Field Monitoring Method Research Articles

Based on Flac3D Research and Analysis of the Mining Pressure Development Law in the Top Coal Section of the Roadway Support of the Working Face Transport

Top coal supporting roadway is widely used in the transportation roadway of thick coal seam face, which can not only increase the coal extraction rate but also reduce the driving cost. Based on the engineering geological conditions of the transportation lane of the working face of Zhongma Cun mine, the law of mine pressure development in the roadway of the top coal section is studied and analyzed based on Flac3D and field monitoring methods. The numerical simulation analysis shows that when the working face is pushed to 55m for the first time, the displacement of the area affected by the leading abutment pressure and the surrounding rock on the mining side of the roadway reaches the peak value, and the step distance of the first time is 55m. According to the analysis of stress monitoring data of single pillar and roof anchor cable on site, the first pressure occurs when the working face advances to 51m, which is consistent with the numerical simulation conclusion.

Study on Deformation Control of Road-Deep Foundation Pit Passing under Elevated Subway Bridge

This paper focuses on the application of pile foundation underpinning technology in a deep foundation pit of a subway Viaduct Project in Beijing. The study aims to address the engineering characteristics of the project, including a large number of new piles, a wide span of underpinning abutment, a long length of deep foundation pit, and a wide range of influences. This research utilizes field monitoring and numerical simulation methods to investigate the pile foundation underpinnings. The impact and management of road-deep foundation pit construction are considered, as well as their combined effect on subway viaducts and track structures. The primary accomplishments are as follows: (1) By analyzing the data from on-site deformation monitoring, it is evident that the pier exhibits maximum vertical deformation and maximum transverse deformation at the same location. The measuring locations are specifically situated on Pier 7# at the pile foundation underpinning. The maximum vertical and transverse deformations of the track are directly proportional to the maximum deformation of the pier. (2) By comparing the numerical simulation results with the field monitoring data, it is observed that although there is some discrepancy between the two, the deformation trend is largely consistent. This suggests that the numerical simulation analysis method is effective in reflecting the deformation of the bridge and track. (3) Through the numerical model and changing the values of the retaining structure parameters, the sensitivity of the pier deformation near the road foundation pit to the retaining structure parameters is systematically analyzed. The sensitivity of the pier deformation to the foundation pit parameters is as follows: the embedded depth insertion ratio of the retaining pile > the diameter of the retaining pile > the pile spacing.

Valorization of agricultural byproducts – The use of mustard seed meal for pest control

Mustard seed (Brassica juncea) meals from biodiesel production can be utilized as a feedstock for sourcing pesticidal compounds that can control ubiquitous soil pests such as wireworms. In the present study, we evaluated the pesticidal activity of B. juncea seed meal on wireworms (Limonius infuscatus) to promote the valorization of B. juncea seed meal with the end goal of increasing the overall sustainability of crop production. In the laboratory soil column study, B. juncea seed meal were applied to typical agricultural soil infested with wireworms. After application, the release of the primary biopesticidal compound was monitored and correlated with the motility, mortality, and metabolomic changes of wireworms. The pesticidal effect of B. juncea seed meal on wireworms was evident by the mass change and metabolomic response consistent with the stress response. Mortality of up to 100 % of wireworms was observed when soils was treated with B. juncea seed meal and tarped. Based on the statistical analysis, the release of the primary biopesticidal compound from B. juncea seed meal correlated well with soil electrical conductivity making it a potential proxy method for field monitoring.

Current status and prospects of algal bloom early warning technologies: A Review

In recent years, frequent occurrences of algal blooms due to environmental changes have posed significant threats to the environment and human health. This paper analyzes the reasons of algal bloom from the perspective of environmental factors such as nutrients, temperature, light, hydrodynamics factors and others. Various commonly used algal bloom monitoring methods are discussed, including traditional field monitoring methods, remote sensing techniques, molecular biology-based monitoring techniques, and sensor-based real-time monitoring techniques. The advantages and limitations of each method are summarized. Existing algal bloom prediction models, including traditional models and machine learning (ML) models, are introduced. Support Vector Machine (SVM), deep learning (DL), and other ML models are discussed in detail, along with their strengths and weaknesses. Finally, this paper provides an outlook on the future development of algal bloom warning techniques, proposing to combine various monitoring methods and prediction models to establish a multi-level and multi-perspective algal bloom monitoring system, further improving the accuracy and timeliness of early warning, and providing more effective safeguards for environmental protection and human health.

