation. The pretreatment algorithm has also been developed to impose springs on the numeric nodes effectively and accurately, forming an elaborate numerical simulation method. Numerical analysis has been exerted and verified considering the homogeneity of the excavation geological condition. Results show that for the shield tunnel excavated in the homogeneous stratum, the mechanical and deformation responses of the lining structure are symmetrical about the vertical central plane. The lining ring deforms from a circle to an elliptic shape. To inquire the effect of the geological cavity, three sceneries for cavity at various positions are studied. Numerical results reveal that the lining segments deform towards the cavity side significantly, leading to over 100 times the deformation increment at the vault and invert, even over 1000 times at the cavity side for the unilateral cavity. At the cavity(ies) side(s), the internal forces of the lining segments increase, and the stress states change from compression on the outer surface to tension. The stress of connecting bolts also indicates the stress concentration for the supporting structures at the cavity side. Reinforced supports are needed for the concrete linings near the geological defects.

Non-uniform variation characteristics of temperature field and corresponding thermal effect of longitudinal continuous slab ballastless track structure

The longitudinal continuous slab ballastless track structure (LCSBTS) easily suffers from interface and joint damage when subjected to extremely high-temperature loads, significantly affecting the running smoothness and safety of high-speed trains. This paper establishes a numerical model of the LCSBTS using the heat transfer principle and real-time shadow technology to replicate the time-varying evolution and spatial distribution of the temperature field. The corresponding thermal effect is obtained based on the sequential thermal-mechanical coupling method. The results show that the temperature variation and the corresponding thermal effect exhibit strong temporal-spatial non-uniformity on the horizontal and vertical planes of the LCSBTS. Solar radiation and heat convection are the dominant factors for the temperature field of the LCSBTS in the daytime and night, respectively, resulting in a higher temperature and greater thermal deformation on the sunny side than on the shady one. The temperature and vertical thermal deformation along the longitudinal direction vary periodically with a specific wavelength between the two adjacent rail support concrete blocks. The thermal deformation increments under the studied non-uniform temperature loads cause an interface damage increment. Finally, the consideration of a non-uniform temperature load produces remarkably different thermal effects from those given by the design temperature load.

A new method for determining the ogden parameters of soft materials using indentation experiments

A full understanding of the material properties of skin tissue is crucial for exploring its tribo-mechanical behaviour. It has been widely accepted that the mechanical behaviour of skin tissue for both small and large deformations can be accurately described using a hyperelastic model, such as the one developed by Ogden. However, obtaining these Ogden parameters for in-vivo skin by in-vivo experiments no matter the indentation or suction tests is a significant challenge. The mathematical model used to describe the material behaviour during the test should consider not only the material nonlinearity but also the geometrical confinement of the tissue, the large deformations induced, and the fact that the specimens are relatively thin.A range of contact models is available to describe the contact behaviour during the indentation test. However, none of them can be used for hyperelastic materials with small thickness under large deformations. Simultaneously explaining material nonlinearity and geometric nonlinearity, either through theoretical equations or numerical calculations, poses a significant challenge.In this research, we propose a pragmatic method to obtain Ogden parameters for in-vivo skin tissue by combining experimental indentation results and numerical simulations. The indentation tests were used to obtain the force-indentation depth curves, while the numerical simulations were used to obtain the strain fields. The method assumes the material behaviour of specimens can be linearized in each small deformation increment, and the contact model developed by Hayes can be applied to accommodate each increment. Then, the linear elastic behaviour in each increment can be described by the elastic modulus E which were obtained using Hayes model, and the principal stresses in each increment were subsequently obtained using Hooke's law. By combining all stress fields, overall stress-strain curves can be constructed, from which the hyperelastic Ogden parameters can be obtained. A second numerical simulation of the hyperelastic indentation was then performed using the obtained Ogden parameters, allowing a comparison of the experimental and simulated relationships between force and indentation.

