Search Results (12)

Grouting power serves as a critical parameter reflecting real-time energy input during grouting operations, and its accurate prediction is essential for intelligent control and engineering safety. Existing prediction methods often struggle to handle the strong nonlinearity, noise interference, adaptability to varying conditions in grouting power data. To address these challenges, an intelligent grouting system that integrates real-time data collection and core control modules has been developed. Subsequently, a grouting power prediction model is then proposed, which combines Complete Ensemble Empirical Mode Decomposition and Adaptive Noise (CEEMDAN) with a Convolutional Neural Net-work-Bidirectional Long Short-Term Memory Neural Network (CNN-BiLSTM) is proposed. The approach employs CEEMDAN to decompose the nonlinear and non-stationary power sequence into multiple intrinsic mode functions (IMFs). Each IMF is then separated into linear and nonlinear components using a moving average method. The linear components are predicted using an Autoregressive Integrated Moving Average (ARIMA) model, while the nonlinear components are predicted using a CNN-BiLSTM model. The final prediction is obtained by reconstructing the results from both components. Experimental comparisons under both normal and heaving grouting conditions demonstrate that the proposed model significantly outperforms LSTM, CNN-LSTM, and CNN-BiLSTM models. With 80% of the dataset used for training, the RMSE for normal conditions is reduced by 95.69%, 85.11%, and 80.55%, respectively, and for heaving conditions by 94.91%, 90.71%, and 84.62%, respectively. This research provides high-precision predictive support for grouting regulation under complex working conditions, offering substantial engineering application value. Full article

SWEET, sugars will eventually be exported transporter, is a novel class of sugar transporter proteins that can transport sugars across membranes down a concentration gradient. It plays a key role in plant photosynthetic assimilates, phloem loading, nectar secretion from nectar glands, seed grouting, pollen development, pathogen interactions, and adversity regulation, and has received widespread attention in recent years. To date, systematic analysis of the SWEET family in Zantedeschia has not been documented, although the genome has been reported in Zantedeschia elliottiana. In this study, 19 ZeSWEET genes were genome-wide identified in Z. elliottiana, and unevenly located in 10 chromosomes. They were further clustered into four clades by a phylogenetic tree, and almost every clade has its own unique motifs. Synthetic analysis confirmed two pairs of segmental duplication events of ZeSWEET genes. Heatmaps of tissue-specific and Pectobacterium carotovora subsp. Carotovora (Pcc) infection showed that ZeSWEET genes had different expression patterns, so SWEETs may play widely varying roles in development and stress tolerance in Zantedeschia. Moreover, quantitative reverse transcription-PCR (qRT-PCR) analysis revealed that some of the ZeSWEETs responded to Pcc infection, among which eight genes were significantly upregulated and six genes were significantly downregulated, revealing their potential functions in response to Pcc infection. The promoter sequences of ZeSWEETs contained 51 different types of the 1380 cis-regulatory elements, and each ZeSWEET gene contained at least two phytohormone responsive elements and one stress response element. In addition, a subcellular localization study indicated that ZeSWEET07 and ZeSWEET18 were found to be localized to the plasma membrane. These findings provide insights into the characteristics of SWEET genes and contribute to future studies on the functional characteristics of ZeSWEET genes, and then improve Pcc infection tolerance in Zantedeschia through molecular breeding. Full article

To obtain timely, accurate, and reliable information on wheat yield dynamics. The UAV DJI Wizard 4-multispectral version was utilized to acquire multispectral images of winter wheat during the tasseling, grouting, and ripening periods, and to manually acquire ground yield data. Sixteen vegetation indices were screened by correlation analysis, and eight textural features were extracted from five single bands in three fertility periods. Subsequently, models for estimating winter wheat yield were developed utilizing multiple linear regression (MLR), partial least squares (PLS), BP neural network (BPNN), and random forest regression (RF), respectively. (1) The results indicated a consistent correlation between the two variable types and yield across various fertility periods. This correlation consistently followed a sequence: heading period > filling period > mature stage. (2) The model’s accuracy improves significantly when incorporating both texture features and vegetation indices for estimation, surpassing the accuracy achieved through the estimation of a single variable type. (3) Among the various models considered, the partial least squares (PLS) model integrating texture features and vegetation indices exhibited the highest accuracy in estimating winter wheat yield. It achieved a coefficient of determination (R²) of 0.852, a root mean square error (RMSE) of 74.469 kg·hm⁻², and a normalized root mean square error (NRMSE) of 7.41%. This study validates the significance of utilizing image texture features along with vegetation indices to enhance the accuracy of models estimating winter wheat yield. It demonstrates that UAV multispectral images can effectively establish a yield estimation model. Combining vegetation indices and texture features results in a more accurate and predictive model compared to using a single index. Full article

