Rock-socketed Piles Research Articles

Discussion on adaptive neuro-fuzzy inference system-based models for predicting ultimate bearing capacity of rock-socketed piles

Discussion on adaptive neuro-fuzzy inference system-based models for predicting ultimate bearing capacity of rock-socketed piles

Experimental study of the effects of the void located at the pile tip on the load capacity of rock-socketed piles

To address the design challenge of the rock-socketed piles posed by the void located below the pile tip, the physical laboratory model tests were designed and performed to simulate rock socketed piles using similar materials. The study investigates the behavior of the single pile under axial loading with the void located at varying distances from the pile tip. Through multi-level load tests, the variations of unit pile side friction, pile tip resistance, pile axial force and pile settlement are obtained for different positions of the void from the pile tip, as well as after grouting. Its comparison to the rock-socketed pile without void is performed as a reference to quantify the reduction in its bearing capacity. The results are presented in the form of graphs for different void positions and its grouting shows the influence on pile bearing capacity and emphasizes the importance of its detailed cautious investigation and introduction in the analysis. The 2D finite element modeling of the model pile-the void based on ABAQUS is performed to further investigate the influence of the void below pile tip on the bearing capacity of model pile, applying the Mohr Coulomb model as the constitutive model of rock mass behavior. The critical distance of the void below the pile tip is determined.

DEM Modeling of the Load-Bearing Mechanisms of Rock-Socketed Piles with Soft Interface Materials

DEM Modeling of the Load-Bearing Mechanisms of Rock-Socketed Piles with Soft Interface Materials

The Load-Bearing Mechanism of Rock-Socketed Piles Considering Rock Fragmentation

The Load-Bearing Mechanism of Rock-Socketed Piles Considering Rock Fragmentation

The implementation of a least square support vector regression model for predicting the ultimate bearing capacity of rock-socketed piles

The implementation of a least square support vector regression model for predicting the ultimate bearing capacity of rock-socketed piles

Correction: Advancing Rock-Socketed Pile Design with a Unified Interface Shear Strength Framework for Soft Rocks

Correction: Advancing Rock-Socketed Pile Design with a Unified Interface Shear Strength Framework for Soft Rocks

Advancing Rock-Socketed Pile Design with a Unified Interface Shear Strength Framework for Soft Rocks

The shaft resistance of rock-socketed piles (RSPs) is primarily influenced by the interactions between the pile, rock and any soft interface materials. This study presents a fundamental experimental and numerical investigation to predict the shaft resistance of model RSPs in soft rocks through a comprehensive shear strength framework incorporating the major variables such as roughness and smear fabric. By calibrating the Discrete Element Method (DEM) results with the experimental outcomes, this study evaluates the load-resistance attributes of RSPs in three different soft rocks for a wide range of roughness and smear configurations. The interface roughness effect of the RSPs in terms of the friction coefficient was correlated with the ultimate shaft resistances, uniaxial compressive strength and Young’s modulus of the rock. The study then incorporated the effect of smear fabric (placement, thickness and area proportion) in the shear strength framework of clean shafts. Comprehensive review of the DEM results revealed that the socket roughness effect diminishes at a critical roughness factor (RF)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$({\ ext{RF}})$$\\end{document} of 0.4, beyond which the smear predominantly influences the shaft capacity. Following this, the effects of roughness and smear fabric were incorporated into a single equation representing the interface shear strength of RSPs, where the existence of smear results in a maximum reduction of up to 75% of the ultimate shaft resistance. The distinctive feature of this unified interface shear strength framework lies in its integration of the new smear fabric parameter and the linkage to the mechanical properties of soft rocks, which is the limitation of the earlier studies. It thereby sets a strong base for future studies aimed at advancing the pile-rock interface models.

Modification of the Constant Coefficient Method for Horizontal Reaction of Foundation of Rigid Rock-Socketed Piles

Modification of the Constant Coefficient Method for Horizontal Reaction of Foundation of Rigid Rock-Socketed Piles

Assessment of ultimate bearing capacity of rock-socketed piles using hybrid approaches

Assessment of ultimate bearing capacity of rock-socketed piles using hybrid approaches

An Analytical Transformation Algorithm for Loading-Settlement Curves of Rock-Socketed Piles in Soft Rock by Self-Balanced Tests

An Analytical Transformation Algorithm for Loading-Settlement Curves of Rock-Socketed Piles in Soft Rock by Self-Balanced Tests

Bearing behavior of pile foundation in karst region: Physical model test and finite element analysis

Abstract The presence of karst formations significantly impacts the load-bearing capacity of pile foundations in karst geological environments, posing a challenge to their design. This study investigated the bearing characteristics of karst pile foundations using the physical model test and numerical analysis. First, the influence of cave height and span on the bearing capacity of pile foundations is examined using model tests. The results demonstrate that the height of karst caves greatly affects the bearing capacity of karst pile foundations. Subsequently, numerical analysis further explores the bearing characteristics of these foundations. It reveals that as the top load on pile increases, an arch-shaped tensile damage zone forms at the top of karst cave and gradually expands. The rock failure in this area leads to a decrease in adhesion between rock strata and pile foundation, consequently reducing its load-bearing capacity. Finally, experimental results are compared with numerical results to validate consistency and mutual verifiability between physical model tests and numerical analyses. The outcomes of the research provide valuable insights for designing rock-socketed pile foundations in similar karst areas.

