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The stability of underground diaphragm walls is crucial for ensuring the safety and integrity of trench excavations in geotechnical engineering. This study addresses this critical issue by proposing a novel destabilization mechanism based on a sliding body model specifically designed for diaphragm wall trenching operations. The research employs an analytical framework rooted in soil mechanics and plasticity theory, utilizing limit equilibrium analysis to develop a method for calculating the minimum required slurry density and corresponding safety factor for trench stability. The study compares two distinct approaches to slurry density computation, analyzing their sensitivity to various influencing factors. Theoretical findings are validated through multiple real-world engineering case studies. Comparative analysis demonstrates the superiority of the proposed method, particularly in assessing trench stability within clay layers. Key variables influencing the safety factor are identified, including trench length, slurry density, soil friction angle, and the relative height difference between slurry and groundwater levels. Results indicate that actual slurry densities observed in practice consistently fall within the bounds predicted by the theoretical calculations. This research contributes a valuable theoretical framework to the field of diaphragm wall construction, offering improved accuracy in stability assessments and potentially enhancing safety in geotechnical engineering projects. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The excavation of the pit causes displacement of the surrounding soil, and the excessive deformation causes damage to the existing support structure, which in turn affects the safety of the pit. Reasonable calculation of structural deformation and internal force is crucial for design and construction. Most of the existing theoretical methods simplify the diaphragm wall(DW) as an Euler-Bernoulli beam acting on the Winkler foundation, consider beam-soil interaction, and simplify the soil as isotropic and continuous. However, the shear effects due to the differential deformation of the structure, the unloading stresses acting on the structure due to foundation excavation, and the discontinuous nature of the multilayered soil are neglected. In this paper, an improved analysis method is proposed based on the elastic foundation beam theory. The DW is simplified as a Timoshenko beam and the foundation is simplified as a Vlasov two-parameter model, and a proposed model considering the shear effect of the DW and the interaction of adjacent springs is established, and the proposed method for the deformation and internal force of the DW is obtained by the finite-difference method. The correctness and applicability of the proposed method are verified by numerical simulation and field monitoring data. The effects of equivalent bending stiffness, equivalent shear stiffness, soil elastic modulus, and excavation depth on the deformation and internal force of the DW were further analyzed. The results show that the proposed method can accurately solve the deformation and internal force of the DW, and the maximum errors between the proposed method and the numerical simulation results are only 4.5 % and 1.3 %, respectively. The equivalent bending stiffness of the DW and the elastic modulus of the soil have more significant effects on the horizontal deformation and internal force. The excavation depth is more sensitive to the deformation of the DW, and there is an exponential decay trend between the two. When the equivalent shear and bending stiffnesses reach 6.8×107 kN·m2 and 2.9×107 kN/m, the effect on the horizontal deformation is no longer obvious. The proposed method in this paper can accurately calculate the internal force and deformation of the DW. [ABSTRACT FROM AUTHOR]

Currently, the use of underground automatic car parks is becoming increasingly popular in Bangkok as it can help maximize space usage without ramps. However, an automatic system requires large openings in the basement slab, resulting in the slab possibly having insufficient axial capacity. This paper focused on one of the latest underground automatic car park construction projects in Bangkok's city center, True Digital Park, which comprises a total of four basements with a 13.20 m maximum excavation depth, including mat foundation and lean concrete. An 800mm-thick diaphragm wall (D-wall) was proposed to serve as a soil-retaining structure with 3 layers of full-temporary bracing. The Finite Element Method (FEM) with the Mohr-Coulomb soil model was employed for the D-wall design and horizontal movement prediction, and the actual construction of the basement and building have since been completed. The field performance of the D-wall construction was evaluated through horizontal movement using installed inclinometers. During every stage of construction, including soil excavation and bracing installation, horizontal displacement was monitored carefully and strictly controlled to minimize the D-wall movement. The monitoring results showed suitable agreement with the FEM analysis. However, movement of the retaining wall was detected during upward construction, even though the basement was fully cast, suggesting insufficient axial basement slab capacity as well as care and control for similar projects. This article describes the construction and monitoring of the project together with field performance results. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ship lock project currently demonstrates a distinct cyclical pattern, accumulating latent hazards that pose a significant threat to project safety. Seepage safety (the condition in which the seepage risk is reduced to an acceptable level) serves as a crucial indicator in the safety risk assessment index system for ship lock project construction, thus necessitating an in-depth analysis of the risk factors impacting seepage safety. Utilizing a ship lock project in China as a case study, this study employs the finite element method (FEM) to analyze the seepage field of the ship lock foundation pit basin and proposes a comprehensive set of methods for risk evaluation and warning models pertaining to seepage safety risks in ship lock engineering. This study reveals that the obstruction of dewatering wells and imperfections in the diaphragm wall are the primary factors contributing to seepage damage. The investigation conducted a quantitative analysis of the impact of these two factors on the seepage field of the ship lock pit, considering pore pressure, water head, gradient, and flow velocity. A comprehensive set of evaluation indicators for seepage safety was formulated, drawing on the principles of multi-objective optimization, and a method for delineating the safe range of ship lock pit excavation under seepage action was proposed. Subsequently, an integrated seepage safety risk assessment system for ship lock pit excavation engineering was established. These research findings offer a scientific foundation for the management of seepage safety in ship lock pit excavation engineering and provide valuable references and guidance for the development of anti-seepage systems. [ABSTRACT FROM AUTHOR]

This study focuses on the complex dynamics of heat dissipation within diaphragm walls during concrete hydration, crucial in construction engineering. Experimental measurements from three sites in Poland, featuring diaphragm walls of varying thicknesses, ranging from 1 to 1.5 meters, were compared to a numerical model. The model, using a Finite Difference Method, incorporated stages of execution of adjacent panels and their thermal influence. The results closely mirrored the measured temperatures, validating the accuracy of its predictions. Despite minor discrepancies, mostly within ±3°C, the method effectively approximated real-life scenarios. Suggestions for model enhancements include incorporating the effect of concrete admixtures and refining the modeling of sequential panel execution. The thermal soil parameters, their possible range, and their impact on hydration heat dissipation in deep foundations emerged as crucial insights. This research serves as a foundation for deeper investigations into early-age behavior in deep foundations, aiming to extend the analysis to stress and strain domains to unravel characteristic cracking patterns observed in diaphragm walls.

