Waterproofing Technology of Underground Subway Tunnels

The waterproof construction of subway tunnels is a crucial and challenging aspect of subway tunnel engineering.Mastering excellent waterproof construction technology is essential to ensure that the construction meets design requirements and guarantees the safe operation of subway lines.This paper focuses on discussing waterproof construction technology for subway station tunnels.By analyzing the main methods and techniques of underground tunnel construction,as well as the key techniques and difficulties of waterproofing construction,this paper examines the waterproofing construction project of Guangzhou Metro Culture Park Station as a case study.It analyzes the methods,quality management practices,and safety management strategies applied in the project.This paper serves as a reference for tunnel engineering design and construction units in our country,offering insights into effective waterproof construction techniques for subway tunnels.

Preparation and Performance Study of Cementitious Capillary Crystalline Waterproof Materials

Cementitious capillary crystalline waterproof materials(CCCW for short)offer durability and excellent waterproofing properties,making them a popular option for building waterproofing.Some scholars have studied the proportioning of such materials.However,these studies lack the relationship between the impermeability pressure of mortar and the components,and the mechanism of action is somewhat debatable.Therefore,we adopted a two-step method in our experiments.Firstly,we screened out the components that significantly impact impermeability from a variety of active components by orthogonal test.We then optimized the design of the active group ratio using the simplex lattice method.Lastly,we conducted a performance test of the optimal ratio and explored the waterproofing mechanism of homemade CCCW.

Application of New Concept Waterproofing in Xiang'an Undersea Tunnel,China

As a kind of transportation mode for crossing channels, undersea tunnel has incomparable advantages for its directness, convenience, fastness, insusceptibility to weather conditions, and smaller influences on environments. In recent years, with the development of undersea tunnel construction, the design and construction technologies have been greatly enhanced. The first undersea tunnel in China has just been built. Waterproofing is the key technique of undersea tunneling. A new concept of waterproofing scheme of grouting, sealing, draining and divided sections was adopted in the construction of the tunnel based on the researches, the in-situ geological features, the astuteness of the current technology and the cost of construction. The structural details of the sealing and draining system are introduced to illustrate the salient features of the new waterproofing technique. It is hoped that experiences described in the paper can offer guidance for the construction of the extensive undersea tunnels in the coming years.

Dynamic Responses of Rotor Drops onto Double-decker Catcher Bearing

In an active magnetic bearing （AMB） system, the catcher bearings （CBs） are indispensable to protect the rotor and stator in case the magnetic bearings fail. Most of the former researches associated with CBs are mainly focused on the dynamic responses of the rotor drops onto traditional single-decker catcher bearings （SDCBs）. But because of the lower limited speed of SDCB, it cannot withstand the ultra high speed rotation after rotor drop. In this paper, based on the analysis of the disadvantages of SDCBs, a new type of double-decker catcher bearings （DDCBs） is proposed to enhance the CB work performance in AMB system. In order to obtain thc accurate rotor movements before AMB failure, the dynamic characteristics of AMB are theoretically derived. Detailed simulation models containing rigid rotor model, contact model between rotor and inner race, DDCB force model as well as heating model after rotor drop are established. Then, using those established models the dynamic responses of rotor drops onto DDCBs and SDCBs are respectively simulated. The rotor orbits, contact forces, spin speeds of various parts and heat energies after AMB failure are mainly analyzed. The simulation results show that DDCBs can effectively improve the CBs limit rotational speed and reduce the following vibrations, impacts and heating. Finally, rotor drop experiments choosing different types of CBs are carried out on the established AMB test bench. Rotor orbits, inner race temperatures as well as the rotating speeds of both inner race and intermediate races after rotor drop are synchronously measured. The experiment results verify the advantages of DDCB and the correctness of theoretical analysis. The studies provide certain theoretical and experimental references for the application of DDCBs in AMB system.

Injection modulation of p^+-n emitter junction in 4H-SiC light triggered thyristor by double-deck thin n-base

To overcome hole-injection limitation of p^＋-n emitter junction in 4H-SiC light triggered thyristor, a novel high- voltage 4H-SiC light triggered thyristor with double-deck thin n-base structure is proposed and demonstrated by two- dimensional numerical simulations. In this new structure, the conventional thin n-base is split to double-deck. The hole- injection of p^＋-n emitter junction is modulated by modulating the doping concentration and thickness of upper-deck thin n- base. With double-deck thin n-base, the current gain coefficient of the top pnp transistor in 4H-SiC light triggered thyristor is enhanced. As a result, the triggering light intensity and the turn-on delay time of 4H-SiC light triggered thyristor are both reduced. The simulation results show that the proposed 10-kV 4H-SiC light triggered thyristor is able to be triggered on by 500-mW/cm^2 ultraviolet light pulse. Meanwhile, the turn-on delay time of the proposed thyristor is reduced to 337 ns.

