Excavations In Areas Research Articles

A Case Study of The Performance of A Pile-Supported Bracing Method for Basement Building

Deep excavations in urban areas are highly hazardous due to extensive settling of the surrounding soil, which can lead to the failure of retaining wall systems and the consequent collapse of adjoining properties. The retaining wall and bracing system are important for completing deep excavations for a basement building project. This paper evaluates the performance of an alternative, innovative, low-cost pile-supported bracing system (PSBS) method during excavation for two-level basement construction. Assessed PSBS performance in terms of ground settlement, lateral movement of supporting systems, schedule, and cost comparison. The PSBS excavation method was designed and then implemented to construct a two-level basement using the bottom-up method. The total station was utilized to monitor three-dimensionally, like the adjacent school building, ground surface settlement, and lateral movement of supporting systems. A schedule and cost comparison were performed using internal bracing and the PSBS technique. The recorded filed data was analysed, and it found that the lateral movement of the support system, adjacent building, and ground settlement is within the allowable limit. According to the estimated results, the PSBS method reduces construction time by 272 days compared to the internal bracing system. The PSBS approach is also less expensive than internal bracing for a two-level basement.

Performance of Diaphragm Walls during Ultra-Deep Excavations in Karst Areas: Field Monitoring Analysis

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.

Influence of Structural Discontinuity on Slope Stability using Numerical Modelling and Sirovision

The rock mass consists of heterogeneous and anisotropic materials, with smaller and larger blocks of rock, and the presence of structural discontinuities is a significant concern. Characterising the rock mass is crucial for the success of engineering excavations in such areas. A detailed study of joints, their orientation, and discontinuities in the exposed rock mass is crucial as they greatly influence stability and fragmentation. Existing rock mass classifications like Rock Mass Rating (RMR) and Q-classification require various geological parameters and physico-mechanical properties of the rock. However, determining these parameters conventionally can be time-consuming, requiring careful on-site measurements. The number of opencast coal mines is increasing compared to underground mines due to shorter gestation periods, higher productivity, and quicker returns. However, opencast mining raises environmental concerns such as air and water pollution, solid waste management, land degradation, and socio-economic issues. Additionally, many opencast coal mines, regardless of size, are reaching greater depths, making analysing bench slopes and ultimate pit slope design crucial. Slope failure in these mines leads to production loss, additional costs for recovery and handling of failed material, pit dewatering, sometimes mine abandonment or premature closure, and loss of life. A study was conducted at Prakash Khani Opencast Mine – IV, Manuguru area, M/s The Singereni Company Collieries Limited (SCCL), to investigate the influence of structural discontinuities on slope stability. SIROVISION software was used to assess rock mass characterisation, while PLAXIS-2D software was employed to analyse the influence of structural discontinuities on slope stability. A comparative conclusion was drawn based on the results obtained from SIROVISION and PLAXIS-2D analyses. The study revealed that the RMR of the mine ranged from very poor to fair due to numerous discontinuities. It was also found that discontinuities in the slope decrease the Factor of Safety (FOS), indicating an impact on slope stability.

Hallstatt Period Rectangular Farmsteads in the Old Bavarian Loess Landscape: The Hascherkeller Site Revisited

Abstract In the occasionally lively debate about the social structure of the Central European Early Iron Age, the Herrenhof as the presumed seat of a high-status farmer now also plays a role. A rectangular farmstead of this type is the famous Hascherkeller site on the northern outskirts of Landshut. The first magnetic prospection ever conducted at such an archaeological structure was carried out here in 1978. The site became widely known for its distinctive complex appearance and the excavations undertaken there between 1978 and 1981 by Peter S. Wells, then assistant curator of European archaeology at the Peabody Museum of Harvard University. After four decades, an opportunity arose to resume excavations in areas not explored at the time and bring them to a conclusion. The most important result of the recent field work, which was completed in 2022, is the stratigraphic disentanglement of the numerous ditches. The loess terrace, most likely, was initially divided by a ditch running across the terrain. This separating landscape feature may have been contemporaneous with the palisaded farmstead on the eastern edge of the study area. Later, the two rectangular ditched enclosures were constructed, probably the eastern one first. In another, more recent phase, they were joined together by connecting ditches to form a larger settlement complex. Already during the investigation, it was revealed that the middle one of the once assumed three rectangular farmsteads had never existed. In addition, about 200 m further to the southwest, a similar double enclosure was discovered. Here, too, two rectangular enclosures were apparently joined by connecting ditches to form a larger settlement area in a more recent phase. About 5 km to the northeast, in the area of the hamlet Holzen not far from Altheim, a group of unconnected rectangular farmsteads dating from the Hallstatt period has recently been magnetically surveyed. These are characterised by a larger number of long, narrow pits indicating former house sites. The following remarks focus on the latest excavation results and the role of the type of habitation known as Herrenhof in the Early Iron Age settlement system.