Translation abstract Reality Capturing – Innovative use of drones for planning, documentation and preservation of evidence in specialist civil engineeringThe GoWest commercial quarter – a future‐orientated, sustainable commercial location is currently being built on the site of the former Reemtsma cigarette factory in Berlin‐Schmargendorf. On an area of approx. 50,000 m2, 12 commercial courtyards with up to 6 upper floors are being built. The entire quarter will have a full 3‐storey basement. The 14 metre deep excavation pit is secured with a diaphragm wall in conjunction with a supporting beam shoring in front of it. A digital 3D model of the construction site created using reality capturing is being used to plan the excavation pit and document the construction work. The possible applications of such a model are presented in this article. [ABSTRACT FROM AUTHOR]

Mixing uniformity plays an important role in the quality control of the deep diaphragm wall in anti-seepage projects. However, there is a lack of quantitative evaluation of mixing uniformity and its effect on the hydraulic conductivity in geotechnical engineering. This study proposed a method to quantificationally characterize the mixing uniformity of the cement-based stabilized soft clay (CBSC) through the X-ray computed tomography. Note that, the phase with the grayscale value (i.e., the mode of the grayscale value of the sample closest to the uniform state) was tracked to obtain its layer-by-layer volume fraction, followed by quantitative analysis with the proposed equation. Additionally, the relationship between the CBSC's mixing uniformity and the hydraulic conductivity was discussed. The results indicate that the characterization parameters of the hypertonic zone are related to the mixing uniformity, including the volume fraction, equivalent radius, channel length and coordination number of the connected hypertonic zone. With a low uniformity, plenty of hypertonic zones with high porosity provide continuous channels for percolation. Hence, a small volumetric and isolated hypertonic zones prevent the connectivity of the seepage channels resulting in the overall low permeability. The hydraulic conductivity decreases sharply, when mixing uniformity more than 81.1% in this study. These findings provide a guidance for the control of the mixing uniformity for the anti-seepage project construction. [ABSTRACT FROM AUTHOR]

The issue of interfacial shear damage has been a significant challenge in the field of geotechnical engineering, particularly in the context of diaphragm walls and surrounding soils. Polymer grouting is a more commonly used repair and reinforcement method but its application to interface repair and reinforcement in the field of geotechnical engineering is still relatively rare. Consequently, this paper presents a new polymer grouting material for use in grouting reinforcement at the interface between concrete and soils. The bonding characteristics and shear damage mode of the interface after grouting were investigated by the direct shear test, and the whole process of interface shear damage was investigated by digital image correlation (DIC) technology. Finally, the reinforcement mechanism was analyzed by microscopic analysis. The results demonstrate that the permeable polymer is capable of effectively filling the pores of soil particles and penetrating into the concrete-soil interface. Through a chemical reaction with water in the soil, the polymer cements the soil particles together, forming chemical adhesion at the interface and thereby achieving the desired reinforcement and repair effect. In the shear process, as the normal stress increased, the horizontal displacement and horizontal compressive strain at the distal end of the loading end decreased, while the maximum vertical displacement and maximum vertical strain of the cured soil also decreased. The results of scanning electron microscopy (SEM) demonstrated that the four groups of test polymers exhibited a reduction in soil porosity of 53.47%, 58.79%, 52.71%, and 54.12%, respectively. Additionally, the form of concrete-soil interfacial bonding was observed in the concrete-cohesive layer-cured soil mode. The findings of this study provide a foundation for further research on diaphragm wall repair and reinforcement. [ABSTRACT FROM AUTHOR]

In order to limit the phenomenon that the global stability safety factor (GSF) of the diaphragm wall slurry trench calculated by the two-dimensional (2D) wedge method is too small, the 2D calculation model on global instability of trench wall is established by assuming the whole critical failure surface (CFS) is a quarter elliptic cylindrical surface, and the determination method of CFS is given too. In view of the successful application of the minimum potential energy principle in slope stability checking calculation and on the basis of the new model established, the 2D minimum potential energy method for calculating the GSF is proposed according to the minimum potential energy principle. The correctness of the 2D calculation model built and the rationality of the 2D calculation method proposed are verified based on ten engineering cases, and the sensitivity of the GSF to various parameters is analyzed on the basis of six design examples. Finally, the new calculation method is applied to the global stability checking calculation of trench wall in practical engineering, and the result shows the new calculation method given in this paper is still conservative, so the result calculated by the new calculation method is advised to be multiplied by a modification factor of 1.67 in practical application. [ABSTRACT FROM AUTHOR]

The coherence of axial force between steel struts in excavation (axial force coherence) is an important factor affecting the axial force control of servo struts. To understand the law of axial force loss of adjacent struts caused by servo struts loading, this paper proposes a calculation method based on the theory of nonlimiting earth pressure. First, the diaphragm wall is simplified to a simply supported beam with both endpoints free horizontally, the soil on both sides of the diaphragm wall is divided into n small sections (n as big as possible) along the depth direction, and the average nonlimiting earth pressure combined force within each section is calculated. Second, a system of nonlinear force-displacement equations is constructed by applying the "graph multiplication" method to calculate the combined nonlimiting soil pressure and deflection of the wall from the axial force of the servo steel strut at each level. The Newton–Raphson method is applied to obtain a recursive equation for the wall displacements. The accuracy of the method is verified by comparison with field measurements. Then, based on the method in this paper, the effect of prestressing and adjustment on the axial variation of each strut course is investigated. The method can provide a reference for the loading scheme of servo steel struts in deep excavation in soft-soil areas. [ABSTRACT FROM AUTHOR]

