Friction Piles Research Articles

Long-term effect of soil settlement on lateral dynamic responses of end-bearing friction pile

This paper presents a closed-form solution to evaluate the lateral dynamic responses of pile foundation adjacent to superficial surcharge. The equilibrium equation of soil is analyzed using continuum solutions, and the Euler-Bernoulli beam theory is employed to model the pile. The consolidation settlement of surrounding soil induced by the superficial surcharge is determined by Terzaghi's consolidation theory. The lateral soil resistance is formulated using potential functions, and the dynamic responses of the end-bearing friction pile are subsequently obtained by considering the vertical load and skin friction. Our results are compared with analytical approaches from previous literature to validate the effectiveness of the present solution. The evolutions of lateral dynamic responses of pile foundation are systematically analyzed. It is suggested that the superficial surcharge influences the distribution of skin friction of the pile foundation, thereby altering its lateral dynamic responses. This phenomenon does not manifest immediately but demonstrates significant long-term effects during the consolidation settlement of surrounding soil.

Experimental and finite element assessment of stabilizing configurations for underground heritage sites

Heritage sites in Alexandria, Egypt, are some of the UNESCO world heritage sites at high risk from geo-environmental hazards, in particular caused by sea level rise and heavy rain due to the climate change. Recently, safeguarding UNESCO world subterranean and built heritage draws more attention. After recent environmental catastrophies in Alexandria, sustainable conservation materials and stabilizing configurations of underground monumental structures has also become urgent and highly demanded. Based on typical damage due to the heavy weathering caused by the ground water table and salt, this paper offers a guide for engineers and conservators, where rock structures consolidation and stabilizing configurations to protect these structures in the static state and against strong seismic events is presented. In this paper, typical geotechnical problems and damage to the Catacombs of of Kom El-Shoqafa are presented first, followed by an experimental evaluation methodology that includes spectroscopic and morphological characterization in addition to the mechanical testing of untreated and treated rock samples with synthetic organosilicone and acrylic compounds. The effectiveness of the new silica-based consolidants was evaluated in terms of the amount of solid adsorbed, mechanical properties (e.g., surface hardness, ultrasonic velocity, modulus of elasticity and modulus of compressive strength), and resistance to salt crystallization. The treated groups showed better mechanical strength than the control group. The ability of the treated samples to resist climate change negative impact was also greatly improved. According to laboratory tests, new silica-based hardeners and hydrophobic materials have great potential for strengthening weathered Calcarenitic rock structures. It was observed that the rock samples containing the modified binder (MTMOS + Wacher BS 15) reach higher mechanical strength parameters. After the experimental study (testing procedures), FEM analysis was performed using PLAXIS 2D code to validate the silica-based consolidants and verify their efficiency in improving the response of rock structures in static and seismic states against strong earthquake events. The results of this work confirm the high potential of low-cost injection techniques and stabilizing configurations (pre- stressed anchors and concrete friction piles) technology, confirming the possibility of achieving significant improvement in the geotechnical properties of Calcarenitic rock structures and enhancing the seismic performance of underground archaeological structures using low-cost injection technology that is easy to manufacture.

New Design Criteria for Long, Large-Diameter Bored Piles in Near-Shore Interbedded Geomaterials: Insights from Static and Dynamic Test Analysis

This paper presents an analysis of long, large-diameter bored piles’ behavior under static and dynamic load tests for a megaproject located in El Alamein, on the northern shoreline of Egypt. Site investigations depict an abundance of limestone fragments and weak argillaceous limestone interlaid with gravelly, silty sands and silty, gravelly clay layers. These layers are classified as intermediate geomaterials, IGMs, and soil layers. The project consists of high-rise buildings founded on long bored piles of 1200 mm and 800 mm in diameter. Forty-four (44) static and dynamic compression load tests were performed in this study. During the pile testing, it was recognized that the pile load–settlement behavior is very conservative. Settlement did not exceed 1.6% of the pile diameter at twice the design load. This indicates that the available design manual does not provide reasonable parameters for IGM layers. The study was performed to investigate the efficiency of different approaches for determining the design load of bored piles in IGMs. These approaches are statistical, predictions from static pile load tests, numerical, and dynamic wave analysis via a case pile wave analysis program, CAPWAP, a method that calculates friction stresses along the pile shaft. The predicted ultimate capacities range from 5.5 to 10.0 times the pile design capacity. Settlement analysis indicates that the large-diameter pile behaves as a friction pile. The dynamic pile load test results were calibrated relative to the static pile load test. The dynamic load test could be used to validate the pile capacity. Settlement from the dynamic load test has been shown to be about 25% higher than that from the static load test. This can be attributed to the possible development of high pore water pressure in cohesive IGMs. The case study analysis and the parametric study indicate that AASHTO LRFD is conservative in estimating skin friction, tip, and load test resistance factors in IGMs. A new load–settlement response equation for 600 mm to 2000 mm diameter piles and new recommendations for resistance factors φqp, φqs, and φload were proposed to be 0.65, 0.70, and 0.80, respectively.