Comparative Analysis of Tunnel Seepage Field under Different Waterproof and Drainage System Using Analytical Methods

Tunnel seepage is an important factor affecting the progress and safety of tunnel construction. In this paper, the mining method tunnel construction in the water-rich weathered granite stratum is taken as the research object. Through the analytical calculation method, the distribution law of tunnel seepage field under different waterproof and drainage types is studied, and the comparative analysis is carried out. According to the analytical solution, the influencing factors of grouting parameters are proposed. The sensitivity of the tunnel seepage field to the variation of grouting parameters is analyzed. A novel waterproof and drainage system, and construction technology suitable for subway tunnels with large buried depth below groundwater level were proposed.

Fabrication of Waterproof Artificial Compound Eyes with Variable Field of View Based on the Bioinspiration from Natural Hierarchical Micro–Nanostructures

Planar and curved microlens arrays(MLAs)are the key components of miniaturized microoptical systems.In order to meet the requirements for advanced and multipurpose applications in microoptical field,a simple manufacturing method is urgently required for fabricating MLAs with unique properties,such as waterproofness and variable field-of-view(FOV)imaging.Such properties are beneficial for the production of advanced artificial compound eyes for the significant applications in complex microcavity environments with high humidity,for instance,miniature medical endoscopy.However,the simple and effective fabrication of advanced artificial compound eyes still presents significant challenges.In this paper,bioinspired by the natural superhydrophobic surface of lotus leaf,we propose a novel method for the fabrication of waterproof artificial compound eyes.Electrohydrodynamic jet printing was used to fabricate hierarchical MLAs and nanolens arrays(NLAs)on polydimethylsiloxane film.The flexible film of MLAs hybridized with NLAs exhibited excellent superhydrophobic property with a water contact angle of 158°.The MLAs film was deformed using a microfluidics chip to create artificial compound eyes with variable FOV,which ranged from 0°to 160°.

Elastic Bio-based Polyurethane Nanofibrous Membrane with Robust Waterproof and Breathable Properties

Elastic bio-based waterproof and breathable membranes(EBWBMs) allow the passage of water vapor effectively and resist the penetration of liquid water,making it ideal for use under extreme conditions.In this study,we used a facile strategy to design the bio-based polyurethane(PU) nanofibrous membranes with the nanoscale porous structure to provide the membranes with high waterproof and breathable performances.The optimization of nanofibrous membrane formation was accomplished by controlling the relative ambient humidity to modulate the cooperating effects of charge dissipation and non-solvent-induced phase separation.The obtained EBWBMs showed multiple functional properties,with a hydrostatic pressure of 86.41 kPa and a water vapor transmission(WVT) rate of 10.1 kg·m^(-2)·d^(-1).After 1 000 cycles of stretching at 40% strain,the EBWBMs retained over 59% of the original maximum stress and exhibited an ideal elasticity recovery ratio of 85%.Besides,even after 80% deformation,the EBWBMs still maintained a hydrostatic pressure of 30.65 kPa and a WVT rate of 13.6 kg·m^(-2)·d^(-1),suggesting that bio-based PU nanofibrous membranes could be used for protection under extreme conditions.

Study on Preparation of Waterproofing Agent for Mineral Wool Board from Modified C_9 Petroleum Resin

The modified petroleum resin emulsion prepared from the C9petroleum resin was modified with maleic anhydride.The effects of maleic rosin and maleic anhydride addition level,the modification time and the alkali liquor on the properties of the emulsion were discussed.The results showed that the optimum process conditions covered:a maleic anhydride mass fraction of 1.5%,a maleic rosin mass fraction of 10%,a KOH mass fraction of 1%,a petroleum resin modification temperature of 200℃,a petroleum resin modification duration of 3 h,and a modified petroleum resin emulsion/wax emulsion mixing ratio of 1:1.The particle size of modified petroleum resin emulsion prepared under these conditions was equal to 104.166μm.

Synthesizing Self-Crosslinking Waterborne Polyurethane-Silanol Dispersion for Waterproofing Application

Polyurethane dispersions (PUD) have diversified into a myriad of applications over the years. This has led to extensive research on both industrial and laboratory fronts as polyurethane dispersions provide liberty to interplay at the molecular level to diversify the properties of the product which has also led to the development of eco-friendly waterborne dispersions. Yet, waterborne PUDs are limited in their mechanical and physical properties as compared to solvent-based products. The incorporation of crosslinkers in the PUD further bolsters these properties thus improving water and solvent resistance. The incorporation of silanols increases solvent resistance and adhesion of the resultant PUD. In this work, a post crosslinking system based on the ketone-hydrazine mechanism was incorporated into the PUD thus providing the required structural reinforcement for construction application. The targeted application for this work is the use of PUDs for waterproofing.

