Lateral Pressure Research Articles

Mechanical analysis of frost heaving of weakly cemented soft rock tunnels in cold regions

To reveal the mechanical response of non-uniform frost heave of surrounding rock in soft rock tunnel in cold region, the stress solution of frozen surrounding rock considering the temperature field was deduced by applying elastic mechanics' displacement potential theory and the superposition principle. Then the plastic zone evolution of frozen surrounding rock was clarified by using the limit equilibrium approach. Furthermore, the analytical solution is verified with the existing solutions, and proved to be reasonable. The calculation results showed that as the temperature drops, the growth rate of the frozen zone radius gradually slows down while the stress increment increases. Frost heaving effect lead to a decrease in the critical state value of the lateral pressure coefficient (λ) for tension–compression. Circumferential stresses show a significant stress drop at the frozen boundary, and radial stresses show extreme values. Frost heaving enlarges the circumferential range of the plastic zone. Under low initial vertical stress conditions (p), when λ or 1/λ decreases from 1 to 0, the plastic zone gradually increases, while its range is always in the frozen zone. However, with an increase in “p” and a decrease in temperature to a certain extent, both inner and outer plastic zones emerged.

Clinical evaluation of pulsatile tinnitus: history and physical examination techniques to predict vascular etiology

BackgroundPulsatile tinnitus (PT) may be due to a spectrum of cerebrovascular etiologies, ranging from benign venous turbulence to life threatening dural arteriovenous fistulas. A focused clinical history and physical examination...

Performance of Pile–Wall System Adjacent to Footings

The performance of a retaining wall is dependent on multiple factors including lateral earth pressure, which results from backfill soils and adjacent footings located behind a retaining wall. The prediction of a retaining wall’s performance in a footing–soil–wall system (FSPS) must incorporate the influences caused by the movement of a retaining wall. This study examines the performance of a retaining wall formed by driven, precast, concrete piles located adjacent to a concrete footing using two- and three-dimensional finite element analysis (2D and 3D FEA) by ANSYS 13.0 software. Both soil and concrete are assumed to behave as non-linear, elastic-perfectly plastic and rate-independent materials in compliance with the upper-bound model of Drucker–Prager yield criterion. Three backfill and foundation soils are considered: kaolin, silty clay, and kaolin–sand. Various conditions of soil type, footing shape ratio, pile width, and footing–pile distance through 180 FEA runs are investigated. The effects of 2D and 3D FEA on the behavior of the pile–wall system are compared. The lateral deflection and pressure distribution profiles along the pile–wall are studied and presented. Two empirical equations predicting lateral deflections at the pile toe and pile head and useful for pile structural design are developed under the ultimate pressure of the adjacent footing.

Study on the Macro-Fine Mechanical Behavior of Ore Flow Based on the Discrete Element Method

The mechanical behavior associated with the flow of ore-rock bulk materials is an important factor leading to the instability and failure of the shaft wall of the ore storage section in ore passes. It is of great significance for accurately understanding the stability failure characteristics of the shaft wall in the ore storage section in the ore-drawing process to understand the flow characteristics and internal mechanical transfer mechanism of ore-rock bulk. The flow characteristics, contact compactness, stress distribution characteristics, and contact force probability distribution of the ore-rock bulk are analyzed by the discrete element method, which realizes the quantitative characterization of the damage degree of ore-rock flow and reveals the damage mechanism of the shaft wall in the storage section of the ore pass. The results show that (1) in the process of ore-rock particle flow in the ore pass storage section, the macroscopic flow pattern of ore-rock particles changes from a “—” shape to a “V” shape, and the friction between ore-rock particles, particles, and the ore-pass wall is an important reason for the change of the macroscopic flow pattern; (2) the probability distribution of contact force strength between the particles decreases exponentially in the whole ore-drawing process, in which the strong force chains play a major role in the stability of the bulk system; and (3) the overpressure frequency and overpressure coefficient could be used to quantitatively characterize the wall damage degree under the action of ore-rock flow. The dynamic lateral pressure fluctuates periodically in exponential form and decreases, and the dynamic load formed by the ore-rock flow mainly acts on the lower part of the ore storage section.

