Engineering Construction Research Articles

Spatial variability of geotechnical parameters of lateritic gravels in an Olama–Ngomedzap road section in a humid tropical area (Cameroon)

Searching for borrow pits often used during civil engineering constructions is an important step that requires a lot of time and money. The nature of the parent rock, climate, topography, vegetation and time influence the formation of lateritic gravels with different geotechnical properties within the same region. The present study aims at finding the spatial variability of geotechnical parameters of lateritic gravels from two different deposits using a variogram and statistical analysis. Out of 122 lateritic gravel samples collected, 69 were from underdeveloped lithic ferrallitic soils (LFS) and 53 from under developed non-lithic ferrallitic soils (NLFS). The mean values of the coefficient of variation (CV) shows that the geotechnical parameters of LFS-derived lateritic gravels are more dispersed than those developed on NLFS. The fines content, plasticity index (PI) and Californian bearing ratio (CBR) variograms observed mainly in the North and NNE parts of the study area, suggest that, the lateritic gravels in this area have average to good geotechnical characteristics. The principal component analysis (PCA) indicates that the CBR and the maximum dry density (MDD) are inversely related to the optimum moisture content (OMC). The discriminant factor analysis (DFA) coupled to the ascending hierarchical classification (AHC) shows three families of lateritic gravels: (1) class 1/3, lateritic gravels characterized by MDD, CBR, consistency index (CI), gravels content, and plastic limit (PL); (2) class 2/3, lateritic gravels characterized by fines content, and maximum grain diameter (Dmax) and, (3) class 3/3, lateritic gravels characterized by OMC, liquid limit (LL), PI, PL, and fines content, that fit for road construction.

New Materials for Controlling Water Inrush and Sealing Tunnel Karst Pipes

Water inrush disasters in karst areas have caused great losses to underground engineering construction, so it is urgent to control water gushing disasters in karst pipelines. In this paper, solution polymerization is used to prepare a grouting and sealing expanded matrix material to control disasters. Noncovalent weak interactions were used to improve the surface properties of the expanded matrix material, the effects of the natural polymer content on the properties of the matrix material were studied, and a modified expanded matrix material with an optimal response rate was prepared. A cross-linked curing agent (CCA) was developed and synthesized, and a new cross-linked expansive grouting and sealing material (WIS grouting material) with various particle sizes was synthesized with noncovalent interactions such as hydrogen bonding, static electricity, van der Waals forces, etc. The results showed that a 4 % solution polymer content (accounting for the particle mass of the expanded matrix) was the optimal dosage, and the optimal ratio of the modified expansion matrix material to the crosslinking curing agent was 1:1. The early compressive strength exceeded 0.2 MPa, and the water absorption rate reached 170 times. There was a power function relationship between the water absorption rate and time, and the rate was controlled by adjusting the particle sizes. The mechanism through which the WIS grouting material underwent expansion and crosslinking was explained at the microscopic level. The gel formed in response to water resisted dispersion in dynamic water and rapidly sealed karst pipe water gushers. This paper proposes a novel approach to utilizing the expansion characteristics of polymer chemical synthetic materials for crosslinking to seal karst pipe water gushers, effectively addressing the issue of poor resistance to dynamic water dispersion in traditional grouting materials used in karst areas. These results provide a scientific basis for the development and application of new materials to control water inrush in karst pipes.

Human Activities Have Altered Sediment Transport in the Yihe River, the Longest River Originating from Shandong Province, China