Fatigue performance analysis of stainless steel cruciform joint with angular misalignment

AbstractWelding distortion causes the change of stress distribution of load‐carrying cruciform stainless steel welded joints, and the weld with angle less than 90° between steel plates became the fatigue performance control weld because of stress magnification. The effect of angular misalignment on fatigue performance of stainless steel cruciform welded joint was experimentally and numerically studied. The fatigue damage evolution equations, under different stress amplitudes, were derived using relative deformation increment as damage variable based on continuum damage mechanics to explain the process of damage transformation from micro to macro crack and finally rapid fracture. The hot spot stress magnification factor was positively correlated with the welding distortion angle and exhibited two discernible stages of rise and fall with increasing nominal stress taking the proportional limit as boundary. A proposed formula considering both misalignment angle and applied stress aimed to enhance accuracy in fatigue performance evaluation compared to current methods.

Early Paleozoic ductile deformation of the South China Block: the polyphase shear zones in the eastern Jiangnan belt

Three parallel east–west-trending shear zones are components of the polyphase shear zones in the eastern Jiangnan belt. The meso- and microstructural characteristics and the estimates of deformation temperatures, vorticities and geochronology of these shear zones provide significant information regarding the tectonic evolution of the South China Block (SCB) during the early Paleozoic. Most shear sense indicators (e.g. asymmetric folds, S-C fabrics and rotating porphyroclasts) reveal that the kinematics were characterized by east–west dextral shear. Finite strain measurements indicate an oblate strain ellipsoid shape with S-type and SL-type tectonites. The rotated rigid porphyroclasts and Mohr circle methods yield vorticity ( Wk ) values of 0.58–0.80 and 0.66–0.89, respectively, indicating that the flow was generally shear-dominated with almost equal proportions of simple and pure shear. Both mineral deformation thermometers and quartz c -axis fabrics indicate that the deformation occurred at medium temperature conditions of 400–550°C. Combined with our new age and regional geological data, the east–west-trending shear zones might represent an increment of deformation during the last period of the early Paleozoic orogeny in the SCB.

Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths

Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation. In this study, to reveal the mechanical parameters of deep surrounding rock under different stress paths, a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed, and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied, including the deformation modulus, elastic deformation increment ratios, fracture degree, cohesion and internal friction angle. Additionally, stress path coefficient was defined to characterize different stress paths, and the functional relationships among the stress path coefficient, rock fracture degree difference coefficient, cohesion and internal friction angle were obtained. The results show that during the true triaxial cyclic loading and unloading process, the deformation modulus and cohesion gradually decrease, while the internal friction angle gradually increases with increasing equivalent crack strain. The stress path coefficient is exponentially related to the rock fracture degree difference coefficient. As the stress path coefficient increases, the degrees of cohesion weakening and internal friction angle strengthening decrease linearly. During cyclic loading and unloading under true triaxial principal stress direction interchange, the direction of crack development changes, and the deformation modulus increases, while the cohesion and internal friction angle decrease slightly, indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks. Finally, the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.

Three-level evaluation method of cumulative slope deformation hybrid machine learning models and interpretability analysis