Underground diaphragm walls are commonly used as a support system for the construction of subway stations, working together with inner side walls of subway stations to withstand the pressure from surrounding soils. However, the effect of diaphragm walls on the seismic response of subway stations is still not well understood yet, or at least not well considered during design. In this paper, a series of 1 g shaking table tests is designed to investigate the seismic response of a typical two‐story and three‐span subway station considering the influence of underground diaphragm walls. The stratum is simulated by synthetic model soil (a mixture of sand and sawdust), and the model structure and diaphragm walls are made by granular concrete with galvanized steel wires. A test case of the structure without diaphragm walls is also involved and taken as a benchmark comparison to understand the impact of diaphragm walls on the seismic response of subway station. The seismic excitations for the test include actual seismic records with the amplitude of 0.2, 0.4, and 0.8 g, respectively. Based on the test data analysis, a comprehensive discussion is conducted on the influence of diaphragm walls on the seismic design of underground structures. Current misconceptions that ignoring the role of diaphragm walls is a conservative way in seismic design of underground structures are also reviewed. Results show that the presence of underground diaphragm walls would enhance the lateral stiffness of the structure, and thus significantly reduce the lateral deformation of subway stations during earthquakes. Notably, the structure with diaphragm walls also exhibits a significant amplification in acceleration response and experiences greater dynamic earth pressures on the sidewalls, and furthermore the strains at the connection between the sidewalls and diaphragm walls are dramatically amplified during the earthquake. It is worth noting that these adverse effects of the diaphragm walls on the amplification of dynamic earth pressures on the structure as well as the increase of internal forces at the sidewalls end‐diaphragm walls connection should be carefully considered in the seismic design of underground structures. [ABSTRACT FROM AUTHOR]

The zoning excavation method is fully employed to control the deformation of foundation pits constructed in urban soft soil areas. However, the similarities and differences in forces and deformations between foundation pits excavated by the zonal method and those excavated by the conventional method still need to be further explored. In this study, the deformation was monitored and analyzed by taking the zonal excavation of a foundation pit of the 'New World' project in Hangzhou City as the research object. The measured results showed that the pre-built diaphragm wall for the first excavated foundation pit restricted the deformation of the first excavated diaphragm wall. The presence of extensive construction and unloading activities also changed the deformation pattern of the soil. Further, finite element simulations were carried out. The simulation results revealed that excavating the foundation pit first caused displacements in the pre-built diaphragm wall. The displacements transmitted by non-adjacent pits through the pre-built diaphragm wall were small and were concentrated at the junction of the two sub-pits. Adjacent foundation pits caused large displacements of the pre-built diaphragm wall with similar displacement patterns. The results of the study can provide effective guidance for foundation pit excavation in soft soil areas in the future. [ABSTRACT FROM AUTHOR]

Background: Seepage control measures are essential in earth dams to enhance their safety against seepage and slope failures. A diaphragm is a thin impervious wall that is used in the core area of the dam to prevent the seepage of water. Any crack in the diaphragm can reduce its efficiency and threaten the safety and stability of the dam. Extensive evaluation of the influence of diaphragm fracturing on dam safety is required to establish a safe design and offer the appropriate measures. This study investigates the effect of diaphragm cracking on the safety of the dam for seepage and slope stability. A permeability tank is first used to validate the numerical model; then, different scenarios for cracked diaphragm walls are studied numerically. The crack's height, width, direction, and number are all investigated. The effect of having a downstream horizontal blanket drain with cracked internal diaphragms is also evaluated. Results: The results showed that the internal diaphragm enhances the safety of earth dams as it reduced the seepage discharge by 98% and increased the downstream slope safety by 34%. Considering the development of a crack in the internal diaphragm, the most critical location was at the base of the dam, wider cracks were more destructive, and the most critical direction was the horizontal crack. The fracturing of the diaphragm at multiple locations proved to be detrimental to the safety of the dam. Having three cracks caused the seepage discharge to reach 74% of its value for no diaphragm, the pore water pressure to raise drastically, and the downstream critical factor of safety to be higher than the case of no diaphragm by 8% only. Conclusions: According to the findings, it is advised to continuously monitor the components of diaphragm-type earth dams and perform the necessary maintenance works whenever any sign of damage or water seepage appears. Furthermore, using a well-graded horizontal drain of sufficient length and high permeability with the internal diaphragm is highly recommended as a mitigation measure if diaphragm fracturing occurs. This helps to quickly release the seeping water and keep the phreatic line away from the downstream slope. [ABSTRACT FROM AUTHOR]

This paper presents a generalised Newmark method (GNM) incorporating a displacement hardening mechanism for the prediction of permanent displacements accumulated by diaphragm walls during earthquakes. A key feature of the proposed approach is the adoption of an evolution law for the critical acceleration, which links its current value to the accumulated wall permanent displacements. This displacement hardening mechanism is based on a simplified relation between the average plastic shear deformations experienced by the passive zone of soil below dredge level and the mobilised soil friction angle. This relation is determined indirectly by the evolution of the passive earth-pressure coefficient with wall displacement/rotation, as obtained in quasi-static model wall experiments. The proposed approach has been validated by comparing its predictions with the experimental data obtained in centrifuge model tests of cantilevered and propped walls. In spite of the simplifying assumptions on which it is based, the GNM has demonstrated that it is capable of capturing the essential features of the retaining structures' kinematics and provides realistic predictions of permanent wall displacements. [ABSTRACT FROM AUTHOR]

The stability and deformation during trenching of ultra-deep diaphragm walls have a greater impact on the construction of diaphragm walls. The conventional limit equilibrium method, known as the vertical slices method, assumes homogeneity within the rock and soil mass, making it challenging to account for their stratification. Based on the limit equilibrium method, the horizontal strip method takes into account the stratification of the foundation soil. Based on the actual project, considering the different mud unit weights and heights, the horizontal strip method was used to analyze the stability of the groove trench and analyze the deformation law of the groove trench by the finite element method. The results indicate the following: The horizontal strip method can effectively assess the influence law of mud weight and height on the safety coefficient of groove trench stabilization. The higher the unit weight and level of slurry, the greater the wall safety coefficient. Moreover, the mud unit weight obtained by the horizontal strip method is about 12.70~12.64 kN/m3, which is close to the actual maximum mud weight of 12.5 kN/m3. The estimated mud unit weight aligns more closely with actual conditions. Additionally, through finite element analysis, the deformation law of the groove trench of ultra-deep diaphragm walls has been analyzed and summarized. The soil around the groove trench does not move inward, which shows three different deformation modes with different depths. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diaphragm walls are rectangular shaped cast in place deep foundations. There are two critical phenomena occurring, according to which the final quality can be affected: bentonite suspension exfiltration and concrete placement. Some imperfections seem to appear recurrently on the surface of the final wall. The defects are known as shadowing pathologies. The main reasons can be attributed to the dual effect of exfiltration mechanisms and kinematics of concrete flow. The objective of this study is developing a numerical tool to prevent the appearance of shadowing pathologies by visualizing the concrete flow in the presence of a bentonite suspension. This paper presents the results obtained from 2D and 3D models of diaphragm wall construction using COMSOL Multiphysics. The CFD model helped in solving a multifluid and particularly a two‐phase flow. The 2D modeling has considered a fresh slurry and an exfiltrated (or polluted) suspension neighboring soil and followed concrete flow with two rheological behaviors in two reinforcement configurations. Then, 3D simulations were compared to actual experimentation results, which were undertaken to construct diaphragm walls in the laboratory. By comparing the results of the simulations to the experimental outcomes, it has been possible to validate the model. The resulting simulations could clearly explain the occurrence of the pathology where the flow pattern and volume fraction of the fluid flow were determined. From the results obtained, it can be conducted that a compliant concrete mix but at the lower limit for the consistency recommendations, leads to pathologies, just like a polluted slurry. [ABSTRACT FROM AUTHOR]

