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Analyzing the seepage and stability analysis of embankment dams built on deep overburden layers is an essential aspect of dam design and operation and is of significance to ensure the safe and effective operation of geotechnical and hydraulic structures in reservoir sites. However, in most existing studies, the seepage and dam slope stability were analyzed separately without considering the interaction between the two fields; thus, the actual operating state of the dam could not be accurately reflected. In this paper, an embankment dam located in Yulin, Shaanxi Province, China, built on a deep overburden layer, was selected as a case study for illustration. Considering the hydrogeological and engineering design information of this project, a three-dimensional fine finite element model reflecting the main characteristics of the reservoir site was established. COMSOL Multiphysics software, which is particularly suitable for multifield coupling calculations, was used to conduct a multifield coupling analysis of the safety state of embankment dams on deep overburden layers by modifying and customizing the porous media and subsurface flow module and solid mechanics module. The method to solve the multifield coupling problem was clarified. Notably, the proposed coupling model involved many parameters, which might introduce uncertainties into the model, thereby requiring considerable work for calibration. Therefore, the Morris method was used to identify the sensitivity of the coupled model parameters to the output results. The results show that the established multifield coupling model can effectively address the seepage and stability problems of embankment dams on deep overburden layers, and the dam can safely operate under the existing design scheme. Even under the condition of a magnitude VIII earthquake at the check flood level, the dam does not experience seepage and slope failure. The safety factor of sliding failure of the dam slope is mainly influenced by the internal friction of saturated soil (φs), material cohesion (c), internal friction of unsaturated soil (φu), soil density (ρs) and Poisson's ratio (ν), while the influence of the seepage parameters is generally small. The methodology and results derived from this study can provide technical support and reference to evaluate the safety in terms of the seepage and anti-sliding stability of similar projects.

Seepage analysis and assessment of the effect of seepage control at reservoir sites are essential parts of dam design and operations, and of considerable significance for the safe and economic design of the masses and hydraulic structures associated with reservoir sites. In this study, a systematic process is provided for the optimal design and assessment of seepage control of reservoir dams under karst development conditions. A reservoir dam planned for construction in the middle-upper reaches of the Huayang River in China is selected as a case example for illustration. A three-dimensional equivalent continuum seepage finite-element numerical model is applied to investigate the effectiveness of the proposed and optimized seepage-control schemes, and it is calibrated by an inversion analysis of the initial seepage field based on the flexible tolerance method and field penetration test data. By analyzing the sensitivity of seepage discharge to the length and depth of the grouting curtain, a safe and economic seepage-control optimization scheme is suggested. Additionally, the sensitivity of seepage discharge to the hydraulic conductivity of the limestone layer is analyzed, and the results show that the hydraulic conductivity of the limestone layer has a significant impact on the seepage discharge of the reservoir site. The methodology and results derived from this study can provide technical support and reference for the optimal design and assessment of seepage control for reservoir dam engineering under karst conditions.

In large-scale hydropower projects, the anti-seepage curtain is an important measure to reduce the leakage of reservoirs and ensure the stability of foundation rocks. In this study, an efficient procedure for the optimization design of an anti-seepage curtain was proposed given the drawback of the time-consuming and low efficiency in optimizing multiple parameters of the anti-seepage curtain. This procedure can dramatically shorten the time for numerical simulation, reduce the workload of planning multiple parameter sets, and effectively avert the probable distortion of optimized results to some extent. This is achieved by identifying and optimizing the parameter that has the greatest impact on the performance of the anti-seepage curtain on the premise of adequate geological investigation and proper qualification of the performance of the anti-seepage curtain. This procedure was applied to the optimization design of the anti-seepage curtain in the upper reservoir of a pumped storage power station. Four different depths were suggested for the anti-seepage curtain according to the optimization results. This procedure can serve as a reference for the optimization design of an anti-seepage curtain with high effectiveness and confidence.

