Open Excavation Research Articles

Calibration of visual measurement system for excavator manipulator pose

The automatic control of excavator operation trajectories is a pivotal technology for autonomous excavators, with the essential prerequisite being the real-time measurement of manipulator poses. Given the complexity of the operating environment, traditional sensor-based measurement methods face limitations, whereas visual measurement emerges as a promising technique. Accurately measuring excavator manipulator poses involves a crucial aspect: mapping the relationship between image information and poses. First, to address the significant errors in pose prediction encountered with machine learning techniques like artificial neural networks, this work introduces a mathematical model for mapping this relationship, referred to as the pose mapping mathematical model, which includes calibrating model parameters. Second, to address the sensitivity of initial values in the calibration process, we propose a residual-guided initialization algorithm. This algorithm aims to ensure that initial values closely approximate the ground truth values, thus preventing matrix singularity at the source and avoiding parameter estimation divergence. Third, to tackle challenges such as unstable lighting conditions and discrepancies between the dataset and the mathematical model, we introduce the random sample consensus-driven Levenberg–Marquardt parameter optimization algorithm to enhance parameter estimation accuracy. Experiments with static and dynamic online measurement demonstrate that our method reduces pose measurement errors compared to existing methods. This research lays a solid foundation for developing visual measurement techniques for excavators and automated manipulator control based on visual measurements, also serving as a valuable reference for research on mechanical arms.

Study on Influence of Tension Height of Steel Strand on Displacement of Foundation Pit Supported by Fish-bellied beams

The steel support system of prestressed fish-bellied beams can reliably control the deformation of foundation pit and provide open excavation space for foundation pit excavation, in which the triangle plate plays an important role in the fish-bellied beams system. But the deformation of the triangle plate and the steel strand is too large is a common problem in the foundation pit support, through the analysis of the stability of the triangle plate, it is found that the tension point height is an important factor leading to the deformation of too large. Through MIDAS/GEN analysis, it is found that the increase of the tension point height of the strand is conducive to the control of the displacement of the connecting part, and with the increase of the tension point of the strand, the anti-impact stability of the fish-bellied beams system is gradually enhanced. Therefore, by changing the tension height of the steel strand, the supporting system of the fish-bellied beams is optimized.

Analisis Stabilitas Lereng Tambang Nikel Kabupaten Morowali

Central Sulawesi Province is a province that has quite high mining activities, so an evaluation of the stability of open pit slope excavations needs to be carried out to prevent collapses during the exploration process which could result in loss of life. Analysis using the finite element method is one method that can be used to analyze slope deformation and stability during the excavation process. This research simulates excavation of a mine slope in 4 stages with a height of 5 m and a slope of 500. The analysis was carried out based on the results of the N-SPT test at three locations (GT-15617, GT-19125 and GT-19841) which are the slopes with the most extreme slopes. The analysis results show that at GT-15617 the maximum deformation occurred at stage 4 of the excavation at 0.18 m with a safety factor of 1.43, the maximum deformation at the GT-19125 location occurred at stage 4 at 0.21 m with a safety factor of 1.26 and at location GT-19841 maximum deformation occurred at stage 4 of 0.21 with a safety factor of 1.21. The overall safety factor analysis results do not meet the required minimum safety factor criteria.

Construction Mechanical Characteristics of TBM Pilot and Enlargement Method for Ventilation Tunnel of Wuhai Pumped Storage Power Station

Investigating the construction mechanics of a ventilation tunnel using the TBM (Tunnel Boring Machine) pilot and enlargement method with reliable rock mechanics parameters ensures the safety of on-site excavation operations. Leveraging the construction project of the ventilation tunnel at the Wuhai Pumped Storage Power Station, TGP sidewall forecasting was employed to explore the geological conditions within a 50 m range of the tunnel’s side. A systematic study of the construction mechanics of the TBM pilot and enlargement method was conducted, along with corresponding construction recommendations and engineering applications. This research indicates that sidewall forecasting can supplement the deficiencies in geological exploration reports, with excavation revealing conditions consistent with the forecast. Deformation at the interface, including the arch crown and sidewall, mainly concentrates during the construction phase from the completion of full-section excavation to the beginning of expansion. As the working face advances, the upper rock mass within the ventilation tunnel outline experiences tension, with stress concentration in the shoulder and bottom corner rock masses. The plastic zone before expansion primarily concentrates within the ventilation tunnel outline, shifting to the sidewall after expansion, with the left shoulder’s plastic zone depth slightly exceeding that of the right. The proposed method effectively ensures construction safety, and the research findings have valuable implications for similar projects.

