Data-driven approach to enhance deep foundation safety: reliable methods for predicting bored pile capacity

As a foundation under the structure can be generally divided into two types, namely the foundation deep and shallow foundation. Selection of the type of foundation depends on the type of structure including the construction load on whether light or heavy loads and also depending on the soil type. For the construction of a light load and soil conditions quite well, usually worn shallow foundation, but the construction of a heavy load is usually the type of deep foundation is the right choice. In general, the more complex the deep foundation of a shallow foundation. To this writer tried to concentrate on planning the foundation of this thesis in which bored pile (Bored Pile Foundations). Bored Pile foundation is a foundation built by drilling the ground first, then filled with steel reinforcement and cast. Bored pile used when soil solid base which has a carrying capacity of it lies very deep, which is approximately 15 m as well as the state of the soil around the many stands a large building and rise to the feared could lead to cracks in the existing building effect vibrations caused by staking activity when administered pile foundation. Carrying capacity of bored pile end bearing capacity is obtained than that obtained from pressure and friction pile tip bearing capacity obtained from carrying friction or adhesion force between the bored pile and the surrounding soil. K e yword :Bored Pile, Axial Bearing Capacity, SPT, Loading Test

The precise prediction of maximum load carrying capacity of bored piles is a complex problem because the load is a function of a large number of factors. These factors include method of boring, method of concreting, quality of concrete, expertise of the construction staff, the ground conditions and the pile geometry. To ascertain the field performance and estimate load carrying capacities of piles, in-situ pile load tests are conducted. Due to practical and time constraints, it is not possible to load the pile up-to failure. In this study, field pile load test data is analyzed to estimate the ultimate load for friction piles. The analysis is based on three pile load test results. The tests are conducted at the site of The Cultural and Recreational Complex project in Port Said, Egypt. Three pile load tests are performed on bored piles of 900 mm diameter and 50 m length. Geotechnical investigations at the site are carried out to a maximum depth of 60 m. Ultimate capacities of piles are determined according to different methods including Egyptian Code of practice (2005), Tan-gent-tangent, Hansen (1963), Chin (1970), Ahmed and Pise (1997) and Decourt (1999). It was concluded that approxi- mately 8% of the ultimate load is resisted by bearing at the base of the pile, and that up to 92% of the load is resisted by friction along the shaft. Based on a comparison of pile capacity predictions using different method, recommendations are made. A new method is proposed to calculate the ultimate capacity of the pile from pile load test data. The ultimate capacity of the bored piles predicted using the proposed method appears to be reliable and compares well to different available methods.

Bored piles comprise an advanced pile foundation technology that has the advantages of high bearing capacity, fast construction speed, stable construction technology, and no noise or mud pollution. To study the applicability of bored piles to collapsible loess sites, the compaction effect and load-bearing characteristics of bored piles before and after immersion were studied via a full-scale field test combined with the theory of hole expansion. The results indicate that when the pile spacing is 1.0, 1.25, and 1.5 m, the average dry density of the soil between piles increases by 23.8%, 18.5%, and 3.1%, respectively, compared with that of untreated foundation soil. When bored piles are used to treat deep collapsible loess foundations, the reasonable pile spacing to eliminate the collapsibility of the loess foundation is 2.5 times the pile diameter. It is feasible to estimate the effective compaction range using the pore expansion theory, and the effective compaction coefficients of similar sites are given. The positive friction of bored piles in the collapsible loess area is more than 95.5 kPa, which increases by more than 48.5% compared with that of non-extruded piles. Therefore, the bearing capacity of a single pile is significantly improved, and it is an effective treatment method for collapsible loess areas. Under immersion, the pile side negative friction did not change significantly with a pile diameter of approximately 27 kPa, and the increase was approximately 14% compared with that of non-extruded piles. Consequently, to avoid the adverse effects of negative friction resistance on the bearing capacity of pile foundations and to fully utilize the technical advantages of bored piles, it is necessary to eliminate or partially eliminate site collapsibility before applying bored piles. The results can provide experimental support and theoretical guidance for the popularization and application of screw–squeeze piles in deep, collapsible loess areas.

