Excavation Project Research Articles

Surrounding Rock Squeezing Classification in Underground Engineering Using a Hybrid Paradigm of Generative Artificial Intelligence and Deep Ensemble Learning

Surrounding rock squeezing is a common geological disaster in underground excavation projects (e.g., TBM tunneling and deep mining), which has adverse effects on construction safety, schedule, and property. To predict the squeezing of the surrounding rock accurately and quickly, this study proposes a hybrid machine learning paradigm that integrates generative artificial intelligence and deep ensemble learning. Specifically, conditional tabular generative adversarial network is devised to solve the problems of data shortage and class imbalance for data augmentation at the data level, and the deep random forest is built based on the augmented data for subsequent squeezing classification. A total of 139 historical squeezing cases are collected worldwide to validate the efficacy of the proposed modeling paradigm. The results reveal that this paradigm achieves a prediction accuracy of 92.86% and a macro F1-score of 0.9292. In particular, the individual F1-scores on strong squeezing and extremely strong squeezing are more than 0.9, with excellent prediction reliability for high-intensity squeezing. Finally, a comparative analysis with traditional machine learning techniques is conducted and the superiority of this paradigm is further verified. This study provides a valuable reference for surrounding rock squeezing classification under a limited data environment.

Interpretable gradient boosting based ensemble learning and African vultures optimization algorithm optimization for estimating deflection induced by excavation

Intelligent construction has become an inevitable trend in the development of the construction industry. In the excavation project, using machine learning methods for early warning can improve construction efficiency and quality and reduce the chances of damage in the excavation process. An interpretable gradient boosting based ensemble learning framework enhanced by the African Vultures Optimization Algorithm (AVOA) was proposed and evaluated in estimating the diaphragm wall deflections induced by excavation. We investigated and compared the performance of machine learning models in predicting deflections induced by excavation based on a database generated by finite element simulations. First, we exploratively analyzed these data to discover the relationship between features. We used several state-of-the-art intelligent models based on gradient boosting and several simple models for model selection. The hyperparameters for all models in evaluation are optimized using AVOA, and then the optimized models are assembled into a unified framework for fairness assessment. The comprehensive evaluation results show that the AVOA-CatBoost built in this paper performs well (RMSE = 1.84, MAE = 1.18, R2 = 0.9993) and cross-validation (RMSE = 2.65 ± 1.54, MAE = 1.17 ± 0.23, R2 = 0.998 ± 0.002). In the end, in order to improve the transparency and usefulness of the model, we constructed an interpretable model from both global and local perspectives.

Hybrid machine learning approach for accurate prediction of the drilling rate index

The drilling rate index (DRI) of rocks is important for optimizing drilling operations, as it informs the choice of appropriate methods and equipment, ultimately improving the efficiency of rock excavation projects. This study presents a hybrid machine learning approach to predict the DRI of rocks accurately. By integrating grey wolf optimization with support vector machine (GWO-SVM), random forest (GWO-RF), and extreme gradient boosting (GWO-XGBoost) models, the aim was to enhance predictive accuracy. Among these, the GWO-XGBoost model exhibited superior predictive performance, achieving a coefficient of determination (R²) of 0.999, mean absolute error (MAE) of 0.00043, root mean square error (RMSE) of 1.98017, and severity index (SI) of 0.0350 during training. Testing results confirmed its accuracy with R² of 0.999, MAE of 0.00038, RMSE of 1.80790, and SI of 0.0312. Furthermore, the GWO-XGBoost model outperformed the other models in terms of precision, recall, f1-score, and multi-class confusion matrix results for each DRI class. The GWO-RF model also demonstrated high accuracy, ranking second, while the GWO-SVM model showed comparatively lower performance. This research aims to advance rock excavation practices by providing a highly accurate and reliable tool for DRI prediction. The results highlight the significant potential of the GWO-XGBoost model in improving DRI predictions, offering valuable intuitions and practical applications in the field.