The study aims to address the issues of limited evaluation metrics and low visualization for Machine Learning (ML) models in Cumulative Slope Deformation (CSD) prediction. Firstly, to establish a representative and balanced CSD dataset, the Grey Relational Analysis (GRA) and Mutual Information (MI) were used to determine the main controlling features influencing CSD. Secondly, combining four typical ML algorithms Support Vector Regression (SVR), Extreme Learning Machine (ELM), Long Short-Term Memory (LSTM), and Gated Recurrent Unit (GRU) with an Improved Particle Swarm Optimization (IPSO) algorithm to develop hybrid ML models. Moreover, a three-level evaluation method is proposed considering prediction accuracy and error, prediction uncertainty, and prediction robustness to determine the optimal hybrid ML model. Then, the effectiveness of the proposed method is validated using data from a diatomaceous earth slope on the site. Finally, the SHapley Additive exPlanations (SHAP) method was used to perform interpretability analysis on the optimal hybrid ML model in three steps: Moment-specific and global interpretation, Overall importance analysis and contribution analysis, and Dependency analysis. The results indicate that: 1) Based on the combined feature analysis algorithm of GRA and MI, the main controlling features affecting CSD were the three-day cumulative rainfall, daily rainfall, daily moisture content, daily deformation increment, and daily moisture content change. 2) The IPSO algorithm has a significant advantage in improving the prediction accuracy of the ML models. 3) The calculated Comprehensive Evaluation Index (CEI) values for each hybrid ML model are as follows: IPSO-GRU (1.980) < IPSO-SVR (2.380) < IPSO-LSTM (2.564) < IPSO-ELM (2.793), which indicated that the IPSO-GRU was the optimal hybrid ML model. 4) In the IPSO-GRU model, the top three features in order of overall importance are Previous CSD, three-day cumulative rainfall, and daily rainfall, and the feature most closely interacting with three-day cumulative rainfall and daily rainfall is the Previous CSD. The research findings can provide a reference method for selecting the optimal ML model and offer a precise, interpretable, and reliable predictive model for CSD.

Instability mechanism and failure criteria of large-span flexible PV support arrays under severe wind

Compared with independent flexible PV support, the entire structure force performance and transfer mechanism of inter-row cables and inter-span rods of flexible PV support arrays are more complex, it is easy to have large vibration or even instability failure under strong wind. In this study, the three-span and five-row flexible PV support array of a 66 MW Fishery-PV Complementary demonstration site in the eastern coastal region of China is used as the research object. The rigid body pressure measurement wind tunnel test was designed and carried out, and the wind pressure distribution characteristics of the PV panels surface were analyzed. A three-dimensional explicit dynamics model of the flexible PV support array considering inter-row cables and inter-span rods is established, and the wind-induced dynamic response characteristics and instability processes of the large-span flexible PV support array are effectively simulated. Finally, the instability mechanism of the large-span flexible PV support array is revealed, and the dual failure criteria based on structural deformation and energy increment are proposed. Results demonstrated that the maximum values of displacement and von Mises stress of the large-span flexible PV support array are concentrated in the 1st row of the span in the windward side. The array under 0° and 180° wind direction angles induces local instability and failure at wind speeds of 51 m/s and 46 m/s due to the failure of the 1st row of triangular rods and crossed diagonal rods on the windward side, respectively, and the rods instability mechanisms are Eulerian buckling mechanism and Limit point buckling mechanism, respectively. When the axial compression ratio [Δ] > 0.1 or the strain energy increment [ΔU] > 1.0 × 105J of the instability rod, the structure will be locally destabilized. This paper presents a systematic work around the wind-induced response and instability characteristics of the large-span flexible PV support array, the results are of significance for the engineering application of solar energy generation structures.

Evaluation on displacement risks of dismantling temporary lining in tunnel and optimization on temporary lining configuration

In tunnel engineering, the temporary lining is adopted as an effective countermeasure in mitigating tunnel failure potential, often featured by extra-large cross-sections and/or driven through weak ground conditions. However, dismantling temporary linings negatively impacts primary linings. In this paper, the comprehensive research is conducted on the displacement risk caused by dismantling temporary lining based on two alternative tunneling methods (TM-1 and TM-2). Besides, the following three influence factors are taken into consideration: the axial forces in temporary linings, the thickness of preliminary linings, and the deformation modulus of ground. After that, the tunneling method optimization plan is proposed from the view of these three influence factors. The results show that TM-1 always induces invert uplift, whereas TM-2 mainly brings about invert uplift or sidewall bulging depending on which transverse or vertical linings are dominant in terms of axial force values. For TM-2, the axial force in transverse linings can suppress the development of maximum deformation increment (MDI) value at invert when the axial forces in transverse linings are smaller than those in vertical linings. It is also found that with the further increase of the axial force in transverse linings in TM-2, MDI relocates to the sidewall. Moreover, on the basis of the displacement risk evaluations, an optimization on the temporary lining configurations has been developed by replacing temporary linings with pre-tension anchor cables to reduce the risk of dismantling temporary linings. All the research results can provide some important reference for the similar tunnel engineering in the future.

