Settlement Control Research Articles

ОСОБЛИВОСТІ ВНУТРІШНЬОГО КОНТРОЛЮ РОЗРАХУНКІВ ПІДПРИЄМСТВА В УМОВАХ ВОЄННОГО СТАНУ

Introduction. In the conditions of martial law, enterprises face new challenges that affect all areas of their economic activity, including settlement operations. Internal control of settlements becomes critical for ensuring financial stability and supporting operational activities. This requires a study of the specifics of the organization of internal control of the company's calculations during the state of war, in particular the issue of ensuring the security of financial operations in conditions of instability and market uncertainty. The purpose of the article. The purpose of the study is to investigate the features and effective mechanisms of internal control of payments at enterprises operating under martial law to ensure their financial stability and competitiveness. Methods. The research methodology includes a comprehensive approach that combines general scientific methods: analysis, synthesis, comparison, as well as specific financial and economic methods of evaluating the internal control system, including methods of risk analysis and auditing of financial operations. Results. The article examines the main principles of ensuring effective internal control of the calculations of economic entities in the conditions of martial law. It was found that failures in the work of banking systems, interruptions in communications and logistics significantly complicate the timely execution of financial transactions. The need to strengthen control over payment discipline on the part of both the enterprise and its counterparties has been identified. The necessity of implementing additional measures to protect the payment system, including increased attention to the verification of counterparties and the use of digital monitoring tools, has been proven. The growing need for rapid adaptation of internal control procedures to new conditions, such as changes in legislation introduced in connection with military operations, or new requirements for financial reporting, which requires the involvement of qualified personnel capable of promptly responding to new challenges and risks, has been studied. Conclusions. It has been proven that the internal control of the company's calculations in the conditions of martial law is an important element of maintaining stable operations and financial security. Therefore, to ensure its effectiveness, it is necessary to constantly update control methods, take into account new risks and challenges associated with war, and implement modern monitoring tools on the basis.

Novel Application of a Swift-Assembled Support Method with Prefabricated Corrugated Steel for Vertical Shaft Excavation in a Metro Station

For the construction of a subway station, temporary vertical shafts were commonly used to facilitate machine operation. In densely urban areas, the requirement of settlement control and environmental impact called for a novel construction method of vertical shafts. In this paper, a novel swift-assembled support (SAS) structure and construction method for vertical shafts of a metro station was proposed, using prefabricated steel components. A comprehensive scheme of full-time monitoring was conducted to evaluate the performance of this novel support structure and ground response. Field monitoring results indicated that the SAS method was able to control the settlement of ground and adjacent buildings. Based on the field measurements, the calculation theory for design parameters were discussed. The active earth pressure yield from the method considering wall movement was closer to the field measurements. All of the local buckling values were both overestimated based on the technical standards’ methods. The calculation methods were thereby adopted carefully to determine the designed loading share ratio of structure components. The advantage of the SAS method, including rapid construction, safety, and lower environmental impacts, were obviously clear.

Numerical simulation for subsidence control in CO2 storage and methane hydrate extraction