Supporting behavior evolution of ultra-deep circular diaphragm walls during excavation: Monitoring and assessment methods comparison

Ultra-deep circular excavations present unique challenges in geotechnical engineering due to their complex behavior and the scarcity of relevant case studies. This paper presents a comprehensive study on the excavation behavior of the deepest circular excavation (77.3 m) ever built in China through field monitoring and computational methods. The excavation process leads to the transformation of the underground diaphragm walls into an elliptical cylinder shape, elongated in one direction and shortened in the perpendicular direction. The outer annular reinforcement primarily experiences compressive stresses, while the inner annular reinforcements undergo tensile stresses, attributed to the spatial deformation of the cylinder structure. The findings emphasize the significance of considering 3D deformation and accurate characterization of internal forces to ensure the structural integrity and stability of such complex geotechnical systems. Three computational methods, including the 2D load-structure method, the 3D load-structure method, and the stratum structure method, were employed to analyze the deformation and internal forces. Comparison between measured data and calculated results reveals differences and highlights the effectiveness of the 3D load-structure and stratum structure methods in capturing the observed behavior. The study contributes to the understanding of circular excavation for designs in geotechnical engineering.

A Study on the Influence of Double Tunnel Excavations on the Settlement Deformation of Flood Control Dikes

This article combines numerical simulation and field monitoring methods to study the stability of the overlying Liuyang River embankment in the tunnel crossing between Huaqiao Station and Rice Museum Station of Changsha Metro’s Line 6. Using AutoCAD, 3Dmine, and COMSOL Multiphysics, a calculation model of the entire subway tunnel section crossing the flood control embankment under the coupling of fluids and solids was established. The process of tunnel-crossing the embankment and the variation in spatial displacement and plastic strain in different geological layers were analyzed from the perspective of time evolution and spatial distribution. The research results show that during the process of crossing the embankment, the deformation of the east bank is greater than that of the west bank, and crossing the west bank is the relatively riskier stage of the entire project. Moreover, during the process of crossing the embankment, the overlying soil layer will produce a plastic strain zone, and only a small amount of plastic strain is generated in the surrounding sandstone layer of the tunnel walls. In terms of the magnitude of plastic strain, the plastic strain area produced by the leading tunnel’s surrounding rocks is larger than that of the following tunnel. As the excavation progresses, a funnel-shaped settlement displacement gradually forms during the passage of the leading tunnel, and this settlement funnel gradually expands during the passage of the following tunnel, with the maximum settlement point transitioning from directly above the leading tunnel to the middle position between the two tunnels. Using the jitter filter algorithm and the adjacent average method to process the field monitoring data, the results show that the monitored deformation results well match the simulated settlement results.

Location and mechanism analysis of curtain water inrush channels based on MTI-derived parameters-a case study

A grout curtain's stability and water-plugging effect are directly related to the safe production of water-rich mines. The progressive damage to the surrounding rocks of the grout curtain under mining disturbance may induce the development and coalescence of fractures and the failure of the grout curtain, further causing the formation of water inrush channels and triggering water inrush disasters. Understanding the mechanisms behind the formation and evolution of water inrush channels is inherently challenging in theory, thus necessitating field monitoring methods. The formation of intersected fracture channels is a necessary and sufficient condition for the occurrence and prediction of the water inrush disaster. Therefore, this paper focuses on studying a set of research methods for locating and understanding the mechanism of curtain water inrush channels. These methods encompass mining-induced fracture characterization, rock mass damage characterization, and water inrush channel identification based on moment tensor inversion (MTI). Finally, through a case study conducted at Zhangmatun Iron Mine, the proposed method successfully determines the location and formation mechanism of the curtain of the water inrush channel. This study presents a novel and feasible approach for analyzing curtain water inrush scenarios and provides a valuable reference for other mines facing the risk of grout curtain instability.

