Dilation Coefficient Research Articles

Classification of infection grade for anthracnose in mango leaves under complex background based on CBAM-DBIRNet

Anthracnose is one of the most harmful fungal diseases in mango orchards. Accurate and rapid detection of anthracnose infection grade for mango leaves in complex natural environments is a prerequisite of precise variable pesticide spraying by robots in intelligent orchards. In this paper, A lightweight double branch inverted residual attention network (CBAM-DBIRNet) model was proposed by combining the inverted residual network and the attention mechanism, which was used to detect the infection grade of anthracnose for mango leaves in natural environment. The model designed two parallel residual branch structures to extract multi-scale features of mango leaves with different infection grades through different dilation coefficients. The inverted residual structure and depthwise separable convolution were used to reduce the complexity of the model. The CBAM attention module was integrated into the model to suppress the interference of complex background information. The mango leaves collected in the natural orchard were used for experiments. The results showed that the accuracy, recall and F1 of the CBAM-DBIRNet model for the classification of anthracnose infection grade were 98.42 %, 97.80 % and 97.89 %, respectively. The model size and parameter were 0.64 MB and 0.15 M, respectively. This study provides technical support for smart orchard management and robotic precision variable application operations.

Elastic-plastic response of tunnel in GZZ-based constitutive model

Investigating the stress redistribution characteristics after tunneling is critical for designing and constructing deeply buried tunnels. Three-dimensional stresses are more prominent in deep than in shallow tunnels, resulting in nonlinear strength. The generalized Zhang–Zhu (GZZ) criterion captures the nonlinear strength well. Therefore, this study established a 2D plane-strain numerical model using a GZZ-based constitutive model. The effects of the axial stress and rock properties on the stress redistribution and plastic zone are discussed. The initial axial stresses changed the axial stress distribution after excavation and had little effect on the radial and tangential stress distributions. The size of the plastic zone decreases with decreasing geological strength index and increasing rock mass mi . However, with increasing dilation coefficient, the stress distributions remained almost unchanged, whereas the radial deformation gradually increased.

A closed-form criterion to identify high-mobility flowslides

This paper derives a closed-form criterion to assess the risk of flowslide runout in loose frictional soil. The derivations rely on a recently proposed framework to simulate pre- and post-failure motion in infinite slopes. An analytical solution of the coupled differential equations capturing flowslide hydromechanics is obtained by specifying them for a perfectly plastic constitutive law. This result enables a comprehensive examination of the factors that control whether the landslide motion, once triggered, autonomously comes to rest (self-regulating behaviour with low mobility) or continues to propagate (self-feeding behaviour with high mobility). It is found that the time history of motion is regulated by non-dimensional property groups reflecting the timescale of excess pore pressure dissipation and the inertial properties of the liquefied zone, which are in turn governed by material (e.g. hydraulic conductivity, dilation coefficient, elastic moduli) and slope properties (e.g. thickness, inclination). The solution is used to build charts identifying the critical ranges of soil properties and triggering factors that differentiate between high-mobility and low-mobility flowslides. Most importantly, it is shown that the fate of flowslide motions is predicted by a critical ratio expressed in terms of excess pore pressure and flow velocity, here defined as the factor of mobility, FM, with values above 1 indicating a self-feeding runout.

Shear failure analysis of slip zone soil with different coarse particle shapes: Visualized shear test and PIV technology

Coarse particle shape in slip zone soil influences the mesoscopic structure of the soil, which in turn affects soil shear strength and failure behavior. In order to investigate the effect of particle shape on the shear characteristics of coarse–fine-grained mixed slip zone soil, three types of coarse particles (spheroidal, rounded, and angular) were selected for mixing and matching, and a total of 10 sets of medium-scale shear tests were designed for this paper. To quantify the shear deformation and failure process of slip zone soils, particle image velocimetry (PIV) technology and the hanging hammer method were used to obtain mesoscopic data of the soil (displacement vector data of soil particles and elevation data of the shear failure surface), which were used to calculate shear band thickness, shear dilatation, and roughness coefficient of the shear failure surface. The results indicate that coarse particle shape can considerably affect the macroscopic mechanical properties (internal friction angle and shear strength) and mesoscopic deformation characteristics (shear band thickness, shear dilatation, and shear surface morphology) of soils. Angular coarse particles have higher interlocking strength than spheroidal and rounded coarse particles, allowing angular coarse-grained slip zone soils to develop large shear band thickness and rough shear failure surfaces. In addition, mesoscopic damage analysis suggests that the damage rate of slip zone soils decreases with increasing coarse particle shape complexity. These findings enhance comprehension of the failure characteristics of soil-rock mixture slopes and serve as a good reference for the stability analysis of similar slopes.

