Abstract:In order to examine the dynamic impact effect of the self-anchored suspension bridge subjected to hangers fracture, model test for suspension hangers fracture was carried out.A 1:80 test model was developed based on the stiffness similarity theory. The test results indicate:the dynamic impact effects of hangers fracture in different regions are dissimilar. The tensile forces of the adjacent hangers on the same-side and same-span are dynamically redistributed after hangers fracture. Compared with shorter hanger that is adjacent to the broken suspension hanger, the Dynamic Impact Factor(DIF) and the Dynamic Amplification Factor(DAF) of the longer one is greater.The dynamic impact effect is obvious and dynamic impact sensitivity is higher. The peak values of dynamic tension forces of the hangers would be more than twice of the original values generally, and the safety reserve is obviously reduced. The dynamic impact effects of hangers fracture is significant, and it will lead to continuous hangers fracture easily on occurrence of corrosion or other defects of the adjacent hangers and affects the safety of bridges seriously.

Abstract:In order to estimate the icing growth characteristics of stay cables in the ice prone area in winter, the grey correlation analysis method is used to analyze the correlation effects of inclination angle, temperature, humidity, wind speed, rainfall and air pressure on the icing thickness of stay cables, and the correlation of each influential factor is determined. Then, the genetic algorithm (GA) and the whale algorithm (WOA) are combined to select the optimal smoothing factor, and a WOA-GA Optimized Generalized Regression Neural Network (GRNN) method is proposed to predict the icing thickness of stay cables. Its characteristic is to take the mean square deviation of output value and actual value as fitness function, and to calculate the fitness value of each particle; introducing the crossover and mutation operator of GA algorithm into WOA algorithm; meanwhile, via weight update strategy, the capacity of global optimization is improved, to prevent the WOA algorithm falling into local optimal; finally, through iterative optimization, the smooth factor corresponding to the minimum fitness value was output, and the GRNN pre optimization model was built. The results show that the correlation of ambient temperature is the highest, followed by dip angle, precipitation, wind speed and relative humidity, and the correlation of atmospheric pressure is the lowest; compared with the traditional GRNN, WOA-GRNN and PSO-GA-GRNN models, the proposed GRNN model has high accuracy, with the average mean absolute percentage error of 3.58% and root mean square error of 0.58 mm; The sensitivity analysis method is used to evaluate the impact of the influential factors on the accuracy of the model. It is found that the temperature has the greatest influence on the model, followed by the cable inclination.

Abstract:With the increasing application of the vision measurement technique in the civil engineering structure health monitoring,more attention has been paid to the long-term all-weather performance of vision measurement.To explore the main error source of vision measurement technique,a new error source analysis method based on Blind Source Separation (BSS) is proposed:First, in order to construct the multi-channel signals as the input signals of the blind source separation model, Ensemble Empirical Mode Decomposition (EEMD) was used to expand the observation signal channels; then, Fast Independent Component Analysis (FastICA) algorithm was used to separate the input signals, to obtain the FastICA components; next,the correlation between each component and environmental factors such as temperature, light irradiation, etc., was analyzed to explore the error source corresponding to the principal component; finally,by using the inverse transformation of the mixed matrix obtained by the separation algorithm, the proportion of the specified error source components was calculated and the main error source of the camera measurement was determined. The error data of long-term vision measurement were analyzed by blind source separation algorithm. The results show that this algorithm has good separation effect and can effectively separate and extract the displacement error components caused by each error source. In long-term vision measurement, temperature is the primary error source.

Abstract:Automatic crack detection based on image analysis is a hot issue in bridge structure health inspection. Crack segmentation based on deep learning is a significant solution, which needs lots of database. The small-scale crack images of open datasets are not sufficient for detection of long and thin cracks of super large-scale image. The study proposes an automatic crack detection method for super large-scale images, based on feature pyramid network. Through four different feature maps in various sizes, the proposed network yields predictions, respectively, which means a highly precise crack segmentation. Experiments are carried on 120 steel box girder crack images in a resolution of 3 264 pixels×4 928 pixels. These images are used to train and test the network. The comparison study is conducted between the proposed method and the models trained with crack images resized into 1 600 pixels×2 400 pixels and 2 112 pixels×3 168 pixels with bilinear interpolation algorithm. The results show that our method can achieve the highest crack Intersection over Union (IoU) of 0.78, and the lowest Dice Loss of 0.12 in the comparison study. The predictions of crack images in testing indicate that resizing images sometimes result in the loss of crack information, and our method can maintain the detail of cracks and detect cracks of super large-scale images automatically and precisely.

Abstract:Deformation of the bridge is an important index of bridge condition assessment. The direct measurement methods for the bridge deformation such as LVDT, RTK-GPS and LDV have a lot of limitations. Because it is difficult to obtain the real-time displacement modes and strain modes from the measured dynamic strains while the sampling frequency of strain measurement is low, the indirect bridge deformation reconstruction method based on strain still has some shortcomings in engineering practice. This paper proposed a data fusion method to reconstruct the deformation of bridge structure based on LSTM neural network using the measured strain and acceleration data. In this paper, the accuracy of the reconstruction results is verified by numerical simulation and experiment without strain modes, displacement modes and neutral axis. The results show that data fusion method based on LSTM can achieve high accuracy under different conditions.