Field Monitoring and Identification Method for Overflow of Fractured-Vuggy Carbonate Reservoir

Since carbonate reservoirs develop pores and fractures and have a complex formation pressure system, overflow and even blowout seriously threaten the exploration and development of these kinds of reservoirs. According to the overflow characteristics of fractured-vuggy carbonate reservoirs, a field monitoring and identification method for overflow has been developed. This method is based on the top-down logic framework for early overflow identification, combined with optimized monitoring parameters. The DBSCAN clustering algorithm is used to identify abnormal logging parameters, and thus, a probability weight coefficient of overflow (K) indicated by the abnormal engineering parameters of a gas well can be calculated. K is divided into four early warning response levels of overflow, and the overflow control operation can be made according to the different levels of early warning response. Based on this method, an integrated software system for field monitoring and identification of early overflow is designed. This software system integrates the functions of data collection and management, overflow risk parameter calculation, overflow early warning, and overflow simulation analysis. Finally, according to a case analysis of overflow prediction for a fractured-vuggy carbonate reservoir in Well XX, this method’s prediction stability and accuracy are demonstrated, indicating that it can be used for the overflow early warning in engineering practice.

Maize Ear Height and Ear–Plant Height Ratio Estimation with LiDAR Data and Vertical Leaf Area Profile

Ear height (EH) and ear–plant height ratio (ER) are important agronomic traits in maize that directly affect nutrient utilization efficiency and lodging resistance and ultimately relate to maize yield. However, challenges in executing large-scale EH and ER measurements severely limit maize breeding programs. In this paper, we propose a novel, simple method for field monitoring of EH and ER based on the relationship between ear position and vertical leaf area profile. The vertical leaf area profile was estimated from Terrestrial Laser Scanner (TLS) and Drone Laser Scanner (DLS) data by applying the voxel-based point cloud method. The method was validated using two years of data collected from 128 field plots. The main factors affecting the accuracy were investigated, including the LiDAR platform, voxel size, and point cloud density. The EH using TLS data yielded R2 = 0.59 and RMSE = 16.90 cm for 2019, R2 = 0.39 and RMSE = 18.40 cm for 2021. In contrast, the EH using DLS data had an R2 = 0.54 and RMSE = 18.00 cm for 2019, R2 = 0.46 and RMSE = 26.50 cm for 2021 when the planting density was 67,500 plants/ha and below. The ER estimated using 2019 TLS data has R2 = 0.45 and RMSE = 0.06. In summary, this paper proposed a simple method for measuring maize EH and ER in the field, the results will also offer insights into the structure-related traits of maize cultivars, further aiding selection in molecular breeding.

Two- and Four-Electrode Configurations for Contactless Reinforced Concrete Corrosion Monitoring

The paper addresses the need for a fast and reliable method for field monitoring reinforced concrete structures. A proof of concept is presented where a noncontact procedure provides quantitative information on the concrete resistivity and reinforcement corrosion rate. A Wenner-type probe is presented, where a combination of two- and four-electrode measurements in a relatively high-frequency domain allows obtaining the information of interest. The method is based on the fact, verified by numerical simulations, that the embedded rebar works as an effective floating counter electrode and, thus, for distances higher than a critical value (1 cm in the simulations done), the ratio of concrete resistivity to the measured impedance at 1 kHz is constant and only dependent on the electrode diameter. The apparent polarization resistance measured with the four-electrode arrangement and normalized to the concrete resistivity allows obtaining the actual polarization resistance without contacting the rebar whose distance to the electrodes shall be known.