Currently, pile foundations are often used in engineering practice. Among the modern types of piles used for foundation structures, the option of foundations made of bored piles is definitely popular. They are used for various types of structures: bridges as part of highways, urban ring roads or high-rise buildings. The main problem in these cases is related to a reliable assessment of the bearing capacity of the pile and the development of a cost-effective design solution for foundation structures. The studies carried out in this direction confirm that the issue of determining the load-bearing capacity of piles remains relevant both at the stage of developing reliable design solutions and in the process of searching for an economically efficient option of the foundation constructions of buildings and structures. Taking into account the design features of bored piles and their installation technology add certain difficulties to the analytical methods of determining the soil bearing capacity of a single pile. The practice of using bored piles on construction sites followed by observation of deformations showed that the soil bearing capacity of the piles, determined by the analytical method of standards used at the stage of developing design solutions for foundations, is underestimated. Therefore, the total number of piles in the foundation needs to be optimized according to the results of further field tests. Geometric parameters of piles, such as length and diameter, in some cases can also be reduced at the stage of rationalization of the design solution of the pile foundation, based on the results of field tests. So, as a result, the underestimated value of the load-bearing capacity of bored piles causes an increase in the cost of construction materials, an increase in the cost of installing foundation structures and an increase in the cost of housing for the end consumer. The problem of reliable assessment of the soil bearing capacity of piles remains a relevant issue at the moment, as evidenced by the practice of designing foundation structures. The paper presents the results of the analysis of the structural features of bored piles, which are aimed at increasing their bearing capacity. Also, the paper examines the features of the technology of installing bored piles, which are determined by both the hydro-geological conditions of the construction site and the need to install the constructive features of the bored pile.

Defect details in bored pile and drilled pier foundations are presented for multiple installation methods to a depth of 70 ft (22 m) in projects along the Texas Gulf Coast. Over 2000 bored pile and drilled pier foundations covering four projects are reviewed. For nearly five decades drilled pier soldier pile walls have been an economic alternate to the reinforced concrete slurry wall which has enjoyed wide spread popularity across the North American Continent; hence the bored pile and drilled pier foundations used to form a basement wall on a project are numerous and are each exposed to the bottom basement level as construction proceeds. The experiences of design, preparation of construction documents and construction geotechnical engineering along with exposure allow a unique assessment of the design and construction compatibility of the completed drilled piers and bored piles. One project includes the observed limitations of low strain nondestructive testing to assess the presence of soldier pile defects for 24 in. (50 cm) diameter bored piles. Bored pile and drilled pier foundation defects are complex and do not lend themselves to easy assessment by non destructive testing. Accordingly, it is concluded that defects in bored pile and drilled pier foundation construction are inherent and that control of the construction means and methods is the only rational means available to build deep foundations with manageable defects. Hidden defect factors or reduced structural factors are needed for the design of deep foundations which will limit concrete carrying capacity below column design values because of the construction limitations, but the hidden defect factor cannot be a replacement for the control of construction means and methods by rational construction geotechnical engineering.

This paper outlines the geotechnical investigations and axial compression, pullout, and lateral pile load tests that were carried out at a site where cast-in-place bored concrete piles were installed. These piles were designed to bear on top of soft weathered rock surface that was under artesian pressures. Pile load test results have been compared with theoretically calculated pile capacities. It has been found that in areas of high artesian pressures in bedrock axial compressive pile load capacities theoretically estimated by conventional methods were significantly higher than the values obtained from load tests. Recommendations have been made that representative exposed bedrock samples be tested to determine their undrained strength, and these values be used for estimating theoretical pile capacities. Construction problems encountered during pile installation, such as locating the top of weathered bedrock without penetrating through water-bearing layers that were under artesian pressures, are presented briefly and a solution provided to install belled piles on top of bedrock is discussed. Key words: bored concrete piles, construction problems, load tests, soft weathered rock under artesian pressures, ultimate pile load capacities.

Bored pile foundations are deep foundations that are often used in the construction of large construction sites located in dense areas with the consideration of reducing noise and the influence of vibrations that would occur if pile foundations were used. This analysis aims to calculate the lateral bearing capacity of the bored pile foundation based on the results of analytical calculations using the Broms method, the Davisson method, the Chin method, the Mazurkiewich method, and analyzing the displacement of the bored pile foundation based on loading tests in the field. and the results of soil modeling with Allpile and finite element methods with the Mohr-Coulomb soil model, and the Hardening Soil model. Based on the analysis that has been carried out, the ultimate bearing capacity of the bored pile based on SPT data using the Broms method is 18.92 tons, while the results of the interpretation of the loading test using the Davisson method are 18 tons, the Chin method is 18.98 tons, and the Mazurkiewich method is 19 tons. For the large deflection of a single bored pile with a load of 200% with the Allpile program the large deflection that occurs is 4.25 mm and analysis based on FEM PLAXIS 3D using soil modeling with Mohr - Coulomb large deflection of 3.0 mm and soil modeling with Hardening Soil 2.99 mm.