Adequate prediction of surrounding ground movement during braced excavation is critically important as excessive soil movement damages adjacent structures. The magnitudes and patterns of ground movement and wall deflection largely depend on excavation parameters like thickness of diaphragm wall, wall embedment depth, strut locations and soil parameters such as soil strength, compressibility and creep parameter. In the present paper a thorough, parametric study has been conducted using finite element (FE) analysis to address the influence of various parameters on deformation characteristics of braced excavation in soft clayey deposits. The importance of correct estimation of soil parameters for braced excavation design is also documented. The analysis of typical braced excavations in soft clay is carried out using PLAXIS 2D software where soft soil creep constitutive model is used. On the basis of numerical study a handy design guideline is recommended. Further multivariate regression models are developed incorporating various important excavation parameters for the adequate prediction of maximum wall and ground displacement along with wall and ground surface deformation profile. Here large numbers of data reported in case histories and generated artificially from FE analysis are used for formation of regression equations. The proposed model is validated comparing results from literatures not used for the development of the model. [ABSTRACT FROM AUTHOR]

New advances in top-down construction are developing with the construction of supertall buildings in China. This study presents a finite element analysis for high-rise structural construction with a top-down method (TDM) considering complex environmental conditions. Based on this analysis model, the forces and the deformation of the diaphragm wall, beams, and soldier piles at various stages of construction are computed. Taking a super high-rise building with a 5-story basement in Nanjing as an example, the reliability and accuracy of the model is verified by comparing the measured and simulated results of displacement and stress values at various locations. The research results reveal the relationship between excavation depth, soil settlement and pile displacement, which is convenient for finding the optimal construction critical surface. It lays a foundation for the study of the critical height of the subsequent construction and facilitates the prediction of the weak link in the process. At present, this project is under construction, so this study has reference value for subsequent construction projects. [ABSTRACT FROM AUTHOR]

Building and ground settlement due to construction dewatering is a well-studied topic. However, most previous investigations have not considered the barrier effect of an adjacent underground structure on the drawdowns and resulting settlements. In this study, the barrier effect and its influence during construction dewatering for a metro station foundation pit is investigated. There are five aquifers at the foundation pit site, and a row of buildings supported on pile foundations, which act as an underground barrier to flow, is present on one side of the pit. On the other sides, there are no deep underground structures to impede groundwater flow. Field monitoring of the groundwater level drawdown, diaphragm wall movement, and ground and building settlements on both sides of the pit was carried out during dewatering. The results indicate that on the side with the pile foundations, the groundwater level drawdown, ground settlement, differential settlement, and angular distortion of building incurred by dewatering were relatively greater, but the diaphragm wall movements were relatively smaller. The effect of preexisting barriers should be considered in the assessment of construction dewatering-induced drawdowns, soil settlements, and building movements. [ABSTRACT FROM AUTHOR]

Because the soft weak soil layer rich in confined groundwater is prone to local instability and failure in the construction of diaphragm wall trenches, in order to check the local slurry wall stability in the construction of diaphragm wall trenches, a new three-dimensional (3D) calculation method on the local stability safety factor (LSF) of slurry walls is proposed based on the minimum potential energy principle. After the new method is applied to two engineering cases, the value of the LSF solved is 0.82 for engineering case 1, and the values of the LSF solved are 0.84 and 1.05 when the phreatic water levels are 2 and 4.5 m, respectively, for engineering case 2. These results are very close to the calculation results in the existing references, so the rationality of the new method is verified. Then the sensitivity of the LSFs obtained from the new method to various parameters has been analyzed and clarified on the basis of ten design examples. Finally, the new method is used to check the local slurry wall stability in the construction of diaphragm wall trenches for a practical project, and the obtained values of the LSF for three concerned weak soil layers are 1.37, 1.19, and 0.82, respectively. These results are in agreement with the actual situation in the construction site. This reveals that both the 3D model established and the 3D calculation method proposed in this paper are suitable for application in practical projects. [ABSTRACT FROM AUTHOR]

Concrete diaphragm walls (CDWs) are widely used as support for deep excavations in saturated soft soils with sensitive construction environments. The lateral deformation of the CDWs is typically measured by inclinometers cast in the wall. This paper discusses the evolution of the lateral deformation of the CDWs during deep excavation and the main sources of errors in inclinometer measurements. Furthermore, a correction method for the most influential errors is proposed. It is found that the multilevel supported CDWs generally experience three types of deformations during the excavation: cantilever, transition, and bulging. Accordingly, the joint error correction method for inclinometer readings can be operated efficiently to reprocess the monitored data, using total station measurement as a cross-reference. Based on the case studies of deep excavation projects located in Suzhou, China, the proposed error correction method has been demonstrated to perform satisfactorily and can assist in guiding key safety control decisions on construction sites. [ABSTRACT FROM AUTHOR]