Non-invasive detection of mental fatigue in construction equipment operators through geometric measurements of facial features

Introduction: Prolonged operation of construction equipment could lead to mental fatigue, which can increase the chances of human error-related accidents as well as operators’ ill-health. The objective detection of operators' mental fatigue is crucial for reducing accident risk and ensuring operator health. Electroencephalography, photoplethysmography, electrodermal activity, and eye-tracking technology have been used to mitigate this issue. These technologies are invasive and wearable sensors that can cause irritation and discomfort. Geometric measurements of facial features can serve as a noninvasive alternative approach. Its application in detecting mental fatigue of construction equipment operators has not been reported in the literature. Although the application of facial features has been widespread in other domains, such as drivers and other occupation scenarios, their ecological validity for construction excavator operators remains a knowledge gap. Method: This study proposed employing geometric measurements of facial features to detect mental fatigue in construction equipment operators' facial features. In this study, seventeen operators performed excavation operations. Mental fatigue was labeled subjectively and objectively using NASA-TLX scores and EDA values. Based on geometric measurements, facial features (eyebrow, mouth outer, mouth corners, head motion, eye area, and face area) were extracted. Results: The results showed that there was significant difference in the measured metrics for high fatigue compared to low fatigue. Specifically, the most noteworthy variation was for the eye and face area metrics, with mean differences of 45.88% and 26.9%, respectively. Conclusions: The findings showed that geometrical measurements of facial features are a useful, noninvasive approach for detecting the mental fatigue of construction equipment operators.

Performance analysis of hydraulic excavators in complex excavation environments and different bucket trajectories

Simulations of excavation operations not only help understand how excavators perform in specific environments but also can be used to optimise operating parameters. In this work, we explore the performance of hydraulic excavators under conditions of cohesive and size-dispersed materials and different bucket trajectories. The results indicate that with the cohesion increasing, the spillage of particles from the bucket is reduced, but the hydraulic power fluctuates greatly due to the strong collision of particle aggregates on the bucket. As the particle size distribution turns wider, small particles exert an intensive interaction force on the bucket, and the stress distribution on the bucket becomes wider. Therefore, some suggestions are given for practical excavation operations in different stockpile scenarios. Additionally, the bucket can be initially placed close to the base of the stockpile to achieve low specific energy consumption and high productivity.

Bantuan Teknis Perencanaan Dinding Penahan Tanah Pada Warga di Area Rentan Longsor

West Bandung Regency is one of the areas that frequently experiences landslides and landslides. Residents of Cililin Village, which is part of it, have concerns that the slope due to open excavation close to residential houses will have the potential for landslides but do not yet understand how to plan appropriate slope reinforcement. This service activity aims to review the stability of the excavation slopes around residents' houses and then plan a retaining wall that meets safe and stable technical rules. A field survey was carried out to measure the slope geometry and observe the situation around the area. Then slope stability modeling is carried out with input of slope geometry and soil property data. From the analysis results, it was obtained that the slope safety factor value was 1,518, exceeding the minimum safety factor of 1.5, so it was considered quite safe. However, this value is considered low considering that Cililin District is at high risk of landslides. Therefore, additional reinforcement of the slopes was made with earth retaining walls made of rock material. Planning for retaining walls is made of 4 types of varying dimensions. The size of the retaining wall varies, from a width of 3-4.5 m, and a height of 5.5 – 7.5 meters according to the height of each trap. From the planned dimensions, the overall safety factor against overturning, shearing and soil bearing capacity exceeds 1.5, the slope is declared safe. It is hoped that this service activity can become a reference for residents in making retaining walls to strengthen structures on similar slopes.

