Excavation Process Research Articles

Effect of Multiple Factors for the Roadway Excavation Process Stability in FLAC3D

Abstract Appropriate simulation set parameters are the precondition to obtain accurate results; while the simulation results are affected by multiple factors, it is thus crucial to investigate the sensibility of different factors. This paper first analyses the application situation of numerical simulation software in the field of geotechnical engineering and finds that Fast Lagrangian analysis of continua in three dimensions (FLAC3D) has been widely used on roadways or tunnels. Then, taking the roadway excavation process as the engineering background, FLAC3D was used to create 171 schemes of different simulation parameters and analyze the influence of different factors on the simulation results. The findings show that there is a considerable difference in the degree of effect of different parameters on the simulation results. Most of the factors have a remarkable effect on the numerical simulation results (displacement and stress), and only some factors (parameter uniformity and density) have almost no effect on the results. Meanwhile, the trend of displacement and stress is opposite in most cases. In addition, some neglected factors can also have a considerable effect on the simulation results, such as the zone amount; therefore, it is necessary to avoid the variation of nonstudy factors as possible when carrying out the numerical simulation. This study may significantly assist concerned engineers and technicians in developing a more organized and thorough grasp of the impacts of various parameters on simulation outcomes.

The Effect of Excavation Disturbance on the Stability of Bedding Cataclastic Rock Mass High Slope Containing Multimuddy Interlayers

In China, slope engineering occasionally faces landslides in rocky slopes containing muddy interlayers, primarily triggered by excavation activities. These incidents lead to considerable human casualties and substantial economic losses. However, existing studies predominantly concentrate on the excavation-induced impacts on the stability of rocky slopes characterized by single-layered soft and weak interlayers. Conversely, reports on how excavation influences the stability of bedding cataclastic rock mass high slope containing multimuddy interlayers remain notably absent in the literature. Moreover, unloading due to excavation can swiftly compromise the mechanical integrity and overall quality of the rock mass, consequently impacting the stability of slopes postexcavation. Therefore, this paper modeled the unstable slope excavated at a waste incineration power plant in Yuxi, Yunnan, using the finite element strength reduction method. This approach was employed to comprehensively simulate the entire process of artificial multilevel excavation in a bedding cataclastic rock mass high slope containing multimuddy interlayers. This study investigated the impact of multilevel artificial excavation on slope stability by thoroughly considering factors including alterations in slope morphology, unloading effects, and the degradation of geotechnical parameters. The research yielded the subsequent conclusions. Multimuddy interlayers were the key to the slope’s instability. For slopes subjected to such multilevel excavation, efforts were made to minimize the exposure of muddy interlayers. Slopes above exposed muddy interlayers did not require additional support, while those below needed prioritized reinforcement. The likely instability mode of the actual slope was local destabilization leading to landslides. Furthermore, when using numerical simulation methods to study the impact of excavation disturbances on the stability of such slopes, it was necessary to consider the deterioration of geotechnical parameters to obtain results more reflective of actual conditions. These research findings provided valuable theoretical and empirical support for studies on similar excavated slopes.

Physics-guided deep learning for driving force estimation in synchronous tunnel boring machines under missing cylinders

To solve the problems of high-dimensional under-constraint and state unknowability in the segment assembly process, this study develops a physics-guided deep learning approach to estimate the hydraulic cylinder driving force and promote the system stability in the synchronous excavation and segment assembly tunnel boring machines (S-TBMs). The Newton's law and the Lagrange multiplier method are used to analyze the force boundary of the S-TBM, where the constraint equations are embedded into the deep learning model. The basic model adopts the multi-head attention deep neural network (MD) architecture, which can capture the extreme data of the cylinder through the attention mechanism. The results show that: (1) The proposed physics-guided deep learning can effectively predict driving force of the cylinder and generate high R2 values which is 0.977. (2) By incorporating the physical laws and simulation data, the model accuracy of R2, RMSE, MAE, and EVS is increased by 9.04%, 53.96%, 55.91%, and 9.89%, respectively. (3) The estimation approach has good robustness, and there is no obvious deviation in the estimation results for 16 cylinders. The novelty to be highlighted is the development of the cylinder driving forces estimation approach with the physical laws incorporated, which is helpful in effectively improving the stability during the excavation and segment assembly process.