The average porosity and permeability in the developed clastic rock reservoir in Tarim oilfield in China is 22.16% and 689.85×10-3 μm2. The isolation layer thickness between water layer and oil layer is less than 2 meters. The pressure of oil layer is 0.99 g/cm3, and the pressure of bottom water layer is 1.22 g/cm3, the pressure difference between them is as bigger as 12 to 23 MPa. It is difficult to achieve the layer isolation between the water layer and oil layer. To solve the zonal isolation difficulty and reduce permeable loss risk in clastic reservoir with high porosity and permeability, matrix anti-invasion additive, self-innovate plugging ability material of slurry, self-healing slurry, open-hole packer outside the casing, design and control technology of cement slurry performance, optimizing casing centralizer location technology and displacement with high pump rate has been developed and successfully applied. The results show that: First, the additive with physical and chemical crosslinking structure matrix anti-invasion is developed. The additive has the characteristics of anti-dilution, low thixotropy, low water loss and short transition, and can seal the water layer quickly. Second, the plugging material in the slurry has a better plugging performance and could reduce the permeability of artificial core by 70-80% in the testing evaluation. Third, the self-healing cement slurry system can quickly seal the fracture and prevent the fluid from flowing, and can ensuring the long-term effective sealing of the reservoir. Fourth, By strict control of the thickening time (operation time) and consistency (20-25 Bc), the cement slurry can realize zonal isolation quickly, which has achieved the purpose of quickly sealing off the water layer and reduced the risk of permeable loss. And the casing centralizers are used to ensure that the standoff ratio of oil and water layer is above 67%. The displacement with high pump rate (2 m3/min, to ensure the annular return velocity more than 1.2 m/s) can efficiently clean the wellbore by diluting the drilling fluid and washing the mud cake, and can improve the displacement efficiency. The cementing technology has been successfully applied in 100 wells in Tarim Oilfield. The qualification rate and high quality rate is 87.9% and 69% in 2019, and achieve zone isolation. No water has been produced after the oil testing and the water content has decreased to 7% after production. With the cementing technology, we have improved zonal isolation, increased the crude oil production and increased the benefit of oil.

The IL-2 gene polymorphisms have been reported to be associated with the development of autoimmune disease. However, there are no published studies examining the influence of the IL-2 gene polymorphisms on the response of myasthenia gravis (MG) patients to tacrolimus (Tac). The goal of this study was to investigate the relationship between the polymorphisms of IL-2 and Tac response in MG patients. Ninety-two MG patients treated with Tac were studied, including 57 Tac-effective patients and 35 Tac-ineffective patients. Then, we selected four single-nucleotide polymorphisms (SNPs: rs2069776, rs2069772, rs2069762, rs2069763) in the IL-2 gene. Next, we analyzed the distribution of genotypes, allelic frequencies of SNPs, and haplotype frequencies among polymorphisms in the two groups of patients. The distribution of the allelic frequency of the rs2069762 variant differed between the Tac-effective and Tac-ineffective patients (P = 0.02). Genotypes G/T and G/G of rs2069762 were differently distributed between the two groups when the wild genotype T/T was assigned as a reference (P

The roughness of concrete lining is one of the essential parameters to evaluate the flow capacity of water conveyance structures such as concrete channels, tunnels, and aqueducts. In this paper, we develop an innovative method to calculate the roughness of a concave-shaped rough surface of concrete and to modify its effects on the seepage characteristics of a rough fracture. We also present the functional relationship between the surface roughness and pixel characteristic parameters of rough surfaces and investigate the effect of the roughness of a fracture surface on the flow capacity through a fracture. The results indicate that the unit discharge of a fracture is positively correlated with fracture aperture and roughness of the rough fracture surface. The relationship between the correction coefficient of the cubic law and relative roughness is represented by a quadratic polynomial. The calculated correction coefficients based on the modified formula match well with the experimental results. The mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R 2) of the corrected calculated and test values are 3.35%, 0.0572, and 0.955, respectively. The proposed roughness characterization method and modified cubic law can thus effectively describe the seepage characteristics of concrete rough fracture.

A novel device is proposed to test hydraulic fracturing in specimen with tensile stress. The device is composed of splitting apparatus and sealing apparatus. The tensile stress in specimen is realized via splitting load. It is confirmed that the sealing apparatus has a less effect on peak splitting load and the Young’s modulus of specimen. Some hydraulic fracturing experiments of cement mortar specimens with tensile stress are conducted. Critical water pressure of hydraulic fracturing will decrease with increase of the tensile stress. Hydraulic fracturing mechanism of cement mortar with tensile stress is revealed based on the Biot’s theory and fracture process zone. Applied high water pressure on initial crack surface, water pressure in water flow zone, and drag force along initial crack surface and water flow zone have a promotional effect on fracture propagation. The T stress in the test and pore water pressure caused by tensile strain near crack tip will restrain fracture propagation. A critical water pressure model (CWP) is proposed based on general maximum tangential stress criterion, and it is verified that the CWP model is rational and accurate. The T stress and pore water pressure gradient along polar angle direction have an effect on direction of crack initiation.