Gas hydrates are increasingly viewed as a promising alternative to traditional fossil fuels. However, their extraction process poses risks to structural integrity, potentially causing significant subsidence. In this study, we developed a Thermo-Hydro-Mechanical-Chemical (THMC) model to analyze the impact of gas hydrate extraction on seabed subsidence. Our investigation focused on the influence of bottom hole flowing pressure, initial hydrate concentration, gas saturation, permeability, porosity, and rock thermal conductivity on subsidence during gas hydrate extraction via depressurization.The results show that seabed subsidence is affected by various factors such as bottom hole flowing pressure, initial hydrate concentration, gas saturation, permeability, porosity, and rock thermal conductivity. It was noted that significant subsidence is associated with low initial hydrate concentration, high permeability, porosity, low gas saturation, low rock thermal conductivity, and a notable pressure drop of 79.31%.To address this issue, we propose a seabed subsidence mitigation strategy involving CO2 injection. This approach not only safeguards offshore infrastructure and coastal communities but also helps reduce CO2 emissions, aligning with global climate change mitigation efforts. In our model, CO2 injection occurs in the subsurface reservoir at the interface between the free water zone and hydrate-bearing formations. The CO2 hydrates formation process releases heat, which dissociates methane hydrates, allowing the methane to be replaced by CO2 molecules and move towards the production well.Our analysis reveals that increasing injection temperature and rate significantly reduces subsidence. Additionally, the range of investigated injection pressures, which included pressures equal to and more than double the initial reservoir pressure, showed inconsequential impacts on seabed subsidence.The effectiveness of subsidence reduction is significantly enhanced by injecting a CO2/N2 mixture compared to pure CO2 injection. The most substantial reduction in subsidence occurred when a mixture of CO2 and N2 in a 50/50 vol/vol ratio was injected at a high rate.These findings offer crucial insights for optimizing the efficiency and control of gas hydrate extraction methods. They emphasize the importance of employing balanced injection strategies to minimize environmental risks and ensure sustainable energy extraction.

Measurement and analysis of surface settlement caused by construction of quasi-rectangular shield tunnel in rich water-sand stratum.

The study is based on a section of the Zhengzhou Metro Line 8 quasi-rectangular shield tunnel. Field excavation trials were conducted to analyze the surface settlement patterns caused by the construction of a large-section quasi-rectangular shield tunnel in the rich water sand layer in Zhengzhou. Based on the characteristics of the rich water sand layer, ground settlement control measures were proposed. The research findings show that the surface settlement caused by the construction of the large-section quasi-rectangular shield tunnel in the rich water sand layer exhibits a temporal curve pattern of slow settlement (Stage I: pre-arrival of the shield), rapid settlement (Stage II: shield passage, Stage III: shield tail exiting 14.4 ~ 18m), and stable settlement (Stage IV: late settlement). In Stage I, controlling the excavation rate to maintain balance between the cutter face pressure and soil pressure is effective. In Stage II, injecting lubricating mud between the shell and the sand layer to reduce soil friction and shear slip is recommended. In Stage III, increasing the synchronous grouting volume at the shield tail and adjusting grouting pressure, as well as timely filling the shield tail construction gap, are effective methods to reduce surface settlement. The Peck formula was used to fit the transverse settlement trough on the surface, with a linear correlation coefficient R²=0.983, validating the use of the Peck formula to predict surface settlement troughs for quasi-rectangular shield tunneling in the rich water sand layer. These research findings can provide data support and reference for similar projects.

Quantitative Evaluations of Pumping-Induced Land Subsidence and Mitigation Strategies by Integrated Remote Sensing and Site-Specific Hydrogeological Observations

Land subsidence is an environmental hazard occurring gradually over time, potentially posing significant threats to the structural stability of civilian buildings and essential infrastructures. This study presented a workflow using the SBAS-PSInSAR approach to analyze surface deformation in the Choushui River Fluvial Plain (CRFP) based on Sentinel-1 SAR images and validated against precise leveling. Integrating the InSAR results with hydrogeological data, such as groundwater levels (GWLS), multilayer compactions, and borehole loggings, a straightforward model was proposed to estimate appropriate groundwater level drops to minimize further subsidence. The results showed a huge subsidence bowl centered in Yunlin, with maximal sinking at an average 60 mm/year rate. High-resolution subsidence maps enable the quantitative analyses of safety issues for Taiwan High-Speed Rail (THSR) across the areas with considerable subsidence. In addition, the analysis of hydrogeological data revealed that half of the major compaction in the study area occurred at shallow depths that mainly included the first and second aquifers. Based on a maximal subsidence control rate of 40 mm/year specified in the CRFP, the model results indicated that the groundwater level drops from wet to dry seasons needed to be maintained from 3 to 5 m for the shallowest aquifer and 4–6 m for Aquifers 3 and 4. The workflow demonstrated the compatibility of InSAR with traditional geodetic methods and the effectiveness of integrating multiple data sources to assess the complex nature of land subsidence in the CRFP.