Analysis of shield tunnel response to bilateral pit excavation with a focus on perimeter pressure and deformation mechanisms

This study aims to investigate the responses of shield tunnel structures subjected to disturbances caused by bilateral pit excavation, and it systematically reveals for the first time the impact mechanism of bilateral pit excavation on the distribution of perimeter pressure and deformation patterns of shield tunnels. Using a bilateral pit excavation project in Nanjing as a case study, this research establishes methods for calculating longitudinal displacement and circumferential pressure of tunnels under bilateral pit excavation conditions, employing the image source method for analysis. A refined three-ring segment model is developed, and the load structure method is used to analyze the impact of deep foundation excavation on the tunnel located between the two excavation sites. The results indicate that, compared to unilateral excavation, bilateral excavation significantly increases the perimeter pressure at the top and bottom of the tunnel, with a smaller increase in pressure at the arch waist. The deformation pattern is characterized by contraction at the top and bottom and expansion at the waist, forming a transverse elliptical deformation. The maximum vertical convergence values of the middle segment ring are 25.00 mm at the top and 25.88 mm at the bottom, with a vertical absolute convergence value of 44.5 mm and a convergence ratio (ΔDt/Dt) of 0.72%. As the foundation coefficient increases, the perimeter pressure at the top and bottom of the tunnel also increases. When the tunnel is closer to the foundation pits (Sp decreases), the perimeter pressure at the bottom of the tunnel increases. Conversely, as the distance between the two foundation pits (S) increases, the impact of excavation on the tunnel shifts from the upper part to the lower part, resulting in decreased upper perimeter pressure and increased lower perimeter pressure. The research findings provide important references for similar engineering projects.

Resilience Assessment of Deep Excavation Engineering Systems Based on Bayesian Network

As a key component of infrastructure, the construction safety of deep excavation is particularly important. In order to improve the safety and stability of Deep excavation construction, research on the risk resistance and rapid recovery capabilities of Deep excavation projects is carried out. By introducing the concept of resilience, we analyze the key factors that affect the safety and resilience of Deep excavation projects, use Bayesian networks to establish a resilience model that expresses the causal relationship between factors, and learn the parameters of the network model through data samples collected through surveys; by adjusting the network Analyze the relationship between each factor and system resilience at each node, and clarify the measures that should be taken and key control objects, thereby improving the system resilience and ensuring that normal construction can be carried out safely and orderly. Research shows that this model can be used to quantify the safety toughness value of deep excavation and reason and analyze the impact of various factors on the toughness value, thereby improving risk management and decision support capabilities.

Archaeological Excavation, Protection, and Display Engineering Design Practice: A Case Study in the Ruins of the Imperial City of the Minyue Kingdom

The Han Dynasty Ruins in Chengcun Village of Wuyishan City, also known as the Ruins of the Imperial City of the Minyue Kingdom, are located on the hilly slope southwest of Chengcun Village, Xingtian Town, Wuyishan City, Fujian Province, China. These are ruins of a Han Dynasty city. Wuyi Mountain’s World Cultural and Natural Heritage Committee declared it a World Heritage Site in 1999. It is also the only imperial city site from the Han Dynasty that has been declared a World Heritage Site in China, and it is the most well-preserved large-scale imperial city site from the Middle Ages on the Pacific Rim. This study used comprehensive archaeological techniques, including archaeological excavation work, site information recording, erosion situation analysis, and geological surveys, to design and implement protective engineering projects in response to existing problems. In this study, the researchers conducted a geological survey of the study area to analyze the topography, rock and soil distribution characteristics, groundwater storage conditions, and geotechnical engineering conditions. At the same time, they explored the preservation status of the site, including the preservation status of the East Gate and the East City Wall, and they analyzed the causes of damage. Finally, the investigation and analysis results guided the design of a site display project, which included safeguarding against collapse and erosion, treating trees and shrubs, and designing the exhibition project for the East Gate. This study provides some practical reference for the excavation and archaeological work of the royal city in the surrounding areas. At the same time, in terms of the technical process of the project, it is also hoped to provide ideas for international ancient city excavation, display, and protection projects.

