Search

The excavation and maintenance of buried natural gas pipelines can lead to deformation and stress redistribution of the pipelines and even cause secondary damage to the pipes with issues. To clarify the impact of excavation unloading on buried pipelines, this study established a finite element three-dimensional pipe-soil model, investigated the mechanical response of pipelines under layered excavation and evaluated various parameters impacting the response. The parameters analyzed include the diameter-thickness ratio of the pipe, excavation length and width, thickness of top covering soil, elastic modulus of soil, specific weight of soil and initial displacement of the pipeline. The study results showed that the pipeline bulges upwards during excavation unloading, the pipe top in the middle is under tension, and the bottom of the pipe is under compression. Therefore, the axial stress and vertical displacement both increase first and then decrease, and they are distributed symmetrically along the pipeline axis; excavating the initially compressed pipeline leads to high strain areas in the pipeline and even local buckling. The response to slope excavation is more pronounced than that to straight trench excavation; the additional response of the pipeline increases with the increase of diameter-thickness ratio, excavation width, thickness of pipe top covering soil and specific weight of soil, but it decreases with the increasing soil elastic modulus. The additional response is closely related to excavation length and the initial displacement. The results of this study can provide a reference for pipeline construction, maintenance, and safety assessment. [ABSTRACT FROM AUTHOR]

When excavating the rock foundation of a hydropower station, it will be affected by the phenomenon of unloading and relaxation, which may increase the risk of stability of the dam foundation engineering system. The dam foundation of Baihetan Hydropower is a columnar jointed rock mass (CJRM), which presents strong brittleness and anisotropy compared to traditional dam foundation rocks. Therefore, this type of rock mass is prone to disturbance to the dam body, structure, etc. during excavation, so it is necessary to accurately evaluate the impact of dam foundation excavation. Establishing a rock mass creep models serve as an effective tool for evaluating such stability but often suffer from significant parameter uncertainty. Digital twin technology, a virtual model, is capable of real-time learning from actual monitoring data obtained from the physical entity to enhance the performance of the built-in mechanistic model. In this study, the researchers employ the classical Burgers constitutive equation as the theoretical framework and integrate it with an ensemble smoother with multiple data assimilation (ESMDA) method based on Bayesian principles, along with displacement monitoring data from the Baihetan Dam foundation, to construct a digital twin model. Within this framework, the researchers analyze the uncertainty of rheological parameters at various measurement points in the Baihetan Dam foundation. Subsequently, the most suitable rheological parameters are selected and incorporated into the constitutive model to obtain displacement estimates, which are then compared with on-site monitoring data. The results demonstrate that the proposed method effectively performs probabilistic parameter estimation and model prediction for rheological mechanics. This research integrates data-driven methods with mechanical principles, offering a reliable approach for assessing the uncertainty of unloading rheological parameters and displacement prediction in dam foundations, thereby providing essential support for the evaluation of excavation projects in the CJRM of the Baihetan Dam foundation. [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]

One of the common excavation methods in the construction of urban infrastructures as well as water and wastewater facilities is the excavation through soldier pile walls. The maximum lateral displacement of pile wall is one of the important variables in controlling the stability of the excavation and its adjacent structures. Nowadays, the application of machine learning methods is widely used in engineering sciences due to its low cost and high speed of calculation. This paper utilized three intelligent machine learning algorithms based on the excavation method through soldier pile walls, namely eXtreme gradient boosting (XGBoost), least square support vector regressor (LS-SVR), and random forest (RF), to predict maximum lateral displacement of pile walls. The results showed that the implemented XGBoost model performed excellently and could make predictions for maximum lateral displacement of pile walls with the mean absolute error of 0.1669, the highest coefficient of determination 0.9991, and the lowest root mean square error 0.3544. Although the LS-SVR, and RF models were less accurate than the XGBoost model, they provided good prediction results of maximum lateral displacement of pile walls for numerical outcomes. Furthermore, a sensitivity analysis was performed to determine the most effective parameters in the XGBoost model. This analysis showed that soil elastic modulus and excavation height had a strong influence on of maximum lateral displacement of pile wall prediction. [ABSTRACT FROM AUTHOR]

With the rapid development of urban underground space, the construction of shield-driven cross-river twin tunnels is increasing, and the complex hydro-mechanical coupling effects and twin-tunnel interactions bring huge construction risks to such projects, which have attracted more and more attention. This study aims to understand the excavation effects induced by shield driving of cross-river twin tunnels through numerical simulation. A refined three-dimensional numerical model based on the fully coupled hydro-mechanical theory is established. The model considers the main components of the slurry pressure balance shield (SPBS) machine, including support force, jacking thrust, grouting pressure, shield-rock interaction and lining-grouting interaction, as well as the detailed construction process. The purpose is to examine the excavation effects during construction, including rock deformation around tunnels, the change in pore pressure, and the response of the lining. The results show the influence range of twin-tunnel excavation on rock deformation and pore pressure, as well as the modes of lining response. In addition, this study also systematically investigates the effects of water level fluctuation and burial depth on twin-tunnel excavation. The results indicate that the increase of water level or burial depth will enhance the excavation effects and strengthen the twin-tunnel interactions. These results provide useful insights for estimating the construction impact range and degree of twin tunnels, and serve as basic references for the design of cross-river twin tunnels. [ABSTRACT FROM AUTHOR]

The probability analysis of ground deformation is becoming a trend to estimate and control the risk brought by shield tunnelling. The gap parameter is regarded as an effective tool to estimate the ground loss of tunnelling in soft soil. More specifically, x, which is a gap parameter component defined as the over (or insufficient) excavation due to the change in the posture of the shield machine, may contribute more to the uncertainty of the ground loss. However, the existing uncertainty characterization methods for x have several limitations and cannot explain the uncertain correlations between the relevant parameters. Along these lines, to better characterize the uncertainty of x, the multivariate probability distribution was developed in this work and a dynamic prediction was proposed for it. To attain this goal, 1 523 rings of the field data coming from the shield tunnel between Longqing Road and Baiyun Road in Kunming Metro Line 5 were utilized and 44 parameters including the construction, stratigraphic, and posture parameters were collected to form the database. According to the variance filter method, the mutual information method, and the value of the correlation coefficients, the original 44 parameters were reduced to 10 main parameters, which were unit weight, the stoke of the jacks (A, B, C, and D groups), the pressure of the pushing jacks (A, C groups), the chamber pressure, the rotation speed, and the total force. The multivariate probability distribution was constructed based on the Johnson system of distributions. Moreover, the distribution was satisfactorily verified in explaining the pairwise correlation between x and other parameters through 2 million simulation cases. At last, the distribution was used as a prior distribution to update the marginal distribution of x with any group of the relevant parameters known. The performance of the dynamic prediction was further validated by the field data of 3 shield tunnel cases. [ABSTRACT FROM AUTHOR]