Subsidence Prediction Method Based on Elastic Foundation Beam and Equivalent Mining Height Theory and Its Application

Grouting technology in overburden separation is recognized as an effective method to prevent surface subsidence and reuse solid waste. This study used mechanical analysis to explore deflection characteristics of key strata and accurately predict and control surface subsidence. Conceptualizing the coal–rock mass beneath the key strata as an elastic foundation, we developed a method to calculate the elastic foundation coefficients for various regions and established an equation for key strata deflection, validated through discrete element numerical simulations. This simulation also examined subsidence behavior under different grout injection–extraction ratios. Additionally, combining the equivalent mining height theory with the probability integral method, we formulated a predictive model for surface subsidence during grouting. Applied to the 8006 working face of the Wuyang Coal Mine, this model was supported by numerical simulations and field data, which showed a maximum surface subsidence of 546 mm at a 33% injection–extraction ratio, closely matching the theoretical value of 557 mm and demonstrating a nominal error of 2%. Post-grouting, the surface tilt was reduced to below 3 mm/m, meeting regulatory standards and eliminating the need for ongoing surface structure maintenance. These results confirm the model’s effectiveness in forecasting and controlling surface subsidence with grouting. The study can provide a basis for determining the grouting injection–extraction ratios and evaluating the effectiveness of surface subsidence control in grouting into overburden separation projects.

Effects on upper masonry structures caused by double-line parallel shield cutting group pile construction

The effects on the upper masonry structure and the construction parameters of shield cutting piles were studied during shield construction, focusing on a shield interval of Zhengzhou Metro Line 5. The study utilized the actual engineering case of left and right double-lane shields superimposed on cutting cement soil group pile composite foundations beneath masonry structures. Findings revealed that masonry structures within approximately 30 m (5.0 times the tunnel diameter) were impacted before and after shield cut pile construction, resulting in deflection and twisting deformations of houses along the central axes of the left and right tunnel lines. Implementation of “clay shock” grouting outside the shield shell, radial grouting through small conduits, shield tail synchronous grouting, and secondary reinforcement grouting effectively mitigated the disturbance caused by shield construction to the ground. When shield cut piles passed beneath masonry structures, pressure on the soil chamber, total thrust, and cutterhead speed were consistently controlled. Furthermore, the cutterhead torque was appropriately reduced, and slurry injection volume increased, contributing to better control of house settlement.

Influence of Freezing Tunnel Excavation on Foundation Settlement of Buildings

In this paper, the effects of the cement content and excavation speed parameters on the improvement effect of the artificial freezing method and the characteristics of frozen walls are studied by means of a field test, numerical simulation and theoretical model. The optimization effect of the cement content in the artificial freezing method is studied. It is found that 10% is the best content, which can maximize the freezing wall thickness and grouting effect, and promote uniform distribution of the temperature field. At the same time, the influence of the excavation speed on the stress and settlement of the foundation soil is analyzed. It is pointed out that the increase of the excavation speed will aggravate the settlement and stress redistribution, which may threaten the building structure. The evaluation method proposed in this paper verifies that the construction deformation and settlement control are within the safety standards and provides theoretical support and construction guidance for tunnel engineering.

Surface settlement induced by frictional force of epb shield tunneling in sandy gravels.

The excavation of Earth Pressure Balance (EPB) shield can be divided into two distinct stages, i.e. advancing and lining installation. The frictional force applied on surrounding soils reverses at these two stages, which is harmful to the settlement control. Based on Mindlin's method, a new model of surface settlement is derived to involve the reversed friction. A closed form formula is then obtained for the major type of metro tunnels. Main operational parameters are also used as input of the formula. Numerous operational data and measured settlements are collected from EPB tunnels of Chengdu Metro, Line 7. The proposed formula is validated against these field data in sandy gravels. It is shown that the new formula gives reasonable prediction of surface settlement along the tunnel sections. The accuracy of new formula is significantly higher than that of Peck's formula. This study provides a new vision in settlement control of EPB shield tunneling. The increase of chamber pressure will induce higher negative friction during the lining installation. Therefore, surface settlement of EPB tunneling cannot be controlled by just increasing chamber pressure. A balanced relationship between the chamber pressure and the thrust should be maintained instead.

