In recent years, bamboo anchors have demonstrated significant potential for application in geotechnical structural reinforcement, owing to their advantages of renewability and low-carbon environmental friendliness. We calculate the carbon emissions of bamboo anchor throughout life cycle assessment based on engineering cases. We compiled the literature related to bamboo anchors. A comprehensive analysis of keywords and research contents was conducted using the VOSviewer software. Summarized the current research trends and key conclusions, and provided directions for future development. The results showed that the total carbon emissions of a single bamboo anchor over its entire life cycle were approximately -1.94 kg CO2e. For a rectangular deep excavation with a depth of 6 m, a length of 30 m, and a width of 20 m, the use of bamboo anchor can directly achieve a carbon emission reduction of approximately 3.49 t CO2. Literature analysis results reveal a clear growth trend in studies related to bamboo anchor. Chinese researchers have made the dominant contribution, accounting for nearly 90% of the available publications. Meanwhile, the proportion of English publications is relatively high. The findings indicate that current studies mainly focus on improving the durability and mechanical performance of bamboo anchors through physicochemical treatments and structural reinforcement technologies. Studies also discussed experimental investigations of the interfacial bonding behavior among bamboo, grout, and surrounding soil or rock media, whereas analyses of failure mechanisms have largely remained at a qualitative level. The mechanical performance of bamboo is strongly affected by factors such as species, age, and growth conditions, leading to substantial variations in experimental conditions across different studies. Currently, the most widely used Moso bamboo has a tensile strength of about 130-220 MPa, a compressive strength of about 60-80 MPa, and an elastic modulus of 8-20 GPa. Application fields have expanded from temporary slope support to a wider range of scenarios. Future research directions need to deepen

Foundation pit dewatering and excavation in groundwater-rich strata severely threatens adjacent large-diameter shield tunnels. However, existing physical models inadequately replicate both dewatering effects and segmental lining behaviour. A novel testing device was developed to simulate sequential dewatering, excavation, and backfilling while dynamically controlling groundwater levels, and two parallel centrifugal model tests were conducted. The results show that (1) the damage to the underlying shield tunnel structure caused by adjacent foundation pit construction first appears at the tunnel crown and arch bottom; (2) tunnel joint deformation is controlled by the excavation location of the foundation pit, construction directly above causes the maximum offset and opening positions to be separated, side construction causes both to be concentrated at the nearest ring position, with deformation magnitude consistently showing crown > arch waist > arch bottom; (3) dewatering is identified as the primary contributor (accounting for 52.1-83.9 %) to the overburden earth pressure reduction on tunnels. Its impact is more pronounced under lateral construction due to the dewatering-induced hydraulic slope curves. These findings provide critical guidance for controlling construction disturbances of foundation pit in water-rich strata and optimizing protective measures for adjacent shield tunnels.

Microbial induced carbonate precipitation (MICP), an innovative soil stabilization technique, has recently emerged as a promising method for mitigating loess erosion. This study investigates the hydraulic properties of MICP-treated loess through comprehensive laboratory tests. The disintegration tests were conducted to evaluate the water stability of MICP-treated loess under different curing days (Cd) and cementation reagent concentrations (CRCs). Results show that the disintegration ratio shows a 57.4% reduction with CRCs = 1.0 M, Cd = 14 d treatment and also the disintegration process is prolonged accordingly. Subsequently, double-line method was applied to investigate the water sensitivity of MICP-treated loess. The collapsibility coefficient of the loess sample after MICP solidification can be reduced by 23.8%. The permeability coefficient of MICP solidified loess can be effectively decreased up to two orders of magnitude after MICP treatment. A quasi-two-dimensional model test apparatus was fabricated to perform infiltration and capillary rise experiments, aiming to characterize the permeability and water retention capacity of MICP-modified loess under laboratory conditions. The spatiotemporal variation of water content and the capillary height, the wetting frontal profile were also characterized. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed to identify the precipitated mineral and reveal the bonding mechanism. Mercury intrusion porosimetry (MIP) tests were further implemented to characterize the pore size distribution and interpore connectivity of MICP-treated loess. This study provides a theoretical basis for the water-resistant protection of loess slopes and foundations in loess areas.