Heat Hazards in High-Temperature Tunnels: Influencing Factors, Disaster Forms, the Geogenetic Model and a Case Study of a Tunnel in Southwest China

The construction of extensive tunnels in regions characterized by high geothermal activity presents significant challenges and inherent risks that affect both the safety and operational efficiency of construction personnel. This study investigated the factors influencing geothermal fields in shallow crustal rock formations through a comprehensive examination of existing literature and a detailed analysis of case studies. In addition, this study categorizes the geogenetic models of high-temperature heat hazards into three major classifications. Research findings indicate that several key factors significantly influence the geothermal fields. These factors, which include the deep geothermal background, heat transfer conditions, and localized additional heat sources, are paramount in shaping the geothermal field. Notably, it is observed that among these factors, the presence of additional heat sources, particularly the circulation of underground hot water, poses the most considerable threat to safety and operational efficiency. Moreover, this study utilizes a representative high geothermal tunnel in Southwest China to conduct a field investigation. This investigation assesses the potential for high-temperature thermal hazards within the tunnels, evaluates the geological conditions, verifies the factors governing the geothermal field, and outlines specific measures for the prevention and control of high geothermal tunnels. In conclusion, this study provides a structured analysis of lessons learned from these experiences, along with practical countermeasures for addressing high-temperature thermal hazards during the various stages of tunnel construction. The findings of this research serve as a valuable reference for those investigating the mechanisms behind geothermal disasters in tunnel construction. Furthermore, they offer practical guidance to ensure the secure and efficient excavation and sustainable operation of tunnels in the challenging geological environments characterized by high geothermal temperatures.

Analysis of deformation law of an airport foundation pit monitoring in loess area

This paper takes an airport foundation pit project in northwest loess area as the research object, and introduces the key method technology of support, construction and monitoring of this foundation pit project. The scope of this foundation pit project is widely distributed, there are no buildings in the surrounding area, and there is less restriction on the construction space, so the GRF01 green assembled support method of Slope release with soil nail wall is adopted, which controls the deformation of the foundation pit well and at the same time, plays the role of green environmental protection and reduces the cost. The analysis of the pit monitoring data shows that the pit engineering support design scheme effectively controls the deformation of the pit, and all monitoring data did not reach the alarm value, which ensures the safety of pit excavation and in-pit operation, and achieves the dual goals of economy and environmental protection. It can provide reference for the design and construction of similar large-scale foundation pit excavation and support in loess area.

Data‐Driven Decision Algorithm for Open Caisson Foundation Construction

The accuracy of instructions for the extraction of large open caissons directly affects the construction quality and safety. This study is focused on developing a smart construction methodology for predicting open caisson excavation instructions. The proposed approach aims to reduce the errors in excavation instructions attributable to the subjective and varying experiences of decision‐makers. The multilabel classification task of predicting the instructions of large open caisson excavation is accomplished through the problem analysis. The study conducted a comparative analysis of a multilayer perceptron model, a classifier chain model, and a multilabel K‐nearest neighbor model (MLKNN) based on Hamming loss and accuracy. The results revealed that MLKNN exhibits significant differences from the other models and is most suitable for predicting open caisson excavation instructions. Furthermore, the traditional MLKNN model was improved by refining the normalization and distance measurement methods for the open caisson scenario. The prediction accuracy of the improved MLKNN model is 89.04% for the excavation instructions and 98.63% for the nonexcavation decisions. The successful prediction of excavation instructions for a large open caisson can compensate for the lack of data mining capability of the existing monitoring system. This can reduce construction risks. Finally, this study discussed the robustness of the improved MLKNN in a real project, highlighting the model’s high accuracy during the midstage of open caisson construction.

Heat-transfer enhancement and optimization design of a roadway with typical angles using field synergy theory

In underground excavation operations, an excavation path with a turning radius of 3.5 meters should be selected which has the best comprehensive performance.