Urban tunnelling can be highly challenging, especially in areas where limited ground settlements and environmental disturbance is required. Mechanised tunnelling is usually preferred in such ground environments, specifically Slurry or EPBM (Earth Pressure Balance Machine), depending on the ground properties. Being able to predict the anticipated tunnel behaviour at the preliminary stages of the project can be very beneficial in optimising not only the design, but also control the construction activities and completion times. In practice, the short-term excavation response and support performance focus primarily on design, since most site characterisation inputs are focused on material properties gained from short-term testing. Although the analysis of tunnelling is a three-dimensional (3D) problem, conventional approaches and design methods employed during the design and construction of underground openings are often based on the ground’s static response in two dimensions (2D). In this paper, an initial 2D model is generated in PLAXIS2D and RS2 (Rocscience) to test advanced constitutive models and compare transverse settlement profiles; subsequently, a complete 3D FEM numerical model in RS3 (Rocscience) was used to simulate an Earth Pressure Balance (EPB) excavation sequence. The 3D numerical model simulates the relevant EPB components such as face pressure, TBM shield, backfilling of the tail void (time-dependent hardening of the grout) and gradual segmental lining erections in the longitudinal direction. The presented numerical approach can be used by tunnel designers and engineers to predict the soil response in EPBM tunnelling. Full article

Relying on the Shenyang Metro Line 4 Shifu Road station, the impact of the construction parameters of the transverse pilot tunnel on the surface subsidence and the pipe curtain deformation was first studied through numerical simulation, followed by the analysis of the impact of the excavation of the transverse pilot tunnel on the deformation characteristics of the pipe curtain through on-site monitoring. The results show the following: the excavation of the middle pilot tunnel is the key stage of the construction. The excavation sequence of H2 and H4 and H6 → H1 and H3 → H5 and H7 caused the least surface subsidence. Increasing the grouting width and improving the strength of the initial support can control the pipe curtain deformation very well, and it is reasonable to choose 1.5 m as the grouting width. Full article

The pipe jacking method is gradually attracting increasing levels of attention and is becoming an important method for constructing underground engineering. However, jacking large-size concrete pipes in urban core areas subjected to complicated geological conditions is still a big problem preventing the employment of the pipe jacking method, and further studies related to pipe jacking are required. This paper presents a case study on the construction of three parallel large-size reinforced concrete circular pipes in the upper-soft and lower-hard composite formations, in which the construction work was implemented using the slurry balance pipe jacking method with the sequence of jacking the 1# and 3# pipes prior to the 2# pipe being implemented in field construction. This case study was implemented by employing numerical simulations with the aforementioned pipe jacking sequence, which focused on the stress and deformation variations of the reinforced concrete circular pipes, as well as the vertical settlement of the ground surface during the jacking processes, and considering the influences from the excavation pressure and grouting pressure of the drag-reducing thixotropic slurry. The simulation results revealed that a higher excavation pressure from the pipe jacking machine can easily induce an excessive pushing and squeezing effect of the excavated soil with the uplift phenomenon, while the increasing grouting pressure can be used to reduce the overall vertical settlement of the ground surface, whereas an excessive grouting pressure may have no effectiveness on protecting the reinforced concrete circular pipes. This work provides the numerical foundations for investigating the behavior of jacked parallel large-size reinforced concrete circular pipes. Full article

In order to solve the problem that the hole-forming rate of boreholes is low and it is difficult to reach the designed length when supporting a long pipe shed in loose stratum in a shallow buried section of a long-span tunnel, it is necessary to pre-reinforce the loose stratum in order to improve the strength and integrity of the surrounding rock. Relying on the grouting project of the shallow buried section at the exit of Botanggou tunnel, it is assumed that the grouting material is Newtonian fluid and the steel floral tube shows cylindrical infiltration and diffusion. Through the analysis of the structural characteristics of the injected stratum, the conceptual model of infiltration grouting is established. Twelve groups of test slurry were prepared with ordinary Portland cement and ultra-fine cement, and through the analysis of the slurry parameters of each group, ordinary Portland cement slurry was selected with a water–cement ratio of 1:1 plus 3% water glass to strengthen the gravel layer, and ultra-fine cement slurry with a water–cement ratio of 1:1 plus 3% water glass and 0.3% polycarboxylate superplasticizer to strengthen the fully and strongly weathered porphyritic granite layer. Through the on-site single-hole grouting test and combining with the empirical formula, the maximum diffusion radius of single-hole infiltration grouting is calculated, and the sliding width of the sidewall is deduced using Terzaghi theory. To ensure the grouting effect, the 5 m expansion of the excavation profile is taken as the grouting range. Grouting construction adopts the overall order of periphery and then interior, and three-sequence opening and grouting are adopted in the same row of grouting holes, which can effectively prevent grouting running and grouting. For the strata treated by surface grouting, the construction of the long pipe shed is smooth and reaches the designed length, and there is no large deformation of the surrounding rock when excavated using the CD method. The treatment effect is analyzed by the P-Q-t control method, excavation observation method, and deformation monitoring method. The results show that the injected stratum is fully infiltrated and gelled, forms an obvious grouting stone body, the integrity and strength of surrounding rock are obviously improved, and the convergence values of the tunnel surface, vault subsidence, and clearance do not exceed the alarm value of 60 mm. The research results provide some awareness and understanding of the grouting pre-reinforcement of loose stratum in a shallow buried section of a long-span tunnel in the future. Full article