Fatigue mechanical properties and Kaiser effect characteristics of the saturated weakly cemented sandstone under different loading rate conditions

Weakly cemented sandstone (WCS) is a unique rock type widely distributed on the surface. Environmental factors such as groundwater and stress variations easily influence its fatigue mechanical properties and fracture characteristics. To design and evaluate the long-term stability of surrounding rock support in tunnel excavation and underground resource mining projects, investigating the fatigue mechanical properties and acoustic emission (AE) response characteristics of saturated WCS under different loading rates is of great practical and theoretical significance. This study employed experimental techniques such as X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and natural water absorption tests to investigate the mineral composition, pore size, and connectivity characteristics of WCS. The multi-level cyclic loading-unloading tests (MCLU) combined with the AE system were conducted on dry and saturated WCS specimens at different loading rates. The results reveal that the deformation modulus of these specimens initially increases and then decreases under cyclic loading conditions. Water significantly influences the fatigue strength and deformation resistance of sandstone. As the loading rate increases, the range of RA values broadens, accompanied by a marked increase in the number of AE signals with high RA values. Saturated sandstone specimens are more prone to developing macroscopic shear fracture surfaces. Water has a more substantial effect on the stress distribution ranges corresponding to the response of the Kaiser effect in WCS than loading rates. The capacity of the Kaiser effect to indicate the extent of rock damage is intricately linked to the progression of internal micro-cracks. When internal damage surpasses the critical value of the Kaiser effect memory damage, the accelerated propagation of shear cracks becomes pivotal in the internal damage of the sandstone. It seems that the presence of water within the interior of the rock may facilitate the dissolution of K-feldspar in WCS, which could result in the formation of kaolinite, which will be further transformed into illite. The hydration expansion of illite may further exacerbate the deterioration effect of the mechanical properties of WCS.

Analysis of vibration signals near ground surface during blasting excavation of a tunnel in fractured rock

This study aims to analyze the vibration signals near the ground surface due to the underneath drilling and blasting activities in a fissured rock tunnel. Blasting induced vibration on the ground surface was continuously monitored in a fissured rock tunnel drilling and blasting excavation project in field. Wavelet packet analysis of the vibration signals using Matlab was carried out for signal denoising, differential blasting delay time interval identification, and three-way time-frequency energy analysis. The results show that within a 30 m range from the palm face, the dominant frequency bands of blasting-induced vibrations on the ground surface were concentrated in the range of 0–130 Hz. Two prominent peak frequency bands were identified at 31.25–39.063 Hz (low-frequency band) and 93.75–101.56 Hz (high-frequency band), accounting for 12% of the total energy. Among the three directions of ground surface vibrations, the energy decay was the most significant in the x-direction (tunnel excavation direction), which amounted to 54.29% of the overall energy decay with increasing distance. The energy decay within the 50–80 Hz range was the most pronounced (more than 90%), when the angle between the vibration propagation direction and the fissure or joint direction was 75°. The conclusions provide the insights in the attenuation of blast-induced vibrations in fissured rock and can potentially assist in the design of blasting vibration control.

Enhancing Deep Excavation Optimization: Selection of an Appropriate Constitutive Model

To minimize the impact on nearby structures during deep excavations, choosing an appropriate soil constitutive model for analysis holds significant importance. This study aims to conduct a comparative analysis of various constitutive soil models—namely, the Mohr–Coulomb (MC) model, the hardening soil (HS) model, the hardening soil small strain (HSS) model, and the soft soil (SS) model—to identify the most suitable model for the lacustrine deposit. To implement these models, the soil’s index properties and mechanical behavior were evaluated from undisturbed soil samples. The numerical simulation and verification of these properties were carried out by comparing the laboratory test results with the outcome of the finite element method; the most suitable constitutive soil model for the soil was identified as the HSS model. Upon analyzing the wall deflection and ground settlement profiles obtained from respective constitutive models, it was observed that the HS and HSS models exhibit similar characteristics and are well-suited for analyzing typical lacustrine soil. In contrast, the MC and SS models yield overly optimistic results with lower wall deflection and ground settlement and fail to predict realistic soil behavior. As a result, this research highlights the significance of selecting the appropriate constitutive soil model and refining the parameters. This optimization process contributes significantly to the design of support systems, enhancing construction efficiency and ensuring overall safety in deep excavation projects.