In the offshore, most foundations are steel pipe piles and most of them are designed using the API RP 2A guidelines. For axial capacity of piles in sand the current guidelines in many cases show definite discrepancies when compared against actual load capacities of piles. An updated data base analysis shows that there are three major weaknesses in the current guidelines with respect to soil characterization:the consideration of the lateral earth pressure coefficient, K, as a constant (1. O or 0.8);the consideration of the unit point bearing resistance, q, as a linear function of depth; andthe absence of an unambiguous soil parameter determination process based on reliable in situ test results. Due to the erroneous assumption of a constant K, the API RP 2A guidelines show a "length effect;" it tends to under predict the capacity of shorter piles and over predict the one of longer piles. Consideration of q as a linear function of depth coupled with a step function bearing capacity factor, Nq, also contribute to over prediction for long piles, and wide variation in the prediction between users for short piles. The absence of an unambiguous in situ test method simply add to the overall discrepancies in the predictions. In this paper, specific modifications to the current API RP 2A guidelines are proposed on the basis of a data base analysis to account for the discrepancies arising from (a), (b), and (c) above. These modifications will reduce the discrepancies in the current API RP 2A method and increase the accuracy of the prediction of axial capacity of pipe piles in sand. Furthermore this will make the method fundamentally more consistent with soil behavior in deep foundations. INTRODUCTION The American Petroleum Institute (API)1 published its first set of recommended practice for planning, designing, and constructing fixed offshore platform in 1969. Since then it gained worldwide popularity and usefulness in the geotechnical community. However, along with the success it also drew criticisms, which led to its improvements2 over the years. This paper includes the results of a data base analysis of pipe piles in sand. The current data base is the updated version of a previous load test data base3 of piles in sand. THE DATA BASE Most offshore foundation piles are piles. In this paper the updated data the load tests of pipe piles in sand, It driven steel pipe base only includes consists of 60 load tests at 18 onshore sites. Most of the tests are from the United States, with a few from Canada, Holland, Taiwan, Israel, Yugoslavia and Japan. The references to the sites including other relevant information are shown in Table 1. The load tests of at least 11 of the 18 sites had already been considered in the revision and/or in the formulation of the API RP 2A previously.

This study intended to analyze the bearing capacity of single bored pile, the bearing capacity of the bored pile group, the load carried, the safety factor, and the settlement that occurs. The first calculation method is Schmertmann and Nottingham method, and the second calculation method is Meyerhof method. Based on the calculation of the bearing capacity of a single bored pile using the Schmertmann and Nottingham method obtained a value Qu = 49005,88 kN, while the Meyerhof method obtained a value Qu = 1633.71 kN. The calculation results for bearing capacity of the pile group using the Schmertmann and Nottingham method obtained a value Qg = 164169,70 kN and the Meyerhof method obtained a value Qg = 5472.93 kN. The results of the load carried by the bored pile group using Schmertmann and Nottingham method is Qi = 353.98 kN ≤ Qg = 164169.70 kN which means it’s still within safe limits. Using the Meyerhof method is Qi = 353.98 kN ≤ Qg = 5472.93 kN which means it is still within safe limits. The safety factor using the Schmertmann and Nottingham method obtained SF = 463.78 and using the Meyerhof method obtained SF = 15.46 which means it is very safe. Total settlement of a single bored pile is S = 0.0142 m ≤ 0.04 m which means it is safe. And the settlement of the bored pile group is Sg = 0.03 m ≤ 0.08 m which also means it is safe