Method for Determining Foundation Bearing Capacity Based on Pressuremeter Test Curve

The pressuremeter test is a horizontal in-situ load test that can objectively reflect the lateral strength and deformation characteristics of the tested soil. The existing methods for determining the characteristic values of foundation bearing capacity through pressuremeter tests are mainly based on the pressure values corresponding to the starting and ending points of the straight line part of the lateral pressure load deformation curve, which has significant uncertainty. Based on the characteristics of the p-s curve, this article uses a cubic polynomial to fit the p-s curve, and the goodness of fit is greater than 0.99; gives a method for determining the characteristic values of foundation bearing capacity based on the pressure value at the inflection point of the p-s curve; and obtains the bearing capacity of the silty clay layer and the fine sand layer in the depth range of 46.0 meters. The calculation results show that compared with the near line method, the relative error of the bearing capacity characteristics of the foundation is within 20%, which can meet the engineering needs. This provides a new approach for determining the bearing capacity of foundations through lateral pressure tests.

Lateral pressure on pile foundations in cohesive soils due to horizontal soil movements

In soft soil layers, piles are frequently loaded laterally by horizontal soil movements. In many cases, the lateral pressure acting on piles due to horizontal soil movements is calculated with empirically or analytically based approaches, respectively. However, most of these design approaches do not consider possible influences on the resulting pile loads. This paper presents the results of model tests and numerical simulations on single piles and pile groups in cohesive soil subjected to lateral loads which were carried out to overcome limitations of available design approaches. Based on extensive small-scale 1 × g-model tests and numerical investigations with the finite element method, influencing factors on the lateral pressure, such as the roughness of the pile–soil interface, the pile size, the pile shape and the pile spacing were identified. A parametric study with the numerical model quantified the most relevant factors influencing the development of lateral pressure on piles due to adjacent surface loads and lead to the development of a simplified analysis approach.

Deformation characteristics and creep behaviour of rigid particulates-EPS beads composites

The compression behaviour of the mixture of glass beads (representing rigid particles) and EPS beads (representing deformable particles) during the loading-unloading process is systematically examined through performing two sets of large-size oedometer experiments, including incremental step-by-step and one-step loading scenarios. At each step during the loading-unloading cycle, the void ratio (e) and the at-rest coefficient of lateral earth pressure (K0) are measured for pure rigid samples and rigid-soft particle mixtures. To consider the creep effect, the overburden pressure at the final loading step is maintained on the sample for 24 h prior to unloading. The results show that at a given overburden pressure, with the addition of soft particles to the pure rigid aggregates, the values of e and K0 decrease. Additionally, for both pure rigid samples and rigid-soft particle mixtures, with increasing the overburden pressure, e decreases whereas K0 augments. Moreover, due to the creep behaviour during the constant loading step, K0 decreases over time for both samples; a phenomenon which is observed to be more pronounced for pure rigid aggregates compared to rigid-soft particle mixtures. Finally, a well-established creep model is used to simulate the creep behaviour of pure rigid samples and rigid-soft particle composites.

Investigation on tunnelling-induced soil pressure changes, a modified trapdoor test study

To investigate the failure mechanics and soil pressure redistribution in cohesive soil during the formation of the arching effect after tunnel excavation, a series of trapdoor tests were conducted on similarity material, and the tunnelling-induced soil movement was modeled. In addition, the moveable soil on the two sides of a tunnel was replicated by modifying the boundary condition of the classic trapdoor. Results indicated that as the trapdoor descended, the cracks extended outward to the ground when the cover ratio (depth to width) was 2, and extended upwards below the ground when the cover ratio was over 2. After the descent of the trapdoor, the unloading effect and arching effect were formed. Therefore, above the trapdoor, the vertical stress (radial stress for the trapdoor) decreased significantly while the tangential stress for the trapdoor increased. Due to the arching effect, the lateral pressure coefficient (K) at the central axis of the trapdoor increased, while it decreased above the two sides of the trapdoor. In the modified trapdoor device, the arching effect was weaker, and reduced the angle between the outermost crack and the horizontal plane, the tangential stress, and the K at the central axis of the trapdoor, and increased the K above both sides of the trapdoor and the range of the soil arch. In addition, in the classic trapdoor device, the arching effect was underestimated at small trapdoor displacements while it was overestimated at large trapdoor displacements. Therefore, the influence of boundary conditions in trapdoor devices should be considered when investigating underground excavation-induced soil deformation and stress redistribution. When calculating the soil pressure, the K should be determined according to the parameters of the soil, the span of the tunnel, and the deformation of the tunnel lining.

