Wall Deflection Research Articles

A numerical analysis on anchored sheet pile wall subjected to surcharge strip loading

Anchored sheet pile walls are practically subjected to a surcharge load that exists on the field in the form of vehicles, buildings, and storage areas, those additional surcharge loads on the ground surface produce additional stress on the wall. In the present investigation, a three-dimensional finite element method is implemented to study the behavior of an anchored sheet pile wall under a uniform surcharge strip load. The influence of surcharge load and foundation soil types on wall deflections, bending moments, anchor forces, and backfill ground settlement are examined. A parametric study is performed by varying the wall stiffness, anchor stiffness, number of anchors and magnitude of surcharge load. The results show that medium dense foundation soil increases the passive resistance, so it reduces wall deflections, bending moments, anchor forces and ground settlement. Moreover, double anchorage effectively reduces wall deflections, bending moments, anchor forces and ground settlement than single anchorage.

Behaviour of anchored sheet pile quay stabilized with deep cement mixing columns in soft soil: Centrifuge and numerical modelling

This paper describes research on the behavior of anchored sheet pile quay stabilized by deep cement mixing (DCM) columns in soft soil through a centrifugal test investigation to understand excavation-induced soil-structure interaction mechanisms. By employing an advanced soil constitutive model, three-dimensional (3-D) finite element (FE) simulations were subsequently performed to back-analyze the centrifuge test. Moreover, a numerical comparison analysis between this case and a null DCM columns case was performed to describe the shielding effect of the DCM columns composite foundation in the anchored sheet pile quay in terms of lateral earth pressure, bending moment, lateral deflection of the quay wall, and quay ground settlement induced by excavation. Finally, a parametric study was carried out to investigate the effect of DCM column arrangement and geometry on the quay wall lateral deflection. Results showed that the presence of DCM columns reduced the adverse effects on the quay wall in excavations, and they could effectively enhance the stability of the anchored sheet pile quay in soft soil, such as the shielding effect. In addition, the parametric study results indicate that length and the elastic modulus of the column are two critical factors affecting the shielding effect of DCM columns. This research provides reasonable explanations and valuable insights to understand the soil-structure interaction mechanism in anchored sheet pile quay and is of use in the preliminary design of sheet pile quay structures in soft soil.

Deep Excavation in Soft Normally Consolidated Clay

This paper presents the case histories of deep excavation for the basements of two projects using 11 retaining walls supported by stabilizing berms. Most of the case studies reported in the literature are confined to the use of stabilizing berms to support retaining walls for deep excavation in firm overconsolidated clays but not soft normally consolidated clays. This paper reviews the performance of 11 retaining walls supported by stabilizing berms for deep excavation in soft normally consolidated clays. Only four of these 11 stabilizing berm-supported retaining walls performed satisfactorily while the other seven performed dismally. The larger horizontal deflection of retaining walls embedded in soft normally consolidated clays as compared to overconsolidated clays is caused by creep of soft normally consolidated clays. The effect of creep of soft normally consolidated clays in deep excavation is not well understood. Based on the case study of an excavation of 8.3 m (27.2 ft) deep, an empirical relationship between the retaining wall deflection due to creep of soft clays and the total thickness of soft clays is established. The present study highlights the need to check the slope stability of the stabilizing berms in soft normally consolidated clays during excavation. This has never been thought to be necessary for stabilizing berms supporting retaining walls in overconsolidated clays for deep basement construction.

Study of Seismic Effect on High Rise Building in Two Different Position of Shear Wall using Staad Pro

Abstract: India at present is fast growing economy & Population growth will increase demands of land to construct high rise structure are more advantage to provide they demands in construction industry. The present study reports the effect of earthquake on high rise building to comparison of two different seismic zone with different position of shear wall using STAAD Pro. V8i SS5 to work out effective ideal location of shear walls. G+9 high rise building in zone III & zone V is considered for the present study. Analysis of the building is conferred with some preliminary investigations, analyzed by varied position of shear wall by considering three models as model 1 without shear wall, model 2 shear wall at corner with different position, model 3 shear wall in corner position. Maximum shear wall deflections are calculated and analyzed for all considered model. M30 grade of concrete is used with Fe415 steel is used for the present study. The seismic analysis performed is Equivalent Static Method as per IS 1893-2002 using the well-known analysis and design software STAAD PRO. V8i SS5 . Seismic performance of the building has been investigated based on parameters such as, Base Shear, Storey Displacements & Storey Drift along X direction & along Z direction of the structure