The long and large diameter uncharged hole boring (LLB) method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior to tunnel excavation. Drilling in this method typically uses a 50 m long with a 382 mm diameter hammer bit in the horizontal direction at the tunnel face. However, the significant weight and uni-directional rotation of the rod head, as well as variables such as geological characteristics, machine conditions, and inexperienced operators result in significant deviation from the target borehole alignment that hinders the vibration-dampening effect of the uncharged holes. Furthermore, since there is no method to verify the alignment of the boreholes until main tunnel construction, borehole misalignment is often not discovered until weeks after construction, which requires tunnel construction to cease until the equipment can be remobilized and an additional borehole be created, causing significant delays and increased costs for the entire tunnel project. In this study, the borehole alignment tracking and ground exploration system (BGS) is developed to predict and monitor the quality and alignment of boreholes for cut blasting methods such as the LLB methods immediately after boring. The BGS was subsequently tested at a subway construction site to evaluate its performance in the field. The measurements yielded by the BGS were compared with manually measured boring positions at every 5 m along the borehole. Although the BGS showed a maximum deviation of approximately 12% at a local point where the hole surface was relatively rough, the accuracy for the final boring position was approximately 97%, demonstrating excellent precision of the alignment tracking system. The BGS demonstrates excellent performance in predicting ground conditions and the boring quality of a cut hole immediately after drilling, and shows promise in various other applications for monitoring borehole alignment. [ABSTRACT FROM AUTHOR]

This paper introduces a novel application of the laser speckle technique in dentistry, focusing on assessing the efficiency of dental excavation methods used to remove decayed tooth structure. The aim is to evaluate the efficiency of two chemo-mechanical agents and the high-speed drill using the laser speckle technique, which offers objective, non-invasive, and real-time evaluation capabilities. Extracted human primary molars with active occlusal carious lesions were sectioned into three parts, with each part allocated to one of three groups: Group 1 (Brix3000®), Group 2 (Papacarie DUO®), and Group 3 (High-speed drill mechanical caries removal). Caries removal was performed using the designated agent or method for each group. After caries excavation, speckle imaging using a 632.8 nm laser was conducted. Additionally, SEM was used to acquire micro-photographs of the surface morphology of the treated samples. The findings reveal insights into the comparative efficiency of the three dental excavation agents and methods using the laser speckle technique. The speckle parameters extracted from speckle patterns generated by treated teeth provide valuable information for evaluating the performance of the excavation methods. The scanning electron microscopy images also offer detailed visual evidence to support the analysis. This paper demonstrates the potential of the laser speckle technique for assessing the efficiency of dental excavation methods. The objective, non-invasive, and real-time evaluation provided offers advantages over subjective visual assessment and manual measurements. [ABSTRACT FROM AUTHOR]

In response to the environmental implications of the massive quantities of excavation soil generated by global urbanization and infrastructure development, recent research efforts have explored the repurposing of calcined excavation soils as sustainable supplementary cementitious materials (SCMs). As it is still at an early stage, current research lacks systematic analysis across diverse soil deposits regarding their reactivity and mechanical properties within cementitious binders, despite recognized geographical variability in kaolinite content. Through comprehensive experimentation with soils sourced from four major southern Chinese cities, this study presents a pioneering assessment of the compressive strength, pozzolanic reactivity (X-ray diffraction, Fourier-transform infrared spectroscopy, solid-state nuclear magnetic resonance), and microstructural development (mercury intrusion porosimetry, scanning electron microscopy) of mortars modified by various calcined excavation soils (up to 28 days curing). The experimental data suggest that soils with a kaolinite content above 53.39% produce mortars of equal or superior quality to plain cement mixes, primarily due to their refined pore structures, microstructural densification, and enhanced hydration reactions. The findings highlight kaolinite—specifically, aluminum content—as the principal indicator of excavation soil viability for SCM application, suggesting a promising avenue for sustainable construction practices. [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]

The remarkable effect of a double primary support has been proven in squeezing soft rock tunnels, but the research on the excavation and support time is still insufficient. In this study, the causes and failure mechanism of the large deformation in the Dongmachang I tunnel were investigated from the geostress field and the surrounding rock conditions. The supporting mechanism of the single and double primary supports in a tunnel and the deformation laws of different bench excavation lengths and support times were analyzed. Based on the Burgers model, creep materials similar to the argillaceous siltstone and materials similar to the concrete and steel arch of the double primary support were designed. The effects of the different bench lengths and the second primary support time on tunnel stability were evaluated by model tests. It was shown that increasing the bench length and delaying the second primary support time makes the second primary support safer, but if the bench length was too long or the second primary support time was too late, then the tunnel supporting structure failed. In the model test of this study, a middle bench length of 20.4 m and a second primary support time of 28 days were more satisfactory. [ABSTRACT FROM AUTHOR]

The river levee settlement derived from shield tunnel excavation face instability is an anticipated safety issue. Serious engineering safety hazards may occur if it is not restricted. Thus, this study selected six influence indicators to quantify the stability level of the excavation face using the AHP-Fuzzy method. A database of the levee settlement prediction indicators containing tunneling speed, supporting pressure, grouting pressure, horizontal distance, lagging distance, and stability coefficient of excavation face was built by collecting 60 samples from a river-crossing shield tunnel project in China. Five models were carried out for predicting the levee settlement, i.e., modified Peck formula, RF, SVM, BPNN, and PSO-BPNN. Their prediction performance was verified by comparing the prediction results with the measured ones in a shield tunnel engineering application. The analytical results indicated that the PSO-BPNN model has the highest correlation coefficient, i.e., 0.8831(in training) and 0.8657(in testing) and the lowest error, i.e., RMSE = 1.901, and MAE = 0.8412, respectively. Thus the PSO-BPNN model has the best ability to capture the nonlinear relationship between the independent and dependent variables compared with the abilities of the RF, SVM, and BPNN model in this case study. The modified Peck formula performed unsatisfactory results (RMSE = 3.2588, MAE = 3.1172). The correlation analysis results of the input characteristic parameters of the model also indicate that the stability of the levee settlement is significantly related to the excavation face stability. The results indicate that the hybrid model is a very useful and powerful means to investigate the levee settlement caused by shield tunneling and can be improved by gathering more data from tunneling operations over time. [ABSTRACT FROM AUTHOR]

Southern China is characterized by widespread karst landforms, which pose a significant threat to the safety of underground construction. This study focuses on the excavation of a metro-station in sandy soils, taking into account the existence of underlying karst caves. Three-dimensional nonlinear finite element analysis (FEA) is employed to investigate the excavation-induced impact on the surrounding ground and structures. The FEA models are validated through comparison with field data. A series of studies are conducted to analyze the impact of support structure reinforcement and various distributions of karst on excavation. This study reveals that (1) reinforcement measures significantly reduce ground surface settlement and lateral displacement of diaphragm walls, while also shifting the maximum wall displacement closer to the excavation face; (2) at different depths, karst at Z=25 m (rock layer) and Z=14 m (soil layer) have the most pronounced impact on ground settlement, with karst at Z=25 m also affecting the wall moment significantly; (3) karst formations within the excavation pit and near the diaphragm wall in the rock layer have the most substantial influence on the lateral deformation of diaphragm wall. Notably, karst on the inner side of the diaphragm wall within the rock layer has the greatest influence on wall moment. The research results can provide guidance for further exploring the influence of karst caves distribution on excavation of foundation pit. [ABSTRACT FROM AUTHOR]