It is important to control grout propagation and ensure the engineering effectiveness of the advanced regional grouting process in the Middle Ordovician limestone (MOL) aquifer. In our study, we found that the physical and mechanical properties of cement grout are affected mainly by the water–cement ratio, followed by water glass content and finally by hydro-chemical type. In a horizontal grouting hole inclined single fracture, the grout spread over time depended on the water–cement ratio, grouting pressure, width of fracture and angle between fracture and grouting hole and the rate of spread increased over time. However, when the grout propagation length was hundreds of meters or more, the length in the fracture above the grouting hole was greater than that in the fracture below. The sensitivity sequence of influencing factors of grout propagation length in an inclined fracture of a horizontal grouting hole was as follows, from large to small: width of fracture, fracture angle, water–cement ratio, grouting pressure. Full article

Shield tunnels are vulnerable to large displacements induced by surrounding environmental changes. Grouting is an effective way to correct excessive shield tunnel displacement, while the grouting scheme design, especially the grouting sequence, is the key factor affecting the correction efficiency. A finite element simulation method considering the construction of multiple grouting zones is verified by the engineering case of Shenzhen Metro Line 1, and the influence of the grouting sequence on the correction effect on the horizontal tunnel displacement is further studied. The results show that the proper grouting efficiency of sandy clay, completely decomposed granite, and strongly decomposed granite is 5.5%, 2.8%, and 1.1%, respectively. The adjacent newly-built grouting zones are significantly constrained by the reinforcement created during the preceding grouting process. It is more efficient to correct excessive tunnel displacement in the “from far to near” sequence and excessive tunnel convergence in the “from near to far” sequence with increasing reinforcement stiffness. The correction effect improves greatly as the elastic modulus of the reinforcement increases up to 100 MPa. Full article

This paper presents an experimental and field investigation on the efficiency of plugging by pouring aggregate in different sequences through multiple boreholes in a tunnel with flowing water. There have been controversies surrounding the selection of the pouring order for different particle sizes of aggregates and the order in different boreholes. A visualized experimental setup is used to investigate the influence of the pouring orders on the efficiency of plugging through multiple boreholes under the flowing-water condition. A case study of the salvage of a flooded mine using ground directional boreholes was investigated and compared with the experimental results. The water-pressure difference at the aggregate-capping moment, when fine aggregate was poured first and coarse aggregate later, was relatively small, compared to that when fine aggregate was poured upstream and coarse aggregate, downstream. The result implies that the efficiency of plugging with the order of pouring fine aggregate first and coarse aggregate later in different boreholes is better than that with the order of pouring fine aggregate upstream and coarse aggregate downstream. When the poured aggregate is about to be capped, increasing the pouring intensity with the same or a larger particle size is more conducive to capping. The case study shows that pouring fine materials in the early stage reduced the cross-sectional area; in the later stage, the aggregate particle size was gradually increased, which can be helpful in forming an effective water-barrier section in the tunnel. The pouring of aggregate provided a base for cement grouting to form a water-plug section with a length of 106 m, resulting in a sealing efficiency of 100% for the case. Full article

Offshore wind turbines in shallow waters are predominantly installed using a monopile foundation, onto which a transition piece and wind turbine are attached. Previously, the monopile to transition piece (MP-TP) connection was made using a grouted connection, however, cases of grout failure causing turbine slippage, among other issues, were reported. One solution is to use bolted ring flange connections, which involve using a large number of M72 bolts to provide a firm fixing between the MP-TP. It is in the interest of offshore wind operators to reduce the number of maintenance visits to these wind turbines by maintaining a preload (Fp) level above the minimum requirement for bolted MP-TP connections. The present study focuses on the effect of the tightening sequence on the Fp behaviour of M72 bolted connections. A detailed finite element (FE) model of a seven-bolt, representative segment of a monopile flange was developed with material properties obtained from the available literature. Three analyses were made to examine the effect on Fp after tightening, including the initial Fp level applied to the bolts, the tightening sequence and the effect of an additional tightening pass. Full article

The key issue for construction of subsea tunnels through unfavorable geological conditions is to determine a reasonable reinforcement scheme, while the core problem for the reinforcement design is to accurately evaluate the mechanical behavior of surrounding rock with ground reinforcement. Considering that advanced curtain grouting and full-face grouting are widely used in subsea tunnels, a mechanical model for the subsea tunnel surrounding rock accounting for both ground reinforcement and seepage effect was established. According to the distribution and extent of the plastic zone(s), six potential configurations were appropriately analyzed, which were validated by numerical simulations and analytical solutions for simplified settings from the literature. The sensitivities of the reinforcement parameters were examined, and by taking into account the tunnel radial displacement and the seepage quantity as the main objectives, the multi-objective optimization of the reinforcement parameters was put forward via the stratified sequencing method. Finally, application of the proposed method to the Qingdao Jiaozhou bay subsea tunnel project in China was explained. Research results could provide insightful ideas for the quantitative design of the ground reinforcement of subsea tunnels and may have reference value for their construction safety through unfavorable geological conditions. Full article