A Novel Imputation Model for Missing Concrete Dam Monitoring Data

To ensure the safety of concrete dams, a large number of monitoring instruments are embedded in the bodies and foundations of the dams. However, monitoring data are often missing due to failure of monitoring equipment, human error and other factors that cause difficulties in diagnosis of dam safety and failure to precisely predict their deformation. In this paper, a new method for imputing missing deformation data is proposed. First, since the traditional deformation increment speed distance index of the deformation similarity index does not take into account the fact that there is little change in deformations occurring in two consecutive days, the denominator of the index tends to be equal to zero. In this paper, an improved index for solving this problem is proposed. A combined weighting method for calculating the deformation similarity comprehensive index and the k-means clustering method is then proposed and used to classify deformation monitoring points. Subsequently, a panel data model that imputes different types of missing data is established. The method proposed in this paper can impute missing concrete dam deformation data more accurately; therefore, it can effectively solve the missing deformation monitoring data problem.

ANALYSIS OF THE STATE OF STRESS AND DEFORMATION OF THE MATERIAL OF THE BILLET WHEN PLANTING BY THE RESOURCE-SAVING METHOD OF STAMPING BY ROLLING

The processes of planting blanks by the rolling stamping method allow for the efficient production of a wide range of high-quality products, but the possibility of material destruction during deformation prevents the expansion of their technological capabilities. Further development of the processes is possible through the development of new technological schemes based on the analysis of deformation kinematics and the appointment of favorable technological parameters, taking into account their influence on the stress-strain state and deformability of the material of the workpieces. In order to widely use the method of assessing the deformability of workpieces, a reliable technique is needed, which provides for the presence of a mathematical model of the trajectory of deformation of material particles in the coordinates "stress state indicator - accumulated plastic deformation before failure." The work uses an approach to finding an analytical representation of the deformation trajectory based on the construction of a differential equation between the components of plastic deformation increments, followed by the solution of this equation and the identification of its parameters based on experimental data. According to the results of the research, the deformation trajectories of the material particles of the peripheral surface of the flange when planting by rolling stamping method were schematically constructed in the coordinates "intensity of deformations - stress state indicator". Based on the built model, damage accumulation can be simulated by changing the values of the model parameters for different materials and deformation paths. An analytical representation of the deformation trajectory in a parametric form was obtained. The advantages of representing the deformation trajectory in the form of parametric equations are the convenience of analyzing these trajectories. The advantage of the model of the trajectory of deformation of material particles in the coordinates "stress state indicator - plastic strain accumulated before failure" is the absence of a material constant in the analytical expression for the stress state, and the consequence is additional convenience of analyzing ratios and selecting the value of the material constant based on experimental data.

Structures evolution along strike-slip fault zones: The role of rheology revealed by PIV analysis of analog modeling

This study investigates how rheology can influence the nucleation and evolution of strike-slip structures and, consequently, the structural architecture. To that end, we carried out a series of analog experiments using materials with different rheological behavior. The materials' properties, such as the angle of internal friction, cohesion, and density, were measured. The Particle Image Velocimetry (PIV) technique was applied to investigate the strain pattern on the surface, the amplitude of damage zones and fault core, the activeness/inactiveness of the structures over the evolution of strike-slip fault, and the earliest nucleation stage of fractures. Two sets of experiments were performed: i) single-layer experiments constituted by rheologically homogeneous material (quartz sand, dry clay, plaster powder, and a mixture of quartz sand and plaster powder), and ii) multilayer experiment using a heterogeneous stratified sequence of materials with different rheology. Except for the plaster powder model, during the first increments of deformation, the strain is widely distributed to give rise to a deforming zone with varying widths, where subsidiary structures nucleate. As deformation evolves, the deformation zone progressively narrows as the maximum strain concentrates along the main fault. Nucleation, development, and relative chronology of structures, such as R, R', P, Y-fractures, pull-apart basins, and positive and negative flower structures, varied according to the material used. The structural architecture of the dry clay and plaster powder models are more similar, with a greater quantity of smaller fractures than the other models. P-shears and pull-apart basins are also present. The quartz sand and mixture models developed a more complex damage zone and a higher topographic relief. The results emphasize that rheology is a controlling factor in the deformation zone architecture. Rheology controls fracture and fault arrangement, structure relative chronology, and the localization of contractional and extensional domains over all the stages of development of strike-slip tectonics.

