Foundation Engineering Problems Research Articles

A predictive analytics model for designing deep underground foundations using artificial neural networks

Artificial neural networks (ANNs) are commonly used to solve nonlinear problems. ANNs are composed of parallel interconnected layers that include processing elements called neurons. These neurons use mathematical functions to process the data, mimicking the human brain. In this study, we use ANNs for designing deep underground supports. We develop a predictive model for the ultimate axial capacity of deep foundations called drilled shafts, commonly used as support for highways, bridges and high-rise buildings. Different single hidden layer ANN architectures are utilized to predict the ultimate axial capacity of drilled shafts. The data used in this study are load tests collected from the extended version of the Nevada Deep Foundation Load Test Database. This study focuses on certain difficulties in foundation engineering problems, such as the variability in the soil or construction method which, conventional methods might not fully address. This can sometimes lead to overestimation or underestimation of the capacity. Consequently, a project can be unsafe or expensive. Therefore, the objective of this study is to improve prediction accuracy which is important and can save design and construction costs and time. A total of 45 load tests were divided into 85% for training, and 15% for validation. The developed ANN model achieved good generalization and prediction accuracy with a Root Mean-Squared Error of 2807.08 Kilopounds force (kips), a Mean Absolute Error of 2380.6 kips, and an R-squared (R2) of 87% on unseen data. The results can be adapted in future studies and the industry as a first-order estimate for the architecture of an ANN predictive model and the ultimate nominal axial capacity of drilled shafts.

Suitability of Engineering-Geological Environment on the Basis of Its Permeability Coefficient: Four Case Studies of Fine-Grained Soils.

The aim of the article is to compare two classifications systems of engineering-geological environment sustainability in terms of its permeability evaluated on the basis of permeability coefficient. The first evaluated classification assumes a permeable environment to be a positive characteristic in the engineering-geological assessment, while the other considers an impermeable environment as favourable. The four fine-grained soil materials were selected, as they had very similar, almost identical grains-size distribution, but different microstructure characterized by grains sphericity, angularity, and roughness. At the same time, the influence of changes in the density of soil materials (density index 10%, 30%, 60%, 90%) was analysed. Permeability coefficient was determined using six methods (empirical formulae, laboratory and microscopic analysis). The laboratory method falling head test (FHT) was taken as a reference test that reflected the actual water flow through the soil. It was found that with an increase in grain angularity and roughness (and a decrease in sphericity), the permeability coefficient was decreasing and this trend culminated along with gradual compaction. Moreover, the research shows that unsuitable methods may classify soil materials into wrong engineering-geological permeability classes, which may have negative consequences during engineering-geological or geotechnical assessment and cause subsequent problems in foundation engineering.

An Upper Bound Solution to Undrained Bearing Capacity of Rigid Strip Footings Near Slopes

The undrained ultimate bearing capacity of rigid strip footings near slopes is one of important problems in practical foundation engineering in soft clay. To solve the bearing capacity conveniently and easily, a calculation method for the undrained bearing capacity is proposed using the upper bound limit analysis. A bilateral failure mechanism is provided and involved in the analysis, and two failure modes including slope face failure and below-toe failure are pointed out considering the location relationship between the critical slip surface and the slope toe. The upper bound solution of the undrained bearing capacity based on the failure mechanism is carried specifically out via the optimization algorithm. Analysis of some typical examples shows that the results calculated by the proposed method agree well with those obtained using other analytical and numerical methods. The maximum error is about 10%. Cohesion of slope soil, slope angle, horizontal setback distance of strip footing from the slope crest, slope height, surcharge on the slope top level, and the footing depth have great influence on the undrained bearing capacity.

