Enhancing the Ability of The Square Footing to Resist Positive and Negative Eccentric Inclined Loading Using an Inclined Skirt

Laboratory model tests were performed to investigate the behavior of shallow and inclined skirted foundations placed on sandy soil with R.D%=30 and the extent of the impact of the positive and negative eccentric-inclined loading effect on them. To achieve the experimental tests, it was used a box of (600×600) mm cross-sectional and 600mm in height and a square footing of (50*50) mm and 10 mm in thickness attached to the skirt with Ds=0.5B and various an angle of (10°, 20°, 30°). The results showed that using skirts leads to a significant improvement in load-carrying capacity and decreased settlement. In addition, when the skirt angle increased, the ultimate load improved. Load-carrying capacity decreased with increasing eccentricity and load inclination. For load inclination (Beta) 15° when the eccentricity changed from e=0.15B to e=0.05B, the load improvement percentages were (323.2 to 263%) and (214 to 220%). The settlement reduction factor was (83 to 78%) and (62 to 58%) for positive and negative eccentric-inclined loading, respectively. Also, the result showed that the positive effect on reducing soil-bearing capacity is more than the negative. Increasing eccentricity increases the improvement percentage for positive eccentric-inclined load and decreases for the case of negative eccentric-inclined load. Increased skirt angle will increase the Improvement factor (IR). When the skirt angle increased from 10° to 30° for an improved foundation with load angles of 5°, 10°, and 15°, the improvement factor (IR) increased from (2.53, 2.51, 2.4) to (3.45, 3.65, 3.97) and (2.43, 2.58, 2.54) to (4, 4.63, 5.3) for both negative and positive eccentric-inclined load respectively and settlement reduction factor for load angle 15° and skirt angle increase from 10° to 30° were 34% and 27% for positive and negative eccentric-inclined load respectively. The (IR) for the positive eccentric-inclined load is more than the negative eccentric-inclined load for all cases. In addition, the skirt angle of 30° significantly improved the improvement factor (IR)

Analyse numérique de la stabilité des pentes renforcées par pieux

The assessment of slope stability is attributed to various critical conditions; one of which is the selfweight sliding stimulus, and the other one induces failure caused by a surface load condition (shallow foundation). In the particular case of a shallow foundation situated on a slope crest, the bearing capacity is significantly reduced. Therefore in practice, anti-slide piles are used to enhance the performance of the nearby footing. Whereas, the studies tend to rely on the hypothesis of purely vertical surface load condition. The present dissertation aims to contribute to the numerical and stochastic analyses by inducing vertical retaining structures, in order to deal with the group problem of slope stability and bearing capacity of an adjacent combined loaded strip footing. Firstly, a bibliographical research is presenting the most common deterministic and probabilistic methods, pertaining to slope stability assessment and bearing capacity of a shallow foundation. Followed by a presentation of bibliographical synthesis concerning studies published in the literature. The second part furnishes a contribution to the numerical analysis using the finite element software OptumG2. The investigation of the factor of safety is conducted under various conditions of a pile row, using elastoplastic shear strength reduction method. Thence after, a conducted study is done on the effect of reinforcing a cohesive slope by a row of multiple number of piles and a sheet pile wall on the undrained bearing capacity of a rigid strip footing, using the limit analysis

Soft Computing Based Prediction of Unconfined Compressive Strength of Fly Ash Stabilised Organic Clay

The current study uses machine learning techniques such as Random Forest Regression (RFR), Artificial Neural Networks (ANN), Support Vector Machines Ploy kernel (SVMP), Support Vector Machines Radial Basis Function Kernel (SVMRBK), and M5P model tree (M5P) to estimate unconfined compressive strength of organic clay stabilized with fly ash. The unconfined compressive strength of stabilized clay was computed by considering the different input variables namely i) the ratio of Cao to Sio2, ii) organic content (OC), iii) fly ash (FAper) content, iv) the unconfined compressive strength of organic clay without fly ash (UCS0) and v) the pH of soil-fly ash (pHmix). By comparing the performance measure parameters, each model performance is evaluated. The result of present study can conclude the random forest regression (RFR) model predicts the unconfined compressive strength of the organic clay stabilized with fly ash with least error followed by Support Vector Machines Radial Basis Function Kernel (SVMRBK), Support Vector Machines Ploy kernel (SVMP), Artificial Neural Networks (ANN) and M5P model tree (M5P). When compared to the semi-empirical model available in the literature, all of the model predictions given in this study perform well. Finally, the RFR and SVMRBK sensitivity analyses revealed that the CaO/SiO2 ratio was the most relevant parameter in the prediction of unconfined compressive strength