Researching and developing a new type of diaphragm wall foundation can solve the probl em that the traditional diaphragm wall structure may not meet the high standards of safety and stability of underground structures in some specific engineering environments. This paper focuses on the horizontal bearing characteristic of a new form of foundation, a strip-walled underground diaphragm wall, through a series of model tests. In the tests, nine plexiglass models with different section sizes, wall spacings and wall heights, as well as loading strategies (horizontal loads along and against the wall in the model), were conducted. The influence of the above factors on the horizontal bearing performance of the foundation and the soil resistance distribution around the wall was studied. The results show that when the horizontal load applied along the wall is greater than 50 N, the growth rate of total displacement at the top of the wall gradually decreases; when a horizontal load is applied against the wall, with a uniform change in wall height, the optimal wall spacing is 11 cm. When the same displacement occurs, the bearing performance of the model under the former loading strategy is generally 10% higher than that under the later loading strategy. In addition, the depth where the maximum bending moment along the wall occurred gradually moves downward with the increase in horizontal load, and the increase in wall spacing and wall height has a positive effect on the horizontal bearing characteristic. With the application of load, the maximum bending moment of the wall will gradually decrease along the depth. The increase in wall spacing and wall height can improve the overall flexural stiffness and horizontal bearing performance of the foundation. Lastly, the group wall effect coefficient, β, is put forward, and a simplified formula for calculating the horizontal bearing capacity of a strip wall foundation is proposed. In the formula, β is negatively correlated with the buried depth of the wall and positively correlated with the distance between the walls, and its coefficient is greater than 1. [ABSTRACT FROM AUTHOR]

Deep excavations near subway tunnels can induce deformation, necessitating a comprehensive investigation into causal factors and mitigation strategies. Field measurements were conducted to assess both vertical and horizontal displacements of existing tunnels near a deep excavation in Shenzhen. Utilizing a validated three-dimensional finite element model that considers structure−strata interactions, this study analyzes tunnel displacements, ground movements, diaphragm wall impacts and the sensitivity of enclosure structure parameters. The results indicate that tunnel deformation correlates with enclosure structure deformation, particularly near the center of the pit. Moreover, shallow soil excavation significantly affects the vertical displacement of shallow-buried tunnels. However, the design parameters of the existing enclosure structures inadequately limit tunnel displacement. Therefore, it is crucial to intensify vertical displacement monitoring in shallow tunnels during early excavation stages and to enhance horizontal displacement monitoring during later phases. Implementing measures such as optimizing central support design or retaining soil at the pit bottom helps control maximum horizontal displacement. While support stiffness plays a greater role than retaining wall thickness, its impact on deep excavation projects is limited. [ABSTRACT FROM AUTHOR]

This study explores the underground structure and soil retention capabilities of a large-scale circular diaphragm wall (93.5 m in diameter) utilized as a soil retention strategy in deep excavation projects. The symmetrical design of the wall facilitates the use of an unsupported construction method, effectively resisting soil and water pressures. Using PLAXIS 3D 2017 software, this study simulates wall deformation and ground settlement, employing three different soil models to assess behavior under standard and emergency water gushing scenarios. The results show that the hardening soil (HS) model most accurately reflects the actual deformations and settlements. This study also finds that adjusting Young's modulus for clay significantly impacts the accuracy of soil behavior predictions, while changes in the properties of sand have minimal effects. This research highlights the challenges posed by water gushing and suggests the need for model improvements to capture better the dynamic interactions between soil and water pressure, which could lead to wall tilting. Overall, this study offers innovative and practical value, providing crucial insights for designing and mitigating strategies in large-scale circular deep excavation projects, especially in regions such as Taiwan, where such constructions are rare and face unique challenges. [ABSTRACT FROM AUTHOR]

Slurry wall protection is the key to the success of the design and construction of underground diaphragm walls; however, in the analysis of its grooving mechanism, the original slurry in the surrounding environment was usually equivalated to the slurry pressure, while the slurry penetration characteristics and the formation of a filter cake were often neglected, leading to obvious defects in the existing literature. In this paper, by combining computational fluid dynamics (CFD) and the discrete element method (DEM), a model based on the strain softening constitutive equation was proposed to investigate the formation of a filter cake by the effects of slurry penetration and cementation and to calculate the stability of grooving. In this model, material parameters were used to describe the mechanical properties of the filter cake, and the microscopic parameters that were calibrated through experiments were used to explore the optimal particle radius ratio of the filter cake. Then, the feasibility and rationality of the model in describing the slurry penetration and failure trends were verified through comparative analysis. In the stability analysis, the safety factor was introduced to evaluate the impact of the slurry and other influencing factors on the grooving process. The results show that the properties of slurry and the environmental factors such as groundwater level have significant effects on the formation of the filter cake and stress distribution, thereby affecting the grooving effect. The findings of this study can provide useful guidance and reference for theoretical research and practical engineering. [ABSTRACT FROM AUTHOR]

The distribution of lateral earth pressure acting on underwater rock-socketed circular diaphragm walls was investigated using theoretical analyses. Emphasis was placed on the relationship between the motion modes associated with the magnitude of the radial deflection of the wall and the lateral earth pressure. A framework for determining the distribution of radial displacement–dependent earth pressure based on the horizontal differential element method was introduced. The applicability of the proposed theoretical method was then verified by comparison with results that considered earth pressure in limit state, and radial deflection of the wall and water level. The predicted earth pressure and its distribution were found to be in good agreement with the analytical solutions and observed data. Detailed parametric analyses were further performed to study the impact of soil properties, excavation radius, and water level on the distribution of radial displacement–dependent earth pressure under different radial wall movement modes of a circular retaining structure. [ABSTRACT FROM AUTHOR]

Tunnel excavation leads to ground settlement and may cause existing buildings to suffer damage due to excessive deformation. Researchers proposed and studied several protective measures to mitigate the risk of damage to above-ground structures. Concrete and steel diaphragm walls effectively reduce the foundation settlement and are considered successful in protecting nearby structures. Compressing compressible material has advantages as the cost and environmental issues are considered. This study aims to investigate the effectiveness of geofoam buffer in reducing surface movement by conducting two-dimensional numerical analyses. Following verification of finite-element analysis through instrumental readings of the Isfahan subway case, numerical models were developed to determine barrier characteristics' effectiveness on the ground deformation. Analysis results show that the pre-installation of the geofoam diaphragm adjacent to the buried tunnel significantly mitigates the ground surface settlement; however, some adverse effects may be developed in the zone behind the Expanded Polystyrene (EPS) diaphragm wall. [ABSTRACT FROM AUTHOR]