Propagation and attenuation characteristics of the vibration in soft soil foundations induced by high-speed trains

The vibration caused by high-speed trains (HSTs) can result in reductions of strength and bearing capacity of the railway foundation, unexpected settlement, and other geotechnical engineering problems. Thus it is essential to estimate the vibration level at different depths of the foundation. This study investigates the propagation and attenuation characteristics of the vibration in the soft soil foundation induced by high-speed trains. A series of field experiments were conducted to measure the HST-induced vibration in the soft soil foundation in Shanghai, China. The measurement provides a unique dataset for numerical model validations. Based on the Bornitz equation, a new attenuation model is proposed for layered homogeneous media. The material damping coefficient and the geometric damping coefficient, two input parameters for the model, are thoroughly investigated using measurements in this study and from the existing literature. The proposed model was applied to estimate the vertical vibration levels at different depths in typical subgrade and foundation of HSTs in the soft area. Model performance is supported by the good agreement between predictions and observations. Our model provides an alternative tool to further investigate the effect of HST-induced vibration on foundation soils and adjacent underground structures.

Soil Physical and Hydraulic Properties over Terrace Adjacent Four Major Rivers

The soil does not only serve as a medium for plant growth but also for engineering construction purposes. It is very weak in tension, very strong in compression and fails only by shearing. The behaviour of the soil under any form of loading and the interactions of the earth materials during and after any engineering construction work has a major influence on the success, economy and the safety of the work. Soils and their management have therefore become a broad social concern. A limitless variety of soil materials are encountered in both agronomy and engineering problems, varying from hard, dense, large pieces of rock through gravel, sand, silt and clay to organic deposits of soft compressible peat. All these materials may occur over a range of physical properties, such as water contents, texture, bulk density and strength of soils. Therefore, to deal properly with soils and soil materials in any case requires knowledge and understanding of these physical properties.The desired value of bulk density varies with the degree of stability required in construction. Bulk density is also used as an indicator of problems of root penetration,soil aeration and also water infiltration. This property is also used in foundation engineering problems. While not conforming to standard test procedures, this work attempts to add to the basic information on such important soil parameters as water content, bulk density.

A General Approach to the Solution of Boussinesq’s Problem for Polynomial Pressures Acting over Polygonal Domains

We outline a general approach for extending the classical Boussinesq’s solution to the case of pressures distributed according to a polynomial law of arbitrary order over a polygonal domain. To this end we exploit a generalized version of the Gauss theorem and recent results of potential theory which consistently take into account the singularities affecting the expressions of the fields of interest, an issue which seems to have been overlooked in the existing literature. For linearly varying pressures we derive analytical expressions of displacements, strains and stresses at an arbitrary point of the half-space as a function of the loading function and of the position vectors which define the boundary of the loaded region. We briefly discuss how bilinear and more general pressure distributions can be accommodated in our formulation since the paper is mainly motivated by the interest in developing efficient computational tools for solving 3D problems in foundation engineering and contact mechanics. Finally, comparisons with existing solutions and numerical examples are discussed.

The Issue of Soft Rocks Causing Problems in Foundation Engineering

Heterogeneity of the geological environment causes different problems related to foundation engineering. Every engineering-geological condition requires specific solutions. The occurrence of soft rock is a risk, especially in interaction with other actors. Among the so-called soft rocks are organic soil, clay and loam (silt), lacustrine sediments, but also soft soils in connection with phase changes in frozen or defrost environments. In connection with these problematic soils, questions of low bearing capacity, different settlement, landslides, heterogeneity of the geological environment and others are solved. The aim of the publication is to highlight the possible occurrence, the most common risks during interaction of this type of geological environment with engineering construction. A series of case studies and investigations of different countries are mentioned in this publication. Creating a simple scheme of soft rock and summarizing the basic problems of soft rock serves as a generalization of this problem. However, it should be understood that each foundation soil is located in a different environments, which is also influenced by other factors.