STUDI KOMPARASI KAPASITAS DUKUNG RENCANA DAN KAPASITAS DUKUNG AKTUAL FONDASI TIANG PANCANG PADA KONSTRUKSI SLAB ON PILE JALAN TOL SEMARANG – DEMAK SEKSI 2

Semarang - Demak Toll Road Section 2 with a length of 16.31 km crosses the North Coast of Java. The regional geological map shows that the North Coast of Java has alluvial soil layers with clay and silt characteristics. The results of soil investigations show that the depth of the soft layer reaches more than 60 m. This condition triggers construction engineering to support the Highway above it. One of the efforts to fulfill the elevation plan (finish grade) is the flyover concept with slab on pile construction. The planned traffic lane is laid on a concrete slab which is supported by piles with a diameter of 600 mm. With sufficiently deep soft soil layers, the bearing capacity of the foundation piles is borne by the frictional resistance provided by the soil along the piles. This comparative study compares the planned carrying capacity calculated by the empirical formula with the actual carrying capacity of the field as a result of the PDA Test. Calculations were made on 5 test poles for later comparisons were made with the PDA test record data. For the case of 14 days driving at the research location, the pile bearing capacity from the PDA test results is still below the design bearing capacity. The average actual carrying capacity obtained from the 5 test piles is 278 tons. This value is below the planned carrying capacity of the Shio & Fukui method of 381 tons, Meyerhoff's 355 tons, Biaud et al's 777 tons, and Luciano Decourt's 605 tons. At the age of the pile 14 days after the erection was completed, the results of the calculation of the bearing capacity of the Meyerhoff method are closest to the actual bearing capacity of the PDA test results with a ratio of 1.26. The next method is Shio & Fukui with a ratio of 1.36, Luciano Decourt (2.16), and Biaud et al (2.81). Some of the results of previous studies showed a positive correlation between the age after completion of the pile and the frictional carrying capacity. For this type of friction pile, this is of course very influential, so that it is possible that when it is realized that it is carried out with a longer service life, the actual bearing capacity obtained will increase. This requires further research to obtain a time relationship with an increase in pile bearing capacity, especially for locations that have deep soft soil layers such as in this study location.

Finite Element Analysis of Combined Bearing Characteristics of Pile–Soil Interaction in Composite Foundation

Composite foundations have been widely used and promoted in practical engineering applications. However, research on the joint-bearing mechanism of piles and soil within composite foundations is still not comprehensive enough. This paper proposes a method for calculating the additional internal forces of piles and soil within composite foundations. Based on a three-dimensional finite element analysis, this study investigates the variation patterns of the stress, displacement, and additional internal forces of piles and soil in the depth direction under the action of upper loads when using friction piles and end-bearing piles. This research aims to reveal the bearing performance of piles and soil. The results showed that, under the same conditions and due to the presence of end-bearing effects, the internal forces experienced by the entire pile body of the end-bearing piles were more uniform, exhibiting significant advantages in resisting deformation and being able to withstand larger loads. Additionally, the diffusion mechanism of the vertical forces, stresses, and displacements of piles and soil is discussed. Due to the negative frictional resistance of soil and the influence of pile end-bearing effects, the distribution of internal forces and the displacements of piles and soil exhibited different characteristics. This study provides a scientific reference for the theoretical analysis and design of composite foundations.