Climate change and human activities affect regional sediment transport and ecological environment construction. Investigating sediment transport and its influencing factors in the Yihe River Basin (YHRB) will provide guidance for regional soil and water conservation and sustainable development. We analyzed the chronological changes, cycles, spatial distribution and influencing factors using Mann–Kendall (M-K) trend analysis, wavelet analysis, and the Pettitt mutation point (PMP) test, then quantified the role of precipitation and human activities in sediment transport changes. The results showed that annual precipitation decreased marginally, whereas sediment load has noticeably declined. Four precipitation cycles were observed: 4–8a, 9–14a, 16–19a, and 20–28a, where 9–14a was dominant; sediment transport cycles were tracked: 3–5a, 9–15a, and 30a, where 30a was dominant with a decreasing trend. The sediment load was higher in the central, northern, and southwestern sub-basins of the YHRB, while it was lower in the southeast. The contribution of human activities and precipitation changes to sediment transport was 73.14% and 26.86% in transitional phase I (1965–1980) and 71.97% and 28.03% in transitional phase II (1981–2020), respectively. Hydraulic engineering construction, water resource development, land-use changes, and soil and water conservation measures intercepted precipitation and sediment, making them the primary factor affecting sediment transport changes in the YHRB.

LithoSegNet: Regional attention-based deep fusion of multi-scale and cross-stage features for real-time lithology segmentation

Lithology identification plays an important role in engineering construction, disaster prediction, reservoir evaluation, and other fields. However, with the development of mechanization and automation, traditional lithology recognition methods are gradually unable to meet existing demands in terms of recognition speed and efficiency. In order to achieve real-time, fast, and accurate identification of lithology, we designed a lightweight model backbone, proposed a multi-scale feature extraction module and a cross-stage feature fusion module based on regional attention, developed a step-wise fusion scheme for multi-stage feature, and developed a real-time lithology segmentation model. The experimental results show that the feature extraction module improves the mIoU of the model by 0.0021; The cross-stage feature fusion module improves the mIoU of the model by 0.0104; The step-wise fusion scheme can effectively fuse shallow spatial features and deep semantic features. The model mIoU using this scheme is 0.0246 and 0.0145 higher than that using SegFormer and SegNeXt fusion schemes, respectively. Our model LithoSegNet can achieve a mIoU of 0.9583 with a speed of 116.25 images per second, comprehensively surpassing many state-of-the-art models. The research results can provide technical support for automated geological sketching in field exploration and on-site construction, and lay the foundation for intelligent construction of underground engineering, which has important scientific and engineering application value.

Crystalline NiCo2O4 and amorphous NiCo2S4 heterostructured electrode for high-performance asymmetric supercapacitors

The construction of well-designed heterostructures and phase engineering have been verified to be a promising strategy to improve electrochemical performance of supercapacitors. However, it is still a challenge to construct well-defined amorphous/crystalline hetero-phase electrode with plentiful heterointerfaces. Herein, a high-performance self-supported NiCo2O4@NiCo2S4 electrode with crystalline NiCo2O4 and amorphous NiCo2S4 heterostructure is synthesized by electrodeposition-anneal-electrodeposition procedure. The interconnected nanosheet structure and rich heterointerfaces effectively promote the exposure of surface area and accelerate the electron/ion transfer kinetics of redox reaction as well as restrain the volume expansion and structural collapse, thus greatly enhancing the electrochemical performance and stability. Impressively, the advanced NiCo2O4@NiCo2S4 electrode delivers a prominent specific capacitance of 2243.0 F g−1 at 1 A g−1 along with outstanding cyclic stability with a capacity retention of 83.29 % at 10 A g−1 after 5000 cycles. Moreover, the asymmetric supercapacitor (ASC) assembled by NiCo2O4@NiCo2S4 cathode and active carbon anode displays a maximum energy density of 66.7 Wh kg−1 at 625.3 W kg−1 and favorable cycling stability (77.23 % after 10,000 cycles at 10 A g−1).

From Bibliometric Analysis to Experimental Validation: Bibliometric and Literature Review of Four Cementing Agents in Soil Stabilization with Experimental Focus on Xanthan Gum

