In recent years, some cities have adopted a new type of tunnel termed quasi-rectangular tunnel (QRT). Compared with the common double-line single-circle tunnel, the QRT has a smaller cross- and narrower spacing. Existing researches about QRTs mainly focus on their mechanical properties, with a lack of research on the influence of vibration and resulting noise on the surrounding environment. The vibration and structure-borne noise in the building along the subway line are adverse to human health when trains pass through the QRT. In this paper, the characteristics of vibration generated by train operation in the QRT and the propagation law in the soil are analyzed based on the finite element method-infinite element method (FEM-IEM) model. Combined with the monitoring data, vibration and indoor secondary structure-borne noise and their annoyance degrees in a 7-storey residential building 18m away from the line are also predicted and evaluated. Results show that during the ground vibration, indoor vibration and structure-borne noise of buildings along the line are mainly concentrated in the frequency band around 40Hz. The vibration and structure-borne noise of the first floor all exceed the night limit specified by an industry standard. The annoyance caused by vibration on the first floor is 0.96, which makes people feel very annoyed, while the annoyance caused by noise is 0.251, which makes people feel slightly annoyed. The research results highlight the effects of railway-induced vibrations in QRT on the building along the subway line, emphasizing their importance in the development of rail transit with QRT. The estimated vibration and noise levels, along with the degrees of annoyance, can be effectively utilized during the design and construction processes of both QRT and buildings to mitigate negative impacts on human comfort and health.

To mitigate the metro-induced vertical vibration of the indoor substation structure, this study proposes a gas-spring quasi-zero stiffness air damping isolator (AD-QZSI) with excellent low dynamic stiffness and high-static stiffness characteristics. The working principle and mechanical properties of the AD-QZSI are introduced and studied through theoretical and numerical methods. A model for substation considering soil-structure-equipment interaction is established using the software ABAQUS, its accuracy is validated based on a series of measured data from actual projects, and the AD-QZSI's simulation method and parameter design method are described in detail. The air damper's stiffness ka is integrated into the isolator's mechanical model, theoretically and numerically achieving an accurate simulation of AD-QZSI's nonlinear mechanical properties. The numerical results have an error of less than 5% with the measured data, indicating that the model is able to better capture the actual structure's dynamic characteristics and is reasonable to be employed for subsequent analysis. Numerical results show that AD-QZSI can significantly reduce the structural vertical vibration, and its control effect is better in the whole frequency band, in particular, the effect is also visible in the low-frequency band, indicating that its vibration isolation frequency band is wider than that of traditional QZS isolator. With the vibration source distance increasing, the control effect of AD-QZSI presents a tendency to decrease and then level off, and its vibration isolation gain is weakened by the continuous increase of the damping ratio greater than 0.01. Moreover, the equipment's dynamic amplification factor of the isolated structure decreases significantly. Finally, the proposed AD-QZSI can obtain ideal quasi-zero stiffness characteristics by adjusting the air pressure, and the adopted air damper belongs to the green low-carbon components, featuring great practical value and application prospects.

This paper reported a series of hysteretic torsion experiment to investigate the torsional behavior of rectangular hollow reinforced concrete (RHRC) column strengthened by fiber reinforced polymer (FRP). Six RHRC column specimens with different number of longitudinal reinforcements, spacing of stirrup and strengthening method using FRP were designed. One was not strengthened, four were strengthened with CFRP, one was strengthened with CFRP and GFRP. The experimental results showed that the primary failure modes of specimens were the spalling of surface concrete with the detachment of FRP. In details, under the hysteretic torsional load, the interaction between adhesive and concrete caused the intersecting diagonal cracks in the internal concrete. Compared with the hysteretic curve of specimen without FRP strengthening, FRP strengthening can significantly improve the initial stiffness by 50 % and peak torsional strength by 70 %. For RHRC column without strengthening, the fullness was poor because of the weak torsional energy dissipation. The FRP strengthening can also enhance the torsional energy dissipation and seismic behavior of RHRC column. To predict the complex torsional behavior of RHRC column strengthened by FRP, a finite element (FE) model and a constitutive model were developed. The FE model considered potential cracks in concrete and FRP-concrete interface based on the application of the cohesive zone model (CZM), whereas the constitutive model accounted for interface damage and plasticity. The results of the performed simulations indicated that the proposed model can effectively represent the hysteretic mechanical behavior of columns under torsional load, which cannot be achieved using conventional FE methods.