In the past, the number of CPU cores/threads was usually less than 8/16; now, the maximum number is 128/256. As a CPU-based parallel method, OpenMP has an increasing advantage with the increase in CPU cores and threads. A parallel combined finite-discrete element method (FDEM) for modeling underground excavation and rock reinforcement using OpenMP is implemented. Its computational performance is validated in the two advanced CPUs: AMD Ryzen Threadripper PRO 5995WX (64/128 cores/threads); and 2 × AMD EPYC 7T83 (128/256 cores/threads). Then, its ability in simulating tunnel excavation under rockbolt-shotcrete-grouting support is implemented using the novel solid bolt model, which can explicitly capture the interaction between bolt, grout, and rock. The parallel performance validation of the uniaxial compression test shows: (i) for the speedup ratio, the OpenMP-based parallel FDEM obtains maximum speedup ratios of 30 (33 k elements) and 41 (3304 k elements) on the Threadripper, and 31 and 43 on the 2 × EPYC, respectively; (ii) for the scalability of speedup ratio, when the number of threads used is less than 128, the speedup ratio is always increasing with the increase of the number of threads; (iii) for the stability of speedup ratio, it has a stable speedup ratio, regardless of whether the rock is pre- or post-fractured. Highlights: A parallel FDEM for modeling underground excavation and rock reinforcement using OpenMP is implemented. Its computational efficiency is validated in the two advanced CPUs: AMD Ryzen Threadripper PRO 5995WX; and 2 × AMD EPYC 7T83 (128/256 cores/threads). Its ability in simulating rockbolt-shotcrete-grouting support is implemented using the novel solid bolt model. It obtains maximum speedup ratios of 30 (33 k elements) and 41 (3304 k elements) on the Threadripper, and 31 and 43 on the 2 × EPYC. It has good scalability and stability of speedup ratio, regardless of whether the rock is pre- or post-fractured. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB), which is associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas), is a devastating disease that affects citrus trees worldwide. Because of the pervasiveness of the bacteria and psyllid vector, the disease is considered endemic in Florida. Although the effects of CLas on tree growth and physiology have been investigated for decades, most studies compared infected and noninfected trees under greenhouse conditions. This study used newly planted field-grown ‘Valencia’ sweet orange (Citrus sinensis) trees on two different rootstocks to monitor the distribution and accumulation of CLas in aboveground and belowground tissues following natural psyllid colonization and assess tree physiological responses and biomass reductions under HLB-endemic conditions. Trees were transplanted into the field with individual protective covers (IPCs), which are used to exclude psyllids and prevent infection. Openings were cut in the IPCs of half of the trees; to promote infection, these IPCs were temporarily removed during the main vegetative flushing period when psyllid populations were high. All trees that were exposed to psyllids became infected and displayed the symptoms typically associated with HLB. Throughout the study, higher levels of CLas were detected in the leaves compared with those in the fibrous roots. Trees that were not exposed to psyllids remained noninfected and healthy. After 18 months, a subset of trees was excavated to assess biomass differences between infected and noninfected trees. Infected trees had root system reductions of 37% and shoot system reductions of 20%, thereby significantly reducing the belowground-to-aboveground biomass ratio. Fibrous root loss was 49% and more severe than the loss of the rest of the root tissue. This study is the first to demonstrate the full extent of damage caused by CLas infection under natural HLB-endemic conditions. The results confirm previous observations that suggested fibrous root loss as one of the major consequences of infection and colonization with CLas. They also reinforce the benefits of using IPCs to prevent infection of young citrus trees during the first years of growth in the field. [ABSTRACT FROM AUTHOR]

To estimate the tunnel response induced by a new tunnel excavation underneath, theoretical solutions are proposed in this study. The overlying tunnel is idealized as an infinite Timoshenko beam resting on the Kerr foundation model, then the vertical force balance equation is established. The unloading stress can be expressed as Fourier cosine series and a theoretical solution can be derived. The effectiveness of the proposed method is verified by a centrifuge test and an actual field measurement, which are extracted from previous investigations. Calculation results from the proposed method show good accord to centrifuge test results and field‐measured data. Meantime the predictions given by the proposed method are more accurate to estimate tunnel response compared with the previous method. Parametric analysis indicates that the volume loss ratio and the vertical clearance between two tunnels, are both significantly alleviate the tunnel response, but the effect of tunnel shear stiffness is slight. The theoretical solutions can be adopted to predict the overlying tunnel response induced by tunneling underneath in real projects. [ABSTRACT FROM AUTHOR]

Strut-free retaining walls are an efficient and cost-effective technology for large-scale excavations, but their application at excavation depths of more than 10 m in soft soils has rarely been reported. An innovative multibench retaining system composed of an inclined–vertical framed retaining wall (IVFRW) and a cantilever wall with anchors was used in a 14.7-m-deep excavation in soft clay in Tianjin, China. To analyze the pile–soil interaction considering the influence of the second stepped excavation, indicators were monitored to provide comprehensive measured data. Field measurements included the lateral deflection and vertical displacement of the retaining wall, the ground water level variation, the ground settlement, and the axial force of the piles within the IVFRW. The measured results indicated that the wall displacements and the ground movements caused by the excavations were small in comparison to those of previous projects and empirical formulas. The influence of the second stepped excavation on the soil|structure interaction and its influence on the axial force of the IVFRW were analyzed. The optimal values of the first stepped excavation depth (H1) for different site conditions were further investigated. This case study reports an application of multibench excavation with IVFRW in a 14.7-m excavation in soft soil area. Compared with propped excavations, the multibench excavation with IVFRW has comparable wall deflection while greatly reducing the material consumption and the construction duration. In addition, the amount of pile wall and pile wall length is greatly reduced in comparison to conventional multibench excavations in similar soil condition and excavation depths. This case history provides an economic and efficient strategy for professional engineers to integrate a similar solution in design. During the excavation process, the compressive stress accumulated on the inclined piles within IVFRW restricting the displacement of retaining structure. Due to the second stepped excavation affecting the development of the axial force of the inclined piles, the optimal excavation depth H1/He varies. In engineering design, a width of earth berm should be first determined according to the available workspace. An optimal stepped excavation depth can then be chosen based on this study to achieve the best deformation performance or a minimum material consumption. [ABSTRACT FROM AUTHOR]