Postural Assessment of Indian Excavation Workers and Prototype Design of Virtual Iron-Pan

The study was conducted among excavation labourers of the construction sites for five different tasks. Five postures were selected from the video recorded at the time of data collection. Analysis of static/dynamic working postures and loads on the various body parts are being done using computer software's which is not possible manually nowadays. In this study, the postures of excavation labourers were assessed using CATIA software during five various excavation operations. Digital Human Analysis (DHM) was developed in the CATIA software for study. RULA, REBA, biomechanical and lifting analysis were performed to detect body risk and loads on the L4/L5 segment of the vertebral column. CATIA software reveals that the excavation labourers are working at high risk. The result evaluated by RULA and REBA for all five working postures indicates that all postures require investigation and need immediate change. The result shows that biomechanical loads at the L4/L5 segments are higher than the NIOSH recommended limit for the task of throwing soil and receiving the pan by some outside labourers. Almost the same effect was observed when lifting of iron-pan where the labourers work in the flexion position. New prototype iron-pan was developed and re-analysis to compare the results with new working techniques in CATIA. This showed that the prototype iron-pan proposed helps to reduce the ergonomic risk during excavation and related work. The CATIA software also provides better results by better evaluation of working postures of labourers at excavation sites.

Методика планирования экскаваторных работ в карьере на основе компьютерного моделирования

Introduction. In-pit excavators, which provide removal and loading of muck piles, are one of the main process links in the system of complex mechanization of open-pit mines. The level of mining operation intensity is determined by the arrangement of excavators in the open pit. Research objective. The research aims to develop a method of automated positioning of excavators at the production benches of the open pit mine. Methodology. Arrangement of in-pit excavators excavators at the production benches of the open pit mine is based on calculations, computer modeling and ia made with account of technical and operational parameters of the excavators, as well as estimation of the active front of mining operations. The main stage of solving the formulated problem is the construction of block models of the ore body, modeling of mining operations, and building a model of the open pit mine by the stages of the deposit development. Based on the results of block modeling, the optimal length of the excavator block at the production bench for the selected model of the face excavator is determined. Results. The article proposes a methodology for planning excavator operations in the open pit mine and positioning of the face excavators based on computer modeling of the mining operations progress with due account of the volume of rock mass handling on the open pit bench, the length of the active front, the mineral grade, the given rate of development, the accepted models of excavators and other attributive computer data. Based on the block model, the excavators are positioned on the production benches of the open pit mine. The proposed approach allows a prompt consideration of many options to arrange face excavators in the open pit ore mine in a semi-automatic mode and select the best option to increase the mining efficiency. Conclusions. The proposed methodology allows to promptly solve in a semi-automatic mode the issues of opening the lower levels of deep pits, to consider many options for placing face excavators in the ore pit and choose the best option, contributes to minimizing the operational risks in the development of complex-structured deposits and complex extraction of raw materials.

Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation

Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation

An inventory of opencast mining excavations recultivated in the form of water reservoirs as an example of activities increasing the retention potential of the natural environment: a case study from Poland

The article presents examples of the employment of various geodetic measuring tools used for a detailed inventory of lake basins and shorelines. The measurement and analysis covered three post-mining open pit excavations recultivated as water reservoirs: two in Krakow (Bagry Wielkie and Bagry Małe) and one in Piaseczno (Piaseczno Sulphur Mine). Attention was paid to the factors that reduce the accuracy of the inventory of some flooded post-mining excavations, which determine the degree of usefulness of the morphometric data set for later analyses. According to available estimates, only about one-third of all water reservoirs in Poland have detailed geodetic documentation in the form of bathymetric maps. This documentation usually does not include water reservoirs of anthropogenic origin formed after the flooding of post-mining excavations (mines: sand, gravel, clay, limestone, sulphur, aggregates, etc.). The authors suggest the introduction of a document known as a reservoir documentation card and the creation of a database covering all anthropogenic water reservoirs. Considering the water deficit in Poland, it may be necessary to develop a detailed database of water resources in the short term.

Thermal monitoring and deep learning approach for early warning prediction of rock burst in underground structures

The occurrence of rockburst has the potential to result in significant economic and human losses in underground mining and excavation operations. The accuracy of traditional methods for early prediction is considerably affected by factors such as site conditions, noise levels, accessibility, and other variables. This study proposes a methodology for identifying the most defected region in a hard rock sample by integrating motion thermogram data obtained from the laboratory monitoring of rock burst phenomena with a cutting-edge deep neural network approach based on a regional convolutional network (i.e. Mask RCNN). The efficacy of the suggested approach was evaluated by determining the F1 score and average precision matrices based on a specific intersection over union value. The findings demonstrate that the proposed approach possesses satisfactory precision with respect to detection, localization, and segmentation, thereby establishing its potential utility as an autonomous predictor of rock bursts.