Risk Management Technologies for Deep Excavations in Water-Rich Areas

Deep excavations play an important role in the construction of urban infrastructures such as metro stations and high-rise buildings [...]

Adaptive Dynamics of Settlement Models in the Urban Landscape of Termez (Uzbekistan) from c. 300 BCE to c. 1400 CE

The archaeological site of Ancient Termez is located in southern Uzbekistan. Despite the arid environment, the city benefited from its strategic position near two rivers, the Amu Darya and the Surkhan Darya. Its significance was mainly related to the expansion of trade routes connecting Eurasia. The city comprises several enclosures that attest long-term human-environment interactions. In order to identify the adaptive dynamics of the settlement models during an extended chronology covering the period from c. 300 BCE to c. 1220 CE (Greco-Bactrian/Yuezhi, Kushan, Kushano-Sasanian, and Islamic periods), a multidisciplinary study has been carried out, which includes: (1) archaeological excavations in several areas of the urban complex; (2) pedestrian surveying inside some enclosures and in the urban periphery; (3) an aerial survey based on high-resolution satellite imagery; (4) AMS dating of charcoal and bone samples; (5) archaeobotanical investigation through anthracological analysis; (6) zooarchaeological studies. The results point to variations in the development of the inhabited spaces, in which abandonment and occupation took place. The zooarchaeological and archaeobotanical data demonstrate the exploitation of natural resources in different environments (i.e., arid areas and irrigated land) and a certain evolution during the period considered.

A Simplified Analytical Method for the Deformation of Pile Foundations Induced by Adjacent Excavation in Soft Clay

The development of foundation excavations in congested urban areas inevitably induces stress release and soil movements, resulting in additional lateral deflections in adjacent pile foundations, commonly referred to as passive loading piles. Prior research on pile deflection resulting from nearby excavations primarily focused on single-pile behavior and paid little attention to the characteristics of pile groups. This paper presents a two-step approach to predicting the behavior of pile deformation resulting from nearby excavation. Firstly, Mindlin solution in combination with the double Gauss-Legendre formula is employed to calculate the additional lateral stress acting on the centerline of the passive pile resulting from nearby excavations. Secondly, the equation governing the deflection of the passive pile is determined using the Pasternak foundation model and solved using the finite difference method. On the basis of the Mindlin equation, shielding influence among piles is developed and applied to the analysis of a laterally loaded passive pile group. Last but not least, the accuracy of the presented approach is validated by comparing the results from two published centrifuge model tests with single piles and pile groups, and good agreements are obtained. Generally, the recommended two-step approach presents effective insight into the interaction between the excavation, soil, and pile, taking into account the influence of the shielding effect between piles. It can be applied as an alternative method for the conservation evaluation of the deformation tendency of pile foundation deformation in the pre-design of nearby excavations.

Effectiveness of compensatory injection as a means of regulating the stresses in complex geotechnical conditions

Deep excavations in dense urban areas often result in additional settlement of buildings that fall within the influence area of new construction. The most sensitive to such settlements, according to the normative literature, are historic buildings. One of the ways to regulate additional building settlement in the influence area of deep excavations is compensatory injection. The hydraulic fracture network created in the foundation creates additional lateral compression of the soil and changes its physical and mechanical properties. The article deals with a real example of an emergency situation at one of the objects in Tyumen, where during excavation of a pit with the designed depth of 7 meters for the construction of a five-storey building with an extended two-level underground space significant excessive settlement of the adjacent historic building and damage to its bearing structures were revealed as a consequence of the additional settlement development. The purpose of the present study is to evaluate the effectiveness of compensatory injection using collar technology to reduce excessive additional settlement of buildings in the zone of influence of deep excavations. A comprehensive analysis of the impact of new construction on the surrounding environment has been carried out by the authors of the article by means of numerical simulation. Analyzing the results of numerical modelling, the authors of the article developed measures to eliminate the emergency situation and stabilise the foundation. Based on the results of geodetic monitoring, it was found that the installation of a geotechnical barrier by injecting soil using the collar technique not only stabilised the foundation but also brought the building into position to meet regulatory requirements.