Simulation on Harmful Gas Control by Balanced Pressure Ventilation in the Fully Mechanized Caving Face under Sealed Fire Area of Small Coal Mine.

The harmful gas in the sealed fire area of a small coal mine rushes into the mining face of the lower coal seam, which restricts the efficient promotion of the working face. In this paper, based on the evolution law of caving coal rock dilatation coefficient, the characteristics of the heterogeneous distribution of permeability and voidage in goaf were obtained, and the mathematical model of gas migration in goaf is constructed. The numerical solution of gas migration in goaf under the sealed fire area of a small coal mine was realized by using the Free and Porous Media Flow module and the Transport of Dilute Matter in Porous Media module in COMSOL Multiphysics, and the corresponding measure was proposed. The results show that the fresh air flows into the goaf from both the inlet air roadway and the working face and then flows out from the upper corner. Driven by the air flow, the CO in the overlying sealed fire area of a small coal mine flows out from the upper corner of the working face, resulting in the CO overlimit. Due to the influence of air leakage and the CO overlimit in the working face, low oxygen occurs in the working face. According to the characteristics of gas emission, balanced pressure ventilation technology is proposed to control the low oxygen in the working face and the CO overlimit in the upper corner. It is found that the balanced pressure ventilation obviously increases the pressure of the working face, reduces the pressure difference between the two ends of the working face by 45.7-26.7%, and decreases the air leakage to the goaf in the upper corner of the inlet air roadway. The field application shows that the problems of low oxygen in the working face and a CO overlimit in the upper corner are effectively solved.

M3YOLOv5: Feature enhanced YOLOv5 model for mandibular fracture detection

BackgroundIt is very important to detect mandibular fracture region. However, the size of mandibular fracture region is different due to different anatomical positions, different sites and different degrees of force. It is difficult to locate and recognize fracture region accurately. MethodsTo solve these problems, M3YOLOv5 model is proposed in this paper. Three feature enhancement strategies are designed, which improve the ability of model to locate and recognize mandibular fracture region. Firstly, Global-Local Feature Extraction Module (GLFEM) is designed. By effectively combining Convolutional Neural Network (CNN) and Transformer, the problem of insufficient global information extraction ability of CNN is complemented, and the positioning ability of the model to the fracture region is improved. Secondly, in order to improve the interaction ability of context information, Deep-Shallow Feature Interaction Module (DSFIM) is designed. In this module, the spatial information in the shallow feature layer is embedded to the deep feature layer by the spatial attention mechanism, and the semantic information in the deep feature layer is embedded to the shallow feature layer by the channel attention mechanism. The fracture region recognition ability of the model is improved. Finally, Multi-scale Multi receptive-field Feature Mixing Module (MMFMM) is designed. Deep separate convolution chains are used in this modal, which is composed by multiple layers of different scales and different dilation coefficients. This method provides richer receptive field for the model, and the ability to detect fracture region of different scales is improved. ResultsThe precision rate, mAP value, recall rate and F1 value of M3YOLOv5 model on mandibular fracture CT data set are 97.18%, 96.86%, 94.42% and 95.58% respectively. The experimental results show that there is better performance about M3YOLOv5 model than the mainstream detection models. ConclusionThe M3YOLOv5 model can effectively recognize and locate the mandibular fracture region, which is of great significance for doctors' clinical diagnosis.

Dry granular flow in a vane shear cell: flow characteristics and rheological laws

The flow dynamics of dry granular flows is significantly affected by a prominent feature of a granular mass known as dilatancy. Although their rheological behaviour has been characterised via friction and dynamic dilatancy laws, the role of dilatancy in a granular flow has not been much appreciated. In this study, using a vane rheometer, an experimental investigation was conducted on uniform glass beads of (d = 3 mm) at different initial relative densities (15 ≤ Dr ≤ 66%) and shear rates that span over four orders of magnitude. The flow characteristics in terms of effective friction, volume change, and velocity field were obtained and evaluated. The effective friction shows a descending-ascending pattern corresponding to a transitional behaviour from a velocity-weakening solid-like to a velocity-strengthening liquid-like behaviour. The volume-change measurements show that all specimens dilate and reach almost the same density at each shear rate. The velocity field follows a Gaussian pattern characterized by the slipping velocity at the boundary, the interlayer slippage between particles, and the interlayer disorder of the particles. A new non-monotonic friction law and a dynamic dilatancy law are presented as governing rheological laws based on the inertial number and by introducing an effective dilation coefficient. This effective dilation coefficient successfully captures the role of dilation-induced secondary vortex flows in the dry granular flows.