A Study on the Calculation Method of Support Pressure in the Structure of Typical Upper Cladding Rock Formations

Aiming at the calculation problem of bearing pressure of typical overlying strata structure, in this paper, mechanical calculation, field monitoring and other methods are used to study the influence range of abutment pressure. Recently, many major rock burst accidents in working surface show that with the increase of mining depth and the change of overlying strata structure, the abutment pressure distribution has become one of the problems of safe mining. The influence range, distribution of high stress area and peak position of working surface support pressure need to be solved urgently; and through theoretical analysis, this paper reveals (whole rock single-layer structure, whole rock layered structure, whole rock single-layer structure—without arch in soil layer, whole rock layered structure—without arch in soil layer, whole rock single-layer structure—with soil arching, whole rock layered structure—with soil arching) the stress transfer mode, transfer size, and arching conditions of overlying strata in different areas. The mechanical system of abutment pressure calculation for typical overburden structure is established, which provides theoretical basis for mine optimization design scheme, mining sequence, and limited personnel distance.

Oil Recovery Performance by Surfactant Flooding: A Perspective on Multiscale Evaluation Methods

Chemical-enhanced oil recovery (cEOR) is a class of techniques commonly used to extract hydrocarbon fluids from reservoir rocks beyond conventional waterflooding. Surfactants are among the chemical agents employed in a cEOR process, as they aid in enhancing oil recovery by lowering the oil–water interfacial tension (IFT) and altering the rock wettability toward less oil-wet conditions. Understanding the flow characteristics and mechanisms involved during surfactant flooding helps improve the performance of injected surfactants and results in higher oil recovery. The objective of this review is to outline the recent applications of the different methods employed to understand the behavior and mechanisms involved during surfactant-enhanced oil recovery. The review begins with a general background highlighting the basic characteristics of surfactants and the main mechanisms by which they exert their influence. Recent studies conducted to investigate the oil recovery performance through different methods are then presented, including traditional coreflooding experiments, microfluidics studies, and oil recovery through sand packs. The methodology of the analysis and the interpretation of the data obtained from the different oil recovery tests, including oil recovery factor, pressure data, and relative permeability, are also described. Pore-scale analysis and imaging methods including nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), and X-ray medical and microcomputed tomography (μCT) scanning and their applicability in assessing the recovery performance are described. Finally, a few examples of field monitoring methods for surfactant flooding are highlighted. This review provides knowledge of the different multiscale evaluation methods and their applicability during surfactant flooding.

Calculation Method for Investigating the Behavior of Ground Surface Settlement of Underpass Buildings in TBM Double-Line Tunnels

This study aims to investigate the behavior of ground surface settlement in TBM double-line tunnels constructed under existing buildings and to devise a calculative representation for that behavior. Numerical simulation and field monitoring methods were used to examine the Zhongcong Tunnel in Chongqing Metro Line 9. The ground surface settlement was analyzed using an orthogonal test of 3D numerical simulation methods. The results showed that ground surface settlement was influenced by TBM tunneling parameters and the location of the existing building in the following manner. The existing building reduced the settlement trough width. Surface settlement was increased by frictional and palm surface thrust forces but reduced by grouting pressure. The settlement trough width of the first excavation iz correlated with that of the last excavation iy. To accommodate the influence of existing buildings, the tilt factor of the settlement trough TR was introduced to improve the formula for calculating the ground surface settlement of TBM double-line tunnels. The improved formula was validated by comparing the calculated results with actual measurements.

Failure mechanism of methane drainage borehole in soft coal seams: Insights from simulation, theoretical analysis and in-borehole imaging

Methane drainage borehole in soft coal seams is prone to instability. This could seriously compromise methane drainage efficiency, leading to risks of methane hazards at coal mines. In this paper, the failure of methane drainage boreholes in soft coal seams is studied through theoretical analysis, numerical simulation and field monitoring methods, which aims to guide the borehole protection and improve the methane drainage capacity. The functional relationship between effective radial normal stress and effective tangential shear stress at the unstable position of the borehole and the in-situ stress and pore pressure is constructed through the theoretical study. The equation to derive borehole wall collapse pressure is established, considering cohesion, internal friction angle, coal seam porosity, pore pressure, in-situ stress and other factors. The numerical modelling shows that the coal around the borehole undergoes tensile breakage towards the borehole in both single and multiple borehole conditions. The vertical displacement at the borehole top is the largest and the borehole turned into an elliptical shape under compression. Also, it shows the opening and the end of the borehole are at higher failure risks than middle sections. The horizontal and vertical displacements of multiple boreholes are larger than that of a single borehole. While the usage of multiple boreholes improves the methane drainage efficiency, it brings more challenges to the borehole stability. The creep deformation law of borehole is revealed based on new developed in-borehole imaging monitoring system, including four stages: first (transient), second (steady-state), tertiary (accelerating state) and closure. The field measurement shows that the methane drainage efficiency was relatively high in the first two stages, and then the efficiency dropped rapidly when borehole closing. The research results are critical for guiding methane drainage borehole protection, improving the methane drainage efficiency and enhancing safety in production.