Experiments and numerical simulation of the reinforcement effect of channel-steel-reinforced shield tunnel segments under unloading conditions

The increasing emergence of foundation pit excavations in dense urban areas has caused a series of adverse impacts on operating tunnels. Thus, the investigation of tunnel segment reinforcement is crucial and essential for geotechnical engineers. This article intends to investigate the reinforcement effect of the channel steel reinforcement method through a three-ring full-scale test and finite element simulation. The three-ring full-scale test is carried out by considering different confining pressures under the influence of different tunnel burial depths and different distances between the foundation pit and tunnel (clearance distances). In addition, a three-dimensional refined FEM numerical simulation verified by the full-scale model test is conducted to study the influence of foundation pit retaining structure deformation. The research results show that channel steel reinforcement can significantly improve the stiffness of the segment and its bearing capacity. The effect of the channel steel is more prominent in tunnels with a large burial depth. The stress and deformation of the segment are relatively uniform under the conditions of different clearance distances after the reinforcement of the channel steel. The top and bottom convergence of the segment and the bolt stress increase as the deformation parameters of the envelope structure increase; furthermore, the top and bottom convergence of the segment can be reduced up to 46.88% after the channel steel reinforcement.

Study of the Factors Affecting the Quality and Safety of Deep Excavations in Urban Areas of Casablanca-Settat Province-Morocco

Understanding the project environment is essential in managing the works and controlling the risks associated with deep excavations in urban areas. The study was carried out on 33 risks related to the project site (SR) and the company (CR). The projects concerned are located in the Casablanca region. A structured survey questionnaire was sent to 100 project managers, researchers, and construction management experts to attract relevant data, which resulted in a relatively high response rate of 54%. This paper applies the principal component analysis (PCA) method to reduce the original data variables and identify risk factors associated with deep excavations. Spearman rank correlation tests show a good consensus among respondents to corroborate the results further. The PCA results in four principal factors (SR) accounting for 68% of the variance explained. Site geology, geotechnics, and hydrogeology account for 32% of the environmental and social impacts of excavation (17%), natural hazards (10%), and proximity to existing structures (8%). Moreover, four main factors (CR) explain about 72% of all the factors analyzed; non-security of the works (32%), non-quality of project staff (18%), project cost overrun (14%), and non-quality of excavation works (9%). These results are useful for critical thinking in planning excavation projects in urban areas. This study provides the urban development community with valuable information to reassess risk factors and realign project management strategies to ensure the quality and safety of deep excavations.

Predicting longitudinal tunnel deformation due to deep excavation-induced ground movement

Many excavations in urban areas are carried out near existing subway tunnels. To protect the tunnels, it is important to predict the longitudinal tunnel deformation induced by the soil movement caused by excavation. A three-stage method is proposed in this paper. In the first stage, a dual-spring Winkler model is proposed to calculate the lateral deflection of the retaining wall by explicitly accounting for the small-strain behavior of soils. In the second stage, the three-dimensional free-field soil movement induced by braced excavation is calculated by an analytical model that considers the lateral deflection of the retaining wall as the only input. In the third stage, the response of the tunnel is evaluated by simplifying the tunnel as an elastic foundation beam on Winkler springs and subjecting it to the soil movement computed in the previous stage. The validity and accuracy of each stage in this method are examined with finite element simulation results and field observations. Finally, parametric studies are also performed to investigate the effects of the small-strain behavior of the soil, the parameters of the retaining system, and the tunnel depth on the susceptibility of tunnels to deep excavation-induced ground movement.