Investigation on behavior of anchored sheet pile quay wall improved by cement-soil: Centrifuge and numerical modelling

By using the centrifuge test and three-dimensional (3-D) finite element (FE) simulation with an advanced soil constitutive model, this study investigated the suitability and reinforcement effect of cement deep mixing (CDM) for stabilizing the anchored sheet pile quay (ASPQ) in soft clay. Besides, a parametric study was designed to analyse the influence of three factors, including the excavation depth ratio, the slenderness ratio and the strength of the CDM block, on the responses of quay wall and quay-surface settlement. The results showed that the effectiveness of CDM was closely related to its strength, slenderness ratio, and excavation depth ratio. There existed a critical slenderness ratio of the CDM block to minimize the lateral deflection of the quay wall. The influence of CDM block strength on the response of the quay wall was significant only when it had low rigidity. As a result of material improvement, the reduction in maximum wall displacement became more significant as the excavation depth ratio increased. A CDM block-to-excavation-strength shape factor was proposed to characterise the lateral response of quay walls in cement-improved soil.

Stochastic analysis of excavation-induced wall deflection and box culvert settlement considering spatial variability of soil stiffness

In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due to a braced excavation. The spatial variability of soil stiffness is modelled using a variogram and calibrated by high-quality experimental data. Multiple random field samples (RFSs) of soil stiffness are generated using geostatistical analysis and mapped onto a finite element mesh for stochastic analysis of excavation-induced structural responses by Monte Carlo simulation. It is found that the spatial variability of soil stiffness can be described by an exponential variogram, and the associated vertical correlation length is varied from 1.3 m to 1.6 m. It also reveals that the spatial variability of soil stiffness has a significant effect on the variations of retaining wall deflections and box culvert settlements. The ignorance of spatial variability in 3D FEM can result in an underestimation of lateral wall deflections and culvert settlements. Thus, the stochastic structural responses obtained from the 3D analysis could serve as an effective aid for probabilistic design and analysis of excavations.

Influenced Zone of Deep Excavation and a Simplified Prediction Method for Adjacent Tunnel Displacement in Thick Soft Soil

Based on the statistics of 42 case histories, 732 finite element numerical simulations are conducted to determine the scope of the influenced zone of deep excavation under different conditions of excavation depth (He) and the maximum retaining wall deflection (δhm). On this basis, the effects of He and δhm on the scope of the influenced zone are studied, and a simplified prediction method for the scope of the influenced zone under any He and δhm conditions and the adjacent tunnel displacement is proposed. Then, the reliability of the proposed method is verified by comparing it with the current research and case histories. And finally, the proposed method is applied to an actual project, and the application effect is evaluated. The results show that the range outside the pit can be divided into “primary”, “secondary”, “general”, and “weak” influenced zones. The influenced zone can be simplified as a right-angled trapezoid shape, and the scope of influence zones can be quickly determined by defining three parameters: width coefficient M, depth coefficients N1 and N2. The parameters M and N2 have a linear relationship with He and δhm, and N1 varies between 1–2 with an average of about 1.5. In actual application, the effect of deep excavation on the adjacent tunnel can be alleviated by using the proposed method to predict the excavation-induced displacement of the adjacent tunnel and take some measures.

Experimental Investigations of Cement Clay Interlocking Brick Masonry Structures Strengthened with CFRP and Cement-Sand Mortar

Many masonry structures are constructed with cement clay interlocking brick (CCIB) due to its added benefits. Recent research has demonstrated the vulnerability of brick masonry walls against seismic loading. Various strengthening materials and techniques are extensively used to improve the structural behavior of brick walls. Carbon fiber-reinforced polymer (CFRP) composites are the most popular strengthening material due to their advantages of easy application, lightweight qualities, and superior tensile strength. The current research work aimed to explore the cost-effective solutions and feasibility of CFRP composite-based strengthening techniques to improve the load-bearing capacity of CCIB walls. Various configurations and combinations of strengthening materials were investigated to customize the cost of repair and strengthening. The experimental results indicated that CFRP composites in combination with cement-sand (CS) mortar are an efficient strengthening material to enhance the strength and ultimate deflection of CCIB walls. The ultimate load-bearing capacity and axial deformation of the strengthened CCIB wall (using two layers of CFRP strips and CS mortar of 10 mm thickness) remained 171% and 190% larger than the unstrengthened CCIB wall. The conclusions of this study are expected to enhance the seismic performance of masonry buildings in developing countries. It should be noted that due to the reduced number of tested specimens, the results to be assumed as general considerations need a wider experimental campaign and a large numbers of tests for each strengthening typology.