Capacité portante des fondations sous charge inclinée par approche numérique

La capacité portante des fondations superficielles est l'un des domaines les plus importants des études dans l’ingénierie géotechnique. La plupart des études ont été effectuées sur le cas où la fondation est soumise à une charge verticale centrée. Alors que les fondations superficielles sont souvent soumises à des charges excentrées et/ou inclinées (moments de flexion et des efforts tranchants transmis par la superstructure). Toutefois, lorsque la fondation est soumise à une charge inclinée et/ou excentrée, sa stabilité devient un problème majeur en géotechnique. Cependant, les projets d’'installation de plates-formes pétrolières et gazières en mer a donné un intérêt important pour la compréhension du comportement ainsi que les mécanismes de rupture des fondations superficielles sous chargement incliné et/ou excentré, ce qui va conduire à l’amélioration des méthodes d’estimation de la capacité portante de ce type de fondations. Par ailleurs, le code de différences finies Flac a été utilisé dans cette thèse pour évaluer numériquement la capacité portante des fondations superficielles en utilisant une loi de comportement de Mohr Coulomb associée et non associée. Toutes fois l’analyse numérique a été effectuée en faisant varier plusieurs paramètres géométriques et mécaniques. Les résultats obtenus montrent que pour le cas d’une semelle reposant sur la surface libre du sable et soumise à un chargement vertical excentré, les valeurs des capacités portantes calculées en utilisant l’approche de la largeur effective de Meyerhof ont tendance à sous-estimer les capacités portantes notamment, quand les excentricités sont importantes. On note que sur la base des résultats obtenus par l'analyse numérique, une nouvelle conception est proposée pour la largeur effective. Pour le cas d’une semelle encastrée dans un sable et sous un chargement vertical excentré, la variation de facteur de réduction (RF) avec l'augmentation du rapport d'excentricité est parabolique, et tend à être linéaire avec l’augmentation de l’encastrement de la semelle. Pour le cas d’une semelle reposant sur la surface libre du sable et soumise à un chargement incliné centré, le facteur d'inclinaison dépend uniquement de l'angle d'inclinaison α. Les résultats de cette étude, ont fait l’objet d’une confrontation avec ceux de la littérature

Stability and strength analysis of leaning towers

Many ancient towers are afflicted by stability problems. The evaluation of the overall safety of historical towers is one of the most important items in the preservation of the national and worldwide artistic heritage. This thesis is concerned with models appropriate for the stability assessment of tower foundations, which is related to: bearing capacity failure, due to lack of soil strength, and instability of equilibrium, due to lack of soil stiffness. Both of these hazards are tackled using a work-hardening plasticity model for surface footings. New developments have been introduced into the foundation modelling in relation to prediction of displacements and creep behaviour. These improvements have been used develop a methodology that can deal in a unified way with the two major failure mechanisms of such foundations. Finally, a new interpretation of the influence of creep on tower stability is explained. Such an analysis provides not only a complete framework within which both possible collapse mechanisms can be assessed but also a prediction of which of them is most likely to occur. The analysis, which has been developed in the form of a Mathematica notebook, and applied to the Pisa Tower and the Santo Stefano bell tower, can be also used to study the influence of foundation strengthening procedures