High dependence on protected areas by the endangered giant armadillo in Argentina

A combination of technics was used to assess landscape variables associated with the presence of the globally vulnerable giant armadillo (Priodontes maximus) in its southernmost distribution in the Chaco region of Argentina. Between 2017 and 2019, 369 km of foot and vehicle transects were run to search and record indirect evidence of the species (burrows and feeding excavations) in areas with different level of protection, including two national parks, three provincial parks, and non-protected areas. Distance sampling was used to estimate density of excavations and effective strip width sampled to estimate the surveyed area. Resource selection functions (RSFs) were used to assess the variables associated to its presence by comparing locations of excavations with available habitat within surveyed areas. In these RSF models covariates that may affect habitat use and survival of giant armadillos were included: three categorical ones: soil type, vegetation cover (forests vs. grasslands), protection level (national park, provincial park, non-protected), and five continuous variables: distance to nearest river, distance to nearest national park, distance to closest protected area, distance to nearest transformed area, and distance to natural grasslands. Habitat use was modelled pooling together burrows and feeding excavations, and models were validated with a pool of records previously excluded from the analysis. A total of 104 records of burrows and 344 of feeding excavations were recorded. The probability of occurrence of giant armadillo excavations was much higher within forests, within or near protected areas, and increased with the distance to rivers, to transformed areas, and to grasslands. In the study area, only 10% of the landscape surveyed has good- to high-probability of occurrence of giant armadillos. The maintenance of large surfaces of native forests and the consolidation, improvement, and connectivity among protected areas seem to be essential for the long-term survival of the endangered giant armadillo in Argentina.

תרומתו של שר המדע והפיתוח יובל נאמן לקידום המחקר הארכיאולוגי ביהודה ושומרון

In addition to his stellar scientific career, Prof. Yuval Ne'eman devoted many years to public service. At the beginning of the 1980s, Ne'eman joined the political arena, through which he sought to actualize his ideological beliefs, such as by helping to establish dozens of Jewish settlements in Juda and Samaria. This article explores his contribution to the advancement of archeological research in Judea and Samaria, which stemmed from his desire to strengthen Israel's ties to this patrimony. Recentlyreleased archival files reveal his substantial behind-the-scenes activity in this field. He established and headed the Israel Ministry of Science and Development, which carried out surveys and excavations in peripheral areas, particularly in Judea and Samaria. His decisive contribution resulted in an unprecedented research drive in this region. Governmental backing, public support, and prevailing calm in terms of security, encouraged senior Israeli archeologists to participate in archeological research over the Green Line, although they could have done so for the preceding 15 years. The result was a golden age of archeology in Judea and Samaria, which has not recurred up to the present day (2021).

3D stability analysis of unsupported rectangular excavation under pseudo-static seismic body force

ABSTRACT In this paper, the seismic stability number of unsupported excavations in cohesive-frictional soil under the influence of pseudo-static seismic body forces is examined. Three-dimensional finite element limit analysis is employed to numerically solve the upper and lower bounded models of unsupported excavations. The results are represented by a dimensionless stability number which is a function of four dimensionless parameters including the excavation aspect ratio, the excavated depth ratio, the soil’s effective friction angle, and the coefficient of horizontal earthquake acceleration. For the first time in literature, the influences of a soil’s effective friction angle and the coefficient of horizontal earthquake acceleration on the mechanisms of excavation failures are examined and discussed. Also presented is a case study to demonstrate the use of the proposed seismic stability number in studying unsupported excavations in seismic risk areas.

A framework for the use of reliability methods in deep urban excavations analysis

Deep excavations in urban areas impose deformation to adjacent structures; hence the reliability of deformation analysis for the real deep excavation projects is very important to be assessed. In this study a framework is presented for the use of reliability methods in deformation analysis of deep urban excavations. The suggested framework is applied for 5 real deep excavation projects implemented during last 10 years. All studied cases were recognized as projects of high importance in urban areas, and were monitored during the excavation process. A non-probabilistic reliability analysis procedure, Random set method, in combination with finite element numerical modeling is applied to obtain the probability of unsatisfactory performance for each case. The reliability analysis results are confirmed by field observations and measurements. Typical results for the probability of analytical deformations exceeding the acceptable values along with the site observations and measured displacements for 5 real deep excavation projects show that the reliability analysis could be a beneficial tool for designer. It is concluded that applying the suggested framework in the design stage of deep excavation projects may lead to design more appropriate systems compared to common deterministic design methods.

