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.

A Review of Innovative Design Strategies for Prefabricated Green Buildings

Prefabricated green buildings are becoming a trend in the construction industry of China.The prefabricated components are made using modern technologies like green materials,artificial intelligence,and low-carbon and energy-saving techniques.This makes them an important aspect of the development of the construction industry in China,representing modernization and sustainable development.This article presents a study on the innovative design of prefabricated green buildings.This article serves to promote sustainable development on a macro level.

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.

Preparation of Cellulose Acetate Butyrate Porous Micro/Nanofibrous Membranes and Their Properties

Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.

Novel protection systems for the improvement in soil and water stability of expansive soil slopes

To improve the soil and water stability of expansive soil slopes and reduce the probability of slope failure,novel protection systems based on polymer waterproof coatings(PWC)were used in this study.Herein,three groups of expansive soil slope model tests were designed to investigate the effects of polyester nonwovens and PWC(P-PWC)composite protection system,three-dimensional vegetation network and PWC(T-PWC)composite protection system,and nonprotection on the soil and water behavior in the slopes under precipitation–evaporation cycles.The results showed that the moisture change of P-PWC and T-PWC composite protected slopes was significantly smaller than that of bare slope,which reduced the sensitivity of slope moisture to environmental changes and improved its stability.The soil temperature of the slope protected by the P-PWC and T-PWC systems at a depth of 70 cm increased by 5.6℃ and 2.7℃,respectively.Using PWC composite protection systems exhibited better thermal storage performance,which could increase the utilization of shallow geothermal resources.Moreover,the maximum average crack widths of the bare slopes were 7.89 and 3.17 times those of the P-PWC and TPWC protected slopes,respectively,and the maximum average crack depths were 6.87 and 3 times those of the P-PWC and T-PWC protected slopes,separately.The PPWC protection system weakened the influence of hydro–thermal coupling on the slopes,inhibited the development of cracks on the slopes,and reduced the soil erosion.The maximum soil erosion of slopes protected by P-PWC and T-PWC systems was 332 and 164 times lower than that of bare slope,respectively.The P-PWC and T-PWC protection systems achieved excellent"anti-seepage and moisture retention"and anti-erosion effects,thus improving the soil and water stability of slopes.These findings can provide important guiding reference for controlling rainwater infiltration and soil erosion in expansive soil slope projects.

Characteristics Evaluation of Modern Bituminous Binders in Group Hydrocarbon Composition and Their Application in Construction

The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directions for their use in construction, the road industry and waterproofing. Commercial oil bitumen, raw tars and heavy oil residues (semi-finished products) of oil refineries aimed at meeting large-tonnage needs have been studied. The assessment was carried out according to the group hydrocarbon composition, by liquid chromatography using model compounds. Comparative analysis showed a general trend for all studied samples of petroleum bitumen: low content of asphaltenes (from 3.9 to 23.9 wt.%), low content of resins (from 11 to 19.07 wt%), insufficient for the formation of stable structuring layers, and a significant content of aromatic hydrocarbons, including heavy aromatic compounds (more than 20 wt.%). An assumption was made about the influence of the origin and the structure obtained during the processing of asphaltenes and resins on the transition from one type of bituminous structure to another based on the lyophility of high-molecular group components. A comparative structural characteristic of heavy oil residues from gasoline and oil production is considered in comparison with bitumens of various viscosities. Recommendations are given on the technology of processing petroleum feedstock and the use of heavy oils in order to obtain a given bitumen structure for the production of rational bitumen products for construction and waterproofing.

Bond condition between surface layer and immediate layer in porous asphalt pavement

Through the shear tests on composite specimens using four different kinds of tack coat material （epoxy resin, SBS modified emulsified asphalt, SBS modified asphalt and H# bridge waterproof material）, the bond condition between layers of porous asphalt pavement under traffic load, temperature variation and moisture situation is evaluated. The test results show that the bond strength decreases with the rise in temperature, and the relationship between shear strength and temperature can be expressed by a logarithm curve at a high reliability. Under the action of traffic load, the value of shear strength of the mixture right under the centre of the wheel track is smaller than that of other parts of the pavement. It is also found that some effects concerning moisture have comparative effects on the bonding of the two layers. Given all the results achieved during the study, it will be quite rewarding to make rational comparisons during selecting the sound type of tack coat.

CA-B /New-type Paraffin Emulsion Compound System: Study on the Mould Preservation Property of Treated Wood

[Objective] The aim was to develop the compound system of paraffin emulsion and CA based on natural surfactants to improve the properties of anti- mould and anti-blue stain. [Method] The paraffin wax emulsion with different con- centrations of 0.5%, 1.0% and 2.0% was added into CA （0.3% and 0.5%） to obtain six groups of compound systems. The full-cell process was applied to treat the sapwood of Pinus spp. at size of 50 mm （L）×20 mm （R）×5 mm （T）. Anti-mould and anti-blue stain tests were conducted using Botryodiplodia theobromae Pat., Spergi/lus niger V. Tiegh and Trichoderma viride Pers.ex Fr. according to the GB/T18261-200. [Result] Both paraffin wax emulsion and CA-B could prevent wood against mould and blue stain. However, within a certain range, anti-mould and anti-blue stain ef- fects of wood samples treated by the compound systems reduced slightly as the concentration of paraffin wax emulsion increased. [Conclusion] The research provides references for advancing use of wood biomass resources in a more efficient and more environment-friendly way.

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.

Calculation of groundwater head distribution with a close barrier during excavation dewatering in confined aquifer

When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.