Research on bearing capacity of piles with negative skin friction based on field test

There are extensive deep soft soil layers in the coastal areas of China, and the drainage consolidation method is widely adopted for foundation pretreatment in these areas. However, there are still dozens of centimeters of post construction settlement, which may produce negative skin friction on the pile foundation. To accurately estimate the magnitude of negative skin friction, two prestressed high strength concrete pipe piles with different pile end holding layers were used to conduct field tests. The development law of negative skin friction of pile foundation with soil consolidation is studied by simulating different pre-load height conditions of soil around pile. The monitoring results of field tests indicate that with the soil settlement around the pile, the dragload increases gradually and the neutral point moves downward. When the relative displacement between the pile and soil is 87 cm, the neutral point position of the end bearing pile is approximately 44.6-m deep, and the dragload is about 3640 kN, while the friction pile is 30 m and 2160 kN. The analysis shows that if the pile foundation construction is carried out during the foundation pretreatment, the dragload is considerably large, and this may lead to excessive settlement and damage of the pile.

Load transfer mechanisms for capped and uncapped non-displacement piles above tunnels: a centrifuge modelling study

This paper presents results from geotechnical centrifuge tests of tunnelling in dry dense sand beneath loaded non-displacement piles, focusing on the effect of a pile cap (representative also of a raft or grade beam) in contact with the soil surface on load transfer mechanisms. Experiments included loading tests to ascertain the foundation capacity and load-displacement response in the presence/absence of an underlying model tunnel. Individual ‘reference’ pile response is compared for cases with and without a pile cap, including pile displacements and load distributions between the head, shaft, and base; the case of ‘friction’ piles with a compressible base are also considered. Results show that uncapped piles with relatively large service loads experience ‘geotechnical failure’ (i.e. large settlements or a significant increase in settlement rate with tunnel volume loss) in order to mobilise base or shaft resistance. Pile caps are shown to reduce settlements and prevent geotechnical failure of both reference and friction piles; they also improve the post-tunnelling foundation performance under loading. The paper provides evidence to enable engineers to consider the beneficial role of shallow elements in contact with the surface on the performance of pile foundations both during and subsequent to tunnelling.

Rapid Prediction of Pile Friction Resistance Based on Soil Deformation Law Caused by a Super Large Diameter Tunnel: A Case Study

Rapid Prediction of Pile Friction Resistance Based on Soil Deformation Law Caused by a Super Large Diameter Tunnel: A Case Study

A Time Duration Optimization Model for the Construction of Piles

Time and adequate management of the scheduling of activities are very critical in every construction project. This study formulated a multiple linear regression optimization model to address issues bordering on delays in pile construction operations. A 300mm diameter reinforced concrete pile, 5.4m long, with a plastic casing was used. A total of 32 piles were constructed in a silty soil completely submerged in water at Bonny, Nigeria. The friction piles were constructed serially with a boring method, while the soil was extracted with the piling auger. The volumes of the extracted soil and concrete poured to fill the holes were accounted for, theoretically and actually. The same was done for the reinforcement cages installed in each pile shaft. The model was formulated and tested using Statistical Package for the Social Sciences (SPSS) software. The model was found to be fit, adequate, and highly accurate with an R2 value of 0.874.

Assessment of Subsurface Competency Using Geotechnical Method of a Proposed Structure F.C.T Nigeria

Structural failure has been recently happenings mostly in the commercially populated states along the coastal line in Nigeria. As a result, an open field at a chosen location in Abuja, Nigeria, was investigated. For the purpose of this study, test bores were drilled and Standard Penetration Tests (SPT) were conducted at every 1.5 m interval up to a maximum depth of 12.0 m with the bearing pressure ranging between 20 kN/m2 and 1000 kN/m2 . 3 test bores’ were drilled within the plot location, and samples were obtained at the test bores locations for laboratory analysis. Findings revealed that subsurface lithology found at the site within the explored depths of 0.0 ~ 12.0 m is mostly silty sand, laterite, sandy clay, silty clay, clayey sand, and weathered rock. The findings from the sub-soils of the different places and their bearing pressures were computed with SPT N value. Building foun dations may be rigid raft foundations at a depth of 2.0 meters below the present ground level, according to bearing capacity values that range from 20 kN/m2 to 60 kN/m2 at 1.5 to 3.0 meters. The recommended building foundations take into account the sub-soil’s characteristics at the drilling places at a depth of between 1.0 and 3.0 meters. The structure might also be supported by frictional piles buried 10 meters beneath the surface.

