This paper presents an evaluation of the Hypoplastic Clay constitutive model for finite element analysis of deep excavations and displacements induced by excavations in the influence zone. A detailed description and formulation of the Hypoplastic Clay soil model is included. A parametric case study of a deep excavation executed in Pliocene clays is presented. FE analysis was performed using several soil models (Mohr-Coulomb, Modified Mohr-Coulomb, Drucker-Prager, Modified Cam-Clay, Hypoplastic Clay) and the results were compared to in-situ displacements measurements taken during construction. Final conclusions concerning the suitability of the Hypoplastic Clay model for deep excavation modelling in terms of accurate determination of horizontal displacements of the excavation wall, the uplift of the bottom of excavation, and, most importantly,vertical displacements of the terrain in the vicinity of the excavation are presented.

Deep excavation walls can be analyzed and calculated by using classical methods (currently rarely in use due to their many simplifications) or numerical methods. Among the numerical methods we can distinguish a simplified approach, in which the interaction between soil and a wall structure is modelled by a system of elasto-plastic supports, and the finite-element method (FEM) in which the soil is modelled with mesh of elements. It is a common view that if we want to analyze only wall constructions, the first, simplified method of calculation is sufficient. The second method, FEM, is required if we want to further analyze the stress and strain states in the soil and the influence of the excavation on the surrounding area. However, as it is demonstrated in the paper, important differences may appear in the calculation results of both methods. Thus, the safety design of a deep excavation structure depends very much on the choice of calculating method.

The demands placed on industry today are increasingly challenging and demanding. To meet these challenges, designers, contractors, and technology managers are constantly looking for effective solutions. Industry has always thrived on new technologies and innovations to achieve better results, so it is critical to undertake new developmental research to simulate and test new technological proposals. In this paper, the author describes a new direction in civil engineering technology that interdisciplinary couples solutions known to the bridge industry with geotechnical aspects in the technology space and the possibility of implementation in the construction industry. The author proposes the application of prestressing together with technological aspects of this solution to diaphragm walls, which are not only a temporary housing but also the foundations of a new investment. Thanks to this solution it is possible, among other things, to resign from one level of diaphragm expansion of diaphragm walls, which translates into cost optimization. It is an innovative approach to designing and most of all constructing the load-bearing structure, which directly influences the technological optimization of selected issues of completing the underground parts of the investment. Additionally, the presented solution contributes to the balanced execution of the investment by reducing the use of materials and construction equipment. The author discusses technological, execution and implementation problems related to the application of innovative solutions in construction companies together with examples of cost optimization. The author presents the results of conducted research with application of the proposed solution in the implementation of the underground commercial investment.

The overall efficiency of a construction of a deep excavation urban project does not depend only on the duration of the construction but also on its influence on the urban environment and the traffic [9, 10]. These two things depend greatly on the excavation method and the construction stages defined during the design process. This paper describes the construction stages of three metro stations (two stations in Warsaw and one in Paris) and discusses their advantages and disadvantages including among other things its impact on neighbouring infrastructure and the city’s traffic. An important conclusion drawn from this analysis is that the shape of the slabs used can considerably affect the design and the construction stages. For example, a vaulted top slab allows an almost immediate traffic restoration and a vaulted bottom raft allows a much shorter dewatering period.

The technology of single bore multiple anchor is well known and mainly used as a method of providing support for retaining walls of deep excavations in weak soils. Multiple fixed lengths in a single borehole is a major difference to conventional anchors. The purpose of it and the most important facts affecting bearing capacity are presented. Due to the reduction of progressive debonding higher bearing capacities can be achieved and the impact of soil consolidation is decreased. Unique properties of this technology potentially reduce construction costs and increase the reliability and safety of the structure. Single Bore Multiple Anchors in most cases are prestressed by synchronised hydraulic jacks to provide that every anchor unit transfers the same load. The purpose of this paper is to present the results of investigation and suitability tests, which took place at the site of Zlote Tarasy Shopping Centre in Warsaw. The carried out research reveals that prestressing of one fixed anchor causes a decrease in lock-off load of the second fixed anchor, regardless of the order of prestressing. Measured values presents range from 6% to 14%. Results indicate mutual influence between loads of fixed anchors from the separate prestressing.

The goal of this study is to assess the application of the Hardening soil model in predicting the deformation of retaining walls of excavations in 2D and 3D finite element analysis at the Ho Chi Minh Metro project. Designed as the deepest underground station in the first metro line built in Ho Chi Minh City (HCMC), Opera House station is located in an area with a dense building zone and close to historical buildings. A summary of the input soil properties is provided using data from site investigations, in-situ tests, and laboratory tests. By numerical simulation using the Hardening soil model, the parameters of the soil stiffness modulus value are verified based on the Standard Penetration Test (SPT), and Pressuremeter test (PMT). The obtained results of the numerical analysis by 2D and 3D finite element methods, and field observations indicate that applying the Hardening soil model with soil stiffness modulus obtained in situ tests gives reasonable results on the displacement of the retaining wall at the final phase. The relationship between the SPT value and the stiffness modulus of HCMC sand is a function of depth. This correlation is obtained through the comparison of wall deformation between the simulation and monitoring at the construction site. The results of the difference between 2D and 3D finite element analysis also are discussed in this study.

The knowledge of impacts and the load-bearing capacity of unstrengthened/strengthened structures is a crucial source of information about the safety of masonry buildings near deep excavations, especially in dense urban areas. Incorrect calculations made for such designs can seriously affect not only an analyzed object, but also the adjacent buildings. The safety of masonry buildings can be determined by many factors that are closely related to the hazards presented during the performance of deep excavations. These factors are at first identified and then prioritized. The AHP process in the multi-criteria analysis was used to support the decision-making process related to the verification of factors affecting the safety assessment of masonry buildings in the area of deep excavations. The proper design of building structures, including the verification of the structure strengthening near deep excavations, was found to be the most significant factor determining the safety of such buildings. The methodology for proceeding with the verification of ultimate (ULS) and serviceability (SLS) limit states in accordance with the literature data, current regulations, such as Eurocode 6 and other design standards, and know-how of the authors, described in this paper was the next stage of the discussed analysis.