Development of calcium coke for CaC2 production using calcium carbide slag and coking coal

A type of calcium coke was developed for use in the oxy-thermal process of calcium carbide production.The calcium coke was prepared by the co-pyrolysis of coking coal and calcium carbide slag, which is a solid waste generated from the chlor-alkali industry.The characteristics of the calcium cokes under different conditions were analyzed experimentally and theoretically.The results show that the thermal strength of calcium coke increased with the increase in the coking coal proportion, and the waterproof property of calcium coke also increased with increased carbonation time.The calcium coke can increase the contact area of calcium and carbon in the calcium carbide production process.Furthermore, the pore structure of the calcium coke can enhance the diffusion of gas inside the furnace, thus improving the efficiency of the oxy-thermal technology.

Effects of Soft Monomers on the Water Resistance and Moisture Permeability of Hydrophilic Polyurethane

Six groups of segmented polyurethanes with amorphous soft segment domains based on mixed hydrophobic polyester and hydrophilic polyether soft monomers were prepared from 4, 4′ diphenylmethane diisocyanate （MDI）, polybutylene adipate glycol 2000 （PBA2000）, polytetramethylene glycol 1000 （PTMG1000） and polyethylene glycol 1000 （PEG1000） with 1,4-butanediol （BDO） as the chain extender. Furthermore, the representative properties of the hydrophilic polyurethanes, moisture permeability and water resistance, were investigated. The results show that the chemical structure, molecular weight and concentration of soft monomers have remarkable effects on the main application properties of hydrophilic polyurethane. The important factors in diffusion are the content of hydrophilic ether bond and the mobility of hydrophilic chain in the soft phase, which is represented with a good approximation by the average mean molecular weight of soft segment. On the contrary, the functional properties of the hydrophilic polyurethane are almost not affected by its hard segment.

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°.

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.

Stress Relaxation of Paraffin Wax Emulsion/Copper Azole Compound System Treated Wood

[Objective] An approach of stress relaxation was proposed in present work to investigate the interactions among the waterproof agent,preservative and wood.[Method] Paraffin emulsion waterproof using natural surfactants was prepared at different concentrations of 0.5% and 2.0%,which were added into two concentrations（0.3%,0.5%） of copper azole（CA） to obtain compound systems,and one-time fullcell process was applied to treat the sapwood of Pinus spp.with a size of 10 mm（L） ×10 mm（R） ×10 mm（T）.[Result] Compressive stress relaxation behaviors at two moisture levels and room temperature were measured and the results were as follows：1） compared with control group,the stress relaxation of compound system treated groups reduced,whether at oven-dried state or air-dried state.2） Under oven-dried condition,CA could weaken the relaxation of treated samples and this effect became greater with increasing concentration of preservative,but an increase in the concentration of paraffin emulsion would slightly promote the relaxation of compound system treated samples.While under air-dried condition,both CA and paraffin wax emulsion lowered the relaxation which was inversely related to the concentrations of both agents.[Conclusion] The results were expected to shed new light on the various macroscopic properties of the compound system treated wood at a microscopic level,and to provide favorable scientific evidences and theoretical supports for the manufacture of waterproofing preservative-treated wood.

The Impermeability Mechanism of Self-compacting Water Proof Concrete

The impermeability mechanism of water-proof self-compacting concrete (WPSCC )w as studied. The mechanism and influential factors, such as water-cement ratio(w /c), dosage of powder, superplasticizer, sand content, aggregate conte nt, fly ash, UEA, PP fiber, on compactibility and crack resistance of WPSCC were analyzed. A type of WPSCC successfully applied in tunnel liner with its validit ies, conveniences and economies by mockup test was developed and optimized. Expe rimental results show that the WPSCC has good workability, mechanical properties and impermeability when reasonable requirements are fulfilled.

Piezoresistivity of Carbon Fiber Graphite Cement-based Composites with CCCW

The electrical conductivity and piezoresistivity of carbon fiber graphite cement-matrix composites（CFGCC） with carbon fiber content（1% by the weight of cement）,graphite powder contents （0%-50% by the weight of cement） and CCCW（cementitious capillary crystalline waterproofing materials,4% by the weight of cement） were studied.The experimental results showed that the relationship between the resistivity of CFGCC and the concentration of graphite powders had typical features of percolation phenomena.The percolation threshold was about 20%.A clear piezoresistive effect was observed in CFGCC with 1wt% of carbon fibers,20wt% or 30wt% of graphite powders under uniaxial compressive tests,indicating that this type of smart composites was a promising candidate for strain sensing.The measured gage factor （defined as the fractional change in resistance per unit strain） of CFGCC with graphite content of 20wt% and 30wt% were 37 and 22,respectively.With the addition of CCCW,the mechanical properties of CFGCC were improved,which benefited CFGCC piezoresistivity of stability.

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.

Development of a large nanocrystalline soft magnetic alloy core with highμ'_(p)Qf products for CSNS-Ⅱ

A waterproof nanocrystalline soft magnetic alloy core with a size of O.D.850 mm×I.D.316 mm×H.25 mm for radio frequency acceleration was successfully developed by winding 18μm 1k107b MA ribbons.Theμ'_(p)Qf products reached 7.5,10,and 12 GHz at 1,3,and 5 MHz,respectively.Theμ'_(p)Qf products of the MA core(O.D.250 mm×I.D.100 mm×H.25 mm)manufactured using a 13μm MA ribbon further increased by 30%.Detailed improvements on the MA core manufacture process are discussed herein.Continuous high-power tests on the new MA cores demonstrated its good performance of waterproofness,particularly its stability of highμ'_(p)Qf products.The MA core with highμ'pQf product and large size can operate under a high average RF power,high electric field,and in deionized water,which will be used in the China Spallation Neutron Source PhaseⅡ(CSNS-Ⅱ).