This article focuses on the search for efficient solutions to enhance the mechanical strength of geomaterials, especially soils, with crucial applications in civil engineering. Four promising materials are explored as soil improvement agents: natural latex (rubber trees), lignosulfonate (paper industry byproduct), xanthan gum (bacterial fermentation), and eggshell lime. While other sustainable options exist, these four were chosen for their distinct characteristics and potential for further study. Natural latex, derived from rubber trees, demonstrates exceptional potential for strengthening the mechanical resistance of soils, offering a path to effective stabilization without compromising environmental sustainability. Lignosulfonate, a paper industry byproduct, emerges as an alternative that can significantly enhance the load-bearing capacity of soils, boosting its applicability in civil engineering projects. Xanthan gum, produced through bacterial fermentation, possesses unique properties that increase soil cohesion and strength, making it a valuable option for geotechnical applications. Finally, despite potential challenges, eggshell lime shows promising potential in enhancing the mechanical resistance of soils. This study highlights the importance of evaluating and comparing these agents in terms of their effectiveness in improving the mechanical strength of soils in civil engineering applications. In the literature review, the impact of stabilizer addition (%) was examined for the four cementing agents studied, along with its influence on key soil properties like optimum moisture content (OMC, %), maximum dry density (MDD, gm/cc), California bearing ratio (CBR, %), uniaxial compressive strength (UCS) at 28 days (MPa), and the change in UCS (ΔUCS, %) among other physicochemical parameters. Appropriate selection of these materials can lead to developing more robust and sustainable geomaterials, promoting significant advancements in geotechnical engineering and civil construction practices. To evaluate their effectiveness, the efficiency of one of them was assessed experimentally. Xanthan gum (XG) was selected to biopolymerize clay soil. Specimens were prepared for strength and stiffness tests, including unconfined compression, scanning electron microscopy (SEM), and ultrasonic wave analysis. The impact of stabilizer concentration was examined (e.g., 1%, 3%, 5% xanthan gum) to assess how dosage affects the soil–stabilizer mixture. The results showed that the rubber increases the unconfined compression and stiffness of the soil, controlled by the XG’s porosity/volumetric quantity ratio. The research demonstrates the potential of XG, but a broader analysis of all four materials with the outlined testing methods paves the way for future advancements in geotechnical engineering.

Dam Construction, Company Towns and Planned Urban Development: The Example of Salto del Esla, Spain

ABSTRACT Company towns are integral to the urban and territorial changes wrought by the Industrial Revolution, especially in remote, resource-rich areas. Among these, villages constructed alongside dams stand out due to their profound territorial impact. This study focuses on one such unique settlement near the Ricobayo dam in Zamora, Spain, exploring its construction and environmental integration. At its inception, Ricobayo was Europe’s largest dam, its creation marked by notable feats like relocating a church, and pioneering hydraulic engineering and bridge construction, including a record-breaking design by Torroja. The adjacent company town set a precedent for creating liveable spaces for workers in isolated locales, influencing later developments. Research included on-site investigations, archival work at Iberdrola’s Historical Archive, and review of historical texts, underscoring the cultural and landscape significance of 20th-century dam settlements and the distinctive features of Ricobayo’s surroundings.

Psychological research in vibration disease: level of alexithymia, psychological defenses

Vibration disease ranks among the first in the structure of diseases in workers at mechanical engineering enterprises, metallurgical, mining, and construction industries, various branches of agriculture, and aircraft manufacturing. A change in the mental status of people working in vibration conditions was identified; the most common are «neurosislike states» with psycho-emotional disorders of anxiety type. Meanwhile, currently existing data on the state of the nervous system in vibration pathology are contradictory and scarce, which requires a more in-depth study. Purpose of the study: to investigate the psychological status of patients with vibration disease from the action of both local and general vibration. Research results. In patients with vibration disease from the action of both local and general vibration, a predominance of destructive psychological defenses (projection and repression) over constructive ones (compensation and rationalization) is observed.

Lap Length of Steel Bars Between Novel Prefabricated Wall and Foundation Floor Structures: Full-Scale Experiment