Impact of polycarboxylate superplasticizer dosage on controlled low strength material flowability and bleeding: Insights from water film thickness

Civil excavation projects frequently yield substantial excess spoil, posing challenges to sustainable construction. This study explores repurposing such spoil for creating controlled low strength material (CLSM), emphasizing the novel use of polycarboxylate superplasticizer (PCE) to reduce the water requirement. The work also distinctively utilizes water film thickness (WFT) theory to elucidate the effects of PCE dosage and WFT on material properties, thereby advancing CLSM mix design. First, using an experimental approach, a series of fresh CLSM samples are prepared, with varying the water-to-solid ratio (W/S) and PCE dosage, to evaluate their packing density, WFT, flowability, and bleeding rate. It is demonstrated that both packing density and WFT experienced a non-linear increase with rising PCE dosage. Regression analysis of the experimental data reveals that the flowability and bleeding rate linearly increase with the rising WFT, and the enhancements are more pronounced at higher PCE dosage. Notably, at a given WFT, the impact of PCE dosage on flowability and bleeding rate reduce as WFT decreases. Additionally, the research identifies specific WFT thresholds correlating with maximum flowability and a 5% bleeding rate. These thresholds mark the critical point at which WFT ceases to influence flowability and delineate the maximum WFT that satisfies the bleeding rate requirements, respectively. These insights are important for optimizing the design of CLSM with PCE in terms of flowability and bleeding rate.

A spatiotemporal data mining method for advanced prediction and assessment of large combined excavation-induced wall deformations and risks

A holistic and precise assessment of retaining wall deformations is critical for on-site risk management of large combined deep excavation projects, where the risk-related points are highly dispersed, evolving, and interacting. Despite extensive exploration of this topic in previous studies, the omission of intricate spatiotemporal characteristics of wall deformations has resulted in diminished prediction accuracy and stability. To mitigate this deficiency, a spatiotemporal characteristics matrix for all data points and time series was first generated for a deep excavation scenario and used as input for a new hybrid model that combines convolutional neural network (CNN) and long short-term memory (LSTM) with incorporated attention mechanism (CNN-LSTM-Att), which enables the cross-learning mechanism and improves interpretability. In addition, by leveraging the attention weight, a new risk assessment index for retaining wall deformations across various scenarios was formulated. Then the proposed method was applied in a large combined deep excavation in Shanghai, China. The results show that: (1) The incorporation of fed-in characteristic data and the attention mechanism enables the proposed method to produce satisfactory prediction results for the holistic spatiotemporal distribution of a large combined excavation; (2) Compared with other published models, the proposed model shows much better prediction accuracy, interpretability, and stability, especially in medium- and long-term predictions; and (3) The new risk assessment index serves as a reliable decision-making tool for assessing the risk evolution of retaining wall deformations and provides valuable guidance for effective risk management in multi-scenario excavation projects.

Creating P’yŏngyang’s Legitimacy: North Korea's Excavation and Reconstruction of the Tomb of King Tongmyŏng