Effect of Permanent Load in Gresik Alluvium on Friction Pile Embedment Depth

Hydrostatic load, approximately 250-35 kPa (i.e., water of 2.5m-3.5m high), has been applied in the project area for about 25 years; hereafter, it will be referred as permanent load. Recently, this permanent load including its perimeter embankment, is demolished for which a new facility will be built. The upper 2-4m soil layer in this area consists of fill soil (mainly cohesionless material) overlying thick Gresik alluvium layer. A bearing layer was not found (down to an investigation depth of 50m). The initial design of pile embedment depth refers to the legacy soil report, pile embedment information from the surrounding area (not being subjected by permanent load), and preliminary soil investigation data (from the surrounding area); in this case, the projected embedment depth is 20-23m with the friction pile design concept. Due to the proximity of project location with existing facilities, the jacking-driven pile method, with HSPD (Hydraulic Static Pile Driver) machine, is selected for installing the precast spun pile. The pile jacking works indicate that piles can only be driven down to a depth of about 12m (far less than the projected depth). This paper provides an analysis on the changes of soil properties due to permanent load, which in turn increasing the pile shaft capacity and effectively reducing the pile embedment depth. The analysis is supported by data from pile jacking record, PDA test, and instrumented test pile. Discussion regarding the conservatism in pile design is also presented.

Performance Study of Casing Piles in Expansive Soil Foundations: Model Testing and Analysis

This study investigates the critical behavioral characteristics of pile foundations in expansive soil foundations through a series of model tests, including settlement, axial force, and side frictional resistance. The experiment initially utilized sand, bentonite, and gypsum as the fundamental materials for the preparation and composition research of expansive soil simulant materials. Subsequently, the performance of different types of model piles under various loads and water immersion conditions was analyzed. The results indicate that non-cased piles exhibit typical friction pile behavior, while PVC-cased and steel-cased piles effectively reduce side frictional resistance, resulting in a more uniform distribution of axial force along the pile. After immersion, the model test materials experience expansion, with a faster initial expansion rate and a more gradual later expansion rate. Different types of model piles exhibit different displacement characteristics, and the presence of an outer casing can reduce the uplift of the inner pile. Furthermore, PVC casing demonstrates better performance in handling negative frictional effects. This study provides valuable insights for the design and construction of pile foundations in expansive soil foundations.

A hydraulic-mechanical (HM) coupling constitutive model for unsaturated soil-continuum interfaces considering bonding effect

Unsaturated soil-continuum interfaces determine the behavior of structures such as friction piles embedded in unsaturated soil and retaining walls with unsaturated backfill. Developing accurate constitutive models for these interfaces is essential for innovative computational design and analysis in geotechnical engineering. This study presents a rigorous mathematical derivation to quantify the bonding effect at interparticle and pore space contact zones, introducing a bonding variable and a state parameter based on the ratio between current and critical void ratios. The novelty lies in introduction of a hydraulic-mechanical (HM) coupling constitutive model for unsaturated soil-continuum interfaces, incorporating the bonding effect and critical-state concept. Despite the 16 parameters in proposed model, all are methodically calibrated using suction-controlled interface shear tests. Effectiveness of the model is demonstrated through predictions in interface shear tests involving unsaturated Toyoura sand, smooth/rough steel, and published tests with unsaturated Minco silt and steel. The model's applicability is extended to diverse conditions, including structural stiffness, interface thickness, counterface roughness, and drying- wetting (D-W) cycles. This model provides a unified framework for analyzing volume changes and stress-displacement responses in unsaturated soil-continuum interfaces, providing valuable insights for design of pile foundations in unsaturated soils.

The influences of vertical load on lateral dynamic responses of end-bearing friction pile

This paper revisits the influences of vertical load on the lateral dynamic responses of a single pile with rigorous analytical methods. The vertical load of pile is supported by the combination of end-bearing and side friction that develops along the pile length. The equilibrium equations of surrounding soil are analyzed by making use of the continuum-based solution, whereas the pile is modeled by the conventional Euler-Bernoulli beam theory. According to the assumption of perfect contact between the pile and the soil, the axial force function is deduced, which yields the analytical forms of vertical load and mechanical parameters of the pile-soil system. Using the formulation of lateral soil resistance and taking into account the influences of vertical load, the dynamic responses along the end-bearing friction pile are subsequently achieved via the Adomian decomposition method. The results obtained in this scheme were compared with analytical techniques available in the previous literature, which are applicable to the dynamic responses in the absence of vertical load. The results of numerical analysis indicate that the influences of vertical load on both the lateral displacement and the bending moment of the pile could be significant and, in general, enable them to undergo remarkable redistribution.