Interface slip of steel–concrete composite beams reinforced with CFRP sheet under creep effect

Under the creep action of composite steel and concrete beams reinforced by carbon-fiber-reinforced polymer (CFRP) sheet, the face of the CFRP sheet, steel beam, and concrete slab beam produce relative slip. This slip affects the interface interaction, reduces the bearing capacity and stiffness of the members, and increases the deformation. In this paper, elastic and energy methods are used to analyze the interface forces between steel beams and concrete slabs reinforced by CFRP sheeting under the action of concrete creep. The calculation formulas for interface slip, axial force, and incremental deformation are established. The influence of design parameters on the mechanical properties of the interface is analyzed. Results show that the increments in interface slip, axial force, and deformation are zero on the 28th day. With increasing age, the increments in interface slip, axial force, and deformation gradually increase, and the increase is large in the first 100 days; it basically remains unchanged during the time interval from 100 to 1028 days. When the load increases by 5 N/mm (5 kN), the slip increments increase by approximately 0.004 mm, 0.002 mm, and 0.002 mm. The increments in axial force are approximately 19.4 kN, 15.9 kN, and 16.1 kN. The deformation increments increase by approximately 1.7 mm, 1.1 mm, and 0.6 mm.

Research on Clamping Action Control Technology for Floating Fixtures.

By adaptively releasing deformation during machining, floating clamping significantly raises the machining quality of aircraft structural parts. The fundamental issue to be resolved is how to precisely control the clamping action of the floating fixtures. In this study, the machining process of aircraft beams was studied, utilizing the finite element method (FEM) from the perspective of strain energy evolution. The study found that the increment of deformation and the variation of the strain energy between adjacent removed layers of the material showed the same trend of change, and targeted clamping loosening at the stage of an excessive strain energy evolution gradient is beneficial to reducing the final deformation of the workpiece. Therefore, a clamping action control method based on strain energy evolution gradient regulation is proposed, and a clamping action control strategy of floating fixtures was formulated. Furthermore, a cutting experiment was carried out, and the results showed that the maximum deformation of the aircraft beam using the clamping action control strategy was only 0.112 mm, which was reduced by 74.6% compared to traditional clamping.

Risk Assessment of Tunnel Face Instability under Multi Factor Coupling Based on Conditional Probability and Tunnel Construction Mechanics

The factors leading to the collapse of tunnel face are diverse, and there is an interaction relationship between multiple influencing factors at the physical and mechanical level. By analyzing the coupling relationship between the factors affecting the instability of tunnel working face, this paper deduces the calculation method of the coupling effect of tunnel construction risk factors for a certain risk event based on conditional probability theory, and makes reasonable assumptions on the monitoring data and risk probability. Finally, it is verified by a model test. The results show that the tunnel construction risk factors have a coupling effect by affecting other risk factors or changing the physical and mechanical parameters of surrounding rock, in which the coupling amplification effect will significantly change the failure probability of the risk carrier, so it is unfavorable to the stability of the tunnel face. The coupling amplification effect of risk factors will cause the increase of tunnel face extrusion deformation. Even if it causes a small deformation increment, it can also make the transition of risk probability and grade of tunnel face unstable, and cause tunnel face instability collapse. The research results of this paper can quantitatively evaluate and predict the stability of the working face in the process of tunnel construction.

