It is crucial to ensure the safety and stability of pipelines buried in slopes during installation and operation. In this paper, the interaction between a pipe and soil was investigated via laboratory model tests. The effects of the slope angle and pipe position on the slope horizontal deformation and pipe mechanical properties were investigated. Furthermore, the restraint effect of tire strip reinforcement (TSR) on slope deformation and its impact on pipe stress and strain were analyzed. The results revealed that the potential sliding surface is located at the middle of the slope. The pipe location has a significant effect on the horizontal surface deformation of the slope, whereas the slope angle has a small effect on the stress and strain of the pipe. In addition, the use of the TSR not only reduces the horizontal surface deformation of the slope but also partially alleviates the vertical stress on the crown of the pipe. As the pipe moves away from the loading plate, the circumferential stress distribution changes from a symmetric state to an asymmetric state, with the most critical location moving from the spring line to the top. The test results provide reliable experimental data to support the design of pipes buried within a slope.

Waterfront and submarine retaining structures are normally exposed to catastrophic seepage conditions under the effect of tidal and occasionally heavy rainfall effect, resulting in a decreased passive earth thrust and thus the higher risk of instability of retaining structures. To examine the effect of seepage flow on the magnitude and distribution of passive earth thrust, this paper assumes a composite curved-planar failure surface and presents a modified method of passive earth pressure considering the seepage flow effect. The flow field and pore pressure are firstly solved by the two-dimensional (2D) Laplace equation using the Fourier series expansion. The effective reaction force acting on the composite failure surface is then obtained using a modified K & ouml;tter equation. Compared to conventional methods based on limit equilibrium, the present method facilitates a straightforward assessment of both the magnitude and distribution of passive earth thrust without the prior assumption of the application point. The outcomes highlight that the passive earth thrust decreases with the ratios of permeability coefficients. The greater effective friction angle and a smaller ratio of permeability coefficients result in the lower application point of the passive earth thrust.

The loose earth pressure in tunnels is closely related to the soil arching effect and the development of the loosening zone. Current methods overlook changes in the shape and position of the slip surface at different stages of the loosening zone, neglecting the relationship between these changes and principal stress rotation. An elliptical slip surface model has been developed to accurately capture variations in the shape and position of the slip surface as the loosening zone evolves. A lateral earth pressure coefficient for various inclinations of the slip surface was established to illustrate the relationship between the geometry of the slip surface and the rotation of principal stresses. Factors such as ground loss, soil arching effect, and elliptical slip surfaces, were integrated into the Terzaghi model, deriving and validating a numerical method for tunnel loose earth pressure. Parametric analysis targeting the volume loss ratio (VL) and cover-to-diameter ratio (C/D) revealed that linear, parabolic, and other slip surface forms presented are approximations of the elliptical slip surface at various stages. Loose earth pressure increases rapidly with C/D and then grows slowly but steadily. It decreases quickly with an increasing VL, then increases gradually and stabilizes.

To adapt to higher and steeper slope environments, this paper proposes a new type of support structure called an anchored frame pile. The study designed and conducted a series of shaking table tests with three-way loading. The acceleration field of the slope, bedrock and overburden layer vibration variability, Fourier spectra, pile dynamic earth pressure, anchor cable force, and damage were analyzed in detail. The results indicate that the overall effectiveness of anchored frame piles for slope reinforcement is superior, and the synergistic impact of front and back piles is evident. Anchor cables effectively reduce the variability of bedrock and overburden layer vibrations. A zone of acceleration concentration always exists at the shoulder of a slope under seismic action. The dominant Fourier frequency in the Y direction of the slope is 11.7687 Hz under Wolong seismic, and the high-frequency vibrations of the upper overburden layer are significantly stronger than those of the bedrock. Slopes under 0.4 g earthquakes first form cracks at the top and then expand downward through them. Under seismic action, the peak dynamic earth pressure in front of the front pile occurs near the bottom of the pile, and the dynamic earth pressure behind the pile occurs near the slip surface. The peak dynamic earth pressure of the back pile occurs at the top of the bedrock. The slope damage is significant at 0.6 g. At this point, the peak dynamic soil pressure at the top of the front pile measures 9.5 kPa, while the peak dynamic soil pressure at the bottom reaches 24.3 kPa. Below the sliding surface of the front pile and on top of the bedrock of the back pile are the critical areas for prevention and control. Elevating the prestressing of the anchor cables will help enhance the synergy between the anchor cables and the piles. Simultaneously, it will reduce the variability of vibration in the bedrock and overburden, thereby improving the stability of the slopes.