In the context of promoting environmentally friendly practices, prefabricated components are increasingly utilized in civil engineering design and construction. Prefabricated shear walls, in particular, have become prevalent in contemporary residential and office buildings. Following an economic analysis of the construction steps for prefabricated walls, Shanghai Hengxu Energy Conservation Company developed a novel type of prefabricated wall for use in building basements. This innovative wall consists of two thin plates joined by distributed tie pieces, with an internal steel bar cage positioned between them. The core concrete is cast in place between the plates. The wall is designed to withstand water and soil pressures from underground and connects to the basement floor through overlapping steel bars. The effectiveness of the wall's integration with the foundation floor depends on the lap length of the steel bars, a critical factor in structural design and construction. To optimize the lap length, three full-scale specimens were tested, differentiated by varying steel bar lap lengths: 0.8 lae, 1.0 lae, and 1.2 lae, where lae represents the basic anchorage length. The specimens were subjected to horizontal loading to assess failure modes, crack propagation, load-displacement behaviors, and stress-strain responses of the reinforcements. The experimental results revealed that increasing the lap length of the steel bars beyond 0.8 lae does not significantly enhance the bearing capacity or deformation potential of the specimens.

Experimental investigation on rockburst characteristics of highly stressed D-shape tunnel subjected to impact load

Rockburst has always been a challenge for the safe construction of deep underground engineering. This study investigated the rockburst characteristics in highly-stressed D-shape tunnels under impact loads from rock blasting and other mining-related dynamics disturbances. The biaxial Hopkinson pressure bar was utilized to apply varying biaxial prestress and the same impact loads to cube specimens with D-shape hole. High-speed camera and digital image correlation (DIC) were used to capture the failure process and strain field of specimen. The test results demonstrate that the D-shape hole specimen experience rockburst under coupled static stress and impact load. Under this circumstance, the rockburst mechanism of the D-shaped hole specimens involves spalling in sidewall induced by impact load, indicating dynamic tensile failure. The high static prestress provides the initial stress field, while the impact load disrupts the stress equilibrium, result in the stress or strain concentration in the sidewall of the D-shape hole, inducing rockburst. Moreover, the rockburst process can be divided into (1) calm stage, (2) crack initiation, propagation, and coalesce stage, (3) spalling stage and (4) rock fragments ejection stage. Impact load triggers rockburst occurrence, while vertical stress further determines the rockburst characteristics. The influence range and magnitude of strain concentration zone and displacement deformation of the tunnel surrounding rock increases with increasing vertical stress, thus inducing more severe rockburst.

Study on deformation characteristics of toppling failure of anti-dip rock slopes under different soft and hard rock conditions

For the widespread exposure of toppling deformation phenomena in anti-dip engineering slopes such as hydropower, transportation, and mining, especially deep-seated toppling, these large-scale deep-seated toppling deformations reaching depths of hundreds of meters have become significant geotechnical engineering problems that restrict large-scale engineering construction and require urgent solutions. There are significant differences in the failure characteristics and mechanisms of anti-dip rock slopes under different soft and hard rock conditions. This study, starting from the failure characteristics and mechanisms under different soft and hard conditions of rocks, summarizes two types of toppling deformation: ductile bending deep toppling (DBDT) and brittle fracture shallow toppling (BFST). The UDEC method is used to preliminarily explore the threshold of rock mechanical parameters for these two types of toppling, with 80 MPa (UCS, uniaxial compressive strength) mechanical parameters serving as the preliminary threshold. The results indicate that hard rock undergoes BFST, whereas soft rock undergoes DBDT. The rock mechanical parameters of 100 MPa (UCS) and 20 MPa (UCS) were selected to study the evolution process and mechanism of DBDT and BFST deformations, respectively. Numerical simulation results have innovatively revealed the mechanical behavior characteristics between rock layers during the process of toppling deformation. Because toppling deformation mainly originates from interlayer displacement deformation and intra-layer tensile deformation of rock layers, the interlayer mechanical characteristics are of great significance for understanding the mechanism of toppling deformation. This research can provide a theoretical basis for the stability assessment and development utilization of anti-dip rock slopes and toppled slopes.