A Review of the Blast Fragmentation Analysis Techniques used in Surface Mines

Fragmentation refers to the process of breaking solid in-situ rock masses into smaller pieces during excavation or material handling operations. The fragment size distribution and degree of fragmentation within the blasted rock mass stand as a critical aspect for optimizing the efficiency of loading, transportation, crushing, and milling operations. The analysis of blast fragmentation analysis is done by several existing modern techniques which include the visual analysis method, photogrammetric method, and image analysis method, etc. In this study, all the blast fragmentation techniques are reviewed, and the advantages and disadvantages of all the methods are discussed. Along with that, a blast fragmentation analysis is conducted for the rock pile images of a blasting site collected from Dongri Buzurg Mine (MOIL), India using the image processing technique in WipFrag software. The feasibility of the blasting patterns is judged based on the uniformity coefficient (Cu) and the coefficient of gradation (Cg) which are found to be 4.47 and 0.94 respectively. The fragmentation for the muck pile is found to be uniform and well-graded for the blast site and the methodology used is found to be simple yet effective for the analysis.

Ore Rock Fragmentation Calculation Based on Multi-Modal Fusion of Point Clouds and Images

The accurate calculation of ore rock fragmentation is important for achieving the autonomous mining operation of mine excavators. However, a single mode cannot accurately calculate the ore rock fragmentation due to the low resolution of the point cloud mode and the lack of spatial position information of the image mode. To solve this problem, we propose an ore rock fragmentation calculation method (ORFCM) based on the multi-modal fusion of point clouds and images. The ORFCM makes full use of the advantages of multi-modal data, including the fine-grained object segmentation of images and spatial location information of point clouds. To solve the problem of image under-segmentation, we propose a multiscale adaptive edge-detection method based on an innovative standard deviation map to enhance the weak edges. Furthermore, an improved marked watershed segmentation algorithm is proposed to solve the problem of low segmentation accuracy caused by excessive noise of the gradient map and weak edges submerged. Experiments demonstrate that ORFCM can accurately calculate ore rock fragmentation in the local excavation area without relying on external markers for pixel calibration. The average error of the equivalent diameter of ore rock blocks is 0.66 cm, the average error of the elliptical long diameter is 1.42 cm, and the average error of the elliptical short diameter is 1.06 cm, which can effectively meet practical engineering needs.

Trajectory planning and control of large robotic excavators based on inclination-displacement mapping

This paper proposes a trajectory planning and control method for heavy-duty manipulators based on inclination-displacement mapping. In this method, inclination sensors are employed to detect the excavator's orientation. By establishing a mapping relationship between joint inclination and cylinder displacement, the cylinder displacement is indirectly derived. Subsequently, considering the typical excavation operation process, the spatial trajectory of the excavator bucket is planned. The displacement of the driving cylinder is determined using kinematic inverse solutions and cubic polynomials. The cylinder displacement is then controlled using a position-velocity (PV) strategy. This method is tested on a 95-ton large excavator, and the results demonstrate several advantages, including easy installation, low maintenance requirements, smooth trajectory planning, and high tracking accuracy. These qualities make it suitable for the demands of intelligent operations in large excavators. Thus, this paper offers valuable insights for the intelligent transformation of heavy excavators.

A novel technique for constructing prefabricated subway stations under open excavation

Prefabricated construction is essential for realising green, efficient and sustainable development of rail transit. However, limited space in foundation pits and cross-interference with inner struts mean that the advantages of existing prefabrication technology cannot be leveraged effectively to build subway stations under open excavation with inner support. In this paper, this problem is addressed by introducing a modular design method and two novel connection technologies. The proposed modular design method is sufficiently adaptable to balance the use of space between the station structure and the inner struts. The two proposed connection technologies provide efficient ways to assemble different concrete segments with two newly developed joints – namely, a CHC joint (comprising two C-shaped and one H-shaped steel members) and a flexible lock joint – in the circumferential and longitudinal directions, respectively. The first application of this fully prefabricated scheme in the Shenzhen Metro shows the huge potential of this technology for constructing subway stations under open-cut conditions, and its advantages in technical, economic and social aspects reveal wide application prospects in rail transit.