Abstract:Given the increasing number of cases where shield machines directly cut through reinforced concrete internal walls during urban tunnel construction, in-depth research on the failure mode of the internal wall during the cutting process and the load variation pattern of the cutter head is crucial for optimizing the tool configuration and improving construction efficiency. Based on the indoor test of roller cutting through reinforced concrete internal walls, a three-dimensional dynamic numerical model of the shield cutter head cutting through the reinforced concrete internal wall was established using ABAQUS. The simulation results show that the concrete mainly exhibits brittle failure, and the failure mode of the steel bars is greatly influenced by the surrounding concrete constraints. By establishing a quantitative criterion for fracture stress ratio, statistical analysis reveals that the steel bars are partial cut-off, and the proportion of complete breakage decreases with the increase in diameter. The simulation data can basically reflect the average trend of the cutter head load change in the test, with the relative errors of thrust and torque being 7.36% and 9.21% respectively. High penetration depth will cause significant load oscillation, while low penetration depth can better exert the grinding effect of the roller.

Abstract:Based on a typical masonry structure project, the number of structural floors and mortar strength are taken as control variables, and three reinforcement schemes are used to perform variable parameter modeling calculations, which results in the difference of comprehensive seismic capacity indices of floors and reinforcement costs of variable parameter models, and establishes a masonry structure reinforcement cost-effectiveness ratio model. According to the established masonry structural reinforcement cost-effectiveness ratio model, considering the economic, technological, functional, and effectiveness impacts of the reinforcement program in an integrated manner, combined with the combined assignment-TOPSIS algorithm, a set of masonry structural seismic reinforcement optimization methods based on cost-effectiveness ratio is established. The results show that the proposed optimization method can better combine quantitative and qualitative indicators to give the optimal reinforcement scheme in a scientific and reasonable way.

Abstract:The long-term cumulative deformation characteristics of offshore wind turbine monopile foundations are key issues that need to be considered in design. However, existing standards do not take into account the impact of the number of cycles and the amplitude of cycles on the cumulative deformation of monopiles. To address this issue, this study conducts numerical analysis and uses a custom field variable subroutine to investigate the cumulative deformation of monopiles with different sizes under different cyclic amplitudes. The specific conclusions are as follows: A threshold for cyclic loading exists in soft soil. When the cyclic amplitude ξ≤0.2, the long-term cumulative deformation of monopiles under cyclic loading can be neglected. However, when the cyclic amplitudes are 0.4 and 0.6, the monopile undergoes significant cumulative deformation, and the deformation increases according to a power function, with the rate of increase slowing down as the number of cycles increases. When the pile length is fixed, the cumulative deformation increases as the pile diameter increases. When the pile diameter is fixed, increasing the pile length effectively reduces the occurrence of cumulative deformation. However, when the cyclic amplitude is 0.4, a pile length threshold exists. Specifically, when L/D≥15, further increasing the pile length will not reduce the cumulative deformation. Under 200 cycles of loading, the cumulative deformation generated by a cyclic amplitude of 0.6 is six times that generated by a cyclic amplitude of 0.4 for the same pile diameter.

Abstract:In order to evaluate the blasting effect of high temperature and high pressure gas and determine the optimal initiation pressure, a crack identification method based on threshold filtering algorithm was designed,along with a crack parameter evaluation method combined with entropy weight method and box dimension. In this method, MATLAB software is used to identify cracks using thre-shold filtering algorithm, quantitative characteristics such as crack perimeter, fracture degree, crack width, and box dimension are obtained based on binary diagrams, and the crack sensitivity index is determined by entropy weight method, and the complexity of analysis is combined with box dimension to evaluate the blasting effect and determine the optimal initiation pressure range. The results show that the growth rate of crack width decreased from 62.2% to 47.6%, and the growth rate of fracture degree decrease from 47.6% to 13.2%. Furthermore, the increase of crack complexity gradually diminished, indicating that the utilization rate of blasting efficiency gradually decreases, and the initiation pressure range corresponding to the optimal blasting effect under the premise of ensuring energy utilization is from 120 MPa to 150 MPa.

Abstract:To explore the influence of different inclination angles between the tail end of the anchor cable and the drilling hole on the fracture of the anchor cable, a theoretical mechanical model of the anchor cable under the shear of the tray, steel strip and other components was established. An anti-shear anchorage composed of self-aligning anchorage and anti-shear steel pipe was developed. The anti-shear performance of anchor cables using ordinary anchorage and anti-shear anchorage under different inclination degrees (10°, 20°, 30°and 40°) was tested. The results show that the inclination angle has a great influence on the ultimate axial force of the anchor cable. When using ordinary anchorage, the anchor efficiency of anchor cable did not reach 95% at the inclination angle of 10°,20°,30° and 40°. At the angle from 30° to 40°, the axial force of the anchor cable decreases the most. With the increase of inclination angle, the failure mode of anchor cable gradually changes from tensile failure to cutting failure. When using anti-shear anchorage, the anchor efficiency at different inclination angles is greater than that of ordinary anchorage. At the inclination angle of 10°,20°and 30°, the anchor efficiency reached more than 95%. The anchoring effect is also greatly improved at an inclination angle of 40°, and the average value of the peak axial force obtained by the three groups of tests is increased by 36%. The inclination angle of the tail end of the anchor cable has a great influence on the performance of the anchor cable. The use of anti-shear anchorage can effectively prevent the tail of the anchor cable from being broken by shear. The research content of this paper can provide reference for similar anchor cable failure problems.