Micro–macro approach of anisotropic damage: A semi-analytical constitutive model of porous cracked rock

A semi-analytical constitutive model of a porous cracked rock is proposed based on the micro–macro approach within a thermodynamic framework. The representative volume element (RVE) of a porous cracked rock is divided into two subproblems, P1 and P2. The porosity evolution equation of a spherical pore is proposed for P1, whereas P2 is an inelastic problem containing numerous anisotropic penny-shaped cracks. First, the relationship between microscopic and macroscopic strains is established through homogenization. This relationship is introduced into the macroscopic free energy equation. A crack propagation criterion based on the Griffith release rate is proposed, and the evolution equations of the shear and tensile crack densities are proposed based on the surface energy function. Subsequently, the Gaussian numerical integration method is used to obtain a semi-analytical explicit expression of the macroscopic stiffness tensor. Finally, based on the proposed crack propagation criterion, a strength-prediction method is developed. A series of uniaxial and triaxial experimental data for different rocks from other references is used to validate the proposed constitutive model and strength prediction method. The results obtained using the proposed model agree well with the experimental curves obtained from uniaxial tension and triaxial compression tests performed on different rocks. The macroscopic mechanical behavior and evolution of microscopic parameters for different rocks with an increase in confining pressure are effectively demonstrated by the proposed model. Strength prediction method can accurately describe the failure strength of different rocks. Furthermore, a sensibility analysis of model parameters revealed that initial porosity e0 and dilation coefficient ζ have a deteriorating effect on the failure strength, and material constant η has an enhancing effect on the failure strength.

The Drucker–Prager criterion-based plasticity theory of amorphous alloys under the complex stress states

The constitutive models of materials are pushed to their limits in a wide range of service scenarios, each with a unique stress state, strain rate, and temperature coupling. This paper successfully captured the stress state sensitivity of amorphous alloys using the free volume theory and the Drucker–Prager yield criterion. The varying yield surface and shear band angle as the dilation coefficient changes are well captured by the FEM simulations. The model can also accurately portray the influence of the stress state, as well as the difference of shear-induced dilation between the tension and compression. This model can facilitate the application of amorphous alloys in complicated local stress states at a large scale and structural level, such as in chiral mechanical metamaterials and gear structures.

Thermally Induced Pore Pressure Build Up in Saturated Porous Low Permeable Formation

Heating a saturated low permeable geological formation induces pore pressure build-up, so-called thermal pressurization, due to the difference in thermal dilation of the solid skeleton and the pore water. The excess pore pressure generally leads to a decrease in the effective stress and can provoke thermally hydraulic fracturing or shear failure. This paper aims at deriving an explicit solution of the pore pressure increase as a linear function of the temperature variation and total mean stress variation in the framework of linear poroelasticity under undrained conditions. The thermal pressurization coefficient is deduced and then under the condition o constant total stress, which is a function of the difference between the thermal expansion coefficients of the pore water and the porous medium, porosity, bulk moduli of water, porous medium and solid phase. The finite element solution is used to show the accuracy of mathematical development. The presence of this solution allows evaluation the effect of temperature dependent thermal expansion coefficient and temperature and pressure dependent bulk modulus of water. An equivalence between thermo-poro-elastic and thermo-elastic problems are established. This equivalence allows determining the pore pressure from a thermo-mechanical simulation. Moreover, the undrained dilation coefficient and undrained bulk modulus are also derived from this analysis.