Julius Haast and the discovery of the origin of alpine lakes

ABSTRACT This article investigates Haast’s claim that in March 1862 he independently reached the same controversial conclusion as Ramsay, that lake basins in previously glaciated regions were formed by ancient glaciers. Both men's views fuelled a passionate debate in British scientific societies. However, science historians largely ignore Haast’s contribution or imply he knew about Ramsay’s ‘theory’ before coming to a conclusion about Southern Alps lakes. To assess whether Haast independently reached that conclusion in March 1862, field records, correspondence, reports, newspaper articles, and scientific publications are examined. Of significance are communications with geologists Hochstetter, Hector, and Ramsay, botanist Hooker, and physicist Tyndall. Consideration of what Haast observed in March 1862 is also critical. However, Haast's 1862 conclusion differs from Ramsay's. While Ramsay was convinced ancient glaciers scooped out rock basins, resulting in deep lakes, Haast believed ancient retreating glaciers left moraines that dammed valleys, resulting in shallow lakes. Regardless of their differences, after Haast read Ramsay’s paper in 1864, he applied Ramsay’s ‘theory’ to New Zealand’s alpine lakes and proposed an excavation process. The essence of both Ramsay’s and Haast’s conclusions has been confirmed by research in formerly glaciated regions worldwide. However, Haast’s contribution to glaciology is overlooked or underemphasized, and warrants being more widely acknowledged.

Experimental Study on Stability Analysis of Shallow-Buried Metro Station Hard Rock Excavation under Blasting Vibration Effect

Abstract By considering a certain metro station of Qingdao Metro Line 4 as the research object, a three-dimensional geotechnical testing model has been developed to analyze the stress and deformation characteristics of the surrounding rocks under blasting vibration effect. The simulation of the surrounding rock blasting process is achieved through an electric spark source. We conducted simulation tests on the excavation stability of shallow-buried hard rock metro stations with and without considering blasting damage effects, respectively. The stress, displacement, and primary support stress changing laws of the surrounding rock under different overburden thicknesses using the arch cover method and the primary support arch cover method have been revealed. Finally, we analyzed the applicability of the primary support arch cover method in terms of vault settlement, clearance convergence, and floor heave. Results show that the surrounding rock of the arch has roughly gone through three deformation stages, namely a slow deformation stage, rapid deformation stage, and stable deformation stage. Whether it is blasting excavation or non-blasting excavation, the settlement of the arch is within a safe and controllable range. Because of the refinement of the excavation process by the primary support arch cover method, the stress release is relatively stable throughout the entire excavation process, but the significant impact of blasting vibration on the surrounding rock cannot be ignored. The excavating of the left and right guide holes is the key process for the displacement and stress variation. The deformation and stress generated by the arch cover method have a small difference compared to the deformation and stress generated by the primary support arch cover method, indicating that the latter excavation method can be used under current engineering geological conditions. No large-area collapse and instability occurred in the experimental process, which provides a theoretical basis for similar projects.

A study of rotary cutting machine (RCM) performance on Korean granite

PurposeDespite the many advantages this type of equipment offers, there are still some major drawbacks. Linear cutting machine (LCM) cannot accurately simulate the true rock-cutting process as 1. it does not account for the circular path along which tunnel boring machine (TBM) disk cutters cut the tunnel face, 2. it does not accurately model the position of a disk cutter on the cutterhead, 3. it cannot perfectly replicate the rotational speed of a TBM. To enhance the knowledge of these issues and in order to mimic the real rock-cutting process, a new lab testing equipment was developed by Hyundai Engineering and Construction.Design/methodology/approachA new testing machine called rotary cutting machine (RCM) is designed to simulate the excavation process of hard-rock TBMs and includes features such as TBM cutterhead, RPM simulation, constant normal force mode and constant penetration rate mode. Two sets of tests were conducted on Hwandeung granite using different disk cutter sizes to analyze the cutting forces in various excavation modes. The results are analyzed using statistical analysis and dimensional analysis. A new model is generated using dimensional analysis, and its results are compared against the results of actual cases.FindingsThe effectiveness of the new RCM test was demonstrated in its ability to apply various modes of excavation. Initial analysis of chip size revealed that the thickness of the chips is largely dependent on the cutter spacing. Tests with varying RPM showed that an increase in RPM results in an increase in the normal force and rolling force. The cutting coefficient (CC) demonstrated a linear correlation with penetration. The optimal specific energy is achieved at an S/p ratio of around 15. However, a slightly lower S/p ratio can also be used in the design if the cutter specifications permit. A dimensional analysis was utilized to develop a new RCM model based on the results from approximately 1200 tests. The model's applicability was demonstrated through a comparison of TBM penetration data from 26 tunnel projects globally. Results indicated that the predicted penetration rates by the RCM test model were in good agreement with actual rates for the majority of cases. However, further investigation is necessary for softer rock types, which will be conducted in the future using concrete blocks.Originality/valueThe originality of the research lies in the development of Hyundai Engineering and Construction’s advanced full-scale laboratory rotary cutting machine (RCM), which accurately replicates the excavation process of hard-rock tunnel boring machines (TBMs). The study provides valuable insights into cutting forces, chip size, specific energy, RPM and excavation modes, enhancing understanding and decision-making in hard-rock excavation processes. The research also presents a new RCM model validated against TBM penetration data, demonstrating its practical applicability and predictive accuracy.