The influence of the organization of the national currency system on the investment climate in Ukraine

The paper examines important aspects of the influence of the organization of the national currency system on the investment climate in Ukraine. The authors consider the functions of the national currency system, including control of international settlements, management of the foreign exchange market, participation in international relations and provision of favorable conditions for economic development. Special attention is paid to the influence of the organization of the currency system on the investment climate through the analysis of various problems, such as corruption, instability of the economic and political situation, lack of guarantees, etc. The paper puts forward recommendations for improving the investment climate in Ukraine, in particular through the improvement of legislation, the fight against corruption, the creation of a competitive business environment and other measures. The analysis of foreign direct investment schedules informs about the dynamics of the investment process in Ukraine and emphasizes the importance of solving problems for attracting new investments. The conclusions of the paper indicate the need for comprehensive measures to improve the investment climate and increase Ukraine's competitiveness on the international market.

OPTIONS SELECTION AND IMPACT STUDY OF INTERCITY RAILWAY TUNNEL CONSTRUCTION UNDER AIRPORT INTERZONE

The selection of tunnel construction program for intercity railroad tunnel under the airport must consider the limitations of environmental conditions and the scale of tunnel construction, and the impact of construction on the airport must be controlled within safe limits. Combined with the intercity rail transit tunnel project through the airport area surrounding environment and engineering geological conditions, the use of theoretical analysis, numerical simulation and other methods, comprehensive navigation, technology, construction period, cost, construction impacts and other aspects of the comparative analysis of the tunnel construction method of open excavation method and shield method, the results show that: (1) Due to the soft soil and groundwater in the tunnel excavation area, the risk of open excavation is greater, while the shield method is more suitable for longer silty soil tunnels without affecting the navigation, accordingly, the shield tunnel construction is more suitable for the tunnel construction under the airport. (2) Open excavation method has the shortest construction period to meet the requirements of rail transit, the unit cost is between 1 and 2 shield machines, and the total cost is close to 2 shield machines; for lower total cost, choose 1 shield machine, for shortening the construction period, choose 2 shield machines. (3) The maximum ground settlement caused by shield tunneling construction is 20mm, the maximum vertical differential settlement perpendicular to the tunnel is 2.8cm, and the maximum differential settlement is 0.93 ‰. On the one hand, it meets the requirements of airport settlement control, and on the other hand, it has little impact on the vertical connecting road and west station apron, and will not affect the opening of the airport runway and the operation of the terminal.

Impacts of synoptic weather patterns on Hefei's ozone in warm season and analysis of transport pathways during extreme pollution events

Extreme ozone pollution events (EOPEs) are associated with synoptic weather patterns (SWPs) and pose severe health and ecological risks. However, a systematic investigation of the meteorological causes, transport pathways, and source contributions to historical EOPEs is still lacking. In this paper, the K-means clustering method is applied to identify six dominant SWPs during the warm season in the Yangtze River Delta (YRD) region from 2016 to 2022. It provides an integrated analysis of the meteorological factors affecting ozone pollution in Hefei under different SWPs. Using the WRF-FLEXPART model, the transport pathways (TPPs) and geographical sources of the near-surface air masses in Hefei during EOPEs are investigated. The results reveal that Hefei experienced the highest ozone concentration (134.77 ± 42.82 µg/m³), exceedance frequency (46 days (23.23 %)), and proportion of EOPEs (21 instances, 47.7 %) under the control of peripheral subsidence of typhoon (Type 5). Regional southeast winds correlated with the ozone pollution in Hefei. During EOPEs, a high boundary layer height, solar radiation, and temperature; low humidity and cloud cover; and pronounced subsidence airflow occurred over Hefei and the broader YRD region. The East-South (E_S) patterns exhibited the highest frequency (28 instances, 65.11 %). Regarding the TPPs and geographical sources of the near-surface air masses during historical EOPEs. The YRD was the main source for land-originating air masses under E_S patterns (50.28 %), with Hefei, southern Anhui, southern Jiangsu, and northern Zhejiang being key contributors. These findings can help improve ozone pollution early warning and control mechanisms at urban and regional scales.