Simulation of the Compaction Behavior and the Water Permeability Evolution of Broken Rock Masses of Different Shapes in a Goaf

The rock mass in the caving zone of a goaf is relatively broken and considered a porous medium. Additionally, it has the characteristics of irregular size and shape and sharp edges, and it is easy to break. In the process of caving zone compaction, the shape characteristic of a broken rock mass is one of the most important factors affecting the evolution of the compaction characteristics and the water permeability of the caving zone. Through discrete element numerical simulation and theoretical research, the influence of the shape characteristic on compaction characteristics and the water permeability of a broken rock mass is analyzed. The research results are as follows: (1) The number of edges on a caved broken rock mass is negatively correlated with the strain limit of compaction, the initial void ratio and the final breaking ratio. It is positively correlated with the deformation modulus and the residual dilatancy coefficient. (2) The smaller the amount of edges on the broken rock mass, the more obviously the rotation movement occurs during compaction. (3) The smaller the number of edges on the broken rock mass, the faster the decline in the rate of the water permeability, and the lower the water permeability at the final stable stage. (4) With an increasing number of broken rock mass edges, the total strain energy and the dissipative strain energy of caved broken rock masses show a decreasing trend, while the elastic strain energy shows a growing trend.

Dynamics of creeping landslides controlled by inelastic hydro-mechanical couplings

Slow-moving landslides affect proximal infrastructures and communities, often causing extensive economic loss. While many of these landslides exhibit slow and episodic sliding for decades or more, they sometimes accelerate rapidly and fail catastrophically. Although it is known that the landslide dynamics are controlled by hydro-mechanical processes, few analytical models enable a versatile incorporation of the inelastic behavior of the shear zone materials, thus hindering an accurate quantification of how their properties modulate the magnitude and rate of coupled fluid flow and landslide motion. To address this problem, we develop a simulation framework incorporating rainfall-induced, deformation-mediated pore-water pressure transients at the base of active landslides. The framework involves the computation of two sequential diffusion processes, one within an upper rigid-porous landslide block, and another within the inelastic shear zone. Although the framework can be linked to any elastoplastic constitutive laws, here we model landslide motion through an elastic-perfectly plastic frictional model, which enables us to account for standard properties of earthen materials such as elastic moduli, friction angle, dilation angle, and hydraulic conductivity. Numerical case studies relevant to slow-moving landslides in the California Coast Ranges show that the proposed formulation captures different temporal patterns of movement induced by precipitation. In each of the case, we achieved a relatively accurate match between data and simulations by incorporating positive dilation coefficients, which leads to spontaneous generation of negative excess pore-water pressure and self-regulating motion. Conversely, simulations with no dilation (hence, reflecting the approach of critical state) produce sharp acceleration, typical of catastrophic runaway acceleration. Our findings encourage the use of the proposed framework in conjunction with constitutive laws tailored to site-specific geomaterial properties and data availability, thus favoring a versatile representation of the variety of creeping landslide trends observed in nature.

Prediction of Seismic Bearing Capacity Considering Nonlinearity and Dilatancy by Sequential Quadratic Programming

Most of the published literature regarding bearing capacity are often focused on linear and associative soils. Concerning the intrinsic strength nonlinearity in dilatancy soils, this study investigates the problem of the seismic bearing capacity in the framework of the kinematic theorem of limit analysis. The conventional linear Mohr–Coulomb criterion is substituted with a nonlinear power law criterion to depict the nonlinearity of the soil strength. The non-associative feature of soil materials is considered by defining a nonlinear dilatancy coefficient. A generalized tangential technique is accordingly introduced to linearize the strength envelope for making the nonlinear criterion tractable in the analysis. A non-symmetrical translational failure mechanism that is comprised of several rigid wedges is used to characterize the failure of the foundation at the limit state. Moreover, the seismic action is considered by the classic pseudo-static method. Based upon the energy equilibrium theory of the upper-bound limit analysis, new analytical solutions are derived from the work-balanced equation with nonlinearity and dilatancy. This rigorous upper-bound solution is formulated as a multivariate optimization problem and is readily addressed by sequential quadratic programming (SQP). To verify the reliability of the new expressions, the present results are compared with already posted solutions and the original pseudo-dynamic solutions. The comparative results show a good agreement with previous works, and the correctness and rationality of the new analytical solutions are validated. The detailed parametric study reveals that, in the non-associative flow soils, the ultimate bearing capacity is significantly decreased with a reduction in the dilatancy coefficient. Particularly in the linear condition, namely m = 1, the larger the internal friction angle is, the more obvious the influence of the non-associative feature on the bearing capacity is.

Constitutive Model of Rock, Nonlinearity and Localization

The paper deals with the key features of rock behavior and their manifestations in loading diagrams. Mathematical models are proposed for describing elastic-plastic deformation, creep, and fracture of rocks. Deformation beyond the elastic limit is described using a model based on the combined yield surface and the nonassociated flow rule. The yield surface consists of tension cut-off segment, modified linear segments of the Drucker–Prager criterion and cup. The dilatancy coefficient depends on pressure and volumetric deformation. Model equations are derived to describe deformation in the dilation and compaction modes, as well as strain localization and fracture with consideration for damage kinetics. Several examples of numerical modeling are given to illustrate these phenomena.