Propagation and complex morphology of hydraulic fractures in lamellar shales based on finite-discrete element modeling

We explore the controls of stress magnitude and orientation relative to bedding on the resulting morphology/topology of hydraulic fractures using a combined finite-discrete element method (FDEM). Behavior is shown conditioned by the ratio of principal stresses λ=σ3/σ1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda ={\\sigma }_{3}/{\\sigma }_{1}$$\\end{document} and relative inclination of the bedding. When the lateral pressure coefficient (λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda$$\\end{document}) is less than 0.67, hydraulic fractures predominantly initiate as tensile fractures along the wellbore, aligning with the maximum principal stress direction. Conversely, for λ≥0.67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda \\ge 0.67$$\\end{document}, shear cracks are favored to initiate for the minor stress difference, leading to a less predictable initiation and extension direction. Simultaneously, diminished stress differences correspond to elevated reservoir breakdown pressures, displaying a linear correlation with lateral pressure coefficients and little influenced by equivalent bedding orientation. Bedding plane orientation significantly impacts the mode and morphology of hydraulic fracture propagation. Bedding parallel to the direction of the minimum principal stress (σ3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\sigma }_{3}$$\\end{document}) favors layer-penetrating and bifurcated fractures, whereas inclined bedding facilitates the emergence of numerous steering-type and capture-type fractures. Especially at steeper inclinations (β=60∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta =60^\\circ$$\\end{document}), hydraulic fractures readily extend along the bedding surface, inducing macroscopic shear slip failure. Under high-stress disparities, the breakdown pressure exhibits greater sensitivity to bedding inclination, and its influence pattern aligns with the variations in tensile strength, typically reaching maximum and minimum values at bedding inclination angles of 0° and 60°, respectively.

Membrane-based optical fiber Bragg grating pressure sensor for health monitoring of pile foundations

A fiber Bragg grating (FBG) pressure sensor is proposed, designed, and fabricated for lateral earth pressure sensing, in which the FBG sensor is mounted on a 3D printed trestle structure combined with a membrane. The applied pressure can cause a deformation on the membrane, and then this deformation applied on the trestle structure causes tensile strain on the FBG. The proposed sensor is functionalized as a high-sensitive pressure transducer capable of converting the pressure into strain on the FBG. Here, the performance of the proposed sensor is numerically and experimentally investigated. The results show that the pressure sensitivity at 30°C is 10.62 pm/kPa within a range of 0–0.6 MPa. Due to the thermal expansion of the structure, the pressure sensitivity coefficient decreases with the increase of temperature; however, the cross effect between the temperature and strain on the sensing sensitivity is investigated and can be eliminated. The fabricated sensor has advantages of high sensitivity, good stability, and high pressure resolution, so it has potential in the field of structural health monitoring.