Displacements under linearly distributed pressures by extended Mindlin’s equations

Analytical elasticity solutions provide an efficient means of performing a first approximate analysis in foundation engineering. One of the well-known solutions is Mindlin’s solution to the stress and displacement induced by a point load at an embedment depth in a half-space. This solution is more superior but less widely used than Boussinesq’s solution. To promote this situation, Mindlin’s displacement equations are integrated to obtain a complete set of explicit formulae for calculating the displacements at an arbitrary point. The displacements are induced by uniformly and triangularly distributed horizontal or vertical pressures, which are exerted over a horizontal or vertical rectangular area in the interior of a homogeneous, isotropic, elastic half-space. These formulae facilitate the future development of computer programs for the analysis of related practical problems in foundation engineering.

Network Parallel Electrical Method for Dam Foundation in Coal Mining Subsidence Area Hazard Evaluation

Thelarge-scale exploitation of coal resources, will cause large area ground subsidence, soil quality to destroy and civil building foundation engineering problems, give the people live and work in peace brings a harm. This article from the network parallel electrical fundamentals and application premise to proceed, with Xie pool mining subsidence area new Xie dam engineering geological background, site layout of the two line, a 128 electrode, analysis of the detection results, on the ground by means of artificial method, electric field distribution, can quickly determine the quality of dam foundation damage points, provide geological basis for its management.

THEORETICAL STUDY OF EARTH PRESSURE AT – REST FOR SANDY SOILS

The solution of many foundations - engineering prob lems requires knowledge of the lateral pressure which may be exer ted by the earth or surcharge loads. The lateral earth pressure is a significant design parameter in many of the foundation engineering problems subjected to latera l pressures commonly used as parts of many civil engineering projects. S ome examples of these structures are, retaining walls, sheet-pile walls, both braced and unbraced excavations, trench excavations, grain pressures on silo walls, cofferdams, caissons, embedded shells and other types of underg round structures requiring an estimation of the lateral pressure fo r design or stability analysis. The different formulae such as Jaky , Hendron , Br ooker and Ireland, Vierzbiczky , Saglamer , Wenkow , Robert Szepesh azi , Matsuoka et al, Bolton , and others were used to determine the fact or Ko. The main aim of this research is to estimate the co efficient of earth pressure at rest equation depending on the theoreti cal relationship between the active, passive earth pressures and the lateral strain of soil. The important result from this research is: ) sin 1 /( ) sin 1 ( 2 2 φ φ + = o K

GEOTECHNICAL FACTORS GOVERNING SHEAR STRENGTH OF QUSEIR SHALE IN DAKHLA OASIS, WESTERN DESERT, EGYPT

This paper presents an extensive study geotechnical factors controlling undrained shearing characteristics of Quseir Varigated Shale in central part of Dakhla Oasis. The clayey soil of Quseir Shale covers the floor of Dakhla Oasis. In recent years, the size of structures in this region has been increasing. The shearing behaviour of soils is of major concern for engineers, since the solution of stability problems in foundation engineering requires knowledge of the shearing strength of the underlying soil. The Quseir Shale in Dakhla Oasis consists of four layers (green gypsiferous shale graded downward into yellowish green shale, green shale and reddish gray shale). The clay minerals of the studied soil consisting of five species namely kaolinite was the predominant clay mineral present, smectite, illite, illite-smectite mixed-layer, and chlorite which arranged in a decreasing order of abundance. The geotechnical parameters of the studied clayey soils show a strong mutual relation between some measurements and undrained shearing parameters. The measured major stress (1) has a close direct proportional relation with sand%, silt%, kaolinite%, calcium carbonate content and depth. The effective cohesion (C) has a close direct proportional relation with clay fractions, initial water content, and smectite%.