An efficient moving pseudo-boundary MFS for void detection

We consider the method of fundamental solutions (MFS) for the determination of the boundary of a void. In the proposed formulation the location of the pseudo-boundary is not fixed. The MFS discretization of the corresponding inverse geometric boundary value problem yields a system of nonlinear equations in which the coefficients in the MFS approximation, the discrete radii in the polar parametrization, the coordinates of the centre of the void and the expansion and dilation coefficients of the pseudo-boundaries are unknown. For the minimization of the resulting functional we employ the nonlinear least squares minimization routine lsqnonlin from the MATLAB® optimization toolbox . In contrast to previous studies, we exploit the option which enables the user to provide the analytical expression for the Jacobian of the system, and show that, although tedious, this leads to spectacular savings in computational time. The case of multiple voids is also addressed.

GNU Octave and Python Implementation of Shor's r-Algorithm with Adaptive Step Control

r-algorithms, or subgradient methods with dilation of space in the direction of the difference of two sequential subgradients, were proposed by N.Z.Shor in 1970 in his doctoral thesis. Respective software implementations proved to be competitive with the most effective methods for smooth ill-conditioned problems, both in terms of reliability and calculation time and accuracy of results. The article is devoted to the description of two software implementations of Shor's r-algorithm modification with a constant coefficient of space dilation and adaptive step control. The first program is implemented using the GNU Octave, and the second program is implemented using Python. Material of the paper is presented in three sections. In the first section, we describe a modification of the r-algorithm with a constant coefficient of space dilation in the direction of the difference of two sequential subgradients and an adaptive method for step size adjustment in the direction of the antisubgradient in the transformed space of variables. The software implementation of this modification is presented in the form of octave-function ralgb5a, which allows to find either approximation of the minimum point of a convex function, or approximation of the maximum point of the concave function. The code of the ralgb5a function is given with a brief description of its input and output parameters. The second section describes test experiments to investigate efficiency of the octave-function ralgb5a to maximizing the piecewise linear concave function, which is obtained using the method of non-smooth penalty functions for the linear programming problem. Another example represents minimization of the piecewise linear convex function, which corresponds to the method of least modules. Results of these computational experiments for test problems with 200, 500, 1000, 1500 and 2000 variables are presented to demonstrate the effective operation of the octave-function ralgb5a. The third section describes the python function ralgb5a and provides its code with a description of the input and output parameters. It is show, how the ralgb5a function can be accelerated by setting two parameters. The results of computational experiments to solve the test problem using the method of least modules for 5,000 variables and 10,000 observations are presented. Keywords: r-algorithm, linear programming problem, nonsmooth penalty function, least modulus method, GNU Octave, python.

A reinterpretation of the mechanical behavior of rubber-sand mixtures in direct shear testing

The mechanical behaviors and properties of rubber-sand mixtures are interesting and of practical importance but are not fully understood yet. In this study, 168 direct shear tests were performed to investigate the shear behaviors and strength of rubber-sand mixtures by considering various rubber content and rubber particle sizes, with an analysis made from the energetic and micromechanical perspectives to illuminate the underlying mechanisms. The experimental results indicate that increasing the rubber content helps reduce the shear strength of rubber-sand mixtures and restrain the mobilization of dilatancy, whereas it aids in promoting the ductility. The role of rubber particle size relies on the rubber content level: increasing the rubber particle size basically weakens the shear strength and dilatancy of rubber-sand mixtures with a relatively high rubber content, but it contributes to a minor increase in the shear strength at large shear displacements, given a low rubber content. The stress-dilatancy behaviors of rubber-sand mixtures can be characterized by a general linear function, in which the dilatancy coefficient ξ and critical state friction angle ϕcs, as two crucial function parameters, are both variables affected by the rubber content, rubber particle size and normal pressure. The energetic and micromechanical analysis based on the idealized conceptual model reveals that the impact of rubber content, rubber particle size, and normal pressure on the critical state shear strength is fundamentally linked with a combined effect stemming from the roughness of shear plane and relative number of particle sliding and rolling behaviors, the variation of which is in essence governed by the deformation of rubber particles.