Multi-Stage and Multi-Parameter Influence Analysis of Deep Foundation Pit Excavation on Surrounding Environment

As urbanization accelerates, deep excavation projects have become increasingly vital in the construction of high-rise buildings and underground facilities. However, the potential risks to the surrounding environment and the inherent complexities involved necessitate thorough research to ensure the safety of those engineering projects with deep foundation pit excavation and to minimize their impact on adjacent structures. This study introduces a multi-stage and multi-parameter numerical simulation method to scrutinize the construction process of deep foundation pits. This approach not only investigates the influence of excavation activities on nearby buildings and roads but also enhances the fidelity of simulation models by establishing a three-dimensional finite element model integrated with on-site investigated geological information. Therefore, the proposed method can provide a more holistic and accurate analysis of the overall impacts of the pit excavation process. To examine the feasibility and effectiveness of the proposed method, this study adopts the multi-stage and multi-parameter influence analysis approach for a real practical engineering case to explore the impact of excavation on the foundation pit support structure, nearby buildings, and surrounding roads. The foundation pit support’s maximum displacement was 8.64 mm, well under the 25 mm standard limit. Anchor rod forces were about 10% below the standard limit. Building and road settlements were also minimal, at 10.33 mm and 16.44 mm, respectively, far below their respective limits of 200 mm and 300 mm. This study not only validates the feasibility of design and construction stability of deep foundation pits but also contributes theoretical and practical insights, serving as a valuable reference for future engineering projects of a similar scope.

Discussion on the Application of Grouting in Underground Engineering

With the development of China's economy, in some large cities, surface transportation alone can no longer meet people's needs today, and the development of underground engineering is increasingly catering to the needs of the public. During the excavation process of subway tunnels, it is inevitable that they may be threatened by groundwater, and grouting technology is one of the effective methods for preventing and controlling water in underground engineering. The mechanism of slurry flow and diffusion varies depending on the soil conditions. When underground projects such as subway tunnels pass through poor geological conditions, it is highly likely to cause significant surface subsidence, and even engineering disasters such as water inrush and collapse may occur. To ensure the safety of underground engineering construction in the geological strata, it is often necessary to carry out advanced grouting in the strata to achieve the purpose of reinforcement or water blocking. Advanced grouting reinforcement belongs to concealed engineering, and the existing advanced grouting construction mostly relies on experience and on-site grouting tests, making it difficult to achieve the expected grouting effect. Therefore, it is of great theoretical and engineering significance to conduct in-depth research on the diffusion mechanism of slurry in geological grouting reinforcement engineering, as well as the influence of factors such as slurry water cement ratio and geological characteristics on the diffusion form of slurry.

Application of physics-informed machine learning for excavator working resistance modeling

Accurate measurement of the working resistance encountered during excavation plays a vital role in improving production efficiency, reducing energy consumption, and enabling intelligent capabilities in excavators. To address the challenges of the inaccurate measurement of working resistance, we present a novel method for measuring excavator working resistance based on physics-informed machine learning (PIML). Firstly, we construct a mechanism model, which incorporates the kinematic and dynamic models of the excavator working device. Next, by integrating the mechanism models with machine learning algorithms, a soft sensing model for excavator working resistance based on the PIML method is developed. Finally, experimental analysis is conducted to compare the predictive performance of three different methods: mechanism modeling, data-driven modeling, and PIML. The results indicate that the PIML method allows for a more precise estimation of the working resistance experienced during the excavation process of excavators, and it holds significant theoretical and practical implications.

