Interface Shear Behavior Between Bio-Inspired Sidewall of a Scaled Suction Caisson and Sand Under Pull-out Load

Many soil–structure interaction problems require the knowledge of the shear resistance and behavior between the soil and construction materials. Although sensitive marine clay deposits are widely found in Canada (Leda clay) and many regions in the world (e.g., Scandinavia), and steel is a common construction material for many civil engineering structures, our understanding of the interface shear behavior between sensitive marine clay and steel is still limited. This paper presents the results of an experimental study on the interface shear behavior between Leda clay and steel. In this research, direct shear tests (DSTs) are conducted to investigate the interface shear strength parameters and behavior between Leda clay and steel, and the effect of several factors (e.g., steel surface roughness, properties of the Leda clay) on the interface shear behavior and parameters. All tests have been carried out with a standard DST apparatus at normal loads which range from 250 to 450 kPa. The results show that the Leda clay interface shear behavior can be significantly affected by the steel surface roughness, the Leda clay’s OCR, dry density, and salt content. The results presented in this paper will contribute to a more cost-effective design of geotechnical structures in Leda clay.

The Lianghekou earth core rockfill dam to be built in China will be the third highest rockfill dam in the world. This study presents the results of a series of direct shear tests between high plastic clay and concrete to study the shear behavior of contact clay-concrete cushion interface of Lianghekou dam. Results showed that water content and normal stress are significant factors affecting the shear behavior of the interface. The higher shear strength is related to lower water content and higher normal stress, and the shear strength can be formulated by the bifold-line type Mohr–Coulomb strength criterion. It is also found that the interface exhibits mainly two kinds of shear failure modes, that is, sliding failure along the concrete surface and shear failure in the clay matrix nearby the interface. Moreover, a nonlinear elastic model is proposed to simulate the shear behavior of the interface, of which parameters can be quickly estimated by water content. The simulation of the model is compared with the experimental results, and the results show that the model is reasonable and practical.

Asphalt concrete core rockfill dam utilizes an asphalt concrete core as anti-seepage structure. Uneven deformation could produce at core wall-transition interface due to differences in material stiffness, potentially leading to crack formation in the core wall. Shear behavior of the interface is more complex under seepage effect. This study investigates the shear behavior of the asphalt concrete core-transition material interface under seepage effects. Shear tests were conducted across five seepage pressure, three shear rates, and five normal stress levels. A nuclear magnetic resonance system was employed to analyze internal pore distribution in the asphalt concrete core within shear-affected region. Additionally, high-pressure permeability tests were conducted to explore the effects of shear action on asphalt concrete core permeability. Findings revealed that the interface exhibited a shear hardening phenomenon, with normal displacement rising in response to increased seepage pressure, while the internal friction angle and cohesive strength diminished. The observed damage patterns primarily involved particle embedding, aggregate cracking, and surface cracking, with damage severity increasing with both normal stress and seepage pressure. Despite shear action leading to increased porosity, the asphalt concrete core remained compliant with porosity control standards.

The effects of dry and wet rock surfaces on shear behavior of the interface between rock and cemented paste backfill

Evaluation of Interface Shear Strength between Geosynthetics Under Wet Condition

ABSTRACTA series of model tests were conducted on Perspex-made suction caissons in saturated dense marine sand to study the sand plug formation during extraction. Suction caissons were extracted by pullout loading or by pumping air into the suction caisson. Effects of the pullout rates, aspect ratios and loading ways (monotonic or sustained) on the pullout capacity, and plug formation were investigated. It was found that the ultimate pullout capacity of the suction caisson increases with increasing the pullout rate. The sand plug formation under the pullout loading is significantly influenced by the pullout rate and the loading way. When the suction caisson is extracted at a relatively slow rate, the general sand boiling through the sand plug along the inner caisson wall occurs. On the contrary, the local sand boiling will occur at the bottom of the suction caisson subjected to a rapid monotonic loading or a sustained loading. Test results of the suction caisson extracted by pumping air into the caisson show that the pressure in the suction caisson almost follows a linear relationship with the upward displacement. The maximum pressures for suction caissons with aspect ratios of 1.0 and 2.0 during extraction by pumping air into the caisson are 1.70 and 2.27 times the maximum suction required to penetrate the suction caisson into sand. It was found that the sand plug moves downward during extraction by pumping air into the caisson and the variation in the sand plug height is mainly caused by the outflow of the sand particles from the inside of the suction caisson to the outside. When the suction caisson model is extracted under the pullout rate of 2 mm/s (0.28 mm/s for the prototype), the hydraulic gradient along the suction caisson wall increases to the maximum value with increasing the penetration depth and then reduces to zero. On the contrary, when extracted under the pullout rate of 10 mm/s (1.4 mm/s for the prototype), the hydraulic gradient along the suction caisson wall increases with increasing the pullout displacement. When extracted by pumping air into the caisson, the hydraulic gradient reaches the critical value, and at the same time, the seepage failure occurs around the suction caisson tip.