Biaxial compressive failure criteria and constitutive model of high-strength geopolymer concrete after high temperature

This paper studies the effect of high temperatures (20℃, 200℃, 400℃, and 600℃) and stress ratios (σ2/σ3) (0.15, 0.3, 0.45, and 0.60) on biaxial compressive strength and strain development patterns of high-strength geopolymer concrete (HGPC). Experimental observations indicate that HGPC exhibits laminar damage similar to ordinary Portland concrete (OPC) before and after exposure to high temperatures, under biaxial compression. Unlike OPC, damage in HGPC initially passes through coarse aggregates at room temperature but shifts predominantly to the aggregate-mortar interface at 600℃. The biaxial compressive strength envelope of HGPC expands with rising temperatures. The increased multiple of biaxial compressive strength (σ3/fm) for HGPC at room temperature rises and then falls with increasing stress ratios, peaking at a stress ratio of 0.45 and surpassing the values for OPC and high-strength concrete (HSC). Before high temperature, the modulus of elasticity of HGPC is higher than that of OPC and decreases with increasing temperature, decreasing by about 45–60% for every 200°C increase, and the reduction is greater than that of OPC. The existing failure criterion is not suitable for HGPC after high temperature, this paper develops a new biaxial compression failure criterion for HGPC before and after high temperature based on Kupfer's criterion, taking into account the effect of temperature. The proposed failure criterion calculation results are well in agreement with the experimental data. A damage constitutive model for HGPC considering the effect of temperature and lateral pressure is also proposed, combining the Weibull distribution model for the ascending branch and a modified empirical model for the descending branch. This combined model effectively predicts the stress-strain relationship of HGPC under various temperature conditions.

A plastic Stillinger-Weber potential-based discretized virtual internal bond approach for modeling soft rock fracture and its application in tunnel failure

Soft rocks present some undesirable behaviors, such as low strength, high plasticity and softening. These traits pose challenges in the design and construction of soft rock tunnels. To address these issues and model plastic fracture behaviors of soft rocks, we proposed a plastic Stillinger-Weber (PSW) potential and integrated it into the discretized virtual internal bond (DVIB) model. The PSW-DVIB model combines the strengths of the plastic DVIB and the SW-DVIB models. It not only effectively reproduces the plastic fracture behavior but also accurately reflects the Poisson’s ratio. Moreover, due to the inclusion of fracture energy in the PSW potential, the simulation results are basically mesh size independent. The PSW-DVIB model is then utilized to investigate the failure behaviors of soft rock tunnels. The effects of the coefficient of lateral pressure, in-situ stress, Poisson’s ratio and tunnel shape on tunnel failure are investigated. The simulated results indicate that the coefficient of lateral pressure has significant influence on the failure zone distribution of the surrounding rock. With the coefficient of lateral pressure increasing, the failure degree of surrounding rock decreases firstly and then increases. The optimum coefficients of lateral pressure for the stability of circular, arched and square tunnels are about 1.00, 0.75 and 0.75, respectively. When the in-situ stress or Poisson’s ratio is larger, the influence of the coefficient of lateral pressure on tunnel failure is more obvious. The influence of the coefficient of lateral pressure on square tunnels are more significant than the arched tunnels, and then the circular tunnels. These findings provide valuable insights for the design and construction of soft rock tunnels.

Analytical solution for displacement-dependent active earth pressure considering the stiffness of cantilever retaining structure in cohesionless soil

The safety and cost-effectiveness of retaining structure designs depend on the interrelationships among the displacement, stiffness, and earth pressure. Nevertheless, the classical earth pressure theories do not account for these factors. To address this problem, the present study proposes an active earth pressure solution model that considers retaining structure stiffness and displacement. The model is based on the Modified Coulomb earth pressure theory and assumes a linear relationship between lateral earth pressure and displacement. The proposed model was compared with existing data, and degradation verification was performed. The verification results are in good agreement. According to existing calculation examples, a parameter analysis was conducted, and based on the analysis results, the critical points of rigidity and flexibility for cantilever-retaining structures of concrete materials were proposed. It was found that the resultant magnitude and point of application of the active earth pressure were related to the stiffness of the retaining structure. Further research was conducted on the variation patterns along the depth direction of the retaining structures with different stiffnesses under different displacement conditions. The computational model proposed in this study provides a practical approach for considering the coupled relationship between structural stiffness and active earth pressure in the design of retaining structures.