This paper traces the trajectory of North Korea’s historiography on ancient history, examining the political and social contexts surrounding the excavation (1974) and renovation (1993) of the Tomb of King Tongmyŏng. The 1974 excavation was a political project aimed at deepening the understanding of ancient history centered on Koguryŏ, an ancient kingdom whose capital was in P’yŏngyang along the Daedong River. The 1972 constitution, which established P’yŏngyang as the capital and proclaimed the Juche ideology, was a driving force behind this project. Over time, the P’yŏngyang-centric viewpoint on ancient history grew stronger, culminating in the excavation and renovation projects in the early 1990s of the tombs of Tan’gun, Tongmyŏng, and Wang Kŏn. The assertion that the legitimacy of Korean history is rooted in P’yŏngyang was used to justify North Korea’s own legitimacy, a concept this paper refers to as the "Principle of P’yŏngyang Legitimacy." In this context, the projects involving the tombs of Tan’gun and Wang Kŏn should be understood as extensions of the renovation of the Tomb of King Tongmyŏng, which had been underway since the late 1980s. In other words, the series of excavations and renovations of the tombs of the founding kings in the early 1990s originated from the Tomb of King Tongmyŏng, which, in turn, inspired the emergence of the "Principle of P’yŏngyang Legitimacy." This legitimacy is constructed as a linear genealogy belonging to a single subject, which is endowed with a legitimate self-identity, while entities outside this narrative are systematically excluded. The evolution and application of the "Principle of P’yŏngyang Legitimacy" serve as a caution against the politicization of history in South Korea’s historical research programs.

Analysis of water inrush of a deep excavation triggered by river bank failure and its reconstruction

Many deep excavation projects are adjacent to river, and hence face the seepage risk. In this study, a through-wall seepage failure of a foundation pit adjacent to river is investigated. It is found that, the accident was initiated by the breakage of revetment along the construction joint and cracks of rubble stone masonry, which further caused the slope failure of river bank and the subsequent seepage of river water through the cold joint of waterproof curtain. The remedial works including construction of cofferdam in the river, backfill outside the foundation pit, reinforcement of cold joint, backfill inside the foundation pit, controllable dewatering outside the foundation pit and axial force adjustment of struts are designed. The monitoring results indicate effective implementation of the remedial works and the following successful reconstruction of the project. A summary of reported seepage failure cases adjacent to river is finally made to provide suggestions for the design and construction of future similar deep excavation projects.

Dynamically documenting archaeological excavations based on 3D modeling: a case study of the excavation of the #3 fossil of hominin cranium from Yunxian, Hubei, China

Documenting tangible cultural heritage using 3D modeling techniques is gradually becoming an indispensable component of archaeological practice. The 3D modeling techniques based on photogrammetry and LiDAR scanning enable high-accuracy and high-realistic reconstruction of archaeological sites, and have been proven a powerful tool for documenting archaeological excavations. However, dynamically documenting an ongoing excavation using these techniques is still considered tedious, time-consuming, expensive, and dependent on expertise. Moreover, the application of 3D modeling techniques in archaeological excavations still faces some technical challenges, such as modeling with multi-source and multi-scale data, fusing local models at different times into a whole, achieving fast modeling while GPU workstations are not available in the field, and evaluating the quality of 3D models. As a result, there are still very few archaeological teams deeply engaged in dynamic documentation with 3D modeling techniques, and traditional drawing sketches and taking photographs still dominate. In these senses, documenting the archaeological excavation at the Yunxian Man site (located in Hubei, China) is an invaluable opportunity for exploration and practice. Archaeologists determined to conduct dynamically documenting at the beginning of the 6th excavation project for the site, and established a rotation system to reconcile physical excavation with digital preservation. Through repeated practice and communication, we proposed a workflow and pursued several new methods to enhance the feasibility of dynamically documenting, and obtained 4D models of the ongoing archaeological excavations. In 2022, the Yunxian Man site unearthed the most intact fossil of hominin cranium from about one million years ago in the Eurasian continent, preserving important and scarce anatomical features of early humans in Asia. As the original taphonomic context of the fossil corroded away during physical excavations, the digital documentation consisting of 4D models serves as permanent original data source in subsequent archaeological research. Moreover, we obtained cross-scale 3D models from geographical environment to archaeological site, excavation area, and cultural remains, and all of these 3D models are in an actual, unified coordinate framework. Thus, we can contribute to multidisciplinary cross-collaborative research through data sharing. Considering that digital documentations serve a great value in archaeological research, this paper focuses on sharing the workflow and methods to facilitate digital preservation for more archaeological projects.