73 The Digital Cullen Chart: An App to Assess the Visual Field in the Context of Sellar/parasellar Tumours

Abstract Aim 30 years ago, Cullen1 (a neuro-ophthalmologist) developed and validated a simple paper chart for evaluation of the central 25 degrees of the visual field. We re-developed this concept in digital form (as a smartphone application) and sought to assess its sensitivity and specificity in detecting field loss, through comparison with formal machine-based perimetry. Method A case series pilot study was performed to test the app-based Cullen chart for concordance with formal machine-based perimetry (Humphrey and Octopus). 18 patients with a range of sellar/parasellar tumours (pituitary adenoma, craniopharyngioma, and meningioma) being managed in a single neurosurgical centre were involved in this study. Patients underwent formal visual field perimetry as part of standard care. They also underwent assessment using the smartphone-based Cullen chart as part of routine outpatient assessment. 37 eye episodes were assessed, incorporating pre- and post- treatment assessment for a range of potentially compressive pathologies. Results The digital Cullen chart had a sensitivity of 75% and specificity of 98% compared with machine-based perimeters. The positive predictive value was 93% and negative predictive value was 92%. Conclusions In the context of visual field assessment for patients with sellar/parasellar tumours, this smartphone-based chart shows strong concordance with machine-based perimeters. It is therefore an accessible visual field screening and monitoring tool for clinicians. With further study, there is also potential for approval as a remote patient-led visual field monitoring method.

Landslide-tunnel interaction mechanism and numerical simulation during tunnel construction: a case from expressway in Northwest Yunnan Province, China

The excavation of the tunnel on the expressway in northwest Yunnan province induced landslide and a series problem such as ground surface cracks of the slope, sliding of the slope, and cracks in the tunnel lining. This research aims to reveal the interaction relationship between the tunnel and the landslide from the prospective of field monitoring and numerical simulation. Firstly, the engineering geological conditions of the slope where the tunnel was located were obtained by field investigation. The “landslide traction segment-tunnel longitudinal tensile failure” mode was put forward based on the spatial relationship between the tunnel and the landslide. Secondly, field monitoring methods were adopted to monitor the surface displacement of the slope, the deep-seated displacement of the landslide, and the propagation of cracks in the tunnel lining. Finally, three-dimensional numerical models were established to investigate the stability of the slope and the tunnel under natural conditions, tunnel excavation conditions, and rainfall conditions. The field investigation results, field monitoring results, and numerical simulation results illustrated that: (1) The tunnel traversed the traction segment of the landslide body in parallel, and tensile failure or shear dislocation failure would occur at different stages of the interaction between the tunnel and the landslide. (2) Two sliding layers were discovered in the landslide, the shallow creep sliding layer and the deep creep sliding layer, which corresponded to the tensile failure and shear dislocation failure modes proposed in the “landslide traction segment-tunnel longitudinal tensile failure” mode, respectively. (3) The slope was in an unstable state under natural conditions. The tunnel excavation disrupted the initial stress equilibrium of the slope, resulting in stress release of the surrounding rock mass. Both excavation and rainfall would exacerbate the deformation of the landslide and the tunnel. Eventually, control measures based on the control grouting technology of the steel floral tubes were suggested to counter with landslide-tunnel deformation problems.