Under complex hydrogeological conditions, the shear creep characteristics of jointed rock masses play an important role in the long-term stability of slopes. Joint angle and submergence are key factors affecting the shear creep behavior of jointed rock masses. To investigate the time-dependent deformation behavior of jointed sandstone with different joint angles, prefabricated jointed sandstone samples are prepared. Shear creep tests are then conducted at joint angles of 25–45° under natural and submerged conditions using a self-developed creep-impact testing machine and a variable-angle shear box. The results demonstrate that creep deformation and strain rate increase with increasing joint angle and vertical load under both moisture states. Compared with the natural samples, the submerged samples exhibit considerably higher creep deformation and strain rates. Furthermore, prolonged immersion results in a more abrupt failure behavior. The submerged environment has a notably greater effect on the shear deformation of jointed sandstone compared with the joint angle and vertical load; however, the joint angle remains a key factor in controlling the creep failure of the sandstone. Finally, a multifactor shear creep constitutive model that combines a shear stress ratio (capturing joint angle, joint roughness, and load) with an exponential time law and damage mechanics is proposed. The proposed model describes the entire creep phase of jointed sandstone accurately and provides theoretical support for the stability assessment of water-influenced slope engineering projects.

The grout-soil (GS) interface is a weak point for ground anchors, which affects the anchorage performance by load-transfer processes. In order to investigate the mechanical properties of the GS interface, direct shear tests were performed on the GS interface under constant normal load (CNL) conditions using a visual shear container. The variations of interfacial shear stress and dilatancy characteristics were analyzed, considering the effects of relative densities (Dr) of sand and soil specimen height. Moreover, the failure evolution mechanism of the GS interface during the shear process was revealed using the digital image correlation (DIC) method. A finite-slip coupled (FSC) constitutive model was developed to characterize the shear behavior of the GS interface, which was then validated by the experimental results. The results show that under a CNL condition, the peak strength phi ' exhibits a linear decrease with the increase of Dr, while the residual strength phi ' first increases and then decreases. Both peak and residual strengths show a linear reduction as the soil specimen height increases. The shear deformation at the GS interface primary occurs within a narrow zone near the soil, with a thickness of approximately 6 times the median particle diameter (d50). The findings deepen the understanding of the shear mechanical behavior at the GS interface, providing valuable insights for the development of a comprehensive evaluation framework for cast-in-place geotechnical structures, including but not limited to ground anchors.

The instability of the hole wall is a prevalent issue in foundation construction. Typically, mud is applied to maintain hole wall stability. However, determining the optimal mud proportion for the multi-layer soft soil strata remains unclear and largely depends on engineers' experience. This study employs cavity expansion theory to calculate the required mud density range for different strata. Subsequently, a numerical simulation model is developed to analyze the impact of mud density on hole wall stability, providing a more accurate design range for optimizing the mud proportion. Furthermore, the single-factor experiment is conducted to investigate the effect of modifiers on mud performance. Finally, response surface methodology is utilized to establish predictive models for mud density and viscosity, enabling accurate forecasting of optimal mud proportions. The results reveal significant differences in mud density requirements among various layers in the multi-layer soft soil strata, as determined through calculations from the cavity expansion theory and numerical simulation. Additionally, the prediction models developed using the response surface methodology exhibit superior and reliable performance, enabling precise prediction of optimal mud proportion ranges for multi-layer clay strata and multi-layer sandy strata. These findings can provide valuable references and offer engineering guidance for adjusting and optimizing mud proportions in the multi-layer soft soil strata.

This study presents an experimental investigation into the effects of microbial induced carbonate precipitation(MICP) treatment factors on the shear behavior of MICP-treated loess soil. Several groups of loess samples were prepared and subjected to MICP treatment with varying cementation reagent concentration, calcium source, and curing duration across three levels. The results indicate that the shear strength of MICP-treated loess achieves optimal performance when treated with the cementation reagent concentration of 1.0 M, cured for 14 days, and using calcium chloride as the calcium source.Compared to untreated loess, the cohesion and internal friction angle increased by approximately 77%and 26%, respectively. To evaluate the influence of these treatment variables, orthogonal analysis was performed on the obtained shear strength parameters.The analysis indicates that the cementation reagent concentration is the primary factor influencing shear strength, followed by the calcium source and curing duration. Additionally, scanning electron microscopy(SEM) tests were performed to investigate the microstructure of the MICP-treated samples. The results reveal that calcium carbonate significantly enhances the loess structure by creating large effective bonding areas, which in turn increases the bridging force. As a result, the overall shear strength of the treated loess shows a marked improvement compared to the untreated samples.