Freeze-thaw effects on pore structure of clay by 3D X-ray computed tomography and mercury intrusion porosimetry

Thaw settlement of soils is a comprehensive reflection of multiscale pore changes induced by freeze-thaw (F-T). In this study, three-dimensional (3D) X-ray computed tomography (CT) tests were utilized to investigate alterations in the macropore and mesopore structures, while mercury intrusion porosimetry (MIP) tests were used to examine the micropore structure in clay due to F-T influenced by different freezing temperatures without water supply. The maximum increase in CT transverse-sectional porosity after F-T can be used to identify where ice lenses formed most abundantly in the clay after thawing, and the diameter and horizontal orientation of the macropores exhibit the most significant increase after thawing. As the freezing temperature decreases, the location becomes farther from the cold end. Macropores are significantly more affected by F-T compared to mesopores, and changes in macropore porosity and diameter can be attributed to moisture migration and freezing shrinkage, with lower freezing temperatures amplifying the influence of freezing shrinkage and weakening the impact of moisture migration. Considering the small size of samples, the MIP porosity was defined to analyze the effects of F-T on the micropores. Compared to the CT volumeratic porosity, the influence of F-T on micropore porosity is less significant. As the freezing temperature decreases, the changes in micropore diameter become smaller. Overall, the lower the freezing temperature, the smaller the changes in macropores, mesopores and micropores. Lastly, a method is proposed for predicting the mass porosity based on the CT volumetric porosity and MIP porosity. This study demonstrates that changes in soil mass porosity reflect a comprehensive representation of multiscale pore variations and provides important theoretical support for thaw settlement control in artificial freezing engineering.

The influence of existing piles on station settlement during the construction of a tunnel undercrossing under existing stations

In the construction of tunnels under existing stations, it is necessary to control their settlement. When there is a pile foundation in the existing station, the pile cutting has a significant impact on the settlement of the existing station. To determine the influence of existing piles on the settlement of subway stations, a reasonable pile-cutting time is proposed. Based on the Chengdu Metro Line 9 underpassing the existing Line 1 hatchery station, the settlement law of the tunnel underpassing the existing Line 1 station is analysed via a numerical simulation. Furthermore, the deformation and stress characteristics of the existing piles, pipe roofs, and tunnel linings and the supporting effect on the existing station are discussed. It is concluded that the cutting of existing piles causes a change in the tunnel bearing system, thus resulting in a certain deformation of the station. The influence of different pile cutting times on the settlement of the existing station is then analysed, and it is clarified that the tunnel support stiffness is significantly enhanced after the construction of the secondary lining. At this time, the settlement of the existing pile station is significantly reduced. Finally, through a field investigation, the effect of surface grouting, pipe shed, and multilayer lining on the settlement control of the existing station while the existing pile foundation exists is determined. This research can provide a reference for the settlement control and foundation underpinning of existing stations at ultra-small distances in underground excavation tunnels.