Constraining well integrity and propensity for fugitive gas migration in surficial soils at onshore decommissioned oil and gas well sites in England

Petroleum resource development generates a legacy of energy wells that must be decommissioned effectively as we transition towards NetZero. Unfortunately, some decommissioned wells (DWs) can suffer integrity failure resulting in release of fugitive natural gas into the surrounding soils and atmosphere. After decommissioning there are typically no ongoing assessments to confirm well integrity, meaning integrity status remains uncertain into the future. Furthermore, factors affecting fugitive natural gas migration in surficial soils around DWs are poorly recognized, inferring integrity assessment and monitoring strategies are lacking. To better understand the integrity status of DWs, identify soil properties controlling fugitive gas migration and help develop more effective monitoring and detection methodologies, we undertook field investigations at six DWs in England involving surficial CH4 measurements, sub-surface soil-gas and sediment sampling and dynamic flux-chamber measurements. We found no evidence of integrity failure at any site. However, the composition and structure of soils in which examined DWs are embedded suggest fugitive gas migration to surface may be severely limited; potentially mitigating methane emissions while making integrity assessment at the surface challenging. Overall, the integrity status of DWs in England is poorly constrained and we show surficial soil properties must be characterised and considered to effectively constrain the fate of fugitive gas and in order to design effective field assessment and monitoring methods.

Numerical Study on Characteristics of Bedrock and Surface Failure in Mining of Shallow-Buried MCS

Coal is one of the important energy sources for industry. When it is mined, it will cause the destruction of bedrock and surface. However, it is more severe in mining shallow-buried multi coal seams (SBMCS). To better reveal the characteristics of the bedrock and surface damage, we have carried out a theoretical analysis, as well as used numerical simulations and field monitoring methods to study the surface and bedrock damage caused by the mining of SBMCS. The characteristics of bedrock and surface failure structure, settlement, and stress distribution were studied and analyzed. The findings show that the collapsed block, formed by the rupture of the overlying stratum, interacts with the surrounding rock to form large cavities and gaps, and the stress concentration occurs between them. The maximum downward vertical concentration stress is about 9.79 MPa. The mining of the lower coal seam can lead to repeated failure of the upper bedrock and goaf. The settlement of bedrock presents gradient change, and the settlement of upper bedrock is large, about 8.0 m, and the maximum settlement is 8.183 m, while that of lower bedrock is small and about 3.5–4.0 m. The weak rock stratum in the bedrock is crushed by the change stress of repeated mining, and formed a broken rock stratum. The cracks in the bedrock develop directly to the ground. On the ground, tensile cracks, compression uplift, stepped cracks, and even collapse pits are easy to cause in mining SBMCS. Affected by repeated mining, the variation of surface vertical stress is complex and disorderly in the middle of the basin, and the variation of horizontal stress is mainly concentrated on the edge of the basin. The maximum stress reaches 100 KPa, and the minimum stress is about 78 KPa. Through theoretical analysis and discussion, the size of the key blocks is directly related to the thickness and strength of the rock stratum.

Characteristics of Overburden and Ground Failure in Mining of Shallow Buried Thick Coal Seams under Thick Aeolian Sand

Mining can lead to overburden failure and ground damage, which are more severe in mining shallow buried thick coal seams (SBTCS) under thick aeolian sand (TAS). We attempted to discover characteristics of mining in this particular geological condition through theoretical derivation and numerical simulation, and field monitoring. Theoretical methods, combined with numerical simulation and field monitoring methods, reveal the essence of the development and distribution of surface cracks caused by mining SBTCS and depth to thickness ratio (DTR) to be 13.43, less than 15. The findings show that, when mining SBTCS, the overburden breaks down periodically, the initial collapse distance is greater than the collapse step, approximately 55 m on average, and the collapse step is approximately 45 m, on average, in the Daliuta Coal Mine. The collapsed blocks are stacked into goaf and form “masonry beams”, and many cracks and pores are generated between the blocks. The weak stress of the aeolian sand layer causes the movement angle in the aeolian sand layer to be smaller than that in the bedrock, and leads to much sheer, tension and compression failure on the ground, and the main forms of cracks are compression uplift, tensile cracking, shear step.

Geology amplification of the seismic response of a large deep-seated rock slope revealed by field monitoring and geophysical methods

Geology amplification of the seismic response of a large deep-seated rock slope revealed by field monitoring and geophysical methods