Waterproof and Oil Repellent Treatments of Cotton Fabric

The waterproof and oil-repellent finishing of the dyed single-sided plain cotton fabric was carried out by two-dip and two-pad process. The influences of baking temperature (°C), baking time (min), concentration of finishing solution (g/L) and percentage of liquid on waterproof effect of fabric were analyzed;the influences of the contact angle and the baking temperature (°C), the baking time (min) and the concentration of the finishing agent (g/L) on the oil repellency of the fabric were investigated. The results showed that the best water-repellent finishing technology for cotton fabric was the concentration of finishing agent 30 g/L, the baking temperature 110°C, the baking time 1.5 min and the liquid-uptake 70%. The best oil-repellent finishing process for cotton fabric is 35 g/L for finishing agent, 150°C for baking temperature, and 1.5 min for baking time and pick up rate of 80%. After cotton fabric is treated with water-repellent and oil-repellent agent, the water-repellent contact angle of the fabric can reach 128°and the oil-repellent grade 6. The best finishing effect is obtained at this time. After the finishing agent acts on the surface of the fibre, the surface properties of the fibre can be changed, and the surface of the fibre can be changed from hydrophilicity to hydrophobicity. The finishing agent has good film-forming property, which makes the surface of cotton fibre smooth and has good waterproof and oil-repellent performance.

Condensation of Water Vapor on Waterproof Breathable Fabrics

Condensation occurs when the local vapor pressure rises above the saturation vapor pressure at the local temperature in theory. A new measuring apparatus were made to obtain temperature and relative humidity simultaneously for the purpose of investigating the mechanism of condensation occurred on the fabrics. The experiment conducted at the standard condition of temperature of 20℃ and relative humidity of 65%. The result obtained from experiment showed that condensation could occur under the situation closed to saturation line as the temperature on fabric may be lower than dew point of water vapor in the measuring box depending on the experiment conducted at an ambient environment temperature of 20℃ The range of fabrics studied showed that PTFE laminated fabrics except nylon gingham PTFE laminated fabric facilitates the loss of water vapor and therefore prevent condensation. It is necessary to develop studies from a wide range of fabrics, especially breathable fabrics and under bad experiment condition in order to develop fabrics, which could eliminate condensation, or transport water vapor through the fabric while remaining waterproof.

Preparation of low-cost waterproofing materials

To address the need for producing a cheap,single-component,hot-applied compound joint sealant with high quality for sealing joints and cracks in concrete and flexible pavements without using primer for installation,a hot-applied modified asphalt sealant was produced by blending up about 30% starch into 20% citric acid.The starch and the asphalt cement were mixed at a temperature of above 160 ℃.Thus the waterproofing asphalt was manufactured to protect the surface of various shapes and types from water leakage using the citric acid.Results indicate that this sealant complies with the requirements of ASTM D-1191,D-6690-06a and D-7116-05.The citric acid is a kind of reliable materials for asphalt cement,which can be widely used in paving and waterproofing construction materials,and this offers profound engineering and economic advantages.

A Research on the Behavior of a Polyurethane Polymer Waterproof Material Used in Bridge Geotechnical Applications

Polyurethane is enjoying a widespread use as a polymer-based waterproof material in civil engineering In the present study we consider a temperature-sensitive waterproof and moisture-permeable polyurethane material(PTPE-PU)characterized by one or more phase transition temperatures(critical temperatures).Near the critical temperature,the waterproof and moisture permeability of polyurethane undergo abrupt changes.The related stability,thermal performance,water resistance,hydrostatic pressure,and moisture permeability are investigated here considering a PTPE-PU traditionally used in bridge geotechnical engineering.The results show that the moisture permeability of the coated bridge rock and soil undergo sudden variations near the crystallization and melting temperature of the soft segment.The moisture permeability is 3000 g/(m^(2)d).The hydrostatic pressure of the coated bridge rock and soil is 3.5 kPa.