Precisely evaluating the soil pressure above parallel tunnels is of paramount importance. In this study, the deformation characteristics of soil above dual trapdoors were analyzed firstly. A novel multi-arch model for calculating the distribution of the vertical earth pressure on deep-buried parallel tunnel was then proposed based on the limit equilibrium method. The height of the dual arch zone caused by the displacement of the dual trapdoors was calculated with consideration of internal friction angle of the soil, width of the trapdoors, spacing between the dual trapdoors, and elastic modulus of the soil. By comparing with numerical simulation results and existing theoretical calculation models that do not account for the interaction of soil arching effect, it is evident that the proposed model in this study adeptly predicts the vertical stress above the trapdoor. Additionally, it captures the characteristic of upwardly convex stress distribution above the trapdoor. The analysis of parameters conducted on the theoretical calculation model showed that the depth of the trapdoor and the internal friction angle of the soil have a substantial impact, whereas the expansion coefficient exerts a negligible effect on the soil arching ratio above the trapdoor.

This paper presents a novel strut-free earth retaining wall system for excavation, referred to as the asymmetric double-row pile wall (ARPW) retaining system. This system comprises three key elements: front-row reinforced concrete piles, back-row walls, and connecting crossbeams at the top of the piles. This paper aims to analyze the deformation characteristics and mechanical behavior of the ARPW retaining system, double-row pile wall (DRPW) retaining system, and single-row pile wall (SPW) retaining system using both physical model tests and numerical simulations. The study reveals that, with reasonable row spacing, double-row structures exhibit substantially lower earth pressure and bending moments compared to SPW. Additionally, all double-row structures display reverse bending points. The optimal row spacing for DRPW and ARPW is within the ranges of 2D to 6D and 4D to 8D, respectively. ARPW outperforms DRPW by efficiently utilizing active zone friction force and soil weight force (Gs) to resist overturning moments, thereby resulting in improved anti-overturning capabilities, reduced deformations, lower internal forces, and enhanced stability. The study also presents a case study from the Jinzhonghe Avenue South Side Plot in Tianjin, demonstrating the practical application and effectiveness of the ARPW system in meeting stringent deformation requirements for deep foundation pits. These research findings provide valuable insights for practical engineering applications.

The resilience and performance of quay walls during devastating events such as tsunamis and earthquake are critical for coastal infrastructure. Conventional design standards mostly address vertical or inclined quay walls, neglecting the potential benefits of more complex geometry, such as bilinear backface. This study presents a seismic design and stability analysis of quay walls with a bilinear backface under the combined action of tsunamis and earthquake. The study findings reveal a significant reduction in safety factors in terms of sliding and overturning when quay walls are simultaneously exposed to tsunami and earthquake forces. The study also proposes a bilinear wall geometry, considering key factors such as tsunami wave height, water depth, submergence height, excess pore pressure ratio, and wall inclination. This study aims to enhance the design and construction of quay walls with a bilinear backface, thereby improving the safety of coastal structures and communities against these rare but devastating events.