Installation of open-ended piles: A numerical investigation into the effects on the state of silica sand

Up to this day, there are great uncertainties in the design procedures of monopiles, especially concerning the soil state condition and penetration response during their installation. A numerical model, based on the Coupled Eulerian method and using the hypoplastic law with intergranular strain, is proposed and validated in this paper, after which a series of open-ended pile installation tests have been carried out numerically, to investigate the influence of the jacked installation on the initial conditions for three types of silica sand. A range of soil densities and pile diameters is considered in this analysis. A full investigation of the installation forces, stress level, changes in volume-stress level and voids ratio is conducted. The numerical solution provided a correlation between the penetration resistance and the granulometric properties of the studied sands. Subsequently, the radial stresses in the surrounding soil mass are correlated with the type of sand and its relative density. The stress-volume state of a set of points in the soil domain during installation is presented and discussed from the critical state framework, revealing the contribution of the in-situ state in the pile installation. Finally, the lateral earth pressure resulting after installation is presented.

The Effect of First Metatarsal Shortening and Sagittal Displacement on Forefoot Pressure in MIS Hallux Valgus Correction

Introduction/Purpose: Minimally invasive surgical (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2mm-diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr’s diameter (2mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. In this study, we examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement. Methods: Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weightbearing stance position.10 Control and post-osteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0mm, 5mm dorsal, and 5mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fifth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. A priori power analysis was performed based on previous peer-reviewed pedobarographic data and our study was adequately powered. Results: 40 measurements were recorded and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure change control versus 0mm displacement, and control versus dorsal displacement was not found to be statistically significant (p=0.525, p=0.55 respectively). Significant medial pressure increase was identified comparing control versus plantar displacement (p=0.006). Lateral pressure increased significantly with dorsal displacement of the osteotomy (p=0.013). Conclusion: MIS hallux valgus correction does not appear to cause increase in lateral forefoot pressure loading when sagittal plane displacements are controlled. Plantar displacement increases medial loading, and dorsal displacement increases lateral loading. The clinician must consider metatarsal head position post-osteotomy, as decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia.

Effects of cornering conditions on the aerodynamic characteristics of a high-performance vehicle and its rear wing

This study investigates the aerodynamic behavior of a high-performance vehicle and the interaction with its rear wing in straight-line and steady-state cornering conditions. Analyses are performed with Reynolds-averaged Navier–Stokes based computational fluid dynamics simulations using a moving reference frame and overset mesh technique, validated against moving ground wind tunnel experiments. The results indicate a significant 20% decrease in downforce and 35% increase in drag compared to straight-line conditions at the smallest considered corner radius of 2.9 car-lengths. Downforce losses primarily stem from performance deficits on the underbody and rear wing, alongside elevated upper body lift. Drag penalties mainly result from additional pressure drag induced by a recirculation wake vortex generated behind the vehicle's inboard side. The vehicle's lateral pressure distribution is also affected, introducing a centripetal force that increases with smaller corner radii. Additionally, analyses of the rear wing reveal alternations of its aerodynamic characteristics in cornering, particularly impacting vortical flow and suction on the lower surface. Throughout the operating conditions, the rear wing's individual downforce contribution falls off beyond its stall angle. At higher angles of attack, the rear wing primarily generates downforce by pressurizing the vehicle's upper surfaces, but its interaction with the near-wake leads to a substantially increased pressure drag. Overall, these findings provide crucial insights into the intricate aerodynamic interactions of high-performance vehicles in diverse operating conditions as well as form an essential foundation for future research on static and active aerodynamic designs in the pursuit to optimize vehicle performance in dynamic driving conditions.