A Prediction Model for the Deformation of an Embedded Cantilever Retaining Wall in Sand

This paper proposes a prediction model based on the mobilizable strength design method with an equilibrium model to predict the deflection of an embedded cantilever retaining wall in sand. The variation in the location of the pivot point within the retaining wall and the sand dilation are considered. Based on the stress–strain relationships obtained by triaxial tests, the designer can determine a specific shear strain and corresponding mobilized earth pressure for the retaining wall to achieve a global equilibrium. Then, the wall deflection, including rotation and flexure, can be derived. The locations of the pivot points obtained by this method are compared with the results predicted by the minimization approach. Finally, the prediction precision is validated via centrifuge tests and numerical model data published in prior investigations.

Supercritical flow overpassing forward- or backward-facing steps non-orthogonal to the flow direction

The work proposes and discusses a theoretical approach to predict the behavior of an open-channel supercritical flow that overpasses a step, either forward or backward facing, non-orthogonal to the flow direction. In this case, a sequence of oblique shock waves and expansion fans is generated close to and downstream of the step. The proposed model is verified by comparing the theoretical predictions with the results provided by a two-dimensional, depth averaged numerical model. Applications include the combined use of oblique steps and abrupt wall deflections to suppress wave fronts that characterize supercritical flow in channel bends. Special attention is devoted to the supercritical to subcritical transition (and vice versa) in overpassing a forward-facing step; this is found to be a rather intriguing problem characterized by complex solutions and by hysteresis. Besides the classic smooth (everywhere supercritical) and choked (with a hydraulic jump and a subcritical flow upstream of the step) solutions, an additional intermediated flow configuration can occur for particular characteristics of the supercritical current and step height. The domain of existence of the different solutions, as well as the hysteresis domain, are obtained based on the theoretical and the numerical models.

A fast semi-analytic solution of liquid sloshing in a 2-D tank with dual elastic vertical baffles and walls

Liquid sloshing characteristics in a lateral excited two-dimensional (2-D) rectangular tank with dual elastic vertical baffles and walls have been investigated analytically. The elastic baffle or wall is regarded as an Eulerian Bernoulli beam. The complex liquid domain divides into six simple sub-domains according to the superposition principle. The formal solution of the potential function in each sub-domain is obtained using the separation of variables method. Then the formal baffle or wall deflection solution can be derived from the transverse vibration equation. The Eigen equation can be established according to the free surface, interface, and coupled vibration conditions. The coupled frequency can be obtained by solving the Eigen equation. The velocity potential under lateral excitation consists of the rigid container velocity potential and the disturbance potential. Then the coupled dynamic response equation is established using the free liquid surface equation and the coupled vibration equation. The correctness of the semi-analytic solution is verified against available data. Therefore, the numerical model of the present work can be computed quickly with semi-analytic solution and obtain the mechanism of liquid-structure interaction. Finally, the effect of baffle parameters and excitation frequency on liquid sloshing is discussed in detail.

Mechanical response of diaphragm wall supporting deep launch shaft induced by braced excavation and pipe jacking operation

The stability of braced structures for the launch pit in pipe jacking plays a vital role in structural safety during excavation and jacking drive. Through a deep launch pit in Foshan, the real-time deformation and mechanical response of the diaphragm walls, internal struts, and the soil behind the wall induced by braced excavation and pipe jacking operation are obtained from in-situ monitoring and three-dimensional finite element model. The internal struts restrict the further wall deflection and earth pressure in the braced excavation, displaying the apparent time–space effect or corner effect of the limited-scale & deep launch pit. Moreover, pipe jacking operation influences the reaction wall within a certain zone, contributing to the apparent spatial effect. The outward deformation and the increase in the soil pressure occurred in the disturbed zone. Although part of the mucky soil reaches the ultimate equilibrium during the deep excavation and jacking drive, the diaphragm walls still indicate superior strength and stiffness.