This paper proposed a new method for modelling joints, using anisotropic plate elements and elastic bar elements to address the issue that joints between panels are usually disregarded in numerical modelling. For small-scale deep excavations, which are frequently performed in the construction of various working shafts but have not been sufficiently studied, two numerical models were developed, using the No.1 Shaft of Tongtu Road Utility Tunnel in Ningbo, China, as a research object. One model considered the joints between the panels as proposed, while the other disregarded the joints as conventional. In comparison to the conventional method, the proposed method was validated due to yielding wall displacements that closely matched the results of the field monitoring, with a notable reduction in the error observed in the calculated displacements for the short side of the excavation. Furthermore, 34 numerical models were developed in order to investigate the influence of excavation length, depth, and diaphragm wall thickness on the relative differences between the calculated displacements obtained by the two models. The results of this study can provide references for the development of finite element models for designing small-scale deep excavation. [ABSTRACT FROM AUTHOR]

Building information modeling (BIM) and finite element method (FEM) models have a wide range of applications in underground engineering design, construction, and operation and maintenance. This study employs a BIM-FEM framework to numerically simulate the impact of excavation on existing subway stations, using the Yanjiang New City Station TOD project as a case study. This framework simplifies the smooth integration of BIM and FEM models, automating functions such as assigning material properties, conducting construction simulations, and generating high-quality meshes. Simulation results reveal significant horizontal and vertical displacements in diaphragm walls, support structures, and subway station structures, with the greatest impacts occurring closest to the excavation site. The BIM-FEM framework is validated as an effective tool for designing foundation pit support structures, enhancing numerical modeling accuracy and efficiency in underground engineering. The findings contribute to a better understanding of the dynamic interactions between excavation and underground structures, informing the development of construction strategies and protective measures to ensure structural safety. [ABSTRACT FROM AUTHOR]

In order to quantitatively study the influence of the weakening of the disconnectable coupling joint (DC joint) on the retaining structure, the pre-axial force retention performance of the steel support, the axial force of the steel support, the horizontal displacement of the diaphragm wall, and the ground settlement around the foundation pit were monitored during the construction of the foundation pit. The evolution process of the monitoring data was analyzed, and the corresponding numerical model verified by the monitoring data was established. The influence of the yield load of the DC joint, the initial compression stiffness, and the weakening of the pre-axial force on the stability of the retaining structure was studied by numerical simulation. The results show that the pre-axial force of steel support is only 67% of the design value when the soil below is not excavated within 24 h. The DC joint has a significant weakening effect on the steel support, which is unfavorable for the stability control of the foundation pit retaining structure. The pre-axial force and initial bending stiffness have a great influence on the stability of the retaining structure. When the yield load is not lower than that of the row piles, the DC joint has no effect on the stability of the retaining structure. This model can predict and analyze the deformation trend under different working conditions to a certain extent, providing certain reference value for safety plans during construction. [ABSTRACT FROM AUTHOR]

Deep foundation pit excavations have become more extensive for the construction of underground spaces with rapid urbanization. Diaphragm walls are commonly used to support deep excavations. However, due to the complex geological conditions in karst areas, construction accidents frequently occur during the excavation of foundation pits. This study aims to investigate the performance of diaphragm walls in karst areas through field monitoring analysis. A kick-in deformation mode of the diaphragm wall is revealed during the foundation pit excavation. Furthermore, the results show that the diaphragm walls present multiple deformation modes rather than a single mode. Additionally, this study proposes a method to calculate the lateral displacement of the diaphragm walls at different depths. It is found that the karst caves have a considerable impact on the stability of diaphragm walls, as demonstrated by their lateral displacement. The hidden karst caves reduce the bearing capacity of the bedrock, rendering it insufficient to resist the active earth pressure. As a result, the bottom of the diaphragm wall is kicked into the foundation pit, causing significant lateral displacement and posing risks during excavation. The findings of this study contribute to the design and construction of similar excavations in karst areas. [ABSTRACT FROM AUTHOR]

This study focuses on the complex dynamics of heat dissipation within diaphragm walls during concrete hydration, crucial in construction engineering. Experimental measurements from three sites in Poland, featuring diaphragm walls of varying thicknesses, ranging from 1 to 1.5 meters, were compared to a numerical model. The model, using a Finite Difference Method, incorporated stages of execution of adjacent panels and their thermal influence. The results closely mirrored the measured temperatures, validating the accuracy of its predictions. Despite minor discrepancies, mostly within ±3 ◦C, the method effectively approximated real-life scenarios. Suggestions for model enhancements include incorporating the effect of concrete admixtures and refining the modeling of sequential panel execution. The thermal soil parameters, their possible range, and their impact on hydration heat dissipation in deep foundations emerged as crucial insights. This research serves as a foundation for deeper investigations into early-age behavior in deep foundations, aiming to extend the analysis to stress and strain domains to unravel characteristic cracking patterns observed in diaphragm walls. [ABSTRACT FROM AUTHOR]

The nodular diaphragm wall (NDW) is a novel foundation that can provide significant uplift load resistance compared to a typical diaphragm wall foundation. With the advantages of low noise, cost‐effectiveness, high work efficiency, and construction abilities close to existing buildings, NDW has excellent engineering application prospects in urbanization construction. However, the scarce knowledge on the uplift resistance, failure mode, and calculation method of the NDW has hindered its application in practice. In this paper, indoor model tests based on particle image velocimetry (PIV) technology are carried out to investigate the uplift behavior of three NDW models with different amounts and locations of nodular parts. The load transfer mechanisms of the three NDW models are discussed in detail, and special attention is given to the failure mode analysis. In addition, a theoretical analysis is implemented based on the load transfer approach. The transfer function and associated critical parameters are discussed in detail. Accordingly, an iterative procedure is proposed to interpret the load transfer information of an uplift NDW in multilayered soils under different loading levels. The findings derived in this paper are helpful to the uplift deformation, capacity calculation, and design of NDW in practical engineering. [ABSTRACT FROM AUTHOR]