Stability of Working Platforms for Tracked Plant

The aim of this research is to improve the design of working platforms for tracked plant in order to guarantee safety but also a more economical approach to the design. The reason for this concern derives in part from incidents of overturning plant which have taken place in the past, some of them resulting in injuries and/or death of operatives, but also from the consequent use of excessively conservative and therefore uneconomical design. Common practice for the design of working platforms is the use of bearing capacity methods normally adopted for the construction of spread foundations. The objective of this approach is the definition of an appropriate platform thickness which is back calculated from a bearing capacity equation. According to this type of design, the thickness of the platform changes based on the characteristics of the platform material and of the subgrade. Among these factors, the one having more influence on the resulting thickness is the design angle of friction of the platform material, which therefore need to be accurately established. A common laboratory method used to measure the angle of friction of soils is the direct shear test. Difficulties in the correct interpretation of the results of this test are mainly associated with the presence of scale effects. As extensively reported by literature, scale effects can derive from testing material with a large particle size which is not suitable for testing in a standard apparatus, that would cause the shear strength of the material to be overestimated. A solution to this issue often consists of testing a scaled sample of the material using the standard apparatus. Nonetheless, even this approach can induce scale effects leading to an underestimation of the angle of friction when an important reduction in particle size is produced. Another method used to derive the angle of friction of the platform material is the plate bearing capacity test which is normally conducted on site. In order to guarantee reliable results for the bearing capacity of the material and the derived angle of friction, an appropriate ratio between plate diameter and particle size must be used. The problem of this method is associated with the high costs of the testing apparatus which are substantially increased by the large particle size of the material requiring large plate diameters to be used during the test and consequently high reaction forces to be applied. In order to investigate the scale effects associated with testing the material at smaller scale using the standard shear box apparatus and with using different plate diameters in case of plate loading tests, a series of small scale direct shear tests and plate loading test using a centrifuge model were conducted on two small scale samples of crushed limestone. The results of these tests were used to derive the angle of friction of the material and were compared with the ones obtained from testing the same material at full scale using a large shear box apparatus which was designed and manufactured for the purpose of this research. Comparison of the results allowed to identify the magnitude of the scale effects on the value of the angle of friction of the material. Differences in results should be taken into account in order to define an appropriate value for the design

Numerical modelling of the behaviour of stone and composite stone columns in soft soils