Gu, L.; Ni, F.; Xu, L., and Li, Z., 2018. Determining the threshold pressure of clay-cutting by a mobile jet for coastal construction. Trailing suction hopper dredgers (THSD) are widely used in channel excavation and coastal construction projects. In such projects, clay is a common soil that is difficult for the drag head of THSDs to dredge. Jet-cutting using a mobile jet is often adopted to improve the efficiency of the drag head, since it can create grooves into the clay surface and reduce cutting forces for the drag head. The jet pressure is an important factor for jet-cutting, so it is necessary to accurately grasp the threshold pressure of clay-cutting by the mobile jet. In this paper, clay samples with three different strengths (undrained shear strength Su = 16 kPa, 35 kPa, and 51 kPa) were prepared, and clay-cutting experiments using a mobile jet were conducted. The effects of parameters such as the nozzle diameter, the moving speed, and the jet pressure on the cutting results were investi...

Transparent polymeric materials with high ductility and antistatic properties have attracted much attention. A room temperature ionic liquid (IL), tributyl(methyl)ammonium bis(trifluoromethane)sulf...

With the development of geomenbrane, geomenbrane has been adopted in more and more hydraulic engineering as anti-seepage arrangement. A three-dimensional finite element model was built to analyze two different anti-seepage schemes for upper reservoir of a pumped storage power station. Under the reinforced concrete face slab & geomembrane anti-seepage scheme or geomembrane anti-seepage scheme, the seepage field and the seepage discharge of the reservoir were calculated and analyzed under normal conditions and local damage of geomenbrane conditions. It is shown that the seepage characteristic was obviously influenced by the fractured zone around right abutment. Moreover, based on the calculation results, seepage discharge under normal working conditions and local damage of geomembrane was analyzed and it was found out that both schemes were able to satisfied requirements of the reservoir under different conditions. After comprehensive consideration, it is recommended that the reinforced concrete face slab & geomembrane anti-seepage scheme should be adopted as the anti-seepage scheme of the reservoir.

Creep deformation of rockfills affects anti-see page systems, such as concrete face, toe slab, and peripheral joint. In particular, it may cause structure damage, such as water stop failure and concrete face cracking, especially in a high concrete-faced rockfill dam (CFRD) on a deep overburden layer. In this paper, viscoelastic constitutive models for concrete materials and bedrocks (a new creep constitutive model for rockfills) are introduced. A comprehensive study method on the stress and deformation of a high rockfill dam on a deep overburden layer is established based on field plate loading tests, laboratory triaxial creep tests, and prototype monitoring data analysis. The long-term deformation characteristics of Jiudianxia CFRD with complex topography and geological characteristics are analyzed and forecasted by using three-dimensional nonlinear finite element model analysis considering the effect of creep. The deformation of the dam shows an evident increment compared with that without considering the creep effect. Rockfill creep obviously influences the deformation and stress of the concrete-face slab. Meanwhile, comparative study of numerical calculation results and monitoring data showed good agreement between the computed settlements and measured values. Overall, the creep model and the adopted parameters are demonstrated to be reasonable, and the deformation of Jiudianxia CFRD is basically stable.

Purpose The purpose of the present study was to present a new method that combines the use of the fibular flap and a custom-made vertical distractor/dental implant device into 1 surgical procedure for simultaneous functional mandibular reconstruction. Patients and Methods The present retrospective case series included 10 patients who were treated using the fibular flap and dental implant distractor (DID) in a single-stage procedure. These 10 patients were treated within a 3-year period (from 2005 to 2007). Results Of the 10 patients included in the study, 5 were males and 5 were females. The mean age of the sample was 33.8 years (range 17 to 48). The cumulative survival rate of the fibular flaps was 100%. The mean vertical bone height attained with the DID device was 11.4 mm. The mean period from the first operation to the start of dental implant loading was 6.3 months. The cumulative survival rate of the dental implants was 93.75%. Conclusions The use of the DID in the fibular flap for mandibular reconstruction is advantageous because it combines vertical distraction osteogenesis of the fibular flap and dental implantation into a single procedure. Implants placed in the reconstructed areas were found to integrate normally, with survival rates comparable to those with 2-stage operations. As such, this novel DID technique can be used for single-stage reconstruction and rehabilitation of segmental mandibular defects in selected patients.