Prediction of ultimate bearing capacity of rock-socketed piles based on GWO-SVR algorithm

The application of rock-socketed pile in engineering is becoming ever more common. Finding the ultimate bearing capacity of rock-socketed piles with a high-performance ratio and precision is an important area of research. The rock-socketed piles underwent a field load test, and ABAQUS software was utilized to create a model of the interaction between the pile and the soil. For the geometric and physical parameters of the pile, soil, and bedrock, a total of eighteen pile-soil parameters were chosen. Reasonably constructed orthogonal and control variable tests are utilized, and a sensitivity analysis of the relevant factors is performed. Ten elements that significantly affect the ultimate bearing capacity of rock-socketed piles (with a probability less than 0.05) are selected as the input for the bearing capacity prediction of rock-socketed piles based on the test's consistent findings. The ultimate bearing capacity of rock-socketed piles is predicted using the support vector regression (SVR) model, and the absolute coefficient, mean absolute error (MAE), mean square error (MSE) and other indicators are chosen as the evaluation indices of the model prediction effect. The SVR model predicts an absolute coefficient of 0.7, which is an unsatisfactory prediction outcome. Consequently, the model is optimized via the nested grey wolf (GWO) algorithm. With a value of 0.995, the GWO-SVR model is more akin to 1 than the SVR model. There are 0.14 and 0.034 for the MAE and MSE, respectively. The models of (Artificial bee colony) ABC-SVR, (Cuckoo search) CS-SVR, (Sparrow search algorithm)SSA-SVR, and (Particle swarm optimization) PSO-SVR are built. When comparing different assessment indicators, the GWO-SVR model is smaller than the MAE and MSE. When the prediction model is used on a real project, the engineering requirements can be satisfied by the prediction effect.

Effect of Smear Distribution on the Load-Bearing Mechanisms of Rock-Socketed Piles in Soft Rocks

Effect of Smear Distribution on the Load-Bearing Mechanisms of Rock-Socketed Piles in Soft Rocks

Laboratory study on bearing capacity of batter rock-socketed pile group under combined loads

The batter rock-socketed pile (BRSP) groups have been gradually introduced in practice to support not only the vertical load caused by overlying infrastructures but also the horizontal loads caused by waves and wind. A series of laboratory model tests were conducted to investigate the bearing capacities of the BRSP groups installed with their batter piles ranging from 0° to 20° under combined vertical and horizontal loads. It is found that the vertical ultimate bearing capacities nonlinearly increase with the increase of the batter angle with its optimum batter angle of 10°. The normalized vertical loads and horizontal ultimate loads are nonlinearly related to their relationship in an ellipse function. The plumb rock-socketed pile groups develop primarily a pair of shear forces and secondary bending moments due to the clockwise rotation under the pure horizontal loads. The BRSP group may fail due to the pile fracture near the pile cap in the form of the plastic hinge or compression failure at the base of the front pile. The corresponding load-displacement curves mostly have no peak or sudden downward trend.

Study on Meso-Structural Evolution of Bedrock Beneath Offshore Wind Turbine Foundation in Pressurized Seawater

In recent years, offshore wind turbine technology has been widely developed, making a significant contribution to the advancement of renewable energy. Due to the predominant subsurface geological composition characterized by rocky formations in some marine areas, rock-socketed piles are commonly applied as offshore wind turbine foundations. Generally, rock-socketed piles need to be driven into rock layers that have not undergone significant weathering or erosion for optimal load-bearing capacity. This design is essential to ensure structural support for offshore wind turbines. However, during the long-term operation period of offshore wind turbines, the contact surface between the rock-socketed pile and the rock is prone to be detached under multiple dynamic loads. The generated channel makes seawater seep into the unweathered rock layer, resulting in the erosion of rock meso-structure and deterioration of mechanical properties. The reduced load-bearing capacity will adversely affect the operation of the offshore wind turbine. In this study, the meso-structural evolution of bedrock in pressurized seawater is investigated by X-ray CT imaging using tuff samples from the marine areas of an offshore wind farm in China. A cellular automata model is proposed to predict the long-term evolutionary process of tuff meso-structure. Results indicate that the porosity of the tuff sample in the pressurized seawater shows an upward trend over time. Based on the erosion rate of pores obtained from the CT scanning test, the proposed cellular automata model can predict the evolutionary process of tuff meso-structure and corresponding failure strength of the bedrock in the long term.