Bendocapillary instability of liquid in a flexible-walled channel

We study the bendocapillary instability of a liquid droplet that part fills a flexible walled channel. Inspired by experiments in which a periodic pattern emerges as droplets of liquid are condensed slowly into deformable microchannels, we develop a mathematical model of this instability. We describe equilibria of the system, and use a combination of numerical methods and asymptotic analysis in the limit of small channel wall deflections, to elucidate the key features of this instability. We find that configurations are unstable to perturbations of sufficiently small wavenumber regardless of parameter values, that the growth rate of the instability is highly sensitive to the volume of liquid in the channel, and that both wetting and non-wetting configurations are susceptible to the instability in the same channel. Insight into novel interfacial instabilities opens the possibility for their control and thus exploitation in processes such as microfabrication.

Field Measurement and Numerical Study on the Effects of Under-Excavation and Over-Excavation on Ultra-Deep Foundation Pit in Coastal Area

An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through the measured data and 3D numerical simulation. The results show that the exceptional performance of the current project is due to the combination of under-excavation and over-excavation during construction. The under-excavation procedure restrained the wall deflections at the middle part of the diaphragm wall, making the corner effects at the corresponding side inapparent. Both the under-excavation and over-excavation procedure can only influence the performance of the excavation in close proximity, while having negligible impacts on the normally excavated areas. Based on the results of this study, practical suggestions are given to improve the performance of similar excavations in the future.

Research on the Mechanism and Control Technology of Coal Wall Sloughing in the Ultra-Large Mining Height Working Face.

One of the primary factors affecting safe and effective mining in fully mechanized mining faces with large mining heights is coal wall sloughing. This paper establishes the mechanical model of the coal wall and uses the deflection theory for the mechanics of materials to find the maximum point of the deflection of the coal wall, which is the most easily deformed and damaged during the mining process, based on the mining production conditions of the 12-2up108 working face in the Jinjitan Coal Mine. In order to simulate the characteristics of the coal wall in the large mining height working face at various mining heights, the FLAC-3D numerical method was used. The stability of the mining area was assessed in conjunction with the multi-factor fuzzy comprehensive evaluation mathematical model, and the corresponding control of the coal wall was suggested. The study demonstrates that: (1) The working surface at Jinjitan Coal Mine 112-2up108 is a typical drum-out sloughing. The coal wall is most likely to sustain damage at the point where it contacts the roof when the frictional resistance between the coal seam and the roof and floor is less than the uniform load, and at 0.578 times the mining height when the frictional resistance between the coal seam and the roof and floor is greater than the uniform load. (2) In the working face with a large mining height, mining height of the coal wall is one of the significant influencing factors. With increasing mining height, the coal wall's height also rises nonlinearly, as does the depth of the coal wall in the working face with the large mining height. The growth is linear. The coal wall's maximum deflection value point moves up and the slab's height significantly increases when the mining height exceeds 7.5 m. (3) The Jinjitan Coal Mine should be supported by a pressurized and enhanced composite support bracket with a support force greater than 0.245 MPa and a support plate of 3500 mm because it belongs to a Class I stable coal wall, according to a thorough evaluation of a multi-factor fuzzy mathematical model. The working face's mining pressure is continuously and dynamically monitored, and the stress is released in a timely manner to prevent the occurrence of dynamic disasters.

Characterization of Wall Deflection and Ground Settlement for Irregular-Shaped Excavations with Changes in Corner Configuration

Characterization of Wall Deflection and Ground Settlement for Irregular-Shaped Excavations with Changes in Corner Configuration

Effectiveness of soil improvement for deep excavation in under-consolidated soil: A case study

The main objective of this article is to investigate the effectiveness of soil improvement methods, such as jet grouting and cement deep mixing, for a deep excavation in under-consolidated soil. A well-documented case history, located in Zhuhai, China, was used for analysis. The analyses were conducted using two-dimensional plane-strain finite element analysis. The studies included an examination of the effect of wall length on lateral wall deformation, the effect between the degree of consolidation and lateral wall deformation, and the influence of soil improvement on lateral deformation and settlement. The deformations induced by under consolidating states are greater than those caused by normally consolidated states. A similar trend was found with or without soil improvement. The greater the degree of consolidation is, the smaller the deflection of the wall. In this case, the retaining wall's length is well designed and stable, but the analysis results showed that the wall length can be shorter than the constructed length. Massive jet grouting was used behind the left wall to successfully reduce wall deflection and ground surface settlement. Finally, deep cement mixing has only a small effect on reducing wall deflection and ground surface settlement.