Closure to “Estimation of Bearing Capacity of Circular Footings on Sands Based on Cone Penetration Test” by Junhwan Lee and Rodrigo Salgado

The authors acknowledge the observations of discussers Decourt and Rodriguez-Roa regarding the adequacy of the bearing capacity equations used in the research. The authors cite the differing views of the discussers, pointing to the concern raised by discusser Rodriguez-Roa that the wide variance in results might serve to entirely discredit the usefulness of the bearing capacity equation; while noting the point of discusser Decourt, who, citing others in agreement, believes that discrediting the bearing capacity equation is precisely the point. However, the authors, themselves, state the belief that the bearing capacity equation, as seen in the forms emerging from current research, should be embraced. The authors add that the purpose of the bearing capacity equation is to calculate the limit or plunging load of the footing. They claim to have not used it beyond its designed purpose. As for discusser Decourt's point that the bearing capacity equation (the so-called triple N formula) is wrong, the authors explain that the equation, initially proposed for the indentation of metals, has evolved over time to include more realistic geotechnical and foundation engineering problems (i.e. shape and depth, along with base, ground, and load inclinations). In its present form, the authors note the bearing capacity equation has high empirical content, despite being derived from rigorous analysis at the beginning. Addressing discusser Rodriguez-Roa's point about using experimental data to determine the validity of the bearing capacity equation, the authors believe that the final solution to the question must first come from establishing a proper analytical basis, as explored by the authors (e.g., Salgado et al. 2004, Lyamin et al. 2006, Martin 2005). These examples rigorously calculate limit loads and then follow this with proper validation against well-performed, well-instrumented load tests on properly and completely characterized soils. The authors note that the bearing capacity equation, even its traditional forms, was never designed to compute ultimate loads defined on a basis of a specific settlement value. The discussers agree with discusser Decourt about the bearing capacity formula having limitations in its present form. At the same time, the authors also agree with discusser Rodriguez-Roa about retaining the concept of the bearing capacity equation as a tool for geotechnical and foundation engineers. The authors predict that practitioners in the near future will be provided with both an extremely useful and nearly exact version of the bearing capacity formula; one that will have a small, precisely known level of uncertainty.

Land subsidence in Bangkok, Thailand

Land subsidence from deep well pumping has been affecting Bangkok for the past 35 years. Its impact is particularly critical because of the flat low-lying topography and the presence of a thick soft clay layer at the ground surface that augment flood risk and foundation engineering problems, respectively. The subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 120 mm/year. The rate decreased in the subsequent period but the subsidence-affected area expanded following the growth of the city. Despite various attempts implemented to remedy the crisis, groundwater pumping from the thick aquifer system underneath the city continued to increase from 1.2 million m 3/day in the early 1980s to more than 2.0 million m 3/day at the turn of the century. Piezometric levels in the main aquifer layers had been drawn down by as much as 65 m. Monitoring data showed a clear correlation between the subsidence and piezometric drawdown. The data suggested that for 1 m 3 of groundwater pumped out in Bangkok Plain, approximately 0.10 m 3 of ground loss occurred at the surface. Significant development has been made in numerical methods for prediction of differential settlements between building foundations caused by the piezometric drawdown in the aquifers. The strict mitigation measures adopted recently, comprising a pricing policy for groundwater management, an expansion of tap water supply, and strict enforcement of groundwater laws, have resulted in a marked drop in groundwater use. However, the land subsidence will continue for a long while owing to the time-dependent consolidation behavior of the soft clay layer and clay aquitards.

Building KBES for Diagnosing PC Pile with Inductive Learning

The damage of a prestressed concrete pile (PCP) during the driving process has resulted in injuries, time delay, and cost overruns. Diagnosing the damage is one of the most important problems in foundation engineering. A knowledge‐based expert system (KBES) for diagnosing PCP is proposed in this paper. To overcome the glut of knowledge acquisition, the ID3 inductive learning algorithm is used to acquire knowledge rules. Five phases for building expert systems with inductive learning—identification, collection, implementation, refinement, and verification—are discussed. The knowledge base obtained from the inductive learning method is compared with that obtained from the conventional interview method in several aspects, including representation efficiency, reasoning efficiency, reasoning predictability, reasoning accuracy, and resources used. The results show that inductive learning is superior to the interview method in most aspects. The characteristics of civil engineering problems that make them good candidates for inductive learning are also discussed in this paper.