Comparison of Field Ultimate Capacity (Static and Dynamic Load Test) with the Analytic Design of Bored Pile in Granular Soil, Batam, Indonesia

A bored pile provides a large capacity obtained to toe and friction pile to support some loads such as axial, lateral, and tensile due to hydrostatic pressure or overturning moment. Static and dynamic load tests are often carried out to validate pile design before pile production in a project. This study aims to compare the ultimate capacity of the pile based on the result of static load test, dynamic load test, and pile design in granular soil of Batam, Indonesia, in which Chin-Kondner, Mazurkiewicz, Davisson, and Hansen 80% methods are utilized to obtain ultimate capacity (Qu) of static load test and dynamic test analysis apply Case Pile Wave Analysis Program (CAPWAP) method to gain ultimate capacity. The result analysis of the static load test of ultimate capacity using Chin-Kondner, Mazurkiewicz, Davisson, and Hansen 80% methods obtained results of 1379, 1300, 1375, and 1182 tons, respectively, with a Qu average of 1309 tons. A bearing capacity (RMX) of 1204 tons was obtained through a dynamic load test. Using the CAPWAP method based on the dynamic test, the ultimate bearing capacity (Ru) of 1248 tons was obtained. Analysis of pile design shows that the ultimate capacity of the bored pile in the granular soil of Batam, Indonesia, was 1157 tons. The Qu examination between field loading testing (1278.5 tons) and design pile foundation (1158 tons) was 9.4%.

Predicting friction capacity of driven piles using new combinations of neural networks and metaheuristic optimization algorithms

Friction capacity is a principal characteristic in designing driven piles. Considering the complexities in analyzing the behavior of piles, many studies have recommended the use of machine learning for this purpose. However, the used methodologies need to be updated and improved with respect to recent computational advances such as the development of optimization algorithms. In this work, three metaheuristic algorithms, namely equilibrium optimizer (EO), biogeography-based optimization (BBO), and salp swarm algorithm (SSA) are deployed to optimize an artificial neural network (ANN) for predicting pile friction capacity based on pile geometry, effective stress, and shear strength. The findings indicate the suitability of the proposed algorithms. More specifically, in the training phase, the ANN supervised by SSA yielded the most accurate results, whereas in the testing phase, the BBO-ANN outperformed the two other models. The calculated mean absolute error, Pearson correlation coefficient, and root mean square error for the models are as follows: 6.0740, 0.9385, and 7.0678 for the EO-ANN, 6.1450, 0.9440, and 6.7343 for the BBO-ANN, and 5.9684, 0.9395, and 7.1322 for the SSA-ANN. It is shown that both SSA-ANN and BBO-ANN can serve as efficient tools for the reliable design of driven piles, providing efficient computational intelligence alternatives to traditional design methods.

Vertical compressive bearing performance and optimization design method of large-diameter manually-excavated rock-socketed cast-in-place piles

To study the vertical compressive bearing characteristics of large-diameter rock-socketed cast-in-place piles, eight manually-excavated rock-socketed cast-in-place piles were subjected to vertical compressive on-site load and pile stress tests. The test results showed that the load–displacement (Q-s) curves of the eight test piles were all slow-varying, and the settlement of the piles was less than 11 mm, which met the minimum engineering requirements. The unloading rebound rate was between 55 and 75%, and the elastic working properties of the piles were apparent. The pile axial force gradually decreased with depth, and the slope of the axial force distribution curve reached a minimum in the moderately weathered muddy siltstone layer while the pile side friction resistance reached its maximum value. Pile end friction increases with the increase of load. But the pile end resistance was inversely proportional to the single pile length-to-diameter (L/D) ratio and the depth of rock embedment for the pile. The percentage of pile side friction resistance under maximum load was 86%, indicating that these were characteristic friction piles. Based on the test results and the current Chinese code, the friction coefficient of the pile side soil layer η and the total resistance coefficient of the rock-socketed section ζ were introduced. A revision to the calculation equation for the vertical bearing capacity of the rock-socketed cast-in-place pile in the code was proposed, together with an optimization design method for large-diameter rock-socketed cast-in-place piles.