Effect of steel fiber content on failure strength and toughness of UHPC-CA at low temperature: An experimental investigation

As a potential and sustainable construction material, ultra-high performance concrete containing coarse aggregate (UHPC-CA) finds promising applications in engineering constructions, particularly in severe cold regions. This study conducts an experimental study to investigate the influence of fiber content (ranging from 0.0 % to 3.0 %) on the uniaxial compression and splitting-tension failures of UHPC-CA across a temperature range of −90 °C∼20 °C. Through microstructure analysis, the underlying mechanisms and quantitative analysis behind the low-temperature enhancement effect and fiber reinforcement effect on the nominal strength and toughness of UHPC-CA were elucidated. The test results show that as the temperature drops from 20 °C to −90 °C, nominal strengths of UHPC-CA monotonically increase (with a maximum increase 88.1 % for splitting-tension strength while 72.6 % for compressive strength), but the compressive toughness reduces with a maximum decrease 54.6 %. Additionally, the incorporation of steel fibers can enhance the nominal strengths and compressive toughness, exhibiting the fiber reinforcement and toughening effects. Compared to the UHPC matrix, all the increases for nominal strengths and compressive toughness of UHPC-CA with 2.0 % steel fibers at room temperature are higher than those at low temperatures, demonstrating that the decreasing temperature can weaken the fiber reinforcement and toughening effects, which may attribute to fact that the formation of microcracks (due to the expansion of phase change of pore ice) in the surface between steel fiber and UHPC matrix at low temperatures, as observed in the microscopic test. However, as the fiber content exceeds 2.0 %, the splitting-tension strength decreases, thereby it is recommended that the optimal steel fiber content is around 2.0 % for UHPC-CA at low temperatures. Finally, considering the quantitative effects of steel fiber characteristics and temperature, the empirical prediction models for cryogenic nominal strengths were proposed and verified, which can well predict compressive and splitting-tension strengths of UHPC-CA with various steel fiber contents at low temperatures. This study can provide an experimental data reference for the safety design of UHPC structures and contribute to promoting the application of UHPC-CA in the engineering construction of cold regions.

A new method for predicting consolidation settlements of soft ground based on monitoring results

Excessive settlement or differential settlement of subgrade will lead to the deterioration of line operational conditions, the reduction of passenger comfort, and even endanger the safety of traffic. Therefore, it is of great significance to study the settlement prediction of subgrade. In order to predict the settlement of foundation under the next level of loading earlier during the embankment construction process, a new method of predicting settlement of soft soil subgrade is proposed. Firstly, based on monitoring results of soft soil foundation, the consolidation parameters of soil layer are back-calculated according to the three-point method. Then, combined with the theory of the consolidation degree of graded loading, the formula that can predict settlement under different loading conditions are derived. Eventually, the practical application of the method is verified by the prediction and comparative analysis of measured settlements based on engineering examples. The result of research shows that the method can predict the foundation settlement after loading during construction of engineering fill. This method has obvious advantages over the traditional curve fitting method and can guide the actual engineering construction.

Emergency logistics siting-path question for engineering construction projects based on quantum particle swarm algorithm

Emergency material security is the key to post-disaster emergency relief in complex environment engineering construction projects. Aiming at the emergency logistics center site path planning problem, the uncertain parameters of congestion time and maximum rescue time are described using trapezoidal fuzzy numbers, and the emergency logistics site path model of the two-phase engineering construction project is established. A quantum particle swarm optimization model is designed to avoid premature population convergence and maintain population diversity. The particle swarm algorithm uses the quantum spin gate’s rotation angle update to represent the particle velocity update. Taking the engineering construction project in the western mountainous area as an example, the validity and applicability of the model are verified through model comparison and sensitivity analysis. The results of the example show that in the complex environment, the quantum particle swarm algorithm takes 29.35 s in convergence time, and the particle swarm algorithm takes 40.12 s, which is 36.69% higher than the efficiency of PSO. In total cost, the quantum particle swarm algorithm has a total cost of 46,632.40 RMB, and the particle swarm algorithm has a total cost of 48,319.51 RMB, which is 3.62% lower than the cost of PSO. The quantum particle swarm algorithm’s total distance is 550.57 km, and the particle swarm algorithm’s total distance is 579.35 km, 5.23% lower than the total distance of PSO. The model established in this study can scientifically select the location of emergency facilities and formulate the emergency rescue path, reduce the response time of emergency rescue and storage costs, and provide decision support for the scheduling of emergency supplies for engineering construction projects in complex and dangerous areas.