A Standard Penetration Test-Based Step-by-Step Inverse Method for the Constitutive Model Parameters of the Numerical Simulation of Braced Excavation

Numerical simulation is an essential method for predicting soil deformation caused by foundation pit excavation. Its accuracy relies on the constitutive model and its parameters. However, obtaining these parameters through lab tests has limitations like long durations, high costs, and potential errors. To improve the simplicity and accuracy of the selection of constitutive model parameters, this study proposes a step-by-step inverse analytical method. Using the braced excavation project in Hangzhou City, China as a case study, the proposed method firstly determines the ratio of the important constitutive parameters then the values of the key constitutive parameters. The results show that the reference secant stiffness (E50ref) and shear strain (γ0.7) of the hardening soil (HS) and hardening soil–small soil (HSS) models are the key constitutive parameters. The step-by-step inverse method not only reduces the number of parameters, but also improves the predicting accuracy. The established empirical relationship between the E50ref and standard penetration test (SPT) blow counts exhibits a good linear correlation. The parameter selection method proposed in this study is an accurate, practical, and efficient method, which can effectively predict the horizontal displacement and surface settlement of the retaining structure in multiple excavation stages.

Fuzzy Cognitive Map for Evaluating Critical Factors Causing Rockbursts in Underground Construction: A Fundamental Study

The rockburst phenomenon in excavation endeavours reveals a multitude of complexities and obstacles that significantly impact both the technical and financial dimensions of project execution. Investigating critical rockburst factors in underground excavations is of considerable importance for addressing pivotal safety issues and operational complexities within the field of underground excavation projects. This research proposes an innovative approach based on an expert-based fuzzy cognitive map (FCM) framework, aiming to identify and prioritize the key critical rockburst factors prevalent in underground excavations and tunnelling. A tailored cognitive map of the parameters of problem was constructed, integrating 56 critical and critical factors meticulously curated by a team of seasoned managers, engineers, deputy managers, trainee engineers and assistant managers. The structured cognitive map was meticulously developed, considering the relative weights of the identified critical factors and their intricate interrelationships—all informed by the invaluable insights and expertise of seasoned engineers in the field. Subsequently, the cognitive map underwent a systematic solution process, whereby the causal relationships and influences amongst the identified critical factors were analysed and factored in. The outcomes of the comprehensive analysis unveiled several critical factors: lack of rockburst risk assessments, high in situ stress, presence of rock seams and weak layers, rock quality variations, and geological heterogeneity as the most paramount concerns demanding immediate attention and strategic intervention. By adopting the proposed FCM approach and leveraging the collective expertise of industry professionals, this research offers a robust and systematic framework for comprehensively assessing and addressing the key challenges associated with rockburst events in underground excavations and tunnelling projects, thereby fostering enhanced project performance and efficacy within the field.

A deep transfer learning model for the deformation of braced excavations with limited monitoring data

The current deep learning models for braced excavation cannot predict deformation from the beginning of excavation due to the need for a substantial corpus of sufficient historical data for training purposes. To address this issue, this study proposes a transfer learning model based on a sequence-to-sequence two-dimensional (2D) convolutional long short-term memory neural network (S2SCL2D). The model can use the existing data from other adjacent similar excavations to achieve wall deflection prediction once a limited amount of monitoring data from the target excavation has been recorded. In the absence of adjacent excavation data, numerical simulation data from the target project can be employed instead. A weight update strategy is proposed to improve the prediction accuracy by integrating the stochastic gradient masking with an early stopping mechanism. To illustrate the proposed methodology, an excavation project in Hangzhou, China is adopted. The proposed deep transfer learning model, which uses either adjacent excavation data or numerical simulation data as the source domain, shows a significant improvement in performance when compared to the non-transfer learning model. Using the simulation data from the target project even leads to better prediction performance than using the actual monitoring data from other adjacent excavations. The results demonstrate that the proposed model can reasonably predict the deformation with limited data from the target project.