Engineering practices indicate that stratum hydraulic conductivity (SHC) has a significant influence on deep excavations. However, this influence has been ignored in previous studies with undrained analyses. In this study, a numerical model, combined with the verified hydromechanical coupled method, is established to investigate the effect of SHCs on the performances of deep excavations. Excavation deformation, pore-water pressure, lateral pressure, and the stress evolution process are presented, respectively, to illustrate these influences. In addition, the model of a beam on an elastic foundation is employed to interpret the influential mechanism of SHCs on excavation deformations. Analysis results indicate that excavation deformations increase significantly with the increase in SHCs from 1 × 10−7 to 1 × 10−5 cm/s (i.e., the range of SHCs of soil containing silt). The influence of SHCs on excavation deformations is mainly attributed to the variation of effective stress levels on the excavated side. As SHC increases, the change in the resultant force of the total stress acting on the retained side of the wall, as loads, can be ignored, while the resultant force of the effective stress acting on the excavated side of the wall, as resistances, decreases dramatically. These findings emphasize the importance of accurate determination of the SHC of strata containing silt. Engineering practices indicate that stratum hydraulic conductivity (SHC) significantly affects the performances of deep excavations in Shanghai soft deposits. Constructions in the first aquitard (AdI) have been involved in the many deep excavations in Shanghai, China, and therefore, identifying the effects of the SHC of AdI on deep excavations can further ensure the safety of constructions. In this study, it is found that excavation deformations increase significantly as the SHC of AdI increases from 1 × 10−7 to 1 × 10−5 cm/s (i.e., the SHCs in soil containing silt). This finding indicates that valuing the SHC of AdI containing silt requires utmost caution, and adopting appropriate methods such as dewatering can significantly decrease excavation deformations. [ABSTRACT FROM AUTHOR]

This study investigates the dynamics of moisture absorption and swelling in soft rock during tunnel excavation, emphasizing the response to support resistance. Utilizing COMSOL numerical simulations, we conduct a comparative analysis of various strength criteria and non-associated flow rules. The results demonstrate that the Mohr–Coulomb criterion combined with the Drucker–Prager model under compressive loads imposes stricter limitations on water absorption and expansion than when paired with the Drucker–Prager model under tensile loads. Restricted rock expansion leads to decreased horizontal displacement and ground uplift, increased displacement in the tunnel's bottom arch, and significantly reduced displacement in the top arch. The study also considers the effects of shear dilation, burial depth, and support resistance on the stress and displacement of the surrounding rock. Increased shear dilation angles correlate with greater rock expansion, resulting in increased horizontal displacement and ground uplift. The research study concludes that support resistance is critical in limiting the movement of the tunnel's bottom arch and impacting the stability of the surrounding rock. Additionally, the extent of rock damage during the excavation of expansive soft rock tunnels is found to be minimal. Overall, this study provides valuable insights into the processes of soft rock tunnel excavation and contributes to the development of more efficient support systems. [ABSTRACT FROM AUTHOR]

In urban areas with limited underground space, the new tunnel construction introduces additional loads and displacements to existing tunnels, raising serious safety concerns. These concerns become particularly pronounced in the case of closely undercrossing excavation at zero-distance. The conventional elastic foundation beam model, which assumes constant reaction coefficients for the subgrade, fails to account for foundation loss. In this study, the existing tunnel is modeled as an Euler-Bernoulli beam supported by the Pasternak elastic foundation, and the foundation loss caused by zero-distance undercrossing excavations is considered. Furthermore, an analytical solution is proposed to evaluate the mechanical response in segments, by establishing governing differential equations and boundary conditions for the excavation and neutral zones, and underpinning loads are also considered. The analytical solution is validated in two case studies. Finally, a parametric analysis is performed to explore the influence of various parameters on the mechanical response of the existing tunnel. [ABSTRACT FROM AUTHOR]

The study presents state-of-the-art requirements verification process for the prediction of the stability of the multi-staged deep excavation in submerged soft soil retained by stell sheet pile walls structures applied at the development of elasto-plastic finite element calculation method performed from Cast3M and Plaxis FE codes. Optimization numerical calculation results are proposed for retained walls design and construction on the basis of the horizontal displacement, earth and water pressures measurements. The transformation of the geometry and stiffness of the stell sheet pile walls to the retaining walls of an equivalent bending stiffness on the one hand and regular geometric shapes allowed in this paper to overcome the difficulties of modelling these stell sheet pile walls in 2D with irregular shapes. The horizontal deflection of the wall, the vertical displacement behind the walls, and the settlement of the excavation bottom are given. They have been compared by those obtained by various authors around the world. The results of this approach are satisfactory in view of the horizontal displacement curves obtained on the stell sheet pile walls compared by the measures. [ABSTRACT FROM AUTHOR]

The Southbank Place project comprised the redevelopment of the UK headquarters of the Shell Company (formerly known as the Shell Centre) in the Waterloo area of London. The project included the demolition of all structures within the site except for the iconic tower building, local extension of the existing basement and the construction of eight new mixed-use buildings. London Underground's (LU) Bakerloo Line and Northern Line running tunnels pass beneath the site. The excavation of the basement and construction of the Shell Centre in the late 1950s caused movements of the underlying Bakerloo Line tunnels that were much larger than expected. The monitoring of these tunnels between 1958 and 1995 has provided a classic case history for the behaviour of London Clay. The proposed redevelopment offered an opportunity to analyse and monitor the behaviour of LU tunnels over a period of 60 years and two phases of significant construction. This paper presents a back-analysis of the historical monitoring of the Bakerloo Line tunnels and the calibration of a sophisticated finite-element model. The model was subsequently used to predict the impact of the redevelopment on the tunnels as part of the assurance procedure with LU. [ABSTRACT FROM AUTHOR]

Bumble bees are known to be amongst the most efficient natural pollinators and their increased scarcity in the ecosystem has led us to study their habitat and ethological preferences, so that future efforts can be designed for their restoration under the natural habitat. The present investigation explores the natural nest architecture, structural features of nest habitat, location of the nest, environmental parameters, population dynamics, emergence of drones, gynes, and variation in the sex ratio of Bombus haemorrhodalis. A total of ten natural nests were excavated at different altitudes ranging from 473.05 to 1258.52 m from different sites in two locations Nauni and Gandhal. The species inhabited the underground abandoned rodent's cavities as nests at a depth of 15 cm to 140 cm with 1–2 external hidden entrances or below ground covered with involucrum made of small dried grass, leaves, pine needles, paper infused on/with wax, etc. The shape of the nest varied from circular to oval with an average size of about 3.88 cubic decimeters. The colony strength of all excavated nests ranged between 15 and 113 individuals, with average internal ambient temperature and relative humidity of the nest cavity varying from 20.9–29.7 °C and 24.6–79.3 percent, respectively. The honey storage (length x width; 16.02 × 15.74 mm), queen (15.02 × 14.60 mm), worker (13.25 × 12.58 mm) and drone cells (11.13 mm × 10.45 mm) varied in dimensions and were constructed by the workers with colony development. As a potential natural strategy to ensure survival, the gynes emerged earlier and higher in number than drones in late summer to early autumn and this progeny survived until the end of autumn. The current study exploring the natural environment of B. haemorrhoidalis helps understand and correlate the natural nest characteristics with laboratory-reared colonies for year-round rearing. [ABSTRACT FROM AUTHOR]