Stability analysis of surrounding rock mass in underground powerhouse considering damage effect of microfractures

A high-precision microseismic (MS) monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station. The surrounding rock damage area with spatiotemporal clustering of MS activities was studied for qualitative analysis of the damage mechanism of surrounding rock microfractures, based on the source parameters of MS events. The surrounding rock microfracture scale characterized by the source radius of MS events was considered to establish the constitutive relation. MS information was imported into the model for numerical analysis using fast Lagrangian analysis of continuain 3 dimensions (FLAC3D). The results indicated that the numerical simulation results considering MS damage can better reflect the actual situation of the field. The surrounding rock microfractures mainly showed mixed failure characteristics. Shear failures appeared in localized areas while the fracture scale of sections from K0–33 m to K0–15 m on the vault was large. The deformation increment caused by microfracture damage in the shallow surrounding rock of the top arch accounted for 10%–13%, and the stress decrement in the surrounding rock caused by microfracture damage accounted for about 10%.

Active Triclinic Transtension in a Volcanic Arc: A Case of the El Salvador Fault Zone in Central America

The El Salvador Fault Zone (ESFZ) is part of the Central American Volcanic Arc and accommodates the oblique separation movement between the forearc sliver and the Chortis block (Caribbean Plate). In this work, a triclinic transtension model was applied to geological (fault-slip inversion, shape of volcanic calderas), seismic (focal mechanisms) and geodetic (GPS displacements) data to evaluate the characteristics of the last stages of the kinematic evolution of the arc. The El Salvador Fault Zone constitutes a large band of transtensional deformation whose direction varies between N90° E and N110° E. Its dip is about 70° S because it comes from the reactivation of a previous extensional stage. A protocol consisting of three successive steps was followed to compare the predictions of the model with the natural data. The results show a simple shear direction plunging between 20° and 50° W (triclinic flow) and a kinematic vorticity number that is mostly higher than 0.81 (simple-shearing-dominated flow). The direction of shortening of the coaxial component would be located according to the dip of the deformation band. It was concluded that this type of analytical model could be very useful in the kinematic study of active volcanic arcs, even though only information on small deformation increments is available.

Evolution models of the damage to the near-field rocks surrounding the drift under the disturbance caused by extraction of the longhole stope

Strong blasting disturbances and excavation unloading effects may result in rib spalling and roof collapse of the near-field rocks surrounding the drift during longhole stope mining. An underground gold mine in Shandong Province, China, was selected as a case study to investigate the evolution of the damage to the near-field rocks surrounding the drift through theoretical analysis and field tests, and the relationship between the convergence deformation and damage zone radius of the rock surrounding the drift was established. The results of this study revealed that the convergent deformation of the near-field rocks surrounding the drift exhibited a stepwise increase with time. At the moment of stope blasting, the maximum increment of the convergent deformation of the rock surrounding the drift reached 30.90 mm. Moreover, the convergence deformation of the rock surrounding the drift exhibited exponential decay with increasing distance from the stope boundary. The area within the vicinity of the drift and 7.32 m from the stope boundary was defined as the strongly affected zone, and the area within 7.32–21.62 m of the stope boundary was defined as the moderately affected zone. In view of the functional relationship between the convergence deformation and the damage zone radius of the rock surrounding the drift, a method of calculating the damage zone depth of the rock surrounding the drift was established by considering the effects of the deformation relief before convergence monitoring and the disturbance caused by the extraction of the longhole stope based on the unified strength theory. The error between the damage zone depth obtained using the proposed method and the actual value was less than 3.00%. It was found that the increment of the damage zone depth reached 2.07 m in the strongly affected zone and the average increment was 1.76 m. The method developed in this study can be used to assess the depth of the damage zone in the near-field rocks surrounding the drift in the longhole stope in similar mines.