The use of stone columns as a means of ground improvement has been in use for over 40 years in the United Kingdom and Europe. Their primary purpose is to reduce settlement, reduce consolidation time and increase the bearing capacity of soils. Currently the technique is applied to a variety of soil types, cohesive and granular. Soft cohesive soils have shown a tendency towards higher settlements due to the inability of the soil to restrain the lateral movement or bulging of stone columns. Current analytical design methods are based upon the unit concept which considers a stone column to be part of an infinite array of columns. Such methods have proved useful when designing large arrays such as those utilised beneath embankments or large rafts. Columns within the group are restrained equally on all sides and held in the same vertical stress conditions. However, at the edge of large (wide) load areas and in smaller foundation configurations columns are not generally restrained on all sides by other columns and must rely on the soil to provide restraint in the outward facing directions. The behaviour of small foundation configurations is more complex due to this lack of restraint with columns subject to deformation at lower stress levels than those in infinite arrays. This dissertation is concerned with the behaviour of stone columns and proposed composite stone columns installed in soft clay. This research compares the behaviour of small foundations supported by stone columns to behaviour within an infinite array of columns. Specifically the settlement and deformation behaviour of stone columns are considered to identify the main deformation mechanisms and to examine the effect of key design parameters and soft cohesive soils on column performance. A new form of composite stone column was then examined numerically to assess the potential for enhanced column behaviour and settlement reduction. PLAXIS 3D Foundation is utilised with column behaviour represented by the Mohr-Coulomb Perfect Plasticity model and the Hardening Soil model adopted to model soil behaviour. The soft soil profile adopted in this research is the well characterised Bothkennar soft clay site which was formerly the UK geotechnical test bed. The influence of key stone column design parameters, area ratio, column length, column confinement and arrangement, column stiffness, column strength, installation effects and the effect of stiff crust thickness was examined for a combination of foundation types with 432 numerical sensitivity studies conducted. The results reveal that area ratio and column length have a significant impact on the settlement performance of stone columns. Increasing the area ratio was found to reduce the restraint provided by neighbouring columns leading to increased settlement. Increasing column length was found to reduce settlement. When columns were modelled with low area ratios increasing column length had a greater effect on settlement reduction than at higher ratios. The design parameters of area ratio and column length are established as the controlling parameters for the mode of deformation. The mode of deformation was examined utilising settlement inferred deformation ratios (compression and punching) with comparison to total shear strain plots and stress states in the column. Two primary modes of deformation, bulging and punching (including sub-type termed 'block failure') were inferred. Punching failure was inferred for short columns by high punching ratios and low compression ratios with a concentration of shear strain observed at the base of the floating columns. A sub-type of punching, block failure, was inferred from low compression and low punching ratios for closely spaced columns with low area ratios in which the columns act as one unit punching into the underlying soil. Bulging failure was inferred by low punching ratios and high compression ratios coupled with a concentration of shear strain in upper region of the columns. The magnitude of bulging was found to be at its most severe for high area ratios. Bulging as a mode of failure occurred for column length to diameter ratios greater than 4 and area ratios greater than 8. Bulging was found to occur at the weakest of the soil profile which coincides with the top of the lower Carse clay. Consideration was given to a method of reducing the potential for lateral column deformation or bulging by the use of a novel composite column. The deformational characteristics of a stone column were identified for a composite of granular and the experimental Protomix materials. Laboratory testing was carried out to gain an understanding of the cohesive, stiffness and unconfined compressive strength properties of the composite before simulation studies were performed on key design parameters such as area ratio, column length, column confinement and arrangement for a combination of foundation types with 108 numerical analysis sensitivities conducted. The inclusion of a cohesive 'binder' material in the bulging zone was found to reduce settlement for all foundation configurations. Similarly to stone columns area ratio and column length were found to be the design parameters which influenced the results most. The composite stone columns (CSC) offered higher settlement reduction than traditional stone columns (SC). It was discovered that CSC with an area ratio of 8 were able to achieve the same settlement improvement factor as those with a ratio of 3.5 which suggests the columns could offer the same settlement control but with large column spacing's making their use more economical. The settlement inferred deformation ratios (compression and punching) were studied while monitoring the total shear strain field cross sections to examine if composite stone columns would behave similarly to a stone column. It was noted that the same modes of deformation of punching (including block failure) and bulging failure were observed. The increased stiffness in the bulging zone saw the transfer of bulging type effects to a depth below the composite treated zone. It was only observed for high area ratios. The improved settlement behaviour of CSC compared to SC is due to the treatment of the bulging zone by CSC and improved column restraint at depth provided by the soil. Punching failure was found to have a higher magnitude and occur to a deeper depth of 3.6 m compared to SC depth of 2.4 m due to the addition of the composite material. The modes of deformation observed for SC were also observed for the new novel CSC columns. This suggests that the same type of foundations can be used and so avoid the need for reinforcement of the foundations as used with piled foundations