Adequate control of shield machine parameters to ensure the safety and efficiency of shield construction is a difficult and complex problem. To address this problem, this paper proposes a hybrid intelligent optimization framework that combines interpretable machine learning, intelligent optimization algorithms, and multi-objective optimization and decision-making methods. The nonlinear relationship between the input parameters and ground settlement (GS) is fitted based on the light gradient boosting machine (LGBM), and the effect of the input parameters on GS is analysed based on SHapley additive exPlanation for further feature selection. Subsequently, the hyperparameters of LGBM were determined based on the sparrow search algorithm (SSA) to better fit the input–output relationship. On this basis, a multi-objective intelligent optimization model is established to solve the optimized operating parameters of shield machine by non-dominated sorting genetic algorithm II and technique for order preference by similarity to ideal solution to reduce GS and improve drilling efficiency. The results demonstrate that the SSA-LGBM model predicts GS with high accuracy, exhibiting an RMSE of 4.775, a VAF of 0.930 and an R2 of 0.931. These metrics collectively reflect the model’s excellent performance in prediction accuracy, ability to explain data variability, and control of prediction bias. The multi-objective optimization model is effective in optimizing two objectives, and the improvement can reach up to 39.38%; at the same time, the model has high scalability and can also be applied to three or more objectives. The intelligent optimization framework for shield construction parameters proposed in this paper can generate the optimal parameter combinations for shield machine manipulation, and provide reference and guidance when there are conflicting optimization objectives.

In geotechnical engineering, the bearing capacity of caisson foundation subjected to combined vertical and horizontal (V-H) load is of significant concern. This study performed laboratory model tests to explore the mechanical response of caisson foundation with different embedment ratios under various load combinations. The caisson foundation was instrumented with displacement transducers to collect the load-displacement (p-triangle s) behaviors of the foundation and the soil displacement (p-u) around the foundation. The progressive failure mechanism was revealed by visualized semi-model test combined with Digital Image Correlation (DIC) technique. Test results show that the ultimate bearing capacity of the foundation increases with the embedment ratio of the foundation and vertical load. The failure envelope of the shear zone exhibits a semi-general shear failure which differs with embedment ratio lambda. Based on the failure modes and soil displacement vector, the soil failure maneuvering field was established. Then, the analytical expression of bearing capacity considering the coupling effect of V-H load was proposed based on the upper limit theorem. The analytical solution was further assessed by comparing with the test results.

Accurately predicting the overlying pressure is crucial for determining an appropriate cover depth of underwater box tunnels to avoid the uplifting failure. Based on the project of box jacking crossing the Beijing-Hangzhou Grand Canal in Suzhou, the characteristics of overlying pressure variation during tunneling are investigated. The monitoring results reveal that the fluctuation of overlying pressure is weakened during the rapid tunneling process. A modified analytical model for vertical earth pressure is conceived, in which the active and passive limit states for multi-layered soils are both considered. The probable range of overlying pressure obtained by the proposed model is suitable to cover the actual values. The anti-floating behavior of underwater box tunnels for two different working conditions is discussed by calculating the minimum cover depth. Using the calibrated analytical models, a parametric study is conducted to explore the influence of injection pressure, hardened slurry unit weight, soil internal friction angle, soil cohesion, and tunnel geometry. It is found that the injection pressure during the construction process is crucial for determining the necessary cover depth, and the change of box tunnel height makes it easier to trigger the variation of minimum cover depth.

Geosynthetic-encased stone column (GESC) has been widely adopted as a reinforcing technology for various civil projects in soft soils due to its enhancement of load-bearing capacity and drainage efficiency. Despite existing substantial body of research, the performance of GESC under cyclic loading and the potential benefits of using steel slag as an alternative aggregate remain underexplored. This study presents a comprehensive experimental investigation comparing the performance of end-bearing and floating geosynthetic-encased steel slag column (GESSC) under static and cyclic loading through model tests. Key parameters including settlement behavior, stress transfer efficiency, pore water pressure distribution, moisture migration, and undrained shear strength were systematically analyzed. The results demonstrate that end-bearing GESSC significantly outperforms floating column in terms of settlement control, load transfer to the bearing stratum, and pore pressure dissipation, especially under repeated cyclic loading. In contrast, floating columns more effectively mobilize shaft friction and enhance shear strength in the upper soil layers. These findings contribute to a better understanding of load transfer mechanisms in GESSC and provide practical guidance for their application in infrastructure projects subjected to dynamic loading conditions, while also promoting the reuse of steel slag as an environmentally beneficial fill material.