The stress status of a soil pressure cell placed in soil is very different from its stress state in a uniform fluid medium. The use of the calibration coefficient provided by the soil pressure cell manufacturer will produce a large error. In order to improve the measurement accuracy of the interface-type earth pressure cell placed in soil, this paper focuses on a single-membrane resistive earth pressure cell installed on the surface of a structure, analyzing the influence of loading and unloading cycles, the thickness and particle size of the sand filling, and the depth of the earth pressure cell inserted in the structure on the calibration curve and matching error, which were analyzed through calibration tests. The results show that when the sand filling thickness is less than D (D is the diameter of the earth pressure cell), the calibration curve is unstable in relation to the increase in the number of loading and unloading cycles, which will cause the sand calibration coefficient used for stress conversion to not be used normally. When the sand filling thickness in the calibration bucket increases from 0.285D to 5D, the absolute value of the matching error first decreases and then increases, such that the optimal sand filling thickness is 3D. The output of the earth pressure cell increases with the decrease in sand particle size under the same load, and there is a significant difference between the theoretical calculation value and the experimental value of the matching error; aiming at this difference, an empirical formula is derived to reflect the ratio of the diameter of the induction diaphragm of the earth pressure cell to the maximum particle size of the sand filling. When the depth of the earth pressure cell inserted in the structure is 0, the sensing surface is flush with the structure and the absolute value of the matching error is the smallest. Changes in the horizontal placement of the soil pressure cell in the calibration bucket result in significant differences in both the output and hysteresis of the calibration curve. To improve the measurement accuracy of soil pressure cells in scaled tests for applications such as in the retaining walls of excavation pits, tunnel outer surfaces, pile tops, pile ends, and soil pressure measurements in soil, calibration of the soil pressure cells is required before testing. Due to the considerable difference in the stress states of the soil pressure cell between granular media and uniform fluid media, calibration in soil is essential. During in-soil calibration, factors such as cyclic loading and unloading, soil compression, sand thickness and particle size, and the placement of the soil pressure cell all affect the calibration results. This paper primarily investigates the influence of these factors on the calibration curve and matching error. This study found that, as the sand thickness increases, the matching error decreases initially and then increases.

This paper presents observed arching-induced ground deformation and stress redistribution behind braced excavation using the top-down construction method. The soil properties around the excavation were determined by laboratory and field tests. The ground deformation, soil displacement vector, strain path, principal strain, maximum shear strain, lateral earth pressure, pore water pressure, and effective stress path are presented based on the measured data. The majority of soil behind the wall is under volumetric expansion, indicating consolidation, creep behavior, or a combination of both. Besides, two periods of increases in pore pressure are observed, due to stress transfer from the lower to the upper parts (i.e., soil arching effect). The deep inward movement of the wall and the nearby soil accounts for the distribution of lateral earth pressure acting on the wall. The soil located behind the area of maximum wall deformation and adjacent to the wall, as well as the soil below the excavation base intersected by the shear plane, is in an active stress state. The lateral earth pressure at 5 m from the left excavation wall showed minimal changes, due to the combined effects of soil arching from lateral excavation and shield tunneling.

Fulfilling the role of a soil conditioner, foam plays a pivotal role in Earth Pressure Balance (EPB) shield tunnelling by enhancing soil properties such as lowering permeability and increasing flowability. This study introduces a macro-model designed to quantify foam penetration behaviour in saturated sand, utilising rheological properties. To validate this model, experiments were conducted to replicate the foam penetration behaviour. Six sand beds characterised by varying particle sizes, along with foam having an expansion ratio of fifteen, were employed for penetration tests under different hydraulic conditions utilising a sand column device. The rheological profile of the foam is described by the power-law model, as also found by rheometer tests, although with different parameters. The flow behaviour of foam within the sand column conforms to the flow equation that governs powerlaw fluids in porous media. The developed model effectively predicts the foam penetration process under varying hydraulic conditions compared with the experimental results. Furthermore, the fitting results of the experimental data indicate that the flow behaviour index of the foam remains approximately 0.09 across all tests, regardless of the type of sand used. In contrast, the model-derived generalised permeability coefficient strongly correlates with the effective particle size (d10) of the sand bed. Overall, the model effectively quantifies the foam penetration behaviour, accounting for changes in infiltration velocity and pore water pressure, which is essential for understanding the transfer of support pressure in EPB shield tunnelling.