Dynamic and Static Performance of Large-Capacity Helical Piles in Cohesive Soils

Large-capacity helical piles can provide immense construction and performance advantages over the conventional concrete and steel piles. Nowadays, there is significant interest in using large-capacity helical piles to support foundations that would be subjected to both dynamic and static loading. The main objectives of this thesis are to: investigate the dynamic response and impedances of large-capacity helical piles; develop an analysis methodology for their dynamic response; and investigate their static axial compression and lateral behaviour, considering installation effects on their dynamic and static performances. The thesis presents the first full-scale vertical and horizontal dynamic field testing program executed on large-capacity helical piles, which involved 190 full-scale field load tests on nine instrumented large-capacity helical piles and two driven steel piles with different geometrical configurations installed in cohesive soils. Six piles were tested two weeks after installation and four piles were tested after allowing a recovery period of nine months following installation. One hundred and seventy six field experiments were conducted to evaluate the dynamic response characteristics of single helical piles and driven piles under different levels of vertical and horizontal harmonic excitations. The effects of various parameters, namely: pile length, number of helix plates and inter-helix spacing, excitation intensity, and soil thixotropy on the dynamic response were investigated. The experimental results were compared to the theoretical predictions of the continuum theory considering linear and nonlinear approaches. Reasonable match was found between the predicted response using the nonlinear approach and the measured response for both vertical and horizontal vibrations. The results demonstrated the significant effects of pile installation on forming weak soil zone around the pile, which stiffened with time following installation. This stiffening was manifested in an average increase in pile stiffness of about 43% and in pile damping of 25 to 90% within a nine month period. In addition, the dynamic response of the helical piles was similar to that of the driven piles. The load transfer mechanism of large-capacity helical piles was found to be predominantly through the helical plates and pile toe end bearing. Based on the results of the pile load tests, it is proposed to define the ultimate load of helical piles as the load that corresponds to pile head movement equal to the pile elastic deformation plus 3.5% of helix diameter. The helical piles displayed a superior axial performance with capacities higher than driven pile by about 17 to 85% based on pile configurations. The effects of attached helices and inter-helix spacing were found to be negligible on the pile lateral capacity and performance. The lateral pile load tests were examined numerically using the p-y approach incorporated in LPILE program. The mobilized soil shear strength parameters and soil moduli of subgrade reaction were back-calculated