The sustainable management of coal slag, a prevalent solid waste byproduct resulting from coal combustion, remains an enduring and paramount subject of investigation. This paper presents an approach of exploring the viability of coal slag as a sustainable substitute for conventional gravel in geosynthetic-encased columns by large-scale model tests and numerical simulation, with a focus on its potential to enhance loose sand foundation performance. The properties of coal slag were characterized through X-ray fluorescence (XRF), X-ray diffractometry (XRD), and leaching tests. The bearing and deformation characteristics of a 250-mm diameter geosynthetic encased coal slag column (GECSC) installed in loose sand foundation were compared with those of an untreated foundation by large scale physical model tests. The parametric study involving the stiffness and encased length of geosynthetic encasement, as well as the relative density of surrounding sand was performed based on the three-dimensional finite element model verified by experimental tests. The results show that the coal slag tested is an environmentally friendly material with huge potential as an alternative to gravel for encased columns in foundation treatment. Increasing the encasement stiffness enhances bearing capacity and reduces circumferential deformation. The GECSC technology is particularly well-suited for loose sand, exhibiting a noteworthy improvement ratio of 2.73 in sand with a relative density of 10 %. The cost-effective encasement length (i.e., double times of diameter) for partially encased GECSC is recommended in terms of controlling the maximum bulge.

Recent field case study shows that the roadbed of ballastless high-speed railway experienced water-induced defect such as excessive fines pumping and even local subgrade-track contact loss affecting the normal operation of highspeed train due to water immersion through gaps of waterproof materials in expansion joints between the concrete base, particularly in rainy seasons. However, the study about the dynamic behavior of high-speed railway subgrade involving water is currently rare. Based on the theory of fluid dynamics in porous medium and the vehicle-track coupling vibration theory, a numerical method of hydraulic-dynamic coupling was established to evaluate the dynamic responses of saturated roadbed surface layer under the high-speed train loading with the validation by comparing the calculated values and field data. The temporal and spatial characteristics of dynamic behaviors (stress, pore water pressure, seepage velocity, displacement) of saturated roadbed surface layer are fully discussed. Also, the effects of train velocity, permeability, on aforementioned dynamic responses of the saturated roadbed surface layer are evaluated. The study shows that improving the drainage of ballastless track roadbed has a significant effect on minimizing the mud pumping of ballastless track, and the influence zone of hydraulic-mechanical coupling is mainly within 0.1 m of the roadbed.

The stiffened deep cement mixing (SDCM) pile is a composite pile composed of the deep cement mixing (DCM) pile and an inner precast core pile. The excellent bearing performance of the SDCM pile that has been successfully witnessed in engineering practice is attributed to the double-layer load transfer mechanism, which effectively transfer the load from the stiffened core to the cemented soil and further to the adjacent soil. The mechanical properties of SDCM piles with stiffened cores that using large-size prestressed high-strength concrete (PHC) piles are rarely studied. This study aims to explore the bearing performance and failure behavior of the SDCM pile with a large-size PHC pile as stiffened core. The relationship between load and settlement as well as the distribution and development of axial force and lateral resistance was studied through field full-scale tests. The effects of the volume ratio, size, and concrete stiffness of the core pile, and the strength of cemented soil on the axial bearing capacity of SDCM piles were explored through the verified three-dimensional numerical model. The load transfer and failure modes at the internal and external interfaces of SDCM piles with different pile lengths were analyzed. Results show that the length of the core pile (Lcore) is a key factor for the bearing capacity of the SDCM pile. The bearing capacity of SDCM pile increases by 57.90

According to the testing of galvanized steel used for transmission tower serving in mountainous areas and serious corrosive industrial corrosive areas, the degradation of galvanized layer of tower steel plate was analyzed. Microstructure of galvanized steel was observed by optical microscope (OM) and scanning electron microscope (SEM), and the thickness of galvanized layer was measured. Results show that the corrosion resistance of galvanized steel gradually decreased when they have been operated for 15 years at serious industrial corrosive conditions. The corrosion test of carbon steel used for transmission tower was carried out by neutral salt spray corrosion chamber for 50 days, and the mechanical properties of carbon steel were tested by microcomputer controlled universal testing machine. Based on the experiment data, we found the mechanical properties of galvanized steels obviously weakened after 50 days of neutral salt spray accelerated corrosion testing. Especially, the decrease of elongation was reaching by 31%. Finite element calculation of transmission tower was carried out based on the remaining corrosion parameters. Calculation results showed that the bearing capacity of the transmission tower significantly decreased, so that it could not met the requirements of safe operation of the transmission line.