The excavation method has significant effects on the response of piles, and post-grouting is a great way to improve the response of piles. In this research, field static load tests were performed on three large-diameter and superlong rock-socketed bored piles (LSRBPs) of superhigh-rise constructions. The effects of composite excavation and combined grouting on the response of LSRBPs were studied. The improved effects of combined grouting on LSRBPs that were drilled by composite excavation were discussed. The results indicate that the composite excavation improves construction efficiency but affects shaft-forming quality, thus lowering the bearing capacity of LSRBPs, while combined grouting can contain this defect. Despite reducing the original pile size, combined grouting still significantly improves the bearing capacity of LSRBS and reduces the dispersion of bearing capacity. Existing pile design methods overestimate the bearing capacity of LSRBPs constructed using composite excavation, but underestimate it after combined grouting. The composite excavation forms different pile-rock (soil) interfaces, which affects the effectiveness of combined grouting. The simultaneous application of composite excavation and combined grouting reduces design pile size and improves construction efficiency, thereby achieving the goals of cost reduction and low-carbon construction. The findings have significant implications for the construction and design of LSRBPs. [ABSTRACT FROM AUTHOR]

With the increase of burial depth, complex geological conditions such as high in situ stress, high seepage pressure and weak faults bring many adverse effects to the construction of deep tunnels. Taking Xianglushan Tunnel of Yunnan Water Diversion Project as the engineering background, we conduct a three-dimensional geo-mechanical model test under hydro-mechanical coupling to investigate the excavation stability and the supporting control of a deep tunnel crossing a weak fault. The test results reveal that: (1) The fault has adverse effects on the distribution of physical fields. In the fault, the stress of the surrounding rock is in the plastic state; the displacement and seepage pressure are larger. Accordingly, the contact pressure and seepage pressure of the lining become larger. (2) The distribution of contact pressure and seepage pressure on the lining is uneven. The contact pressure of the lining at the vault and the bottom is generally larger than that at the hance. The largest seepage pressure appears at the bottom, while the smallest at the vault. (3) There is a coupling effect between the stress field and the seepage field in the surrounding rock. The stress field affects the seepage field by changing the deformation of the surrounding rock. The seepage field simultaneously acts to the stress field. Test results obtained in this study will provide an experimental basis for further theoretical studies and engineering designs. [ABSTRACT FROM AUTHOR]

In recent decades, East Borneo has become an increasingly important archaeological "hot-spot" in Island Southeast Asia as a result of early dates for rock art ca. 38,000 BP and the greater number of excavated sites that support a much longer period of human occupation. However, the chronology of settlement and adaptation to environmental changes during the Pleistocene–Holocene transition is still poorly known. Here we report on an excavation at the Liang Abu rock shelter which has contexts dating from the Late Pleistocene (12,660 ± 58 uncal. BP) to the present day, indicating a terminus ante quem (TAQ) for human occupation at 23,790 BP. We present the results of an attempt to systematically integrate and compare data from Liang Abu and Kimanis, a geographically close site with a previously published sequence. Particular attention is paid to post-depositional issues in tropical settings and to data compatibility, reuse, and reproducibility, relying on open-source software for data processing (R scripts) and Bayesian chronological modeling. Two Bayesian models are built and compared using the ChronoModel software, which can handle outliers and uncertainty (e.g., freshwater reservoir effect). This first inter-site comparison for Borneo results in a new chronology of human settlement and mainland–coastal interactions in East Borneo and paves the way for future regional synthesis. [ABSTRACT FROM AUTHOR]

The exploration and utilization of water resources on the Moon are of substantial global interest. To utilize lunar resources and construct bases, the construction machinery should travel over the lunar surface (which is mainly covered with powdery regolith) and excavate the regolith. However, various technical issues should be resolved to achieve this efficiently. In this study, a new platform rover was developed, and its motion behavior was analyzed to better understand the traveling and excavation behaviors of construction machinery on the Moon. The rover is a four-track vehicle equipped with a robotic arm consisting of a boom, arm, and bucket. To analyze the rover's motion behavior in sandy terrain, we first developed a simulator based on terramechanics and performed a numerical analysis. Subsequently, various experiments were conducted using the rover in the JAXA Space Exploration Field, which simulates the lunar environment. In the experiments, the rover traveled over level and sloped terrains and excavated the ground. The simulation and experimental results revealed similar trends in the traveling and excavation behaviors of the rover. These results can serve as basic guidelines for the design and operation of construction machinery on the Moon. [ABSTRACT FROM AUTHOR]

During new Austrian tunnelling method excavation, it is necessary to carry out an analysis of the compliance of the actual surfaces with the theoretical lines prescribed in the support types for each tunnel excavation step. With our own software solutions, we created point clouds of the excavation and shotcrete of the primary tunnel support through the automated process of photogrammetric data. Together with the tunnel axis and theoretical profiles, the georeferenced and filtered point clouds were then used in the analysis of the deviation from the theoretical lines of excavation and primary support shotcrete and shotcrete thickness. The final products of the independent analysis are deviation profiles and unwrapped extrados views with numerical results and a color legend. [ABSTRACT FROM AUTHOR]

Segmental lining elements – Full scale test considering optimized force transmission During excavation of a tunnel by means of shield tunnel boring machines, segmental lining elements provide stability for the excavated cavity and act as internal liner. Therefore, it is essential to have knowledge about their structural load‐bearing capacity and performance under specific stress situations. After installation, the segmental lining element is exposed to a variation of loads from the surrounding rock mass. For the full‐scale tests performed at the Montanuniversität Leoben, a combined force application was used to simulate a realistic loading of a segmental lining element. To simulate the normal forces resulting from the circular load carrying behavior in the cross‐section, a force is applied in the horizontal direction at the beginning of the test. After reaching this load value, the vertical force is increased until failure of the element occurs, while the horizontal load is kept constant. Due to the specific segment geometry, a force in the vertical direction is also necessary simultaneously during the loading of the horizontal force in order to prevent buckling of the test specimen. The required force can be determined using a numerical simulation, or as an alternative, the vertical force can be determined in a simplified form by means of conventional static calculation, which is demonstrated in the present paper. Different considerations are shown and compared. [ABSTRACT FROM AUTHOR]