Some numerical simulations of drained and undrained triaxial tests on granular materials with different initial densities are carried out with the three-dimensional discrete element method. An in-depth particle-scale analysis is performed quantitatively to illustrate the physical mechanism of the shear mechanical behaviors, with a special attention paid to the characteristics of quasi-steady state and critical state. The simulation results show that the initial density and shear drainage condition both have significant effects on the evolution of stress-strain, coordination number, fabric anisotropy factor, force chains and clusters. The chained grains ratio and the mean length of force chains in the specimens are constantly adjusted to bear and transfer the changing external loads. The transitions between small clusters and large clusters are also continually taking place in varying degrees, correlating to volumetric contraction or dilation. For the loose undrained triaxial specimen presenting quasi-steady state during shearing, the coordination number decreases obviously to nearly 4 and then increases again; the chained grains ratio decreases after a slight increase in the initial loading stage, and then begin to increase again after a period of lower value of around 0.285; the volume ratio of small, submedium and medium clusters all first decreases and then increase gradually, meanwhile volume ratio of large clusters increases sharply to as much as 0.28 and then decreases gradually. The macroscopic critical state of granular materials is a comprehensively external manifestation when the microscopic coordination number and mesoscopic force chains and clusters all evolute to a dynamic equilibrium. At the critical state, the deviator stress, void ratio, coordination number, fabric anisotropy factor, and the volume ratio of small clusters and large clusters all manifest a respectively unique linear relationship with the mean effective stress.

Fresh market vegetables are an essential component of the human diet. Maximizing yield is critical, and to achieve this goal, fi elds must be weed-free when vegetable crops are planted. Historically, removing emerged weeds just before planting has been accomplished using the herbicide glyphosate. However, recent research has indicated that glyphosate applied to sandy, low-organic-matter soils just before transplanting vegetables can be injurious. Two fi eld experiments investigated 1) the response of transplanted squash to the residual activity of glyphosate, and 2) the effects of implementing tillage, irrigation, or extending the plant-back interval after application and before planting to mitigate injury from glyphosate. Glyphosate applied at 1.3, 2.5, or 3.8 kg ae/ha 1 day before transplanting injured squash 13%, 29%, and 53%, respectively; extending the interval between application and planting to 7 days reduced injury to 1%, 11%, and 28% at the same rates. An interaction between application rate and planting interval was also observed on squash plant widths and biomass, as well as early-season and total marketable fruit numbers and weights. Total marketable fruit number was reduced 29% and 52% by glyphosate at 2.5 or 3.8 kg ae/ha, respectively, and a reduction in fruit production of 36%, 28%, and 23% was observed when glyphosate was applied 1, 4, or 7 days before transplanting, respectively. In a separate study, light tillage (5 cm deep) was the most effective cultural practice evaluated because it eliminated damage by glyphosate. Overhead irrigation of 0.6 cm was not beneficial fi cial in mitigating injury by glyphosate. Recommendations from this research will help vegetable growers avoid injury from the residual activity of glyphosate through a FIFRA 2(ee) recommendation label.

Local scour has been reported as a common phenomenon for pile-group foundations in marine, coastal, and riverine sites, while its effects on the seismic behavior of pile-group foundations are yet to be well documented. This paper reported a pair of quasi-static cyclic loading tests on 2 x 3 scoured pile-group foundation specimens, one in global scour and the other in local scour, to understand the influence of local scour on the seismic behavior, particularly in terms of soil-pile interaction features and failure mechanisms. Test results indicate a flexural failure mode for both specimens. Local scour does not change the order of limit states but postpones the occurrence of concrete cover cracking and rebar yielding due to the reduced lateral stiffness of the locally scoured piles. Moreover, local scour rarely changes the aboveground damage regions at the top of outer piles (one time the side length of squared pile section, D ), but significantly aggravates and deepens the underground damage regions at outer piles (from 4 5D D for global scour to 3.7 6D D for local scour). Besides, local scour reduces the displacement ductility factor from 2.50 to 1.25 for the Easy-to-Repair limit state, resulting in adverse impacts on pile-group foundations in general.