Flexural durability of BFRP bars reinforced geopolymer-based coral aggregate concrete beams conditioned in marine environments

Geopolymer is an environmentally friendly material that utilizes industrial solid waste, boasting reduced greenhouse gas emissions and energy consumption. It exhibits superior performance in terms of corrosion resistance and thermal stability compared to ordinary Portland cement (OPC). These excellent properties are crucial for marine engineering construction, offering significant value and application potential in marine engineering materials. In this study, geopolymer was employed as the cementitious material, with marine resources like seawater and coral aggregates sourced from remote island areas effectively utilized, and basalt fiber-reinforced polymer (BFRP) bars were incorporated as reinforcements to develop BFRP bars reinforced geopolymer-based coral aggregate concrete (GPCAC) beams. Laboratory aging procedures were employed to investigate the deterioration patterns and damage mechanisms affecting the flexural behavior of GPCAC beams under seawater immersion and dry-wet cycling conditions, comparing them with cement-based coral aggregate concrete (CAC) beams. The experimental results indicated that both CAC and GPCAC beams under simulated marine environments experienced a reduction in the number of cracks upon damage, but their crack spacing and width increased. Moreover, the flexural stiffness of CAC and GPCAC beams after seawater attacks tended to increase, but this increased stiffness did not translate to a higher loading capacity. Conversely, as the corrosion age increased, the ultimate load and deflection values of both CAC and GPCAC beams decreased to varying extents, with the load-carrying capacity degradation more pronounced in seawater dry-wet cycling environments than in seawater immersion conditions. Compared to CAC beams, GPCAC beams exhibited superior resistance to seawater erosion. Following 12 months of seawater dry-wet cycling, the ultimate loading capacity of CAC beams decreased by 12.2%, while that of GPCAC beams only degraded by 9.5%. Predictions of the flexural capacity of GPCAC beams using equations from existing FRP-reinforced normal aggregate concrete (NAC) specifications indicated slightly higher values than the experimental values, with an error margin of less than 15%. Overall, the formulas for the flexural capacity of NAC beams in existing FRP-reinforced NAC codes remained applicable to CAC and GPCAC beams.

Biomimetic Design of Soil-Engaging Components: A Review.

Soil-engaging components play a critical role in agricultural production and engineering construction. However, the soil-engaging components directly interacting with the soil often suffer from the problems of high resistance, adhesion, and wear, which significantly reduce the efficiency and quality of soil operations. A large number of featured studies on the design of soil-engaging components have been carried out while applying the principles of bionics extensively, and significant research results have been achieved. This review conducts a comprehensive literature survey on the application of biomimetics in the design of soil-engaging components. The focus is on performance optimization in regard to the following three aspects: draught reduction, anti-adhesion, and wear resistance. The mechanisms of various biomimetic soil-engaging components are systematically explained. Based on the literature analysis and biomimetic research, future trends in the development of biomimetic soil-engaging components are discussed from both the mechanism and application perspectives. This research is expected to provide new insights and inspiration for addressing related scientific and engineering challenges.

Automated geometric reconstruction and cable force inference for cable-net structures using 3D point clouds

Laser scanning provides an efficient solution to digital twin construction in civil engineering. The complexity and redundancy of large-scale point clouds substantially prolong the labor-intensive model reconstruction process. This paper presents an automated and high-precision geometric reconstruction approach for cable-net structures with a complete workflow from raw points to the extraction of cable shapes and forces. The strategy involves the extraction of coordinates of key cable regions through the characterization of cable geometry and local registration methods, followed by the computation of cable forces and shapes using segmented catenary theory and nonlinear optimization. The approach is validated with a single-curvature cable-net structure, with the accuracy of cable shapes within ±5 mm and errors in cable forces <5%. The method contributes to health monitoring and rapid reconstruction of cable-net structures. The precise geometry and forces will facilitate the creation of the mechanical models reflecting the physical authenticity of structures.