Study on the dynamic construction mechanics of side piles in metro station using the pile-beam-arch method

Based on the Tianhe East Station in Guangzhou Metro Line 11 engineering, this paper analyzes the formation mechanism of soil arching effect (SAE) of station by pile-beam-arch (PBA) method in the excavation process and studies the mechanics and deformation laws of side piles in different construction stages under different pile spacing conditions. The results show that the formation, development and destruction of SAE between piles are closely related to construction process. Both too large and too small pile spacings are not conducive to the development about SAE between piles; when it is located between them, the SAE between piles exerts greatly. In the form of composite lining system, supporting piles as well as SAE between piles play an effective role in supporting soil behind piles. The lateral deformation of pile body is most significant in the completion of buckle arch to the excavation of first soil layer, which is the critical construction phase to reduce lateral deformation of side pile. The axial forces of side pile increase gradually with the excavation of station, and the change is the most drastic at the excavation for first soil layer. The influence of pile spacing on vertical settlement and axial force of side piles is much greater than that of horizontal displacement and bending moment.

Experimental studies of screw drill with frozen soil interaction

Introduction. The process of formation of wells in frozen soils is one of the complex processes of excavation. A drilling tool of a new geometric shape forms a well by brittle destruction of the rock. The purpose of the conducted experimental studies was to determine the effect on the energy intensity of the drilling process and on the well diameter coefficient of the angle of rotation of the radius of the screw blade, at which its increment occurs on the destructive part and the angle of inclination of the forming upper surface of the screw blade to the axis of rotation.Materials and methods. The article describes a methodology for conducting laboratory experiments to study the interaction of a drilling tool of a new geometric shape with frozen soils. The ranges of values of the studied factors are determined. The matrix of the complete factorial experiment is constructed.Results. As a result of laboratory experiments, the influence of the geometric parameters of the drilling tool on the energy intensity of the drilling process and on the well diameter coefficient was determined. The dependencies of the torque and the well diameter coefficient on the angle of rotation of the radius of the helical blade, at which its increment occurs on the destructive part, the angle of inclination of the forming upper surface of the helical blade to the axis of rotation and the angle of elevation of the middle helical line of the helical blade are established.Discussions and conclusion. It is established that the drilling tool carries out the formation of a well due to the brittle destruction of the well, which makes it possible to achieve more efficient drilling. And also the dependences of the rational values of the investigated geometric parameters of the drilling tool of a new geometric shape are determined.

Mechanical Difference Analysis of Single-row and Double-row Side Piles in Stations by PBA Method Based on Model Test

This study employs the pile-beam-arch (PBA) method to investigate the force-evolution law of micro-steel pipe piles during the excavation process, focusing on a Guangzhou metro-station project. Through laboratory model tests, we compared and analyzed the mechanical evolution laws of single-row and double-row side piles. Our findings revealed a significant soil arch effect in both single-row and double-row piles; with similar distribution patterns and peak-stress range. As soil excavation progresses, the soil arching effect shifts downward. Notably, the stress concentration in double-row piles is weaker than that in single-row piles, especially in the soil range of 0–50 mm after the piles. This is attributed to the looser soil between single-row piles, resulting in more evident stress release. The attenuation amplitude of the Y-direction stress of the double-row piles was considerably smaller than that of the single-row piles. The soil arching between the back-row piles in doublerow configurations exhibits shielding effects on the force of front-row piles, significantly weakening the soil pressure on them. This impact alters the force of the front-row piles, even causing the tip of the front-row piles to bend in reverse. The research results provide important insights for similar projects and can serve as a valuable reference.

LABORATORY INVESTIGATION OF THE EFFECT OF SODIUM SILICATE AND BENTONITE ON THE MECHANICAL PROPERTIES OF THE GROUT BEHIND THE SEGMENT IN MECHANIZED EXCAVATION

Nowadays, the use of Tunnel Boring Machines (TBM) in tunnelling has increased in urban environments. One of the effective parameters in the excavation process is the use of grout behind the segments to prevent ground settlement and penetration into the tunnel. The investigation of the effects of two-component grout (bentonite and sodium silicate) on the mechanical properties of the grout plays a crucial role in mechanized excavation. Therefore, this article aims to investigate the effect of various parameters on the properties of the two-component grout. Eight different mixing designs were considered in this research. Gel-time tests, viscosity test, water bleeding test, uniaxial compressive strength tests (UCS), and direct shear tests were conducted for each mixing design. The UCS tests were performed for eight mixing designs and at four different ages of the grout, while the direct shear test was conducted for five mixing designs at the age of one day. The results showed that increasing the sodium silicate content from 4% to 9.4% reduced the Gel-time to 7 seconds, and increasing the bentonite content from 2.3% to 4.58%, increased the marsh funnel time to 12 seconds. The uniaxial compressive strength of the grout increased to 0.682 MPa at the age of 28 days. Finally, by conducting the direct shear test on the grout and obtaining the parameters of cohesion and internal friction angle, it was determined that these two parameters depend on the values of bentonite and sodium silicate, and they change with the increase or decrease of these grout components.