Abstract:Compared with the medium-field and far-field earthquake, the near-field earthquake contained velocity pulse of high-energy, which would introduce significant displacement of the structure. To study the influence of the velocity pulse on Train-Bridge System (TBS) of high-speed railway Simply Supported Beam Bridge (SSBB), the trigonometric function method was used to simulate the velocity pulse and superimpose with the far-field earthquake without pulse to synthesize the pulse type near-site earthquake with different pulse types, pulse periods and pulse amplitude. Taking a typical high-speed railway SSBB with a span of 32 m as an example, the simulation was carried out by using the self-designed program of TTBSAS. The near-field seismic velocity pulse can significantly increase the dynamic response of the TBS of the high-speed railway SSBB, and the influence of the velocity pulse cannot be ignored in analysis of TBS coupling vibration in the near field. The influence of pulse type, pulse period and pulse amplitude on the displacement of SSBB is much greater than that of bridge acceleration and train safety index, and the influence of train on bridge cannot be considered in selection of pulse parameters. The dynamic response amplitude of the bridge under the near-field earthquake action of double half-wave pulse and three-half-wave pulse is obviously larger than that of single half-wave pulse, and the dynamic response of TBS is the largest when the pulse period is 2.0 s.

Abstract:In order to study the influence of residual stress on the fatigue performance of welded structures, a thermo-elastoplastic finite element (FE) model was established via thermal coupling method to simulate the temperature field and stress field during both the whole T-joint welding process and the post-welding heat treatment process. Based on the extended FE method, the numerical model of fracture mechanics of T-shaped welding joints was established. The initial condition of welding stress field was introduced into the model and its influence on the dynamic propagation behavior of fatigue cracks was analyzed. The results show that when residual stress is not taken into account, the fatigue crack of welding joint develops uniformly at both ends of the welding seam, and the crack propagation pattern is not consistent with the experiment. Post-welding heat treatment can significantly reduce the high tensile stress and compression stress generated by welding, but the increase of fatigue life span is less significant, at only 6.1%; considering the residual stress, the fatigue crack growth path is more consistent with the experiment. The influence of welding residual stress on the fatigue crack growth path should be considered in FE simulation of welded structure.

Abstract:Double-sided welding is expected to improve the fatigue resistance of rib-to-deck welded joints, and the initial welding defect is the key factor affecting the fatigue performance of these joints. A multi-scale finite element (FE) model of steel bridge decks with initial cracks was established by combining FRANC3D-ABAQUS based on the fracture mechanics theory. The stress intensity factor of fatigue crack in the rib-to-deck welded joints was studied. The influences of weld penetration rate, thickness of deck plate and initial crack shape ratio on the stress intensity factor were analyzed. The results showed that the fatigue cracks in rib-to-deck welded joints details are mixed mode cracks of sequenced Ⅰ-Ⅱ-Ⅲ. The maximum stress intensity factor of fatigue crack of rib-to-deck double-sided welded root was 64.3% lower than that of single-sided weld, which can effectively improve the fatigue performance. The weld penetration rate has marginal effect on the stress intensity factor of fatigue crack in the rib-to-deck double-sided welded joints. Thickening the deck can effectively reduce the stress intensity factor of the fatigue crack in the rib-to-deck double-sided welded joints. With increase of the initial crack shape ratio, the crack stress intensity factor decreases.

Abstract:To solve the problem of huge data and analysis paralysis in bridge state assessment,the Five Indices Method is used to analyze the superstructure components of a cable-stayed bridge according to monitored data. Then, a comprehensive evaluation index incorporating weight coefficients is proposed to evaluate the safety condition of the cable-stayed bridge superstructure based on the existing five indices. After that, to overcome the calculation difficulty in bridge evaluation activities, a series of 3A indicators are proposed and individually termed as the amplitude offset, the abnormal degree and the average value fluctuation. Compared with the previous five indices, the three new indicators require less computation, and thus, are more convenient for engineers to conduct on-site evaluation. The 3A indicators are used to evaluate the safety condition of the cable-stayed bridge, and the results are compared with the five indices.The analysis results show that the superstructure state of the cable-stayed bridge evaluated by the 3A indicators is basically consistent with the five indices.

Abstract:High-speed railways are designed with high speed and therefore with deformation control requirements. Due to the structural mechanical characteristics and the material properties of concrete, the concrete arch bridge inevitably exhibit downward deflection in operation, which directly affects the track alignment and operation safety. In order to ensure the driving safety and comfort of Beipanjiang Bridge in Shanghai Kunming passenger special line, an automatic deformation observation system was established to monitor the deformation and temperature changes. The extraction methods of creep and temperature effect were studied. The impact factor of temperature and deformation were determined with polynomial fitting. The results show that:The accuracy and effectiveness of the observation system satisfy the requirements; the bridge deck alignment is sensitive to the temperature change, the uneven settlement is great under low temperature, which decreases as the temperature rises; using the proposed creep analysis method, the relative creep deformation is only about 6% different from that of the theoretical value, which meets the computational precision requirements in engineering practice.