Analysis and effect of lateral forces on Micropiles

Micro piles are small diameter pile (less than 300mm). Micro piles are generally used when there are difficult ground conditions, such as natural or man-made obstructions, sensitive ground with adjacent structures, limited access/low headroom. Micro piles are small diameter drilled and grouted friction piles. Each pile includes steel elements that are bonded into the bearing soil or rock – usually with cement grout. The bearing stratum is logged during installation drilling to assure that bearing capacity is adequate. This chapter presents a summary of various parameters defining the computational models. The bearing capacity and spring constant values for different pile diameter and different length is studied in this paper. Also, lateral pressure is also checked on the pile. The software SAFE 2016 used for the analysis of model.

Study on Vertical Load Distribution of Pile Group–Liquefied Soil System under Horizontal Seismic Environment

The dynamic responses of pile–liquefied composite soils are complex, and the bearing capacities of single piles or pile groups in liquefiable soils remain unclear. For friction piles, the friction resistance determines the vertical bearing capacity of the pile. In a pile–soil system, it is very important to study the friction resistance changes in the pile during vibration. Based on a shaking table test, this study investigated the vertical bearing capacity of a pile foundation–liquefied soil system under simulated horizontal seismic forces, using the MIDAS GTS software. The load borne by the top of the pile was studied under a horizontal earthquake with a certain vertical load, different pile spacings, and different vibration times, along with the cumulative coefficient CCPF of the pile side friction. The distributions of the CCPF along the pile body of a single pile and pile groups with different pile spacings were analyzed at different vibration times. It was found that the CCPF intuitively reflected the distribution law of the pile side friction during vibration. When the CCPF at the bottom of the pile was equal to 1, the load on the top of the pile was equal to the average value of the total load. When the CCPF at the bottom of the pile was less than 1, the load on the top of the pile was less than the average value of the total load. When the CCPF at the bottom of the pile was greater than 1, the load on the top of the pile was greater than the average of the total load.

ОБОСНОВАНИЕ ЗАМЕНЫ И РАЗРАБОТКА ТЕХНОЛОГИИ РЕМОНТА ЦИЛИНДРИЧЕСКИХ ЩЕТОК ПОДМЕТАЛЬНО-УБОРОЧНЫХ МАШИН НА СТАДИИ ИХ ЭКСПЛУАТАЦИИ

The study objective is to develop and justify the technology to repair cylindrical brushes with the replacement of traditional cassette prefabricated space plates with non–space ones and to assess the influence of the shape of pile cross-section on the effectiveness of forming the drawing prism in front of the pile. The task to which the paper is devoted is the computational justification of the technology to replace traditional sweeper brushes with modern non–space ones; determination and optimization of the parameters of the cylindrical brush pile capacity; laboratory modeling of the dependence of the removed swept stuff mass on the relative distance between piles. 
 Research methods: computational and analytical methods for adapting mathematical dependencies of the sweeping efficiency indicators at the stage of operation of a repaired machine with replacement of brushes and optimization of machine performance indicators by increasing the volume of the swept stuff prism.
 The novelty of the work. The calculation method is used to justify the change in the design of a cylindrical brush when replacing worn elements of a cylindrical brush with non–space ones. The results of a laboratory study of the effect of the relative distance between the piles on the volume of the swept stuff prism are presented. 
 Study results. Technological methods used for the repair of mounted working equipment of road machines are analyzed. It is shown that the most promising for repair with an increase and optimization of brush equipment is a set of brush discs without spacers made of polypropylene pile and base. A technological process is developed in the form of a route map for the repair of a cylindrical brush and brush discs of the working equipment of a sweeper.
 Conclusions: calculations justify the effectiveness of the technology to repair the working equipment of sweepers with the replacement of a traditional cassette brush with a non–space one of Beeline type. Increasing the sweeping efficiency is ensured by optimizing the pile capacity of the cylindrical brush, reducing the cost of deformation of such a pile and reducing the loss of pile friction on the surface to be swept. The effect of the relative distance between the piles on the mass of the sand formed in front of the conditionally rigid pile is experimentally found out.