Effective methods for extending the storage capacity of tailings for a mining company include expanding and increasing the height of the tailings dam. However, this change could lead to an uplift in the phreatic line and a decrease in the slope stability. In this paper, a new drainage system combining a horizontal drainage pipe with an upward bending slotted pipe was proposed and applied to the design of a seepage-proof system for the Xigou tailings dam with an increased height. To accurately simulate the performance of the seepage control system, a three-dimensional finite element model was established on the basis of a geological investigation of the site conditions. In this work, a substructure technique was used to model the drainage pipe with a small radius and dense spacing to reduce the difficulty in mesh generation, and a back-analysis method called MPSO-BP (modified particle swarm optimization algorithm and a back propagation neural network) was used to correct the measured permeability coefficients. The results show that the new drainage system can effectively dissipate the seepage pressure, decrease the phreatic surface, and improve the safety factors of the slope stability. The proposed drainage system can also meet the seepage stability requirements of the higher tailings dam. Additionally, this system can be widely deployed in similar projects.

In this paper, we propose a (n−1)2 parameter, multistage ranking model, which represents a generalization of Luce's model. We propose then×n item-rank relative frequency matrix (p-matrix) as a device for summarizing a set of rankings. As an alternative to the traditional maximum likelihood estimation, for the proposed model we suggest a method which estimates the parameters from thep-matrix. An illustrative numerical example is given. The proposed model and its differences from Luce's model are briefly discussed. We also show some specialp-matrix patterns possessed by the Thurstonian models and distance-based models.

The element-free method (EFM) simplifies the pre-processing and has high calculation efficiency since it requires only the information of nodes and boundaries instead of elements. By taking the adaptive influential radius and arranging nodes flexibly, homogenization could be reduced significantly. Such method was applied in this paper to calculate the steady seepage field of a core wall dam with anti-seepage curtain and concrete cushion. The comparison of the calculation results with that calculated by the finite element method shows they match well and both the seepage field and free surface distribution accord with the general rules, which mean the element-free method can be applied to solve the seepage problem of complex earth dam.

Multimedia technology plays an important role in dredging simulation. The paper briefly presents the main aspects of the multimedia technology used in the dredging simulation of cutter suction dredger, such as construction environment, vessel and its motion, soil cutting, transport in pipeline, sound, vibration and so on, particularly introduces the principles of the key technologies and the relevant skills. The simulation system has been developed and confirmed in the practical application.

Dredging simulation is of great significance to the development of dredging engineering technology of harbor, waterway, rivers, lakes, etc. The design and implement of the dredging simulation system are introduced. The modeling and key techniques for the virtual reality of construction site, the movement of dredge vessel, the soil cutting of cutter, and the hydraulic transport of sand in a pipeline, etc., are discussed. The cutter suction dredger simulator with a multi-channel round screen has been put into operation and produced good results.

The car-following traffic flow model proposed by Bando et al. is modified by adding an acceleration-adjustment term. Moreover this modified model is extended by incorporating multi-vehicle characteristics. Analysis of linear stability on circuitous road is done. Numerical simulations for two-type-vehicles traffic systems and three-type-vehicles traffic systems show that the growth and decay of a small disturbance are related not only to the vehiclespsila behavioral parameters but also to the proportion of each type of vehicles.

A large mandibular discontinuity defect is most often due to severe trauma, infection or resection for neoplasm. Reconstruction plates have been popularly applied to bridge mandibular defects without bone grafting. The esthetics and continuity of the mandible with segmental defects could be rehabilitated successfully. However, the function is difficult to reconstructed using this type of plate. Furthermore, skin or mucosii perforation, plate fracture and loss of screw retention were the serious complications resulting in reconstruction failure. In this paper, a lateral biomechanical titanium mandibular prosthesis (BMMP) with new retention structure has been design. Problems of masticatory muscle attachment and other soft tissue overlay on the prosthesis have been considered. The biomechanical effect of the BMMP has been analysed by the three-dimensional finite element method (FEM). And the analysis of biomechanical effects of the retention on the BMMP was performed comparing with that of traditional reconstruction plate. Analysis results have shown that the BMMP was of better load conductibility and reliable retention. The function, continuity and esthetics of the mandible bone with a lateral defect were reconstructed successfully using the BMMP

The statistical evaluation of structural chromosome aberration is a very important biological dosimetry method. An automated chromosome aberration scoring system is fully detailed. This system can find meptaphases, recognise and score aberrant chromosome automatically. The whole procedure of recognising and scoring aberrant chromosome includes preprocessing of digital image of metaphases, the selection and extraction of features and the construction of a hierarchical classifier, etc. The results of experiments are discussed.