Numerical Study on Effect of Axial Loading on Rock-Socketed Piles in Two-Layered Soil Slope

Numerical Study on Effect of Axial Loading on Rock-Socketed Piles in Two-Layered Soil Slope

Rock-Socketed Piles Under Axial Compression: A Review

Rock-Socketed Piles Under Axial Compression: A Review

Experimental study on deterioration of bedrock strength and P-wave velocity by pressurized seawater

Bedrock has to be excavated before the construction of rock-socketed pile foundations for offshore wind power turbines, leading to the exposure of fresh and dry rocks to seawater. The pile-rock interface is partially separated under the long-term action of various cyclic loads during the operation stage of offshore wind turbines, and the infusion of seawater will further weaken the bedrock. To comprehensively investigate the deterioration of bedrocks by pressurized seawater, tests on point load strength and slake durability were carried out to study the long-term deterioration of mechanical properties of granite, sandstone, and tuff collected from an offshore wind power farm. The elastic P-wave velocity was measured to analyze the variation trend of P-wave velocity, the mechanism of which was revealed by means of Gassmann’s equation. The results of mechanical experiments indicate that granite is almost impervious to pressurized seawater, while the mechanical properties of sandstone and tuff are deteriorated by water, especially by the pressurized seawater. After 60 days of immersion in seawater at 0.5 MPa pressure, decreasing amplitude of point load strength and slake durability index for the sandstone specimens in seawater reaches 53.2% and 18.5%, respectively, and that for the tuff specimens is 14.6% and 1.52%, respectively. The elastic P-wave velocity of granite shows an upward trend with increasing immersion time in different environments, but there exists a different tendency between the P-wave velocity of sandstone and tuff specimens in water or seawater with normal pressure and that in seawater with 0.5 MPa pressure. The variation of P-wave velocity of different types of rocks is studied based on Gassmann’s equation that takes into account the change of saturation degree, porosity, and compressibility of the matrix material.

Model Testing of Rock-Socketed Piles under Combined Vertical–Lateral Loading

Abstract This paper presents the findings from a model experimental setup designed and fabricated for conducting single gravity (1-g) model experiments on model aluminum instrumented piles embedded in synthetic rock subjected to both independent vertical–compressive and lateral loading and combined vertical–compressive and lateral loading. Synthetic rock was prepared based on a mix design that can simulate the strength and modulus of soft rocks. Model tests were carried out on single piles of different socketing lengths (L/D ratios: 6, 9, and 12). Combined loading tests were done such that the resultant of the vertical–compressive and lateral loads was at constant inclinations (30° and 60°). Piles with smooth and rough surfaces were simulated for examining the effect of the pile–rock roughness profile. The vertical load–settlement and the lateral load–deflection response were measured from the tests. The bending behavior of piles under both independent and combined loading was also measured. The deflection profile of the rock-socketed pile was obtained by tracing the tested/failed piles after extracting them. The axial and lateral resistance of the rock-socketed piles are interpreted and discussed. It is observed that the rock-socketed piles behave in a distinctly different manner under combined loading compared with independent loading.

Field Measurement and Theoretical Analysis of Sidewall Roughness on Shaft Resistance of Rock-Socketed Piles

Sidewall roughness is a key factor influencing the shaft resistance of rock-socketed piles. Owing to the difficulties in onsite measuring and the inconsistency in quantitatively characterizing the roughness degree of sidewalls, existing approaches for estimating the shaft resistance of rock-socketed piles often cannot take this factor into account. Based on the measured surface curves of the 68 sockets in No. 6# and 7# group piles of the Chishi Bridge on the Ru-Chen Expressway in China, sidewall roughness is described by introducing the roughness factor (RF) based on the Horvath and Monash models, respectively, while a statistical analysis of the sidewall roughness in rock-socketed sections is also conducted. In addition, an analytical solution to the shaft resistance of rock-socketed piles with consideration of sidewall roughness and the relative settlement of the pile–rocks interface (∆s), is proposed and further compared with the field load tests. The results showed that: the RF obtained by the Horvath model is bigger than that obtained by the Monash model; the larger RF is, the bigger the mobilized shaft resistance; the analytical solution generally overestimates the mobilized shaft resistance of rock-socketed piles under the same ∆s, and the deviation is less than 15% if ∆s is larger than 3.00 mm. The Horvath model is recommended to quantitatively characterize the roughness degree of sidewalls for its good operability in practice.