Evaluating the effects of tunnel construction on buildings

New tunnels are continually constructed beneath the surface of large and developed cities due to the lack of surface space. These new tunnels will undoubtedly interact with existing surface and subsurface assets, such as building foundations, pipelines and other buried structures. There will be a two-way interaction whereby the tunnel construction affects the existing structure by inducing displacements in the underlying soil, and the structure influences tunnelling induced displacements via its weight and stiffness. The design of tunnels should include the consideration of this soil–structure interaction to avoid significant damage or failure to the existing structures due to the effect of the newly constructed tunnel. The research presented in this thesis focuses on tunnel–building interaction, and more specifically on buildings with shallow foundations. Previously, numerical methods have been used to study specific scenarios or to obtain design charts for use by geotechnical engineers. The proposed design charts have various limitations. For instance, they are suggested for specific types of soils, the 3D nature of buildings is disregarded to a great extent, and most importantly, several main parameters that influence the behaviour of a building when affected by tunnelling have not been accurately considered. In this research, the 3D behaviour of buildings is investigated with a focus on the main parameters that affect the deformation of a building in reality. These parameters are determined based on mathematical relationships of the stiffness of a structural member. Furthermore, computationally efficient methods are proposed to estimate building bending stiffness that can be readily used by engineers. The focus of this work is the effect of tunnelling on concrete framed buildings. The research deals with three main areas: [i] the estimation of the bending stiffness of a building’s superstructure and foundation, [ii] the analysis of tunnel–soil–building interaction using realistic ground displacements achieved from the field or experimental studies, and [iii] the behaviour of a 3D building (weightless and weighted) in a soil–building system during the construction of a tunnel. Finite element analysis (ABAQUS 3D) is used to investigate these problems. In research area [i], the building superstructure and the foundation are treated separately. Approaches are proposed in which the building response to tunnelling is related to the bending of a beam and empirical-type relationships are developed to predict building bending stiffness. These approaches are somewhat unconventional, but it is shown that they capture the real 3D response of buildings and foundations to tunnelling induced ground displacements more accurately than previously proposed methods. The approaches are relevant to scenarios where the building is perpendicular to the tunnel axis. Additionally, two cases of tunnel–building relative position are considered: (1) a case where a tunnel is constructed outside the building plan area (i.e. the tunnel axis and the nearest edge of the building to the tunnel do not overlap by more than half of the tunnel cross-section), which is called the ‘cantilever approach,’ and (2) a scenario where the tunnel is located under the building centreline, which is called the ‘fixed–ended approach.’ It should be noted that a detailed understanding of how structural elements of a building contribute to the stiffness of the entire building system is missing in the literature. The results of research area [i] show that the contribution of the building storeys to the global building bending stiffness is not uniform; the lower storeys have a larger contribution than the upper ones. Furthermore, buildings are mainly represented by 2D beams or frames in the current methods of building stiffness estimation. The proposed methods of this thesis (cantilever and fixed–ended methods) present accurate estimations of the true bending stiffness of 3D buildings subjected to tunnelling induced ground movements. In addition, the length of the building subjected to deflections, the length that is not affected by deformations, and the cross sectional flexural rigidity play the main role in the estimation of bending stiffness. These parameters are strongly interconnected, and should be considered together in the analysis of tunnel–building interaction. The results of this research show that the bending stiffness of a building decreases dramatically as the length affected by ground displacements increases. In contrast, the length of the building that is unaffected provides resistance to the building against rotation, which in turn increases the bending stiffness. This is because the unaffected length determines the boundary condition of the building, which is an important parameter in determining the bending stiffness. Research area [ii] aims to provide a method to overcome issues arising when using numerical analyses to investigate tunnelling and its impact on structures, since ground displacements predicted with conventional numerical methods are generally wider and shallower than those observed in practice. A two-stage numerical technique is proposed to estimate the effect of building stiffness on ground displacements due to tunnelling. In the first stage, greenfield (no existence of structures) soil displacements are applied to the soil model and the nodal reaction forces are recorded. In the second stage, the effect of tunnelling on a structure is evaluated by applying the recorded nodal reactions to an undeformed mesh. Results show that by using this technique, the role of the soil constitutive model is removed from the process of evaluating tunnelling induced ground displacements; it is only used in the evaluation of the soil–structure interaction. A realistic prediction of the structural stiffness effect can therefore be achieved due to the application of realistic ground displacements. For research area [iii], the response of weightless and weighted 3D buildings to tunnelling in a global soil–building system is considered. For the weightless case, the degree of stiffness contribution of the foundation and the superstructure to the bending resistance of the building is investigated. Buildings in the literature are assumed to act as a single entity when affected by tunnelling. Results of this research show that the effect of the foundation stiffness has the most significant contribution to the global building resistance to soil deformations while the contribution of the superstructure stiffness is less significant. Using insights from these results as well as those of research area [i], an equivalent beam method is proposed to model 3D buildings as 2D beams in plane strain analyses. The equivalent beam considers the effect of parameters influencing bending stiffness of a member, and the non-uniformity of stiffness contribution of building storeys to the global building bending stiffness. For the weighted buildings, a study is presented about the approach used to design a building, and the assumptions made in the analysis and design stages prior to the construction of a tunnel. The design parameters most affected by the tunnel construction are determined and examined numerically. It is explained that there is a strong relationship between the weight and bending stiffness of a building