A beam on elastic foundation method for predicting deflection of braced excavations considering uncertainties

AbstractPredicting wall deflection is important to provide a critical reference to evaluate the current construction conditions and prevent potential damage risks of adjacent facilities during excavations. This paper presents a combination of a beam on elastic foundation model (BEFM) and the Bayesian framework to realize effective probabilistic predictions of wall deflection at various depths in braced excavations. First, a finite element solving algorithm to calculate wall deflection for the BEFM is developed and incorporated into the Bayesian framework. Next, the most suitable distribution pattern for soil resistance and an appropriate set of uncertain parameters in the BEFM are determined through the application of the Bayesian model selection technique. Meanwhile, the uncertain parameters are updated. A prediction is then made using the optimal model and corresponding posterior probability distributions of the updated parameters at each stage. The parameter updating and prediction process are repeated as additional field observations become available during construction. The performance of the proposed method is examined using a field case study. The results show that this method provides a satisfactory approach to predict both the magnitudes and profile of deflection when considering uncertainties. Additionally, comparisons with a Bayesian updating framework using a surrogate model (i.e., the KJHH model) indicate higher updating efficiency of the developed method.

Numerical study on the thermal-induced mechanical behavior in deep energy diaphragm wall (EDW): The long-term soil elastoplastic effects

The energy diaphragm wall (EDW) attracted increasing attention due to its high energy exchange rate and low space occupation. The current research on EDW primarily focused on its heat exchange capacity and performance. The elastoplastic effects on thermal-induced mechanical behavior caused by soil were neglected, which might underestimate the wall deflections in deep EDW due to the asymmetrical surrounding pile height pressure on both sides. This paper investigated the thermal performance and the induced mechanical behavior in deep energy diaphragm wall (EDW) based on the finite element analysis method (FEA) by the COMSOL Multiphysics software. Firstly, the thermal performance of varied pipe configurations (e.g., single U-shaped; W-shaped; double-U shaped; horizontal arrangement) was studied. Then it was followed by a study of a single heating–cooling cycle with a single U-shaped pipe, where the elastoplastic impact of the soil in the deep EDW was observed. Moreover, a parametric analysis with a long operation period (30 years) perspective was proposed regarding the heat load modes, the pipe buried locations, the air temperature of the adjacent underground space, and the excavation level. Results revealed that the heat transfer process caused an obvious impact on thermal-induced mechanical behavior. Higher levels of heat injection (Case 3) and extraction (Case 2) both led to a relatively large wall deflection after 30 years. The horizontal displacements at the top of the wall under Case 3 and Case 2 were up to 30.5 mm and 25.9 mm, respectively, while 22.9 mm under balanced case (Case 1) and 21.1 mm under the no heat load case (Case 0). When the pipe was close to the side of the excavation, the plastic deformation was about 1.25 times greater than that on the soil side, where the thermal contraction effects were emphasized. Besides, the air temperature in the underground space caused a small impact on the plastic strain in the soil domain. Because of the enhancement in the heat transfer process from the air to the wall while the air temperature increased, resulting in the average wall temperature raised. In addition, the influence caused by the excavation levels was quite evident. The deeper the excavation level, the easier the plastic strain to occur. This paper proposed a new perspective for understanding thermal-induced mechanical behavior in deep EDW, especially the long-term soil elastoplastic effects, which exerted a complex impact on the deformation variation of the diaphragm wall.

Effect of wind load on waveguide strength

The article considers the features of the influence of wind load in the Arctic and Far North regions on the static and dynamic state of direct waveguides. Waveguides have a thin-walled design with restrictions on wall deflections, so the theory of plates and shells is used to calculate them. In the static state, the wind load is modeled by uniform pressure on one side of the waveguide. This made it possible to obtain an analytical solution to the problem by the plate theory, identify the features of the stress distribution over the waveguide structure, and clarify the solution compared to the beam theory. Comparing the results of the calculation according to the proposed method with the results of beam theory showed good convergence. The dynamic state was estimated by the first natural frequency of waveguides, considering ice deposits. The results of the calculations showed a significant impact of ice deposits on the frequency of oscillations and showed the need for deicing.