The soil beneath buildings constructed in cold regions is affected by frost heave, causing the walls to crack and even the buildings to incline and collapse. Therefore, predicting the frost heave when subjected to overburden pressure is crucial for engineering buildings in cold areas. Utilizing the conservation equation of mass, Darcy's equation, and the assumption that the pore water pressure at the top of a frozen fringe, denoted as uw, during the quasi-steady state can be approximately estimated using the Clapeyron equation, a quasi-steady frost heave rate model considering the overburden pressure was proposed. This study considered the difference in pore water pressure within the frozen fringe, which causes water to move from the unfrozen zone to the ice lens, where it subsequently accumulates and freezes into ice. The pore water pressure at the bottom of the frozen fringe, denoted as uu, can be estimated using the soil water characteristic curve (SWCC). The thickness of the frozen fringe was determined using the freezing temperature, segregation temperature, and temperature gradient. The segregation temperature was determined using the two-point method. Additionally, the model suggested that, when uw = uu, the movement of water stopped, leading to the end of frost heave. To validate the proposed model, three existing frost-heaving experiments were analyzed. The findings demonstrated that the estimated rates of frost heave of the samples closely matched the experimental data. Additionally, external pressure delayed water migration. This study can offer theoretical support for building engineering in cold regions.

Quasi-brittle fracture in geo-materials plays a crucial role in geotechnical engineering, and numerical methods represent a valuable approach for modeling this complex problem. This study introduces a mixed bilinear failure model considering bond effects in a modified Discontinuous Deformation Analysis (DDA) framework. Several benchmark crack-propagation problems for different materials and geometries, including three-point beam, Lshaped structure, semi-disc test and cemented granular packing, are presented to validate the novel DDA method proposed in this study. The simulation results show the accuracy of the model in predicting the mixed-mode failure of quasi-brittle materials with complex structures and assess its great potential for investigating the mechanical properties of geo-materials.

In the context of increasing global food demand and the urgent need for production processes optimization, plant protection products play a key role in safeguarding crops from insects, pests, and fungi, responsible of plant diseases proliferation and yield losses. Despite the inaccurate distribution of conventional aerial spraying performed by airplanes and helicopters, Unmanned Aerial Spraying Systems (UASSs) offer low health risks and operational cost solutions, preserving crops and soil from physical damage. This study explores the impact of UASS flight height (2 m and 2.5 m above ground level), speed (1 m s-1 and 1.5 m s-1), and position (over the canopy and the inter-row) on vineyard aerial spraying efficiency by analysing Water Sensitive Papers droplet coverage, density, and Number Median Diameter using a MATLAB script. Flight position factor, more than others, influenced the application results. The specific configuration of 2 m altitude, 1.5 m s-1 cruising speed, and inter-row positioning yielded the best results in terms of canopy coverage, minimizing off-target and ground dispersion, and represented the best setting to facilitate droplets penetration, reaching the lowest parts generally more affected from disease. Further research is needed to assess UASS aerial PPP distribution effectiveness and environmental impact in agriculture, crucial for technology implementation, especially in countries where aerial treatments are not yet permitted.

The behavior of center columns in shallow-buried underground subway station structures resembles that of high-rise buildings. In both cases, these columns experience significant vertical loads during earthquake events and are susceptible to brittle failure due to inadequate deformation capacity. In this study, the design concept of split columns, commonly employed in high-rise structures, is adapted for application in a two-story, two-span subway station. Initially, a comparative analysis was conducted using quasi-static pushover analysis to assess the horizontal deformation characteristics of traditional and split columns under high axial loads. Subsequently, a comprehensive quasi-static pushover analysis model encompassing the soil-structure interaction was formulated. This model was employed to investigate differences in seismic performance between traditional and innovative underground structures, considering internal forces, deformation capacity, and plastic damage of crucial elements. The analysis results demonstrate that the incorporation of split columns in a two-story, two-span subway station enhances the overall seismic performance of the structure. This enhancement arises from the fact that split columns mitigate excessive shear forces while effectively utilizing their vertical support and horizontal deformation capacities.