The behavior of polymer-bentonite interface under shear stress

Interface Shear Behaviour between Precast and New Concrete in Composite Concrete Members: Effect of Grooved Surface Roughness

The performance of geosynthetic layered systems during their service life in terms of interface shear behavior and strength properties is of major importance in certain geotechnical applications. The interfaces between geotextiles and geomembranes in landfill applications are subject to temperature changes. In this respect, interface shear behavior requires assessment of the engineering strength properties of the components, both independently and collectively, at different temperatures. To this end, an extensive research study was undertaken to investigate temperature effects on the interface shear behavior between needle-punched nonwoven (NPNW) polypropylene (PP) geotextiles and both smooth polyvinylchloride (PVC), as well as smooth and textured high-density polyethylene (HDPE) geomembranes. A temperature-controlled chamber (TCC) was utilized to simulate the field conditions at elevated temperatures and evaluate shear displacement and frictional response mobilized at different temperatures. The physical laboratory testing program consisted of interface shear tests between material combinations found in landfill applications under a range of normal stress levels from 10 to 400 kPa and at a range of ambient temperatures from 21°C to 50°C. An increase in temperature from the standard laboratory test temperature of 21°C to an equivalent in situ temperature of 50°C increases the peak and postpeak interface friction values by a minimum of 14%. For selected combinations of materials, the amount of increase can be in excess of 20% and as high as 22%. Consequently, interface shear behavior determined at room temperature yields interface friction values that are conservative at higher temperatures.

A landslide has been one of the many problems in geotechnical engineering, whereas, from one of the cases, a failure happened at the interface layer between the overburden and its underlying soil. As interface shear strength has become one of the growing topics in research, this paper summarizes and discusses the research development of interface shear strength and its possibility to explain the interface shear behavior at a slope. The discussion was limited to cohesive soils and experiment-based behavior of the interface shear. Some research has been selected in order to understand the development of interface shear strength through time and two examples of slope interlayer shear behavior were selected. It was known that there are three common tests of interface shear behavior used: simple shear, direct shear, and ring shear test. The development of interface shear strength started at 1960s between soil and construction materials where the four major components were defined. As the research grows, many other types of soils, interfaces, and the effect of the tests became the topic of the research. In the end, the examples given from modeling the interface shear behavior from a slope gives a new perspective of cases for interface shear strength in slope analysis.

Understanding the interface shear behavior between clay and structures is crucial in geotechnical engineering. The mechanism of the roughness effect in the shear process between the clay and structures was studied to reveal the macroscopic and microscopic interface shear behavior. The different surface protrusion shapes of the structures were produced using a three‐dimensional (3D) printer. Direct shear tests were conducted to analyze the shear failure modes and peak and residual strengths under different conditions. Subsequently, a discrete element method (DEM) numerical analysis was employed to study the contact network, soil fabric evolution, shear zone, coordination number, and void ratio variations in the interface shear. The test results indicated that the shear interfaces exhibited the same failure mode under various conditions, and the peak and residual strengths showed a strong positive correlation with roughness. The results obtained from numerical calculations match the experimental findings. The contact orientations and principal stresses shifted during the shear process, and the shear zone, coordination number, and void ratio also showed regular changes with the change of roughness. The evolution of microscopic parameters in DEM can effectively help explain the macroscopic interface shear behavior.

The interface can be defined as the zone in which the transfer of stresses occurs between soil and structure. The behavior interface is significantly influenced by stress state variables. In this paper, the influence of matric suction and counterface roughness on the interface shearing behavior was examined by conducting a series of suction controlled direct shear test on the interface formed between completely decomposed granite soil and steel specimens. Experimental tests were performed on two different types of soil–steel interfaces under different stress state variables. Test results show that matric suction has a significant influence on the interface shear behavior. The counterface roughness influences the dilative-contractive behavior of the interface. The critical interface shear strength at specific counterface roughness and net normal stress is controlled by the matric suction. The experimental results are compared with an analytical model that considers the influence of suction and dilation on apparent interface friction angle. The analytical model works reasonably well for predicting the unsaturated soil–steel interface shear strength under different stress state variables.

Dynamic shear behavior of CFRP-concrete interface: Test and 3D mesoscale numerical simulation

The thermo-hydro-mechanical (THM) shear behavior of the interface between a textured geomembrane (GMX) and a geosynthetic clay liner (GCL) was investigated using large-scale direct shear tests. The GCL was comprised of granular bentonite sandwiched between two non-woven geotextiles bonded by needlepunching. The geomembrane was textured high density polyethylene. Influence of normal stress, hydration condition, and temperature on interface shear behavior was evaluated, and changes in the surface characteristics of the interface were documented photographically. The peak shear strength of the GMX/GCL interface was higher under dry conditions than when hydrated. In some cases, two peak strengths were observed in the hydrated condition, whereas shearing under dry conditions consistently yielded only one peak strength. The peak shear strength and large-displacement shear strength of the GMX/GCL interface were highest at room temperature. Increasing the temperature resulted in a reduction in shear strength and less post-peak strength loss. Three failure modes were observed: GMX/GCL interfacial failure, partial interface/internal GCL failure, and internal GCL failure. Increasing normal stress and temperature caused a transition in the failure mode between interfacial failure and internal GCL failure. Extrusion of bentonite into the interface under hydrated conditions also influenced the interface strength and the failure mode.

The aim of this study was to provide a general conceptual understanding of the effect of hardness and roughness of a continuum surface on its interface shear behavior against granular materials. A carefully designed experimental program was conducted to investigate this issue. The results were utilized to define schematically the general geometric configurations of the constitutive interface shear surface (CISS) in the three-dimensional domain of surface roughness, surface hardness, and interface shear coefficient. The proposed CISS provides a robust mean to understand the coupling effect of continuum surface roughness and hardness on the interface shear behaviour.