Concrete-filled steel tubular (CFST) composite supports have a high bearing capacity and are suitable for the support of roadway intersections with complex cross-sections and stress concentrations, especially for cross-point intersections. According to the cross-sectional shape and support frame combination, CFST composite supports are divided into three types: circular arc concrete-filled steel tubular composite support (CCS), rectangular concrete-filled steel tubular composite support (RCS), and circular arc + rectangular concrete-filled steel tubular composite support (CRCS). Through engineering practice and literature review, the top component of portal support frame is the key bearing structure of CFST composite support. Taking the top component of portal support frame as a key component, the bearing performance tests of the circular arch and straight beam were conducted. The bearing performance variation of key component influenced by the diameter of steel pipe, wall thickness of steel pipe, beam to span ratio and bending strengthening parameters were analyzed, providing guidance on the structural optimization of portal support frame. Numerical investigation of these three types of composite supports was carried out. The findings demonstrate that while the maximum deformations of the composite support under the constrained surrounding rock load exhibit the order CCS support frame structure optimization, the ultimate bearing capacities of the composite supports exhibit the order CCS > RCS > CRCS. The simulation found that the portal support frame is the key bearing structure of the composite support. Taking the top arch section of the portal support frame as a typical component, bearing capacity testing of the CFST straight beam and the arch was performed. The difference in the circular arch bearing performance was analyzed based on changes in the steel pipe diameter, steel pipe wall thickness, rise-span ratio, and anti-flexural strengthening, and the results provide a basis for portal support frame structure optimization. Three roadway intersections in practice were used to evaluate the performance of the three types of composite supports. After structural optimization, the composite supports meet practical requirements and generally produce good results, making them a suitable reference for other roadway intersections.

In the context of global climate change and urbanization, model predictive control (MPC) has been increasingly applied in the field of real-time control of urban drainage systems to cope with frequent urban flooding events caused by extreme rainstorms. However, the computation time of the predictive model calculation greatly hinders further development of MPC in this field. In this study, we propose two surrogate models, namely the water tank-water balance model 1 (TWBM1) and the water tank-water balance model 2 (TWBM2), to replace the storm water management model (SWMM) as the prediction model for MPC, thus improving MPC computational efficiency. Both surrogate models can obtain the total outflow process at the downstream outfall of the study area and the corresponding overflow process. In comparison with TWBM1, TWBM2 requires 26 % fewer calibration parameters, and its structure is simpler. These results have been verified in the real-time optimal scheduling of a rainwater drainage system in the Doumen area of Fuzhou City, China. The results show that TWBM1 and TWBM2 have shorter computation time compared to SWMM, which improves the efficiency of MPC computation. Additionally, in comparison with the existing scheduling results, MPC has better performance in terms of economy, security and computational efficiency.

Microbially induced carbonate precipitation (MICP) has been utilized as a new method to improve loess soil strength. In this study, we investigated the influence of the main parameters on the shear strength of MICP-treated loess specimens. Initially, culture media with different formulas and pH values were examined to identify the most efficient medium for loess soil. To explore the shear behavior of MICP-treated loess under general stress levels, unconfined compressive strength (UCS) tests and triaxial tests relevant to the compression strength and vertical loads were performed on MICP-treated loess with different calcium sources, cementation concentrations, and curing periods. Subsequently, calcium chloride was selected as the optimal calcium source based on the ultimate strength of the MICP-treated loess. The effective cementation concentration in the loess soil was between 1.0 and 1.25 M. The ultimate strength of the MICP-treated loess was 3.6 times of the untreated loess. The stress-strain curves indicate that a higher cementing effect can be expected with an increase in the curing period. The formation process of calcium carbonate and the micromorphology of the MICP-treated loess samples were examined using scanning electron microscopy. In this study, we present an environmentally friendly technique for improving loess soil strength.

Urban flooding resulting from severe rainstorms is an increasing challenge for cities worldwide due to climate change and rapid urbanization. Model predictive control (MPC) has emerged as a promising approach for real-time management of urban drainage systems to mitigate flooding impacts. However, existing MPC research often relies on idealized rainfall forecasts without adequately accounting for forecast uncertainty, which can compromise the effectiveness of MPC strategies. This study aims to address this critical research gap by developing a framework to evaluate the impacts of forecast uncertainty on MPC performance for urban drainage management. The framework consists of 3 components, (1) martingale model of forecast evolution based on Langevin dynamics for generating rainfall data under different uncertainty conditions (2) MPC, which accepts the rainfall inputs and obtains the real-time control results under different uncertainty conditions and (3) the Scheduling Performance Indicator module, which performs a systematic evaluation of the real-time control system. Using a case study of the Doumen region in Fuzhou City, the results reveal two key findings: First, MPC performance remains close to optimal when forecast uncertainty levels are between 0.1 and 0.3, but deteriorates significantly at uncertainty levels from 0.3 to 0.5. Second, while the MPC error feedback module can occasionally degrade performance for individual events, its overall impact is beneficial in reducing performance deviation risks.