Study on the dynamic constitutive model of coal at different depths in Pingdingshan mining area

The environment of deep in-situ occurrence is complex, and secondary dynamic disasters occur frequently. Exploring the dynamic constitutive models of coal at different depths is the foundation for deep resource development, which can help promote the safe and efficient mining of coal resources at different depths and reveal the mechanism of sudden dynamic disasters. Dynamic mechanical testing of coal at different depths of the Pingdingshan mine (China) was carried out using a split Hopkinson pressure bar system with confining pressure. On the basis of statistical damage theory, dynamic constitutive models of coal at different depths were explored, and the theoretical models were compared and verified using the experimental results. An expression relating to the infinitesimal element strength of coal and loading rate was derived, and the parameters σ1dp, Ed, and ε1dp were determined. Inversion verification of the model showed that the experimental results agree well with the theoretical results prior to the peak stress. These research results are expected to be applied to the exploitation of deep resources, laying a foundation for the law of deep earth science and the construction of deep engineering.

Evaluating the Positional Stability Status of the Druk Corsnet: A Preliminary Study

Abstract— The continuously operating reference station (CORS) that provides a Global Navigation Satellite System (GNSS) enables precise location and height data for various applications such as site selection of important engineering projects and constructions and hazard analysis. Similarly, the most common applications of the CORS network, in Bhutan, are for engineering, cadastral, geodetic, and topographical surveys. In this regard, the consistency and dependability of the data from the CORS station are crucial. Moreover, the ability of such applications heavily depends on precise and reliable data from the CORS network. However, Bhutan has not conducted any studies on the stability, in terms of its position, and height fluctuation of the CORS station. Therefore, the goal of this study is to determine the positional and height variation of the 9 CORS stations that are operational in Bhutan between the years 2016 to 2022. Assessing the stability and dynamic behavior of reference stations in a CORS network is part of position variation analysis. It is feasible to identify and quantify a variety of geodetic occurrences by examining the time series of positional analysis. Analysis of height variation focuses on changes in orthometric heights throughout the CORS network. In our study, all the available GNSS CORS data are processed and the displacement in height and position is computed and compared. The analysis consists of a simple method (mean value subtraction) of time series data, which is computed and compared. The major findings show that the absolute mean standard deviation in the position of the stations was 5.49 cm, 6.36 cm, and 4.24 cm vertical (height), ease, and north horizontal component respectively. The findings highlight that the proposed method of determining the variation in height and location of the CORS stations is fairly practical and will help the user community to guide them in using the CORS network across Bhutan wisely. Similarly, the result of this study will be a relevant source of information to organizations such as the National Land Commission Secretariat (NLCS) as a means to augment the system in the future.

Prediction of Buildings’ Settlements Induced by Deep Foundation Pit Construction Based on LSTM-RA-ANN

In view of the shortcomings of existing methods for predicting the settlement of surrounding buildings caused by deep foundation pit construction, this study uses the monitoring data of a foundation pit project in Shanghai and divides the construction process of the pit into three working conditions, that is, enclosure construction, earthwork excavation, and basement support construction. The attention mechanism and residual update are integrated into the artificial neural network (ANN) model, and the root-mean-square error, average absolute error, and determination coefficient are used as the evaluation indices of the model. The artificial neural network prediction model LSTM-RA-ANN for building settlements in deep foundation pit construction was then established. The prediction performance of the model was also analysed under different working conditions, and the influences of the main factors (including the soil parameter, monitoring point location, activation function, hyperparameter, and input number) on the evaluation index was further explored. The results indicate that the performances of the established LSTM-RA-ANN model are closely related to the construction conditions, the predicted settlements agree well with the monitored ones in three working conditions with the greatest errors occurring at a later time of the working conditions, and the prediction accuracy of the great–small order corresponds to basement support, enclosure construction, and earthwork excavation respectively. The farther the monitoring point is from the edge of the pit, the better the model performance is. The activation function, initial learning rate, and maximum iteration batch have a great influence on the evaluation indices of the model, while the number of input points has little effect on the evaluation indices. These results may serve as a reference for the safe construction and normal operation of foundation pit engineering.