Analysis of Vibration Characteristics of Hydraulic Excavator Device Under Flat Ground Conditions

Hydraulic excavators, characterized by their high efficiency and versatility, are crucial equipment in engineering construction. During the automatic excavation process, the excavator may experience resonance phenomena, which can affect the stability of the entire system. In order to study the vibration harmonic response of the excavator arm in the process of reciprocating motion, firstly, the model of the excavator arm is designed in three‐dimensional software, and the finite element meshing software is used to perform hexahedral meshing of the excavator arm model and define the material properties. Secondly, the modal analysis of the excavator arm is carried out by finite element simulation software, and the displacement and acceleration harmonic response analysis is carried out using the modal superposition method. Finally, the vibration experiment of reciprocating motion with different frequencies is carried out on the experimental platform of the excavator arm. The simulation and experimental results show that the maximum value of the displacement and acceleration response of the excavator arm corresponds to the frequency near the second‐order intrinsic frequency, and the excavator arm is greatly affected by the second‐order intrinsic frequency; controlling the frequency of the reciprocating motion of the hydraulic cylinder within 13 Hz can effectively avoid the resonance phenomenon of the excavator arm device.

DEM-based analysis of water inrush process of underground engineering face with intermittent joints in karst region


 
 
 
 Water inrush disaster of karst tunnel often lead to significant economic losses and serious casualties, which is an urgent engineering roadblock to be solved in the construction of tunnel in karst area. In this paper, three-dimensional discrete element method considering fluid-solid coupling effect and structural characteristics of water-mud resistant rock mass is adopted to systematically study the evolution law of displacement field and seepage field of intermittent joint type water-mud resistant rock mass of tunnel face and its water inrush critical characteristics during the process of sequential excavation of karst tunnel close to the frontal high-pressure water-rich karst cavity. The results show that: With the tunnel face gradually approaching the front-concealed high-pressure water-rich karst cavity, the stability of water-mud resistant rock mass is increasingly affected by high-pressure karst water, and karst water pressure gradually becomes the main control factor. The closer the tunnel face is to the front-concealed high-pressure water-rich karst cavity, the greater the extrusion displacement of karst tunnel face and its increase amplitude, the higher damage degree of water-mud resistant rock mass of face. With the advance of tunnel excavation, the intermittent cracks in the water-mud resistant rock mass of face gradually connect and form a stable hydraulic connection. The flow velocity and seepage pressure of karst water rise significantly at the moment of overall instability of face and the formation of water inrush channel, showing obvious precursor characteristics. The research achievements provide a reference for early warning and prevention and control of water inrush disaster of karst tunnel face.
 
 
 

Geophysical Techniques for Monitoring of Integrated Mine Waste Storage Facility: Case Study of Southeastern Bulgaria

The extraction of mineral resources usually generates varying amounts of extractive waste, which require appropriate management. Extractive waste management is complicated and difficult process. It encompasses a lot of actions and many different competences. Here must be taken into account the mining excavation method, processing methods, beneficiation and overall mineral treatment. The results obtained from these study provide an important basis for the quantification and management of environmental impacts of the Integrated mine waste facility (IMWF) at the “Ada Tepa” gold mine. The aim of this research is to monitoring the process of internal water drainage into constructed cells of the facility. This task is performed using geophysical method based on electrical resistivity measurements made on the ground surface. Electrical resistivity tomography is commonly used to solve mining and engineering issues, because it is efficient and environmentally sound. This study demonstrates the efficiency of electrical resistivity tomography in detecting the saturated zones in the IMWF.