Pile foundations are used for buildings where the firm soil is located at a considerable depth. This type of foundation is often employed in the construction of tall buildings (high-rise buildings) that bear exceptionally heavy loads. Before undertaking any construction project, the first on-site task is foundation work (substructure). The foundation is a crucial element in civil engineering because it is responsible for supporting and carrying the load imposed by the upper structure, namely the structural load. The aim of this study is to calculate the bearing capacity of bored piles based on the results of soil investigation and to assess the settlement that occurs in bored piles. The calculation of the bearing capacity of bored piles is performed using the Meyerhoff method, and the settlement of bored piles is calculated using the Vesic method. According to the soil investigation data, the calculated bearing capacity of the bored pile is 426.86 tons, with an allowable bearing capacity of 138.52 tons. The planning of pile foundations also takes into account the magnitude of pile settlement. The settlement of a single pile is 0.02m, and the allowable settlement is 0.05m. Pondasi tiang dipergunakan untuk bangunan dimana tanah kerasnya berada pada posisi yang cukup dalam. Jenis pondasi ini juga sering digunakan untuk konstruksi bangunan tinggi (high risebuilding) yang memikul beban yang sangat besar. Sebelum melaksanakan suatu pembangunan konstruksi yang pertama dikerjakan dilapangan adalah pekerjaan pondasi (struktur bawah). Pondasi merupakan suatu pekerjaan yang sangat penting dalam suatu pekerjaan teknik sipil, karena pondasi inilah yang memikul dan menahan suatu beban yang bekerja diatasnya yaitu beban konstruksi atas. Tujuan dari Penelitian ini untuk menghitung daya dukung bored pile dari hasil sondir dan menghitung penurunan yang terjadi pada bored pile. Pada perhitungan daya dukung bored pile dilakukan dengan menggunakan metode Meyerhoff dan untuk perhitungan penurunan bore pile dilakukan dengan menggunakan metode Vesic. Berdasarkan data sondir hasil perhitungan daya dukung bore pile sebesar 426.86 ton dengan besar daya dukung ijinnya 138.52 ton. Analisis pondasi tiang juga memperhitungkan besar penurunan tiang. Penurunan tiang tunggal sebesar 0.02m dan penurunan tiang yang diijinkan sebesar 0.05m.

Concrete bleeding in bored pile scan cause substantial defects such as channelling or air pockets in pile shaft of diaphragm walls. The repair of such damage can be costly and time consuming. The mechanism of concrete bleeding in bored piles and diaphragm walls is well known among construction professionals, but there a sons how concrete bleeding occurs remain insufficiently understood to date. This paper introduces a potential model to explain the fundamental mechanism of concrete bleeding or channelling in deep foundations (e.g. concrete bored piles or diaphragm walls). The model is based on a well-established theory from the disciplines of soil mechanics and geotechnical engineering. The transfer of knowledge from the discipline of geotechnical engineering to another (concrete technology) assumes that fresh concrete is a three-phase system consisting of aggregate (gravel and sand), fluid (cement paste and excess design water) and air. The application of external pressure on to fresh concrete inside a deep foundation due to self-weight of the fresh concrete column causes the redistribution of pore-water pressure, resulting in a reduction of void space inside the aggregate matrix. This change in aggregate density is likely to cause concrete bleeding if potential drainage paths exist inside the fresh concrete matrix. Such drainage paths will provide ‘escape routes’ to release the excess pore-water pressure (water or cement paste) to the surface of the pile by forming bleeding channels or voids inside the hardened concrete. The existence of potential drainage paths, the lack of fines in the fresh concrete matrix in combination within sufficient aggregate grading and the addition of too much design water (above the optimal water content for a given aggregate combination) have been identified as key factors contributing to concrete bleeding and channelling in deep foundations (e.g. bored piles and diaphragm walls).

PHC파일을 사용한 매입말뚝은 시공 중에 발생하는 소음과 진동을 최소화할 수 있다는 장점 때문에 많은 경우 도심지에 건설되는 건축구조물의 기초로 사용된다. 그러나 매입말뚝의 시공을 위해 굴착공을 천공하는 과정에서 굴착공 저면에 슬라임이 형성되고 그 하부의 지반은 응력이완으로 인해 조밀도가 느슨해져서 매입말뚝은 원지반의 강도에 비해 선단지지력이 작게 발휘된다는 단점을 갖고 있다. 본 연구에서는 매입말뚝의 선단지지력을 증대시키기 위해 PHC파일의 선단에 길이가 짧고 PHC파일과 직경이 동일한 강관을 부착한 새로운 형태의 PHC파일을 개발하였다. 새로운 PHC파일을 사용한 매입말뚝의 선단지지력 증대 효과를 검증하기 위해 현장 말뚝재하시험을 수행한 결과 새로운 PHC파일은 경타에 의해 파일 선단이 굴착공 저면의 슬라임과 그 하부의 이완된 지지층 영역을 관통해서 강도가 큰 원지반에 관입됨으로써 기존 PHC파일보다 매입말뚝의 선단지지력을 상당히 증대시키는 것으로 나타났다. Bored pre-cast piles using PHC piles is widely used in foundation of building structures constructed in urban areas because noise and vibration due to pile installation are low. However, since slime is formed at the base of borehole and the density of bearing stratum surrounding the base of borehole is decreased due to stress relaxation in drilling process of bored pre-cast pile method, the base load capacity of bored pre-cast piles is very low compared to the strength of bearing stratum. In this study, a new type of PHC pile, which short steel pipe with the same diameter as the PHC pile is attached to the pile tip, is developed to increase the base load capacity of bored pre-cast piles. In order to check the effect of the use of new PHC pile on the base load capacity of bored pre-cast piles, field pile load tests are performed for bored pre-cast piles using the new and existing PHC piles. Results of the pile load tests show that the new PHC pile gives higher base load capacity to bored pre-cast piles than the existing PHC pile, since the tip of new PHC pile is penetrated to undisturbed bearing stratum passing through the slime at the base of borehole and the loosened bearing stratum under the slime by pile driving using light hammer.