Abstract:In order to study the welding residual stresses of the butt joint of the U-rib stiffened plate during the on-site assembly of the steel box girder bridge, this paper were designed and fabricated the butt joint specimen of the U-rib stiffened plate during the on-site assembly of the steel box girder bridge. The blind-hole method was used to measure the welding residual stress on the surface of the specimen, and the ABAQUS finite element software was used to simulate the welding of the specimen. The distribution law of the welding residual stress of the specimen model was obtained, and the numerical simulation results were compared with the experimental results. The results show that the longitudinal residual stress are mainly the tensile stresses distributed around the butt weld and near the U-rib fillet weld, and the compressive stresses mainly distributed in the base metal near the outer side of the U-rib and the end of the U-rib fillet weld. The transverse residual stresses are mainly the tensile stress distributed around the U-rib fillet weld, and the compressive stresses mainly distributed at the end of the butt weld.

Abstract:Taking the post earthquake repair project of a prestressed concrete continuous beam bridge as an example, a finite element model of the bridge was established using Midas Civil software. Three working conditions were analyzed, including single pier uplift, single pier uplift+moving load, and single pier uplift+gradient heating. The variation laws of support reaction force, upper and lower edge stress of the beam, and stress of prestressed steel bars were studied. Research has shown that when the bridge pier is lifted, the prestressed steel bars on the top plate of the main beam at the separated pier first break. When the bridge pier is lifted, the concrete on the top edge of the main beam section corresponding to the jack experiences tensile cracking and damage. When the lifting height reaches the requirement for bearing replacement, traffic restrictions must be implemented for passing vehicles when lifting at the bridge pier, and traffic should be interrupted when lifting at the bridge pier. The gradient heating has a relatively small impact on the reaction force of each support, the stress of the lower flange of the beam, and the stress of the prestressed steel bars, while the stress of the upper flange has a greater impact. However, the tensile stress and compressive stress of the upper flange of the beam at the jacking point have a certain positive impact on the jacking construction.

Abstract:In order to solve the problem of dynamic response of the support of the curved cable-stayed bridge of semi-floating steel box girder under the action of moving vehicles, the right width of the No.1 bridge of the main line of Taizicheng interchange was taken as the research object, the bridge model was established based on the finite element software ABAQUS, the moving load was used to simulate the driving process of the vehicle on the bridge, different vehicle speeds, different levels of bridge deck unevenness and eccentric load conditions were set, and the influence of moving vehicles on the bearing stress at the junction of the tower girder was explored, so as to provide reference opinions for the design and maintenance of related bridge types. The results show that the stress on the outer support is slightly greater than that on the inner support. In view of the large radius of curvature of the bridge, the speed of the moving vehicle has little influence on the bearing stress, while the unevenness of the bridge deck and the eccentric load of the vehicle have a great influence on the bearing stress. At the same time, under the condition of internal and external eccentric load, the peak stress response of the support is almost unchanged, and the bridge is not prone to the phenomenon of the main girder rollover.

Abstract:Based on the upper-bound theory of limit analysis, the pseudo-static method was carried out to assess the amplification effects of seismic acceleration on stability of homogeneous earth slopes. The least upper-bound solutions of seismic slope stability are determined and then compared with other results for verification of the presented method. A parametric sensitivity analysis is conducted for the horizontal seismic acceleration at the bottom of the slope and the seismic amplification coefficient to investigate their influences on slope stability. The results demonstrate that the stability of seismic slopes decreases with the increase of seismic amplification coefficient, while the most critical slip surface becomes deeper. Finally, according to the correlation between the factor of safety for seismic slope and dimensionless parameters, a fitting formula is established to calculate the factor of safety for slopes subjected to the seismic amplification. It is convenient for practical engineering to quickly evaluate the influence of seismic amplification effect on slope stability.

Abstract:To investigate the impact of variable-speed vehicles on the creep of curved girder bridges, a typical ramp bridge was selected as a case study to analyze the influence of vehicle-related factors on this phenomenon. A finite element model of the curved bridge was developed using ANSYS, incorporating a solid main girder model and bilinear spring bearings. The validity of the computational model was verified through comparison with a MIDAS/Civil model. Moving vehicle loads were equivalently transformed into vertical loads superimposed with time-varying radial centrifugal forces. These loads were applied to the curved bridge model using shape functions to generate load files. Subsequently, vehicle-related factors affecting lateral displacement—including initial entry speed, acceleration/deceleration, and vehicle weight—were systematically analyzed. Results indicate that the lateral displacement at key bridge sections initially increases and then decreases as the radial force approaches and moves away from the key sections. Higher initial vehicle entry speeds and greater vehicle weights lead to increased lateral displacement of the main girder, vertical displacement at mid-span sections, vertical reaction forces of outer bearings, and transverse reaction forces of both inner and outer bearings. Conversely, higher initial entry speeds reduce vertical reaction forces of inner bearings. Larger deceleration magnitudes (absolute values) reduce lateral displacement but exhibit negligible effects on mid-span vertical displacement and bearing reactions. Vehicle entry speed and weight are identified as primary influencing factors for lateral displacement, while deceleration plays a secondary role.