A simplified estimation of excavation-induced ground movements for adjacent building damage potential assessment

Adjacent building damages induced by excavations is crucial for excavations in urban areas. Excavation induced damage involved complex soil-structure interactions and complicated ground movements which should be evaluated at the depth of foundation of adjacent buildings. Empirical or semi-empirical methods for evaluation of ground movements induced by excavations have not been well-established because the observed ground movements are very limited. The objective of this study is to establish a simplified assessment for building damage potential based on subsurface ground movements caused by excavations. A series of parametric study by numerical analyses with an advanced soil model was carried out. A set of simplified equations for predicting the profiles for both subsurface ground settlements and lateral ground movements were proposed. Three assessment models with or without considering structural stiffness and subsurface ground movements were employed in estimating the damage potential index (DPI) for two case histories. The models were proved to yield a more reasonable assessment result for building DPI based on the proposed simplified expression of subsurface ground movements.

Early agricultural colonisation of peripheral areas of loess uplands: new data from Sandomierz Upland, Poland

Excavations in marginal areas of the loess uplands in southern Poland have revealed that the northern periphery of the Sandomierz Upland was intensely colonised in the sixth and fifth millennia BC by Linearbandkeramik and Malice Culture Danubian communities. This research suggests that analogous settlement clusters may exist in other marginal regions of the Central European loess belt, previously thought to be uninhabited.

Investigating Stabilized Excavations Using Soil Nailing Method in Urban Context

There are various methods for stabilizing excavations in urban areas which one of them is the nailing method. Designing a nailing system and analyzing the performance of excavations is done by various software applications. One of these computer programs is PAXIS software which run based on the finite element method (FEM). In the present study, a numerical analysis of the performance of the excavations was investigated under different soil model and the most appropriate model was introduced. In addition, the excavation performance was evaluated based on certain designing conditions affected by the soil resistance specifications (cohesion and internal friction angle) and surcharge. The results indicated that, using an appropriate behavioral model which contains increasing soil stiffness with depth, shows results close to reality. They also indicated that under certain designing conditions, the lateral deformation of the soil nail wall and ground settlement decrease as soil resistance specifications increase.

Predicting Excavation-Induced Tunnel Response by Process-Based Modelling

Potential damages to existing tunnels represent a major concern for constructing deep excavations in urban areas. The uncertainty of subsurface conditions and the nonlinear interactions between multiple agents (e.g., soils, excavation support structures, and tunnel structures) make the prediction of the response of tunnel induced by adjacent excavations a rather difficult and complex task. This paper proposes an initiative to solve this problem by using process-based modelling, where information generated from the interaction processes between soils, structures, and excavation activities is utilized to gradually reduce uncertainty related to soil properties and to learn the interaction patterns through machine learning techniques. To illustrate such a concept, this paper presents a simple process-based model consisting of artificial neural network (ANN) module, inverse modelling module, and mechanistic module. The ANN module is trained to learn and recognize the patterns of the complex interactions between excavation deformations, its geometries and support structures, and soil properties. The inverse modelling module enables a gradual reduction of uncertainty associated with soil characterizations by accumulating field observations during the construction processes. Based on the inputs provided by the former two modules, the mechanistic module computes the response of tunnel. The effectiveness of the proposed process-based model is evaluated against high-fidelity numerical simulations and field measurements. These evaluations suggest that the strategy of combining artificial intelligence techniques with information generated during interaction processes can represent a promising approach to solve complex engineering problems in conventional industries.

The conditions for Philistine ethnogenesis

The origins of the Philistines have traditionally been understood within the context of a migration of “Sea Peoples” at the beginning of the Iron Age. However, excavations in other areas of the eastern Mediterranean have not yielded compelling evidence of a large-scale migration. We contend that migration is still the best explanation of the evidence, but the effect on the archaeological record of the disparate responses of the hostcommunities into which the immigrants settled has been overlooked. Whereas those immigrants who settled in places such as Cilicia, the Amuq Plain, and Phoenicia encountered a decentralized political landscape into which they were quickly absorbed, the immigrants who landed in the southern Levant faced a still-powerful Egypt which was able to confine them. Within a restricted space, the immigrant Sea Peoples and indigenous Canaanites were galvanized into a unique Philistine ethnos.