Introduction : Saint Petersburg is characterized by complex engineering and geological conditions due to the presence of a significant mass (with a thickness of 20…30 m or more) of highly deformable soils with deformation moduli of 5…10 MPa. Besides, due to long-term geological processes that took place in the territory of Saint Petersburg thousands of years ago, these soils are extremely unevenly distributed in depth and area of occurrence. However, according to modern requirements for city development, deeper underground structures and higher buildings are needed. In terms of geotechnical solutions, it is possible to meet these requirements by using deep piles. Purpose of the study: The authors of the paper made an approximate brief classification of the geological conditions of Saint Petersburg based on the genesis, depth of occurrence, and physical and mechanical properties, and developed a method for more accurate calculations of the bearing capacity of deep bored piles. Methods: In the course of the study, the authors performed statistical processing of 600 values of the bearing capacity of bored piles, calculated according to the requirements of standards and determined by the results of field tests. In addition, they performed a non-linear extrapolation of side friction and resistance values (for soils with a depth of up to 100 m). Results: The paper presents the assessment of the bearing capacity of bored piles depending on their depth in glacial moraine and pre-quaternary vendian deposits. Using the nonlinear extrapolation, the authors calculated the side friction and resistance under the toe of bored piles for further design of pile foundations with deep bored piles (at a depth of up to 100 m). Discussion: According to statistical studies, the actual bearing capacity of bored piles is significantly higher than the design one calculated according to the requirements of corresponding standards (by 1.6...2.6 times). This is due to the fact that soils with significantly differing strength and deformation characteristics are located along the side and under the toe of bored piles. The stronger the soil where the most part of the pile is located, the more the bearing capacity error is (towards underestimation). The paper presents studies confirming this statement.

The pile foundation is usually designed to exceed the weak soil to the strong stratum. There is very close relation between the pile capacity and surrounding soil conditions. In cohesionless soil, the bored pile is effecting surround soil by loosening deposits through a combination of pile volume replacement and exist of pile case used for installation of bored pile. In this study, the improvement of the weak soil that surrounds the pile and observing the effect of improvement on pile increase the skin friction of the bored pile capacity for bored pile carried out. This study conducts research into the use of expansive additives in concrete bored piles. The aim of this project was to investigate how Na2Co3 as an additive in concrete can increase the shaft resistance of a bored pile. Several tests were conducted on concrete single piles with a variation of length to the diameter ratios and different percentages of soda ash additives. All tests were made in dry, sandy soil at loosening state. All tests showed that the shaft capacity could be increased using expansive additives due to increase the volume of the pile or enlargement of pile volume during concrete setting; it was also concluded that the shorter expansive piles could be able to achieve the same pile capacity as a longer conventional pile. This would lead to reductions on the volume of concrete poured, the amount of steel reinforcement used and the amount of soil excavated. Therefore, construction costs can be decreased and construction times can be shortened.

The determination of load carrying capacity of bored piles generally uses the conventional semi-empirical static methods. For piles in expansive soils, more concern was given to the uplift forces. Few researches dealt with the prediction of the load carrying capacity of bored piles in expansive soils. In this paper some published CPT based methods are used to predict the ultimate capacity of bored piles and the change in capacity due to increase of moisture from semi-dry to excessive wetting. The results show that the CPT based design methods are promising when used to predict the capacity of small diameter short bored piles.