Aerodynamic drag analysis of double-deck container vehicles with different structures

To study the aerodynamic performance of a new six-axis X2K double-deck container vehicle, numerical simulation was done based on three-dimensional, steady Navier-Stokes equations and k-e turbulence model. The results show that the pressure on the front surface of vehicle is positive, and others are negative. The maximum negative one appears as a ＂gate＂ shape on front surfaces. The pressure on vehicle increases with train speed, and pressure on vehicles with cross-loaded structure is smaller than that without it. The airflow around vehicles is symmetrical about train vertical axis, and the flow velocity decreases gradually along the axis to ground. Airflow around vehicles with cross-loaded structure is weaker than that without the structure. The aerodynamic drag increases linearly with the train speed, and it is minimum for the mid-vehicle. The linear coefficient for mid-vehicle without cross-loaded structure is 29.75, nearly one time larger than that with the structure valued as 15.425. So, from the view-point of aerodynamic drag, the cross-loaded structure is more reasonable for the six-axis X2K double-deck container vehicle.

Nonlinear stability of double-deck reticulated circular shallow spherical shell

Based on the variational equation of the nonlinear bending theory of doubledeck reticulated shallow shells, equations of large deflection and boundary conditions for a double-deck reticulated circular shallow spherical shell under a uniformly distributed pressure are derived by using coordinate transformation means and the principle of stationary complementary energy. The characteristic relationship and critical buckling pressure for the shell with two types of boundary conditions are obtained by taking the modified iteration method. Effects of geometrical parameters on the buckling behavior are also discussed.

Chongqing Sino-Australia Waterproof Material Co.,Ltd

China West International Holdings Limited is an Australian listed company.It specialized in in- dustrial investments in construction materials,energy development,infrastructure,etc.At present, China west International Holdings Limited wholly controls Yuan Construction and sale of common Portland cement,limestone mining,etc.,also controls advanced technology companies.Wholly owns Chongqing Sino-Australia Waterproof Material Co.,Ltd.

Present Situation and Problems Analysis of Waterproof and Seal of Prefabricated Building Exterior Wall

With the continuous development and progress of China's social economy,the construction speed of our construction industry is also accelerating.Compared with the traditional cast-in-place reinforced concrete and masonry building,it has been unable to meet the requirements of the construction industry and the development of the times.Because the prefabricated building has the advantages of fast speed,water saving,land saving,noise reduction,material saving and energy saving in installation.Compared with traditional buildings,the prefabricated building is more energy efficient and practical.Therefore,the new type of precast assembly architecture is constantly highlighted and has become the mainstream of the development of the future construction industry.However,the technology started late in China,and the immature technology and imperfect supporting standards led to slow progress and even stagnation in China's construction industry.Through the analysis of the present situation and problems of the waterproof and sealing of the prefabricated building exterior walls,the suggestions for the healthy development of the construction industry in China are put forward in time.

Design of a Novel Waterproof Electronic Sphygmomanometer

A novel waterproof electronic sphygmomanometer is presented in this paper, the special design of sealing structure is used in this sphygmomanometer that allows the system to function normally in water. The system also adopts the rigid air cylinder as air source to ensure accurate detection and chooses the MP3VS050 piezoresistive transducer to ensure the measurement precision of the systolic and diastolic pressure. TI＇s MSP430FC,437 is used as the central processor so that the system can be of advantages of low-power, fast digital processing and high-reliability. The sphygmomanometer was validated by three groups of participants. The experimental data indicates that the measured values of this waterproof electronic sphygmomanometer are consistent with the results of common electric sphygmomanometer, the measure error is less than 5 mmHg, and the system is stable and credible. So the waterproof electronic sphygmomanometer can realize real-time monitoring of blood pressure and heart rate in the water and other special environment.

深埋岩溶隧道爆破开挖对围岩损伤及渗流特性的影响

深埋岩溶隧道开挖会造成围岩特殊的损伤破坏形式,并且损伤区也会影响围岩渗流场及隧道边界的涌水状况,对深埋岩溶隧道爆破开挖作用下围岩的损伤及渗流特性有重要的研究意义。为了研究爆破开挖对深埋岩溶隧道围岩损伤及渗流的影响规律,基于COMSOL Multiphysics软件建立数值模型并嵌入应力-渗流-损伤耦合方程式进行计算,采用解析法计算了简化条件下岩溶隧道开挖时围岩的应力分布,并与数值计算结果进行比较。结果表明:解析法与数值法计算的围岩应力分布有一致性,爆炸荷载使靠近溶洞侧隧道肩部及脚部区域会产生较大的拉应力;爆破后会在隔水岩柱形成“齿”状损伤区,同时引起肩部及脚部区域流速的增加,其可作为判断溶洞方位的参考依据;溶洞净距减小、洞径及水压增加会引起“齿”延伸倾角及最大涌水位置变化、隧道边界涌水量的增加,可根据“齿”延伸方向判断损伤区检测的合理方位,根据最大涌水位置变化、隧道边界涌水量的变化,合理调整涌水防治措施强度及重点防治部位。研究成果可为溶洞位置判定、隧道损伤区检测以及边界涌水防治措施提供参考。