The inclined retaining wall has been demonstrated to be an effective and efficient retaining structure for limiting deformation during excavations. However, a design method regarding wall deformation and soil movement of excavations with inclined retaining walls is lacking. The mobilizable strength design (MSD) method has been used to provide reasonable deformation results for excavations with cantilever retaining walls. The deformation of an excavation is calculated based on the moment equilibrium of the strain field, and the deforming regions are divided by straight zero-extension lines (ZELs). The boundary of the deforming region of an inclined retaining wall is observed to be curved by performing centrifuge tests. Hence, a logarithmic spiral-type function of the ZEL is fitted to the generated numerical data. Based on the fitted function of the ZEL trajectory, the stress distribution on the retained side of the inclined retaining wall is modified, and the wall deformation is calculated within the framework of the MSD. Finally, the soil movement vectors at the ground surface, deduced by the fitted ZEL function and calculated wall deformation, are used to evaluate the influence of excavation on adjacent buildings. [ABSTRACT FROM AUTHOR]

Chiaia station is one of the art stations of Line 6 of the Naples underground network; it was constructed in a 50-m-deep excavation, a few meters from historic buildings and 4.5 m from the main façade of a sixteenth-century Basilica. The excavation, carried out partially in loose to medium dense sands overlying the soft rock formation of Neapolitan Yellow Tuff (NYT), was supported by a retaining wall made of contiguous bored piles braced with internal struts and prestressed ground anchors. The excavation sequence was quite complex due to archeological findings and to the presence of anthropic cavities used over the centuries to quarry NYT blocks. One of the key goals of the design was to limit movements around the shaft to prevent damage in the historical buildings. Long-term monitoring data obtained during nearly 9 years confirm the success of the overall construction process. A rather complex three-dimensional (3D) finite-element model with constitutive relationships for both the upper sandy layers and the soft rock is presented in the paper; this model was adopted to back-analyze the data from the monitoring and explore the influence of some of the key features of the case study. The role of the building bending and shear stiffness, of the soft rock stiffness, and of further apparently minor issues—such as the seepage and the ground anchors' prestress—were investigated and discussed with the support of the model calculations. Observed settlements at the end of the excavation were in the range 10–15 mm, and in the long term they increased by 20%–50% to as much as 20 mm. The deflection ratios were very small, in the range 0.05‰–0.15‰ , and no visible damages to the buildings were recorded. These values were reproduced by the finite-element model only after the introduction of the relevant building stiffness. [ABSTRACT FROM AUTHOR]

An extended ordinary state-based peridynamic model was developed to investigate the crack propagation of surrounding rock due to tunnel excavation. The frost heave effect on the crack surface was described by an equivalent pressure density. Two numerical examples were conducted to verify the effectiveness and robustness of the proposed model. Moreover, the influence of frost heave pressure, buried depth and rock elastic modulus on damage characteristics of the surrounding rock was investigated. The results demonstrate that massive microcrack damage will be formed at the invert when the tunnel is excavated in a deeply buried rock mass or soft rock stratum. A peridynamic model of rock mass under excavation and frost heave was constructed. Damage characteristics of surrounding rock could be simulated efficiently. Frost heave load was exerted on the crack surface by an equivalent pressure density. The effects of frost heave load, buried depth and rock elastic modulus were studied. [ABSTRACT FROM AUTHOR]

This document serves as a closure to a previous article on the effect of ground improvement on basal heave stability in deep excavations. It includes a discussion by Ye Lu, who questions the reliability of the numerical simulation results and suggests using a more advanced soil model. The closure also acknowledges that the deformation analysis may not be accurate and discusses the undrained modulus and Poisson's ratio for the excavation problem. The document further explores ground movement patterns and mechanisms of ground improvement, emphasizing the role of ground improvement in reducing basal heave and increasing soil stiffness. The authors agree with the points raised by the discusser and provide additional analysis and validation of the proposed methods. [Extracted from the article]

This document discusses a research paper that proposes a modified method for evaluating the stability of deep excavations in soft clays. The discussion raises concerns about the proposed method and questions the assumptions made by the authors. It suggests alternative explanations for the observed behavior of excavations in soft clays and criticizes the models used in the study for not accurately representing actual ground movement patterns caused by excavation. The author invites the study authors to respond to these criticisms. [Extracted from the article]

Shanghai clay exhibits overconsolidation, soil structural, and small-strain characteristics. While there have been several studies on the effects of small-strain characteristics on the deformation caused by deep excavation, the effects of overconsolidation and structural behaviors on this deformation remain unexplored. Therefore, in this study, a constitutive model considering the aforementioned three characteristics is developed and then implemented in the commercial software program FLAC3D (version 7.00) to investigate the effects of overconsolidation and structural behaviors. Initially, validation and parametric study of the constitutive model are conducted based on a cylindrical numerical model. Subsequently, the constitutive model is validated by a well-documented case history of a deep excavation in Shanghai. Thereafter, the effects of overconsolidation and structural behaviors on wall deflection and ground settlement induced by deep excavation are investigated. It is observed that overconsolidation has a significant effect on the deformation induced by deep excavation, while the effect of soil structure is negligible. With an increase in excavation depth, the effect of overconsolidation on the deformation increases, and its effect on ground settlement is more significant than that on wall deflection. According to the results of the parametric study, it is revealed that by the time the shear strain induced by deep excavation reaches a maximum value, overconsolidation has partially degraded while soil structure has not yet collapsed, which accounts for the magnitude of the aforementioned effects induced by deep excavation. [ABSTRACT FROM AUTHOR]

Excavations of foundation pits around tunnels can induce alterations in stress and deformation within the tunnel, thereby influencing the safety of pre-existing tunnels, especially those with curved tunnel segments. This study focuses on investigating the effects of excavation processes and diverse construction methods on underlying curved tunnels, including excavation sequencing, reinforcement techniques, and support strategies. The efficacy of different construction methods in controlling deformation was assessed by a numerical analysis using finite difference software. The results show that adopting a skip excavation approach, positioned at a distance three times that of the excavation width, effectively diminishes heaving at the foundation pit bottom. In situations where tunnels intersect foundation pits at small angles, the generation of the hoop effect through intermittent reinforcement minimizes lateral extrusion forces, thereby enhancing control over both vertical and horizontal deformation of the curved tunnel. Deformation control within the tunnel, ranked from the least to the most effective, includes configurations of discontinuous reinforcement without a bottom plate, discontinuous main reinforcement, no reinforcement, damaged lining with discontinuous reinforcement, discontinuous reinforcement, and portal reinforcement. Moreover, the incorporation of a bottom plate in conjunction with discontinuous reinforcement methods proves efficient in restraining tunnel heave within safety limits. This study provides insights into safeguarding curved tunnels during irregular foundation pit excavation, offering potential time and cost savings through improved protective measures. [ABSTRACT FROM AUTHOR]