Abstract:In order to identify the constraints that affect the application of BIM technology in prefabricated buildings, 11 influencing factors were selected from the four dimensions of policy, economy, market, and technology and organized into a factor set. Firstly, the decision-making trial and evaluation laboratory (DEMATEL) method was used to evaluate the centrality and causality among the constraints; then, the interpretive structural modeling (ISM) was employed to establish a multi-level structure model of the constraints; finally, the cross-impact matrix multiplication applied to classification (MICMAC) method was utilized to obtain the driver-dependency relationship matrix of the constraints. The three modes were coupled to establish a composite mode, and on this basis, the logical relationship, hierarchical relationship, and relative importance among the constraints were clarified. The results show that the resistance of the design and construction parties is the primary reason for the restraint of BIM technology in prefabricated buildings, and the lack of innovation and professional talents are the fundamental reasons.

Abstract:In order to study the deep extension characteristics of the western Helan Mountain eastern foothills fault and the eastern Yellow River fault that control the northern boundary of the Yinchuan Basin, as well as the hidden Luhuatai fault and Yinchuan fault within the basin, Considering previous research methods and scales, the magnetotellurics method was employed to conduct a detailed exploration of the electrical structure in the northern part of the basin. The article obtained the electrical structure information of the middle and deep parts of the northern Yinchuan Basin through long-period magnetotelluric profile measurements for using near-reference processing techniques and impedance tensor decomposition techniques; The 2D NLCG inversion results show obvious electrical zoning characteristics in the northern part of the Yinchuan Basin. The main fault reflects clearly, and a high conductivity channel has been found in the deep part, which is highly likely to be the upwelling of mantle derived material from the deep part. This study indicates that the magnetotelluric sounding method is an important geophysical sounding method for detecting hidden faults, seismic environments in earthquake prone areas, and geological structures related to geothermal genesis in northern part of the Yinchuan Basin.

Abstract:In order to make up for the shortcomings of the existing fire investigation technology, a Fourier transform infrared spectrometer was developed based on infrared remote sensing technology. The equipment is mainly composed of a telemetry probe and a two-dimensional turntable. The telemetry probe is used for the scanning of toxic and harmful gas clouds and the acquisition of infrared spectral data. After data interpolation and filtering, fast Fourier transform, spectral calibration, database spectral format conversion, poison type identification and relative concentration calculation, the remote identification of hazardous toxic gases is realized and the display alarm is performed. In order to verify the feasibility of the research and development equipment in the application of fire investigation, the application effect of Fourier transform infrared spectrometer was measured in a chemical industry park and simulated fire scene. The results show that the developed Fourier transform infrared spectrometer can compare the measured spectrum after pretreatment with the established toxic and harmful gas library, and then mark the range of leaked gas, locate the leak location and determine the leak source. The equipment can not only provide reference guidance for fire fighting and rescue, but also play an active role in determining the scope of investigation, finding the direction of investigation, providing data support and strengthening personal security.

Abstract:To address the prevalent social and psychological health issues stemming from the inadequate expression of architectural emotion, an empirical study was conducted on the visual perception characteristics of the rural landscape in Linjiahe Village, Southern Hebei Province, leveraging eye-tracking technology. By establishing an evaluation system encompassing four key elements: roads, boundaries, nodes, and landmarks, and adopting a methodology that integrates subjective and objective analyses, the study identified notable issues in the current rural landscape, including the absence of a visual focus and attention dispersion. Importantly, optimized design was found to substantially enhance participants’ visual attention in critical scenes. Furthermore, the research unveiled a clear interval effect between spatial feature parameters, such as green vision ratio and enclosure degree, and visual perception outcomes. Specifically, optimal visual perception was achieved with a green vision ratio ranging from 20% to 40%, an enclosure degree of 50% to 60%, an openness of 12% to 26%, and a visual discriminability of 10% to 31%. This discovery offers a quantitative evaluation approach and optimization strategies grounded in visual perception for rural landscape design.

Abstract:This study explores the impact of courtyard layout on emotional recovery and stress relief, using traditional southern Hebei courtyards as a case study. Four typical courtyard scenarios were created using virtual reality technology, with eye-tracking and heart rate variability measurements to assess the emotional regulation effects. The results show that courtyards with high greenery and plant diversity signifi-cantly enhance parasympathetic nervous activity and emotional recovery. In high-greenery courtyards, the LF/HF ratio (0.68±0.06) was significantly lower than that in non-greenery courtyards (1.40±0.21), while pNN50 (29.60%±1.76%) was significantly higher compared to non-greenery courtyards (15.98%±1.28%). Eye-tracking also indicated improved visual focus and comfort. The study highlights the key role of natural elements in promoting emotional recovery and relaxation in rural courtyard environments.