Intelligent prediction method for underbreak extent in underground tunnelling

Underground tunnel excavation using the drill-and-blast method often results in underbreak occurrences due to improper blasting parameters and complex geological environment. This underbreak phenomenon has a profound impact on tunnel safety, stability and construction costs. Traditional approaches for predicting underbreak extent (UE) through field measurements and theoretical models exhibit limitations in terms of accuracy and efficiency. Consequently, it is urgent to develop a novel approach for UE prediction in tunnelling operations. In this paper, extreme gradient boosting (XGBoost) is first applied as the foundational algorithm, and slime mould algorithm (SMA) is implemented for tuning hyper-parameters of XGBoost. Meanwhile, six chaotic maps are integrated with SMA to initialize the population and improve the optimization performance. Subsequently, a dataset of 250 samples is collected from three underground mines in China, involving ten influential factors (RMR, uniaxial compressive strength (UCS), vertical principal stress (σv), lateral pressure coefficient (λ), excavation area (EA), powder factor (PF), specific charge (SC), advance length (AL), periphery hole burden (HB)and periphery hole spacing (HS)). Additionally, four indices, i.e., coefficient of determination (R2), variance accounted for (VAF), mean absolute error (MAE) and root mean square error (RMSE), are used to evaluate the comprehensive performance of these proposed COSMA-XGBoost models and four common machine learning models. Finally, a parametric sensitivity analysis is performed, and the optimal intelligent model is applied in practical tunnelling projects. The results indicate that chaotic optimized SMA models have better convergence ability and higher accuracy compared with the original SMA model. Notably, the PSMA-XGBoost model outperforms other models as the R2, VAF, MAE and RMSE values for the testing set are 0.979, 95.79%, 4.176 and 4.884, respectively, whereas 0.968, 94.25%, 4.274 and 5.012, respectively for training set. EA, RMR and UCS exhibit significant effects on UE. In practical tunneling projects, the engineering application of the PSMA-XGBoost model demonstrates its feasibility and efficiency in predicting UE within underground tunnels.

Experimental Investigation of the Effect of Strip Footing on Shear Band Development and Lateral Pressure Distribution in Helical Soil-Nailed Walls

Experimental Investigation of the Effect of Strip Footing on Shear Band Development and Lateral Pressure Distribution in Helical Soil-Nailed Walls

Study on the bond performance of steel bars in early-age concrete considering the effect of circumferentially lateral pressures

The interface performance between steel bars and concrete is the fundamental necessary parameter in the bearing capacity evaluation of reinforced concrete structures, especially for those during construction in some developing areas where the plain bars were still adopted as the reinforcing materials. The age-correlation of the chemical adhesive force and frictional resistance at the plain bars-concrete interface needs to be investigated in detail but has not yet been deeply understood. Therefore, a systematic study including both the experimental and theoretical investigations on the bond behavior of plain steel bars in early-age concrete with lateral pressures was performed on the pullout specimens, with consideration of the influencing parameters including the bar diameters, the concrete strengths, and the ages. On the base of the experimental results, the calculation models for predicting the bond parameters of plain bars in early-age concrete under lateral pressures were derived and verified with the test results, and then a suited local bond-slip model was presented. Finally, a comparison of enhanced early-age bond strength caused by lateral pressure obtained from the experimental and the theoretical approaches was provided with reasonable agreement.

Experimental study on stress and deformation characteristics of foundation pit considering excavation width using 3D printing technology

A sophisticated model of the foundation pit support structure was developed via a model test that incorporated 3D printing technology. A meticulously scaled-down simulation of foundation pit excavation was conducted, utilizing the excavation width of the foundation pit as the sole variable, to evaluate and compare the impact of various foundation pit widths on the force and deformation characteristics of the foundation pit following layer-by-layer excavation. The findings indicate that the stress and deformation characteristics of the retaining structure shift from the “cantilever” mode to a composite mode of “internally convex” or “concave-convex” as the pit is excavated and internal support is installed. The change in pit width has minimal influence on the mechanical response law of the support structure during excavation. Nonetheless, the alteration in the pit width had a direct effect on both the internal force and deformation of the support structure, as well as the change in surface settlement value. In the experiment, wider pits had monitoring values that increased multiple times compared to narrower pits. The width of the foundation pit has a considerable impact on the mechanical response and stability of the pit, which is evident in the relatively lower lateral earth pressure on the outside of the retaining structure in narrower pits. This results in less stress and deformation of the pit structure. Moreover, the decrease in the passive zone of the pit contributes to better stability, indicating that the lower lateral earth pressure on the outside of the retaining structure is an innate reason for the excellent stability of narrower pits.