이요인 모형 기반 혼합형 검사를 위한 다차원 IRT 척도 연계 방법

Like unidimensional item response theory (IRT) models, bifactor models in multidimensional IRT have a scale indeterminacy problem, and due to this problem scale linking methods are needed to place all bifactor model parameter estimates from separate calibrations on a common ability scale. Four bifactor scale linking methods including the direct least squares (DLS), mean/least squares (MLS), item category response function (ICRF), and test response function (TRF) methods have been presented for use with single-format tests. Parallel to the 2006 paper of Kim and Lee, this paper extends the four scale linking methods to a mixture of bifactor models for mixed-format tests. Each linking method extended is intended to handle mixed-format tests using any mixture of the following bifactor extensions of four unidimensional IRT models: the bifactor three-parameter logistic, bifactor graded response, bifactor generalized partial credit, and bifactor nominal response models. For generality, symmetric criterion functions are proposed for the ICRF and TRF methods. Given two sets of parameter estimates for the common items linking two test forms, each linking method estimates the dilation (slope) and translation (intercept) coefficients of a linear transformation. Simulations are conducted to investigate the performance of the four linking methods. The results indicate that overall, the ICRF method performs very well, the MLS and DLS methods perform well (the MLS method is slightly better than the DLS method), and the TRF method performs poorly in estimating the linking coefficients. The inferiority of the TRF method is mainly due to its poor estimation of the translation coefficients.

Atomistic Understanding of Ion Exchange Strengthening of Boroaluminosilicate Glasses: Insights from Molecular Dynamics Simulations and QSPR Analysis.

Ion exchange (IOX) is an effective and widely used method to enhance mechanical properties of various glass products ranging from the touch screen of consumer electronics to window shields of airplanes and spacecrafts. IOX or chemical strengthening is achieved through the creation of a compressive surface layer on the glass product. Although widely studied experimentally, the fundamental understanding of the IOX strengthening process is still limited. In this work, we have applied large-scale atomistic simulations to understand IOX-induced mechanical property changes and their relation to the glass composition and structural characteristics. Two series of borosilicate glasses are studied to elucidate the composition effect, with boron oxide for silica and alumina for silica substitutions, respectively, on the mechanical properties of different levels of K+ to Na+ ion exchanges by using molecular dynamics (MD) simulations with a set of recently developed effective partial charge potentials. The linear network dilation coefficient (LNDC), a common measure of IOX behaviors, was calculated for each of the glass compositions. Quantitative structural property relationship (QSPR) analysis based on the MD-generated structural features was used to establish the structure-property correlations of mechanical and other properties. The results show strong composition dependence of the LNDC, hence the suitability of IOX strengthening. This behavior is discussed based on glass structure features of the glasses. It was found that glass compositions with a higher amount of mixed glass formers, higher network connectivity, and less complex components tend to show higher calculated LNDC and higher surface compressive stress. MD simulations, in combination with QSPR analysis, can thus provide atomistic insights into how the glass composition and structural characteristics affect IOX behaviors.

A Proposed Algorithm to Compute the Stress-Strain Plastic Region and Displacement of a Deep-Lying Tunnel Considering Intermediate Stress and Strain-Softening Behavior

Past studies on deep-lying tunnels under the assumption of plane strain have generally neglected the influence of intermediate principal stress even though this affects the surrounding rocks in the plastic zone. This study proposes a finite difference method to compute the stress strain plastic region and displacement of a tunnel based on the Drucker–Prager (D–P) yield criterion and non-associated flow rule and considering the influences of intermediate principal stress and the strain-softening behavior of surrounding rock. The computed results were compared with those of other well-known solutions and the accuracy and validity of the method were confirmed through some examples. Parameter analysis was conducted to investigate the effects of intermediate principal stress on stress-strain, the plastic region, the ground response curve, and the dilatability of surrounding rock. The results showed that the plastic radius Rp, the residual radius Rd, and radial displacement of surrounding rock first decreased and then increased with increasing intermediate principal stress coefficient b from 0 to 1, with the minimums occurring at b = 0.75. On the contrary, the peak and rate of variation of the dilatancy coefficient first increased and then decreased with increasing b and the dilatancy coefficient Kψ gradually transitioned from nonlinear to linear variation. Meanwhile, the inhibition of the plastic radius and radial displacement gradually weakened with increasing support pressure, whereas the dilatancy coefficient of the tunnel opening gradually increased.