Osteosarcoma is the most common tumour that develops in the chest wall of dogs; an extensive excision is the treatment of choice. Various methods have been reported for reconstruction of chest wall defects following extensive excision. The objective of this report was to describe the complete resection of an extensive costal osteosarcoma with an extended resection of the ribs and part of the diaphragm in a dog. An 11‐year‐old neutered, male, miniature pinscher was presented with dyspnoea: An extensive mass was observed, stretching from the right chest wall to the abdominal wall. On computed tomography, the mass originated from the right 9th rib and exceeded the 6th rib on the cranial side and the 13th rib on the caudal side; it was compressing the lungs, diaphragm, liver, stomach and duodenum. When the patient's condition was medically stabilized, the tumour was removed from the right 9th rib. In consideration of the surgical margin, the 5th–13th ribs were excised, and the tumour was resected with the thoracoabdominal wall and part of the diaphragm. The missing thoracoabdominal wall and section of the diaphragm were reconstructed using two sheets of a polypropylene mesh. Postoperatively, flail chest was observed, although dyspnoea was not observed in the patient. Histopathological examination confirmed the diagnosis of osteosarcoma with a clean margin. Although 60.6 months have passed post‐surgery, no metastasis has reoccurred. In this case, complete resection and reconstruction of the chest wall and diaphragm were achieved using a polypropylene mesh without fatal postoperative complications, despite extensive osteosarcoma resection. [ABSTRACT FROM AUTHOR]

This document is a closure to a previous paper titled "Effects of Movement Induced by Ground Improvement on the Performance of an Excavation Support System in Underconsolidated Clay." The closure addresses comments and requests for additional information made by a discusser. The closure provides construction information, including the layout of ground improvement works and the installation of deep soil mix columns and jet grout piles. It also discusses the selection of jet grout pressures, undrained shear strength properties of marine clays, and field performance observations. The closure concludes by addressing the limitations of the numerical modeling used in the original paper. [Extracted from the article]

The stability of underground diaphragm walls is crucial for ensuring the safety and integrity of trench excavations in geotechnical engineering. This study addresses this critical issue by proposing a novel destabilization mechanism based on a sliding body model specifically designed for diaphragm wall trenching operations. The research employs an analytical framework rooted in soil mechanics and plasticity theory, utilizing limit equilibrium analysis to develop a method for calculating the minimum required slurry density and corresponding safety factor for trench stability. The study compares two distinct approaches to slurry density computation, analyzing their sensitivity to various influencing factors. Theoretical findings are validated through multiple real-world engineering case studies. Comparative analysis demonstrates the superiority of the proposed method, particularly in assessing trench stability within clay layers. Key variables influencing the safety factor are identified, including trench length, slurry density, soil friction angle, and the relative height difference between slurry and groundwater levels. Results indicate that actual slurry densities observed in practice consistently fall within the bounds predicted by the theoretical calculations. This research contributes a valuable theoretical framework to the field of diaphragm wall construction, offering improved accuracy in stability assessments and potentially enhancing safety in geotechnical engineering projects.

The recent construction of an underground mass rapid transit (MRT) station in Singapore involved 21 m deep excavations within underconsolidated marine clay. The lateral earth support system comprised 1 m thick diaphragm walls socketed into the underlying Old Alluvium and 4 levels of preloaded cross-lot struts. Deep soil mixing (DSM) and jet grouting piles (JGP) were used to improve up to 15 m thickness of the marine clay formation. Field monitoring data showed that these ground improvement processes caused large outward deflections of the diaphragm wall panels at some locations prior to the excavation and may have caused yielding within the wall panels. In this paper, the impacts of these prior wall deformations on the subsequent performance of the excavation support system are investigated. The measured performance at two indicative cross sections is compared with results from simplified 2D finite element analyses. The analyses simulate the effects of ground improvement through prescribed boundary pressures and represent the yielding of the diaphragm wall panels through zones of reduced bending stiffness. We show that large outward wall deflections and curvature observed during jet grouting at one section contribute to higher inward wall movements and strut loads measured during excavation, while smaller movements (and curvature) prior to excavation at a second similar cross section cause negligible change in the performance of the temporary earth retaining system. The results highlight (1) the importance of controlling ground movements associated with ground modification processes such as jet grouting, (2) the uncertainties in estimating mechanical properties for the improved soil mass, and (3) the need to improve the representation of non-linear, flexural properties (M-κ) of reinforced concrete diaphragm panels. [ABSTRACT FROM AUTHOR]

A 1257 m long special-shaped deep excavation was performed in the city centre of Nanjing, China. Full-width and half-width top-down construction methods were adopted. Based on long-term monitoring data from the project, the evolution characteristics of the diaphragm wall (DW) deformation, the ground settlement and the settlement of adjacent buildings were analysed. The interrelationships among these parameters and their relationships with the excavation process, structural system and geological conditions were also studied. The results showed that the horizontal displacement of the DWs was less than 1% of the excavation depth and the position of the maximum horizontal displacement was generally located from 4 m above the excavation surface to the vicinity of the excavation surface. The influence range of the excavation on the surrounding ground settlement was mostly within three times the excavation depth. The ground settlement varied from 0.1–0.5% of the excavation depth to 0.3–5.0 times the maximum horizontal displacement of the DW. During the construction process, the settlement rate suddenly increased only when the excavation reached the soft soil layer. Building settlement was found to be related to the excavation deformation, structure forms, foundation types and distance to the foundation pit. [ABSTRACT FROM AUTHOR]

This study proposes a new form of underground diaphragm wall foundation with hexagonal sections, called the grid pile foundation (GPF), which is used for long-span bridges. To investigate the lateral bearing capacity characteristics of the integrated pile foundation, the quasi-static test as well as numerical simulations were conducted. Firstly, the quasi-static test was conducted to obtain the lateral load–displacement curve, the soil pressure distribution, and the deformation and stress distribution of the pile foundation and the surrounding soil. Then, the finite element model of the proposed GPF foundation was built, which was verified and calibrated based on the test data. Finally, the parametric analysis was performed to investigate the effects of soil friction angle, pile foundation Young's modulus, and pile length on the lateral bearing capacity characteristics of the proposed GPF. It is concluded that the GPF would transition from the stiffness stage to the plastic strain stage under lateral load, and deformation occurred simultaneously. The stress in the soil around the pile foundation is high in the upper portion and low in the lower portion, and the active and passive failure zones of the soil are formed under the action of the GPF. Both experimental and numerical simulations indicate that the GPF has a good lateral load capacity, and the lateral load capacity is most affected by the length of the piles. The GPF is expected to provide a new solution to the construction of large-span bridges with diaphragm wall foundations. [ABSTRACT FROM AUTHOR]