Evaluating the effects of tunnel construction on buildings

New tunnels are continually constructed beneath the surface of large and developed cities due to the lack of surface space. These new tunnels will undoubtedly interact with existing surface and subsurface assets, such as building foundations, pipelines and other buried structures. There will be a two-way interaction whereby the tunnel construction affects the existing structure by inducing displacements in the underlying soil, and the structure influences tunnelling induced displacements via its weight and stiffness. The design of tunnels should include the consideration of this soil–structure interaction to avoid significant damage or failure to the existing structures due to the effect of the newly constructed tunnel. The research presented in this thesis focuses on tunnel–building interaction, and more specifically on buildings with shallow foundations. Previously, numerical methods have been used to study specific scenarios or to obtain design charts for use by geotechnical engineers. The proposed design charts have various limitations. For instance, they are suggested for specific types of soils, the 3D nature of buildings is disregarded to a great extent, and most importantly, several main parameters that influence the behaviour of a building when affected by tunnelling have not been accurately considered. In this research, the 3D behaviour of buildings is investigated with a focus on the main parameters that affect the deformation of a building in reality. These parameters are determined based on mathematical relationships of the stiffness of a structural member. Furthermore, computationally efficient methods are proposed to estimate building bending stiffness that can be readily used by engineers. The focus of this work is the effect of tunnelling on concrete framed buildings. The research deals with three main areas: [i] the estimation of the bending stiffness of a building’s superstructure and foundation, [ii] the analysis of tunnel–soil–building interaction using realistic ground displacements achieved from the field or experimental studies, and [iii] the behaviour of a 3D building (weightless and weighted) in a soil–building system during the construction of a tunnel. Finite element analysis (ABAQUS 3D) is used to investigate these problems. In research area [i], the building superstructure and the foundation are treated separately. Approaches are proposed in which the building response to tunnelling is related to the bending of a beam and empirical-type relationships are developed to predict building bending stiffness. These approaches are somewhat unconventional, but it is shown that they capture the real 3D response of buildings and foundations to tunnelling induced ground displacements more accurately than previously proposed methods. The approaches are relevant to scenarios where the building is perpendicular to the tunnel axis. Additionally, two cases of tunnel–building relative position are considered: (1) a case where a tunnel is constructed outside the building plan area (i.e. the tunnel axis and the nearest edge of the building to the tunnel do not overlap by more than half of the tunnel cross-section), which is called the ‘cantilever approach,’ and (2) a scenario where the tunnel is located under the building centreline, which is called the ‘fixed–ended approach.’ It should be noted that a detailed understanding of how structural elements of a building contribute to the stiffness of the entire building system is missing in the literature. The results of research area [i] show that the contribution of the building storeys to the global building bending stiffness is not uniform; the lower storeys have a larger contribution than the upper ones. Furthermore, buildings are mainly represented by 2D beams or frames in the current methods of building stiffness estimation. The proposed methods of this thesis (cantilever and fixed–ended methods) present accurate estimations of the true bending stiffness of 3D buildings subjected to tunnelling induced ground movements. In addition, the length of the building subjected to deflections, the length that is not affected by deformations, and the cross sectional flexural rigidity play the main role in the estimation of bending stiffness. These parameters are strongly interconnected, and should be considered together in the analysis of tunnel–building interaction. The results of this research show that the bending stiffness of a building decreases dramatically as the length affected by ground displacements increases. In contrast, the length of the building that is unaffected provides resistance to the building against rotation, which in turn increases the bending stiffness. This is because the unaffected length determines the boundary condition of the building, which is an important parameter in determining the bending stiffness. Research area [ii] aims to provide a method to overcome issues arising when using numerical analyses to investigate tunnelling and its impact on structures, since ground displacements predicted with conventional numerical methods are generally wider and shallower than those observed in practice. A two-stage numerical technique is proposed to estimate the effect of building stiffness on ground displacements due to tunnelling. In the first stage, greenfield (no existence of structures) soil displacements are applied to the soil model and the nodal reaction forces are recorded. In the second stage, the effect of tunnelling on a structure is evaluated by applying the recorded nodal reactions to an undeformed mesh. Results show that by using this technique, the role of the soil constitutive model is removed from the process of evaluating tunnelling induced ground displacements; it is only used in the evaluation of the soil–structure interaction. A realistic prediction of the structural stiffness effect can therefore be achieved due to the application of realistic ground displacements. For research area [iii], the response of weightless and weighted 3D buildings to tunnelling in a global soil–building system is considered. For the weightless case, the degree of stiffness contribution of the foundation and the superstructure to the bending resistance of the building is investigated. Buildings in the literature are assumed to act as a single entity when affected by tunnelling. Results of this research show that the effect of the foundation stiffness has the most significant contribution to the global building resistance to soil deformations while the contribution of the superstructure stiffness is less significant. Using insights from these results as well as those of research area [i], an equivalent beam method is proposed to model 3D buildings as 2D beams in plane strain analyses. The equivalent beam considers the effect of parameters influencing bending stiffness of a member, and the non-uniformity of stiffness contribution of building storeys to the global building bending stiffness. For the weighted buildings, a study is presented about the approach used to design a building, and the assumptions made in the analysis and design stages prior to the construction of a tunnel. The design parameters most affected by the tunnel construction are determined and examined numerically. It is explained that there is a strong relationship between the weight and bending stiffness of a building