Research on the control of high-fill roadbed with tunnel slag in karst sections

In this study, based on the Kaihua section of the G205 (China) national highway reconstruction project, the construction area of the K4+550–K4+940 section was chosen to conduct settlement control research on the high-fill roadbed of the karst section within the construction area. The viability of using clayey gravel and tunnel slag as roadbed fill was evaluated through laboratory soil tests. The construction technology of grouting was used to manage the substructure of the karst section. After installing prestress anchors on the top of the foundation, a ‘layered’ filling scheme was utilised to fill the tunnel slag and clayey gravel. The Flac3D simulation software was used to contrast the deformation curves of key nodes on unanchored and anchored roadbeds. The test results indicate that the California bearing ratio satisfies the requirements of the specification and that the uniaxial compression strength of the tunnel slag satisfies the requirements of the specification when the clayey gravel is near the optimal moisture content and dry density and when the compaction is controlled within 94%. The use of prestress anchors can strengthen the rock and soil layers of the foundation and reduce the plastic zone distribution. This paper provides a corresponding engineering experience for the treatment of high-fill roadbeds in karst areas.

Laboratory tests on the traffic-induced cyclic behavior of anisotropically overconsolidated clay under different drainage conditions

In road engineering on clay foundation, the subgrade clay is often anisotropically overconsolidated, and the drainage boundary is commonly partially drained. Considering that few laboratory studies focused on the traffic-induced cyclic behaviors of anisotropically overconsolidated clay, and investigated intensively the differences in deformation between undrained and partially drained conditions, this study performs a series of one-way cyclic tests on the overconsolidated clay with various consolidation stress ratios (K) under different drainage conditions. The emphasis is put on the comparison of undrained and partially drained tests in terms of the permanent axial strain and its accumulated rate, resilient modulus and damping ratio. Test results indicate that the relative magnitude of permanent axial strain and its accumulated rate between the two drainage conditions is highly related to cycle number, K and CSR, with decreasing K and increasing CSR exacerbating the difference. The resilient modulus of partially drained tests is greater than that in undrained tests overall, while the relative relationship of degradation index between the two drainage conditions is reversed. In addition, the increase of consolidation-induced anisotropy degree promotes the strain development and improves the resilient stiffness, which should be noted for the traffic-induced deformation of subgrade clay. Based on the shakedown theory, the allowable cyclic stress ratio is determined as 0.44, and it is affected little by K or drainage condition. Finally, prediction models of permanent axial strain and resilient modulus are established for the anisotropically overconsolidated clay under both drainage conditions, where the deformation prediction is found to be related to the shakedown behavior. It is recommended that the prediction and control of subgrade clay settlement in engineering practice should take into account the in-situ consolidation sate and drainage condition.

Near Real-Time Monitoring of Large Gradient Nonlinear Subsidence in Mining Areas: A Hybrid SBAS-InSAR Method Integrating Robust Sequential Adjustment and Deep Learning

With the increasing availability of satellite monitoring data, the demand for storage and computational resources for updating the results of monitoring the surface subsidence in a mining area continues to rise. Sequential adjustment (SA) models are considered effective for rapidly updating time series interferometry synthetic aperture radar (TS-InSAR) measurements. However, the accuracy of surface subsidence values estimated through traditional sequential adjustment is highly sensitive to abnormal observations or prior information on anomalies. Moreover, the surface subsidence associated with mining exhibits nonlinear and large gradient characteristics, making general InSAR methods challenging for obtaining reliable monitoring results. In this study, we employ the phase unwrapping network (PUNet) to obtain unwrapped values of differential interferograms. To mitigate the impact of abnormal errors in the near real-time small baseline subset InSAR (SBAS-InSAR) sequential updating process in mining areas, a robust sequential adjustment method based on M-estimation is proposed to estimate the temporal deformation parameters by using the equivalent weight model. Using a coal backfilling mining face in Shanxi, China, as the study area and the Sentinel-1 SAR dataset, we comprehensively evaluate the performance of unwrapping methods and subsidence time series estimation techniques and evaluate the effect of filling mining on surface subsidence control. The results are validated using leveling measurements within the study area. The relative error of the proposed method is less than 5%, which can meet the requirements of monitoring the surface subsidence in mining areas. The method proposed in this study not only enhances computational efficiency but also addresses the issue of underestimation encountered by InSAR methods in mining area applications. Furthermore, it also mitigates unwrapping phase anomalies on the monitoring results.