A “shaman” burial from the PPNA settlement of Çemka Höyük, Upper Tigris Basin, Turkiye

Knowledge of the burial customs of the Pre-Pottery Neolithic A (PPNA) in the Near East is increasing. Particularly, lately a large number of burials and skeletal remains have been unearthed in the Upper Tigris Basin, thanks to a number of new excavation projects in recent years. The newly revealed findings indicate that PPNA burial customs varied considerably in the region from site to site. However, the 10th millennium BCE burial ÇH 2019/05 at Çemka Höyük shows as well that there are also different burial practices with in settlements. ÇH 2019/05 belongs to a female individual, accompanied by animal skeletal elements, who appears to may have been a shaman or at least had been buried by someone practicing ways associated with what we understand nowadays as animism or shamanism. Hence, the burial may represent one of the earliest known examples of its kind in an Anatolian Neolithic context.

Direct Field Curve Fitting Method to Determine Hardening Soil Parameter for Geotechnical Projects

Abstract In a wide archipelago country like Indonesia, transporting soil samples for laboratory tests are quite a bit of challenge in terms of cost and time as those need to be transported for weeks to nearest big cities. In-situ tests and correlation methods can be used as an alternative solution for preliminary or detailed design beside having on site laboratory. Correlating in-situ test results to hardening soil parameter (e.g. E 50) is common but it is not clear how those should be adjusted for Plaxis input. Two deep excavation projects and a lateral pile load test are used to see the performance of direct field curve fitting method utilizing SPT correlation to HS parameter. From the analysis, using E 50=4000N for clay soils and E 50=2800N for sand soils as upper bound parameters produce the best results with lesser discrepancy with the field measurements compared to calculations with lower bound parameters. For the deep excavation cases (Case 1 and Case 2), calculated lateral displacement results using upper bound parameters overestimates inclinometers measurement for less than 1.5 cm for both cases. For the case of lateral pile load test (Case 3), calculation using upper bound parameters succeed to capture a high detail of unloading-reloading curves similar to the actual measurement. This method can be used as a technique to design geotechnical projects and it proposes a framework for future research regarding a new possibility to establish various E 50 correlations.

Vegetation response to large-scale mountain excavation and city construction projects on the Loess Plateau of China

Since 2012, the “Mountain Excavation and City Construction” (MECC) project has been implemented extensively on the Loess Plateau of China, transforming gullies into flat land for urban sprawl by leveling loess hilltops to fill in valleys. However, this unprecedented human activity has caused widespread controversy over its unknown potential ecological impacts. Quantitative assessment of the impacts of the MECC project on the vegetation is key to ecological management and restoration. Taking the largest MECC project area on the Loess Plateau, Yan'an New District (YND), as the study area, this study investigated the spatiotemporal pattern of vegetation dynamics before and after the implementation of the MECC project using a multitemporal normalized difference vegetation index (NDVI) time series from 2009 to 2023 and explored the response of vegetation dynamics to the large-scale MECC project. The results showed that the vegetation dynamics in the YND exhibited significant spatial and temporal heterogeneity due to the MECC project, with the vegetation in the project-affected areas showing rapid damage followed by slow recovery. Vegetation damage occurred only in the project-affected area, and 84 % of these areas began recovery within 10 years, indicating the limited impact of the large-scale MECC project on the regional vegetation. The strong correlation between vegetation dynamics and the MECC project suggested that the destruction and recovery of vegetation in the project-affected areas was mainly under anthropogenic control, which highlights the importance of targeted ecological policies. Specifically, the MECC project induced local anthropogenic damage to the plant population structure during the land creation period, but regeneration and rational allocation of the vegetation were achieved through urbanization, gradually forming a new balanced ecological environment. These findings will contribute to a full understanding of the response of vegetation to such large-scale engineering activities and help local governments adopt projects or policies that facilitate vegetation recovery.