There has been limited research conducted to date on the role and significance of soil parameters in an unsaturated state on the amount of deformation and safety of reinforced deep urban excavations. This study investigates stress–deformations and static/pseudostatic safety factors against the general failure of an anchored deep excavated wall in an unsaturated soil deposit through two-dimensional finite-element modeling and limit equilibrium analysis, respectively. A suction-dependent elastic–plastic Mohr-Coulomb model is used in the analyses considering the effective stress approach in unsaturated soils. The results obtained from numerical modeling are validated against field monitoring data, including wall deformations and tensile forces in the anchors. A series of parametric studies are then performed assuming different groundwater levels, surcharge loads, and surcharge load distances from the wall crest to investigate their effects on the stability and deformation of the unsaturated soil excavation. Results are compared with those obtained from the corresponding routine analyses, in which the unsaturated state of the soil is not considered. The parametric study shows that the depth of the groundwater table is more influential on the results compared with the intensity and location of the surcharge load. The study demonstrates that unsaturated soil conditions result in a reduction of up to 37% in the maximum horizontal deformations of the excavation and increase the static and pseudostatic safety factors against general failure by 28% and 19%, respectively. In addition, taking unsaturated soil conditions into account during analysis leads to a decrease of up to 31% in the estimated tensile forces in the anchors. More importantly, it is shown that a more cost-effective stabilization plan can be developed for deep urban excavations by considering soil unsaturation effects, as demonstrated by comparing the results of the numerical analyses with the field data. Practical Applications: Presenting a safe and economically feasible plan for stabilizing deep urban excavations is a significant challenge for geotechnical engineers. Traditionally, engineers have relied on classical methods that consider soil parameters under dry or saturated conditions. However, in practice, the soil above the water table is unsaturated, and its mechanical properties are greatly influenced by the saturation level. Contrary to common belief, rainfall or pipe leakage near an excavation site does not fully saturate the soil and eliminate suction effects. Previous studies have shown that percolation from rainfall or other factors does not completely infiltrate clay-rich soils, mainly affecting moisture content and suction at shallow depths. This study evaluates the stress–strain behavior and the factor of safety against sliding in a deep excavated wall in Tehran, Iran, by considering unsaturated soil parameters. Comparing the outcomes with conventional methodologies, the results demonstrate that incorporating unsaturated soil parameters provides more accurate results aligned with field observations. This approach also results in smaller displacements of the excavation wall and higher safety factors against wall sliding. Accordingly, incorporating unsaturated soil parameters ensures accurate safety assessments for urban excavation walls and enables the creation of cost-effective and optimized design suggestions. [ABSTRACT FROM AUTHOR]

China, situated in the circum-Pacific seismic belt, experiences frequent seismic activity and faces diverse geological conditions, making structural stability of paramount importance, especially under seismic conditions. The majority of current earthquake generation methods do not consider the nonstationary nature of earthquakes. This paper introduces a spectral representation-random function model for generating nonstationary earthquakes, effectively simulating stochastic seismic ground motion. Furthermore, traditional slope stability analysis methods are deterministic and incapable of providing probabilistic assessments of slope instability. Therefore, this paper proposes a unified framework for static and dynamic structural reliability analysis based on the direct probability integration method, quantifying the impact of stochastic seismic ground motion on the dynamic reliability of slope stability. Finally, the proposed methods are applied to an excavation slope in Nanjing, using sliding displacement and safety factors as evaluation criteria to study the reliability of the slope under the influence of stochastic seismic events. [ABSTRACT FROM AUTHOR]

The construction of super large section (SLS) shallow buried tunnels involves challenges related to their large span, high flat rate, and complex construction process. Selecting an appropriate excavation method is crucial for ensuring stability, controlling costs, and managing the construction timeline. This study focuses on the selection of excavation methods and the mechanical responses of SLS tunnels in different types of surrounding rock. The research is based on the Yangjiashan tunnel project in Zhejiang Province, China, which is a four-line highway tunnel with a span of 21.3 m. Three sequential excavation methods were proposed and simulated using the three-dimensional finite difference method: the "upper first and lower later" side drift (SD) method, the central diaphragm method, and the top heading and bench (HB) method. The mechanical response characteristics of tunnel construction under these methods were investigated, including rock deformation, rock pressure, and the internal forces acting on the primary support. By comparing the performance of the three construction methods in rock masses of Grades III to V, the study aimed to determine the optimal construction method for SLS tunnels considering factors such as safety, cost, and schedule. Field tests were conducted to evaluate the effectiveness of the optimized construction scheme. The results of the field monitoring indicated that the "upper first and lower later" SD method in Grade V rock mass and the HB method in Grade III to IV rock mass are feasible and cost-effective under certain conditions. The research findings provide valuable insights for the design and construction of SLS tunnels in complex conditions, serving as a reference for engineers and project managers. [ABSTRACT FROM AUTHOR]

It is essential to establish a digital twin scene, which helps to depict the dynamically changing geographical environment accurately. Digital twins could improve the refined management level of intelligent tunnel construction; however, research on geographical twin models primarily focuses on modeling and visual description, which has low analysis efficiency. This paper proposes a knowledge-guided intelligent analysis method for the geometric deformation of tunnel excavation profile twins. Firstly, a dynamic data-driven knowledge graph of tunnel excavation twin scenes was constructed to describe tunnel excavation profile twin scenes accurately. Secondly, an intelligent diagnosis algorithm for geometric deformation of tunnel excavation contour twins was designed by knowledge guidance. Thirdly, multiple visual variables were jointly used to support scene fusion visualization of tunnel excavation profile twin scenes. Finally, a case was selected to implement the experimental analysis. The experimental results demonstrate that the method in this article can achieve an accurate description of objects and their relationships in tunnel excavation twin scenes, which supports rapid geometric deformation analysis of the tunnel excavation profile twin. The speed of geometric deformation diagnosis is increased by more than 90% and the cognitive efficiency is improved by 70%. The complexity and difficulty of the deformation analysis operation are reduced, and the diagnostic analysis ability and standardization of the geographic digital twin model are effectively improved. [ABSTRACT FROM AUTHOR]

The site of Jebel Moya, situated in the center of the southern Gezira Plain in southcentral Sudan, has an occupational sequence spanning at least five millennia until around 2000 years ago. Renewed excavation is shedding new light on its occupational chronology and socioeconomic history, including activities such as burial, savanna herding, and domesticated sorghum cultivation practices dating to at least the mid-third millennium BC. In the present study, predominantly final phase pottery sherds from the first millennium BC to the start of the first millennium AD (Assemblage 3) have been analyzed via a combination of thin section petrography and instrumental geochemistry to determine their raw materials and place of manufacture and reconstruct their manufacturing technology. Organic residue analysis was also conducted to identify the products processed within vessels found at the site. The results suggest the existence of a well-developed local ceramic craft tradition that persisted for over one thousand years. Pots from Assemblage 3 were used to process, store, and consume animal and plant products, thus reinforcing emerging evidence for early agro-pastoral activities. [ABSTRACT FROM AUTHOR]