Анализ грейферной выемки волокнистого торфяного сырья

The purpose of the study was to confirm the possibility of implementing the operations of the working cycle of mining equipment with the determination of the range of forces required to introduce the elements of the grab into the deposit and close the jaws in the massif, taking into account the design features of the grab. Research methodology. A series of field studies was carried out using full-scale models of the working bodies of a fork grab in the conditions of a peat deposit to confirm the possibility of implementing the process of extracting raw materials of a low degree of decomposition. Results. It has been established that the average value of the force required overcoming the resistance to the introduction of the grab model: on the site with magellanicum peat – 44.4 kN, with fuscum-peat – 61.5 kN. The average value of the normal stress when immersed in an array of a clamshell equipment element, taking into account the end surface area, is 89 kPa for: magellanicum peat, 123 kPa for fuscum-peat. The average value of the total deformation modulus in the natural occurrence of a peat deposit is 116 kPa for magellanicum peat and 126 kPa for fuscum-peat. The rational distance between the teeth of the jaw model of the fork grab has been determined. With a distance between the teeth of the grab jaw model l=0.25 m, a single drawing body is formed when the captured area of the material is shifted. Conclusion. With the determination of the effort ranges for the implementation of the two main operations of the excavation process, as well as the establishment of the design features of the grab for surface excavation, it was concluded that it is possible to use grab equipment for the surface extraction of fibrous peat raw materials.

Estimation method of earthwork excavation using shield tunneling data -- a case study of Chengdu Metro

The occurrence of over-excavation or under-excavation in tunnel construction poses significant safety risks. Moreover, there is currently no automatic estimation method available for real-time estimation of earthwork excavation, particularly in the case of shield tunnels. In this study, we tracked the excavation process of Chengdu Metro Line 19, acquired tunneling parameters and earthwork excavation data using various sensors, and subsequently proposed an automatic estimation method that combines Bayesian optimization (BO) and gradient boosting regression tree (GBRT) algorithm. The results of our case study indicate that the BO-GBRT model improves the performance of earthwork excavation estimation, reducing the residual after each calculation with a root mean square error (RMSE) of 1.712 and mean absolute error (MAE) of 1.331. Furthermore, compared to other machine learning methods, the proposed BO-GBRT model demonstrates superior estimation performance. Additionally, the importance distribution of input parameters reveals that propulsion pressure, foam pressure, and rotation speed are the most critical factors affecting earthwork excavation. Overall, the proposed automatic estimation method shows great promise as a tool for efficiently estimating earthwork excavation in shield tunnel construction.

Недетская наука: о некоторых фактах участия детей в раскопках Херсонеса Таврического

The sociological, psychological, ethnographical, demographical, sexological and other research of childhood is focused on the systematic study of various phenomena in the child population. The archaeological methodology is based mostly on natural science types of knowledge, therefore it has become possible to make some observations in the field of archaeological childhood in the meaning of “children in archaeology”. The fund of photographic documents from the scientific archive collection of the State Museum-Reserve “Tauric Chersonesos” includes documents on which children are present — these are family members of famous archaeologists, as well as unknown persons, who, however, were not accidental participants in the excavation process. The work carried out made it possible to date the images and, in certain cases, to identify some persons, including children. Not only the photo archive, but also other documents (mainly correspondence of archaeologists) has been studied, which contain other examples of the involvement of children in the study of Chersonesos.

Study on Instability Change Law of Surrounding Rock of Tunnel Crossing Fault Fracture Zone Based on Cusp Point Mutation Theory

The instability process of surrounding rock is a nonlinear mutation. To truly reflect the nonlinear mutation in the failure of surrounding rock and grasp the opportunity of instability of surrounding rock, it is necessary to study the stability of surrounding rock by combining the existing methods with nonlinear scientific theory. Based on the numerical simulation results of a tunnel project crossing the fault fracture zone, the mutation theory is introduced to study the instability law of surrounding rock during tunnel excavation. The dynamic excavation process of surrounding rock tunnel in fault fracture zone is simulated by the finite difference software FLAC3D. Based on the cusp point mutation theory, the deformation law of each excavation step to the working face under different dip angles, strike angles and thicknesses of fault fracture zone is studied. Combined with the dichotomy method, curve fitting is used to analyze the instability threshold of surrounding rock and predict the opportunity of surrounding rock instability. The results indicate that (1) As the dip angle and strike angle of the fault gradually increase, the settlement of the surrounding rock arch first decreases and then increases, while as the thickness of the fault increases, the vertical displacement of the surrounding rock gradually increases. (2) When the dip angle of the fault is less than 90°, the sudden instability of the surrounding rock is advanced, while when it is greater than 90°, the time for sudden instability is delayed. (3) As the strike angle and thickness of the fault gradually increase, the excavation step for the tunnel to undergo sudden instability is gradually advanced. The research conclusion can provide theoretical guidance and suggestions for similar engineering construction in the future.