Settlement control in large span tunnels under shallow over burden: a case study of the Arash-Esfandiar-Niayesh tunnel

Settlement control is pivotal in the construction of large span tunnels, particularly when situated under shallow overburden. The importance of settlement control in the context of the Arash-Esfandiar-Niayesh tunnel project, a multi section tunnel designed to facilitate two-way traffic in Municipality of Tehran District 3, is studied. The tunnel, which possesses an overburden of 4–15 m, faces unique challenges such as low overburden, urban location, and proximity to tall structures. By integrating the New Austrian Tunneling Method (NATM), this paper examines the effects of various support systems on construction of the tunnel project. Two critical sections are analyzed, and the settlement control strategies are examined according to a combination of various support elements. Analysis and numerical modeling based on PLAXIS 2D finite element code revealed the impact of these support systems on ground settlements on the structural and geotechnical stability. They had a substantial impact of tunnel geometric shape on sustainability and stress distribution. The inadequacy of common support systems, especially in tunnels with a horseshoe section, is highlighted. The impact of removing temporary lattice girderson surface settlements emphasizes the importance of settlement monitoring. Field data, including a maximum vertical displacement of 2.6 cm on the ground and in the tunnel, validate the numerical analysis results. Despite the challenges, the consistency between numerical and instrument data underscores the effectiveness of settlement control strategies.

Prediction of dredged soil settlement based on improved BP neural network

Based on the measured settlement data from the Reclamation Project of Eastern Hengsha Shoal, two improved BP neural networks optimized by the particle swarm optimization (PSO) algorithm and genetic algorithm (GA) respectively are employed to predict the long-term consolidation settlement of the dredged soil in the reclamation area. By comparing the prediction results of the improved neural networks with those obtained from standard BP neural network and various curve fitting methods including hyperbola method, Hoshino method, and Asaoka method, as well as field-measured data, the improved neural network methods are validated to have a better predictive performance. The error analysis results indicate that compared with the standard BP neural network and curve-fitting prediction methods, the improved BP neural networks exhibit smaller prediction errors in terms of MAE, MSE, RMSE, MAPE, etc., and have a closer match between the predicted settlement values and the actual values. The selected GA-BP and PSO-BP neural network prediction methods in this study demonstrate higher prediction accuracy. Meanwhile, GA-BP demonstrates higher prediction accuracy and generalization ability than PSO-BP, but PSO-BP shows faster convergence in terms of prediction speed. The preferred methods presented in this paper exhibit good robustness and high reliability, which can achieve accurate prediction of dredged soil settlement. Additionally, unlike the traditional curve-fitting methods, the selected methods can effectively reduce the influence of subjective factors during the settlement prediction, and provide a new approach for settlement prediction, which can be effectively utilized as a substitute for long-term settlement monitoring and give reference for the design of settlement control of foundation of further construction projects.

Ground Deformation of Shield Tunneling through Composite Strata in Coastal Areas

In order to mitigate ground deformation during shield construction in both upper soft and lower hard strata of coastal areas, a numerical simulation was executed. This simulation assessed surface deformation under varying stratum ratios, grouting pressures, and earth bin pressures. The evaluation was primarily based on the amount of ground deformation, which revealed that hard rock strata offer superior settlement control compared to soft rock strata. The excavation of the right tunnel line increased disturbance to the left line at higher stratum ratios. Surface deformation demonstrated a linear correlation with earth pressure, with 130 kPa identified as the optimal point. Higher pressures resulted in extrusion deformation and ground uplift. Grouting pressure had a minimal impact on stratum deformation over time. The stratum ratio exerted the most significant influence on settlement, followed by earth pressure, with grouting pressure having the least impact. In the context of coastal tunnel construction, hard rock excavation is favored. Earth pressure must be balanced to prevent subsidence or uplift, while excessive grouting pressure does not significantly reduce subsidence. Grouting pressure should ensure the complete filling of voids.