Expert System for Diagnosing Damage of Prestressed Concrete Pile

The damage of prestressed concrete pile (PCP) during the installation process has resulted in injuries, time delay, and cost overruns. Diagnosis of the damage is one of the most important problems in foundation engineering. This paper describes a diagnosis expert system PCPILE (prestress concrete pile) for diagnosing the damage of PCP during the construction process. Because there is no way to avoid subjective judgment, imprecise data, and experience‐based knowledge in this problem, fuzzy logic is employed to solve it efficiently. In PCPILE, the inference is mainly implemented by the deductive inference mechanism with depth‐first backward chaining. But, when the deductive inference mechanism cannot satisfy a diagnosis goal directly, a specific case base is opened for the analogical influence mechanism. The expert system is novel in at least two respects: (1) Case base is employed for knowledge representation; (2) analogical inference technique is applied when there is a lack of sufficient experience in ge...

Computing costs for FEM analysis of foundation engineering problems and possible ways of increasing efficiency : Schad, H Int J Num Anal Meth GeomechV9, N3, May–June 1985, P261–275

Computing costs for FEM analysis of foundation engineering problems and possible ways of increasing efficiency : Schad, H Int J Num Anal Meth GeomechV9, N3, May–June 1985, P261–275

Practical problems in soil mechanics and foundation engineering

Practical problems in soil mechanics and foundation engineering

Computing costs for FEM analysis of foundation engineering problems and possible ways of increasing efficiency

AbstractThe application of finite element methods (FEM) is often restricted by the available computer capacity and the computing costs. The purpose of this paper, therefore, is, to present test results and to discuss possible ways of achieving a substantial reduction in computing times. Dividing the numerical analysis into the five levels–hardware, software, element‐mesh and element‐type, iteration technique (approximation of non‐linearity) and constitutive model–one can show that the computing time can be reduced by about 20 per cent at every level. In particular, the use of the modified Newton‐Raphson method for approximation of non‐linearity and the constitutive model–apart from the theoretical concept (elastoplastic, hypoelastic etc.)—must be formulated in a manner which does not produce substantial changes in the coefficients of the material matrix caused by small stress changes. On the whole, computing time can be reduced to about 10 per cent of present computing costs. Thus, it would even be economically viable to solve three‐dimensional non‐linear problems by FEM.

Assessment of relative slope stability of Kodiak shelf, Alaska, using high‐resolution acoustic profiling data

Abstract The use of marine high‐resolution geophysical profiling data, seafloor soil samples, and accepted land‐based methods of analysis have provided a means of assessing the regional geotechnical conditions and relative slope stability of the portion of the Gulf of Alaska Continental Margin known as the Kodiak Shelf. Eight distinct types of soils were recognized in the study; the seafloor distribution of these indicates a complex geotechnical setting. Each soil unit was interpreted as having a distinct suite of geotechnical properties and potential foundation engineering problems. Seven categories of relative slope stability were defined and mapped. These categories range from “highest stability”; to “lowest stability,”; and are based on the degree of slope of the seafloor, type of soil underlying the slope, and evidence of mass movement. The results of the analysis indicate that the highest potential for soil failure exists on (1) the slopes forming boundaries between the submarine banks and the broad sea valleys, and (2) the upper portion of the continental slope, where evidence of past slope failure is common. Also of concern are gently sloping areas near the edges of submarine banks where evidence of possible tension cracks and slow downhill creep was found.

Degree problems in soil mechanics and foundation engineering : IPC SCI. TECH. PRESS, ISBN 0 902852 434, APR. 1975, 102P

This book contains over one hundred degree problems in soil mechanics and foundation engineering which are included under the following headings: physical properties; effective stress; shear strength; soil stresses, bearing capacity and consolidation; seepage; earth pressure; stability of slopes and earth dams; foundations. The problems are based on several sources including the Institution of Civil Engineers, the Council of Engineering Institutions, the University of London and the University of Surrey. Answers are provided for all the problems with one in five having worked solutions. To aid the working of the problems a comprehensive selection is given of design charts and tables. /TRRL/