• Decayed artefacts are especially problematic to remove via archaeological excavation. • Micro-CT scanning soil blocks containing artefacts benefits conservation. • Georefencing tags embedded in the soil blocks enrich the useability of the data. • Information garnered impactful for interpretation and conservation strategies. • Georefenced 3D models derived from micro-CT-data are a powerful resource. The cultural heritage sector has increasingly explored the use of micro-CT (µCT) across numerous projects seeking to better understand past cultures and the materials they have left behind. As such, the role of micro-CT (µCT) is still being developed and projects continue to show novel ways that the technology can be adapted to. The Gjellestad ship, located in Halden (Østfold in Viken), Norway, is dated to the Viking Age and was found in a poor state of preservation. Both organic and metallic materials were deteriorated to the degree that standard excavation methods would have resulted in further damage to, or even the destruction of, these elements. A new approach was needed, and this presented an opportunity to explore the use for µCT as a documentative tool for field archaeology and conservation. As the remaining rivets were too fragile to handle directly, they were removed together with the surrounding matrix as soil blocks. To retain important stratigraphic and position information, a georeferencing system was developed that would be visible to µCT and included within each soil block. This enabled the spatial (re)positioning of the soil blocks by use of 3D GIS and in alongside with other spatial documentation gathered at the time of excavation. The quantity of soil blocks will give us a large dataset to work with and, although we continue to document the soil blocks with µCT, we now can discuss our preliminary results pertaining to the positive impact that µCT has for the documentation, conservation, and reconstruction of cultural heritage. [Display omitted] [ABSTRACT FROM AUTHOR]

This study focuses on the thermal behavior of tunnel boring machines (TBMs) through an in-depth investigation into the temperature distribution of their disc cutters. Utilizing the differential quadrature method (DQM), the research conducts a comprehensive numerical analysis to assess the impact of excavation and geological parameters on disc cutter temperature and wear. The accuracy of the DQM model is validated against the finite difference method (FDM), demonstrating comparative results with reduced computational requirements. The findings indicate a significant correlation between disc cutter temperature and various factors, such as rotational speed, spacing, geological conditions, and material strength. Notably, increased spacing or cutter speed leads to higher temperatures and accelerated cutter wear. Moreover, geological factors, particularly rock strength, influence friction coefficients, affecting disc cutter temperatures significantly. For instance, even a slight increase in cutter spacing results in a substantial 65% rise in cutter consumption, underscoring the relevance of these findings for life cycle assessment (LCA) evaluations across diverse geological and environmental conditions in TBM operations. [ABSTRACT FROM AUTHOR]

This note presents the application of the mobilisable strength design (MSD) method to the monitoring results of the multi-propped excavation in the south area of the British Library Euston, constructed in a highly overconsolidated stiff clay deposit. The MSD method is an energy-based approach (a nonlinear finite-element method for a single-degree-of-freedom soil-wall system) introduced to develop a simplified design methodology that satisfies both ultimate and serviceability limit states. Wall displacement predictions based on the MSD method are compared with considerable field monitoring data. The sensitivity of the method to reasonable variations in input parameters is considered. A spreadsheet and python code demonstrating the MSD analysis from this paper are provided in the online supplement alongside details of the mathematical formulation. [ABSTRACT FROM AUTHOR]

Excavation often results in a decrease in the stability level of natural and manmade slopes. To address this issue, a new reinforcement method––structuralized cementation––has recently been introduced to reinforce coarse-grained soil slopes. However, previous studies have not adequately considered the interaction between excavation and structuralized cementation. Consequently, in this study, a series of centrifuge model tests were conducted to investigate the deformation and failure characteristics of structuralized cemented slopes under excavation conditions. It was found that structuralized cemented slopes exhibit significant progressive failure from bottom to top when subjected to excavation. The depth of the slip surface and the safety limit of the structuralized cemented slope increases with an increase in the extent of the solidification zone. During the failure process, slope deformation occurs inside a limited region that expands toward the interior of the slope. Structuralized cementation induces a nonuniform distribution of displacement direction and increases the dilatancy extent of the potential slip surface. The failure mechanism of structuralized cemented slopes can be explained by the significant coupling processes of deformation localization and local failure, which may also elucidate the variation in the position and shape of the slip surface of the slope from using different cement contents. Structuralized cementation reinforces slopes by weakening and delaying the deformation localization of the slope under excavation conditions. [ABSTRACT FROM AUTHOR]

This paper reports a field case of the excavation of a large-scale basement parallel to twin existing shield-driven tunnels in soft soils. A comprehensive field monitoring program was conducted to measure the performances of the shield tunnels during excavation. The trapezoid-shaped basement with an excavation area of 26,982 m2 was excavated at the side of twin existing shield tunnels using a bottom-up excavation sequence. The tunnel horizontal and vertical displacements, and the tunnel convergence, were extensively measured. Based on field observations, the existing shield tunnels developed horizontal movements toward the excavation side, and settlements in the shield tunnels were observed due to the stress relief of the excavation of the large basement. The tunnel rings within the excavation width generally experienced horizontal elongation as a result of the reduction in the lateral earth pressure because of excavation. During the excavation of the elevator shaft, soil flow occurred, which resulted in a sudden and continuous increase in the tunnel horizontal displacements, tunnel settlements, and tunnel convergences. The down track suffered more serious adverse impacts than the up track, with eight leakages and 61 cracks observed in the down track. The newly induced cracks mainly occurred in a range within the excavation width, and were generally consistent with the distributions of the tunnel horizontal displacement and tunnel convergence. The measured data for the normalized tunnel horizontal and vertical displacements mainly fell between δh/|δhm| = δv/|δvm| − 0.5 and δh/|δhm| = δv/|δvm| + 0.4, and it was difficult to establish a direct linear relationship between them. However, a fairly good relationship between the tunnel convergence and horizontal displacement can be observed, the measured data mainly falling along δc/|δcm| = δh/|δhm|. An approximately linear relationship can be roughly found between the normalized tunnel vertical displacement and the tunnel convergence. The data mainly fell between δc/|δcm| = δv/|δvm| + 0.2 and δc/|δcm| = δv/|δvm| − 0.3. [ABSTRACT FROM AUTHOR]

This paper provides a historical analysis of the peak and demise of the international view on cultural heritage. In the 1980s, cultural internationalism emerged as a conservative reaction against the adoption of the 1970 UNESCO Convention, which organises the restitution and return of stolen cultural properties. Internationalist and cosmopolitan scholars who have claimed that cultural heritage 'belongs to humanity', generally condemned restitution, and pushed back against the ratification of the Convention. The international view on cultural property became traditionally dominant in milieus such as universal museums, antiquity markets and some academic disciplines. However, over the past half-decade, the growing importance of research on provenance has challenged cultural internationalism in two areas. Firstly, research on provenance focused on art and archaeological crime has shown that artefacts allegedly excavated in the past are often the proceeds of recent looting, especially in conflict zones. Secondly, recent studies on historical provenance have revealed that many objects were collected using colonial violence. As a result, developments in criminology, postcolonial history, and indigenous peoples' rights have generally led to the retreat of cosmopolitan narratives on cultural property. Ultimately, this paper highlights that cosmopolitanism in cultural heritage has historically hinged on the imperialist past. [ABSTRACT FROM AUTHOR]