Recently, with the continuous increase in the protection of groundwater resources, the need for excavation without dewatering for foundation pit engineering has become increasingly urgent. In order to solve the problem of dewatering in the construction of foundation pits in water-rich strata, this paper proposes a new foundation pit support method-the combined artificial ground freezing method. The combined artificial ground freezing combines traditional suspended impervious curtain and horizontal frozen curtains and can realize no-dewatering excavation of foundation pit engineering. According to the construction experiences of the freezing method in past municipal engineering, the construction process of the combined artificial ground freezing is summarized. The frost heave control measures, pressure relief pipes, temperature limit pipes, local freezing technology, and the interface area strengthening measures using freezing pipes embedded in the diaphragm wall are proposed. The model test verifies the feasibility of the combined artificial ground freezing method. The test results show that the method can effectively realize the support of the foundation pit. The bearing capacity of the frozen curtain close to the temporary shaft and the diaphragm, which is the weakest zone of the frozen curtain, can meet the design requirements. The observation found that the freezing had no apparent effect on the strength and deformation of the diaphragm wall. [ABSTRACT FROM AUTHOR]

In deep excavations, pre-excavation dewatering (PED) usually causes notable diaphragm wall (D-wall) deformation and ground settlement. However, this problem has not attracted sufficient attention. In this paper, the mechanisms and control methods of settlement caused by PED in a deep excavation in Tianjin, China are analysed. A hydraulic connection between the soil inside and outside the excavation area due to aquifer leakage was observed during PED. Therefore, although the first level of struts had been installed before PED, the deformation of the D-wall and ground settlement reached 6·9 mm and 12·5 mm, approximately 29·0% and 73·5% of the maximum allowable values, respectively. The monitoring results demonstrated that leaky aquifers could reduce the deformation of the D-wall but increased the magnitude and extent of ground settlement. Based on the numerical simulations of D-wall deformation and groundwater change, in this case, the ground settlement within the area extending two times the depth of unloading (two times the depth of dewatering, 2Hd) from the excavation was found to be caused by both the deformation of the D-wall and the drawdown of the groundwater, whereas the noticeable settlement in the area beyond 2Hd was caused by only the drawdown of the groundwater. When hydraulic connections exist between the soil inside and outside the excavation area, artificial recharge should be used to control the noticeable settlement induced by groundwater drawdown. [ABSTRACT FROM AUTHOR]

The ground response during diaphragm wall panel installation is strongly affected by the support slurry pressure, and by the subsequent lateral pressures during the tremie placement and set-up of wet concrete. The support slurry pressure can be reliably assumed as hydrostatic within the excavated trench, whereas the lateral concreting pressure is much more complex due to the stiffening effect of wet concrete. This paper reviews the measurements of wet concrete pressures from a series of instrumented diaphragm wall panels which show that lateral pressures in the concrete slurry increase as the tremie displaces bentonite slurry and reach a maximum condition about 1 h after placement, while conditions over the longer term closely approximate the hydrostatic pressure of the bentonite-filled trench. The maximum increase of pressure varies at different heights of the same trench, and also varies for two separate panels in the same project, reflecting the varying velocity of concreting. Model tests of concreting pressure on formwork also demonstrate that the lateral pressure reduces from hydrostatic wet concrete pressure a few hours after casting. A time-dependent lateral concreting pressure model is developed to represent these measurements more realistically. This proposed model is implemented into a finite-element program to investigate its effects on the ground response due to the concreting process. Computed results from a reference case can capture the progressive variations of ground movement, earth and pore water pressure in the soil adjacent to the trench during and shortly after the concreting process, which is consistent with the reported measurements. [ABSTRACT FROM AUTHOR]

Stability analysis of retaining walls in seismic areas is generally performed by calculating a safety factor against a possible mechanism of collapse. However, considering that limit conditions usually occur in some time intervals during an earthquake, a more rational approach consists in assessing the performance of the structure in terms of accumulated permanent displacements. In this context, a novel method is proposed in the present study for predicting the earthquake-induced permanent displacements of embedded cantilever retaining walls, such as diaphragm or sheet-pile walls. This method requires solving a simple motion equation of the structure subjected to the soil–structure contact stresses evaluated using a closed-form solution. Specifically, it is assumed that the wall undergoes a rigid rotation around a point located in its embedded portion. Comparisons are presented with both experimental and numerical results documented in published studies. In all cases considered, a satisfactory agreement is found between these results and those provided by the proposed method. In addition, the method accounts for some features of the seismic behaviour of embedded cantilever retaining structures observed during centrifuge tests. Summarising, the method is reliable, simple to use and requires few conventional parameters as input data. Therefore, it is suitable for routine applications. [ABSTRACT FROM AUTHOR]

The seismic performance of diaphragm walls adjacent to tunnels plays a pivotal role in ensuring the stability of underground infrastructure. This article presents an extensive investigation into the seismic behavior of such diaphragm walls through advanced two-dimensional (2D) numerical modeling. The primary objective is to establish the accuracy and reliability of the numerical model by comparing its results with a reference case history from Tianjin, China. Following successful validation, the study employs rigorous two-dimensional (2D) numerical analyses to examine the response of the diaphragm wall to seismic events while considering crucial factors. These factors encompass the dynamics of pore water pressure, the diverse acceleration histories of earthquakes, varying tunnel positions, and their combined influence on the horizontal displacement of the wall. From our findings, we can conclude that earthquake duration has a more substantial impact on displacement and wall deformation compared to peak ground acceleration (PGA). Longer earthquake durations are associated with greater displacement. In dynamic analyses, the presence of water diminishes soil displacement and concentrates plastic deformation points. The distance between the tunnel and the diaphragm wall significantly affects wall displacement and deformation. The effective distance is approximately 10 m. Our findings can inform better design and construction practices to enhance the stability of underground infrastructure in seismically active regions. [ABSTRACT FROM AUTHOR]