Abstract:The development of membrane-based wastewater treatment technology faces two challenges, i.e.:(i) improvement in the environment quality requires high-standard treatment, and (ii) carbon emission peak and carbon neutrality calls for green and sustainable techniques. Under such circumstances, methods to break the bottleneck of water permeability and pollutant removal efficiency trade-off, to reduce the energy consumption and carbon emission of membrane technology, and to stimulate the sustainable development of membrane-based wastewater treatment are of great significance.Recently, remarkable progress in membrane-based wastewater treatment has been achieved in terms of membrane separation fundamentals, antifouling membrane preparation, membrane process innovations, and engineering applications. Current efforts have been dedicated to precise design of membrane materials, functionalization of membrane interface, and process greening transformation. In this work, recent research progress has been reviewed in terms of functional extension of membrane technology/process, design of high-performance membrane materials, sustainable utilization of membranes, and green development of membrane processes. Further analysis and discussion on future development are also presented.In the context of future multi-target needs, multi-functionalization, selective and customized separation, and green development are worthy of in-depth research for promoting the sustainable evolution of membrane-based wastewater treatment technology.

Abstract:Electro-oxidation technology, as one common seen electrochemical water treatment technology, can effectively address the problems in which conventional water purification technology cannot or cannot easily solve.It has becoming a promising strategy for its extraordinary features and advantages, especially in ultra-low discharge requirements of water treatment. The development of electro-oxidation technology enriches green catalytic oxidation system and is of great scientific significance for constructing "carbon neutral" water treatment technology. In the past ten years, electro-oxidation technology has drawn increasing attention and achieved great progresses.In aiming of aqueous pollutants removal, resource and energy recovery from wastewater, numerous studies focused on the design and modification of functional electrode materials, as well as exploiting efficient reactors. In this review, the mechanism and research progresses of electro-oxidation water treatment technology were systematically discussed. A conclusion on its future development was summarized.

Abstract:Colored dissolved organic matter (CDOM) is an important component of natural organic matter in water. CDOM with high concentrations may cause eutrophication of drinking water sources such as lakes and reservoirs, and even directly pollute municipal tap water. Phytoremediation is regarded as an effective, economical, and ecological technology for the treatment of CDOM non-point pollution, and the purification of CDOM polluted wastewater treatment plant discharge. For the sake of aquatic environmental protection and drinking water safety, it is very necessary to study the decolorization mechanism and environmental behavior of CDOM by plants. In the present study, the decolorization, distribution, and composition of CDOM in the rhizosphere of Phragmites australis were investigated, as well as the influence mechanism of plant root exudates and enzyme extracting solution on the CDOM removal. The results showed that CDOM was difficult to be hydrolyzed, and its effective decolorization depended on the effect of plants. In the rhizosphere, CDOM was mainly removed by plant uptake and supplemented by root adsorption, forming the distribution characteristics that most of the CDOM were accumulated by plants as low molecules (92.2%) and the rest were adhered to root surface as high molecules (7.7%). Although root exudates cannot directly affect the decolorization process of CDOM, they can enhance the carbon source utilization ability of rhizosphere microbes to the high molecular CDOM, by improving the rhizosphere microenvironment, promoting the microbial growth, enriching the related-degrading bacteria, and changing the CDOM bioavailability. Low molecular CDOM generated by microbial degradation was transported into the plant through root uptake, and then were metabolized under the effect of plant enzymes, so as to achieve the purpose of CDOM purification by plants.

Abstract:NF-HF and NF-HS nanofiltration membranes were employed to separate SO₄^2- from Cl^-in secondary reverse osmosis concentrate discharged from coal-chemical wastewater treatment plant. The separation of SO₄^2- from Cl^-, rejection of scaling ions and anti-fouling performance of the two types membrane were investigated. Spiral Tube Reverse Osmosis (STRO) was used to concentrate permeate of NF-HF. The results showed that NF-HF membrane had better separation Cl^- from SO₄^2- and rejection of scaling ions than NF-HS membrane, whose rejection were 3.38%-16.03% for Cl^-, 91.18%-97.16% for SO₄^2-, 90% for Ca²⁺, 80% for Mg²⁺ and 40% for SiO₂, respectively. Moreover, NF-HF showed excellent antifouling property. The operating pressure rose slowly from 3.2 MPa to 4.5 MPa after continuously running 336 h and the membrane flux reduced by 11%, which was recovered completely after alkaline washing. STRO could effectively concentrate the NF-HF permeate and reject organic matter, but the anti-fouling performance was poor. Therefore, separating and concentrating coal chemical wastewater with NF-DTRO (Disc Tube Reverse Osmosis) combination process is practicable.

Abstract:In order to remove the typical refractory pollutant carbamazepine (CBZ) in water, a vacuum ultraviolet/chlorine advanced oxidation system was constructed, and the difference of CBZ removal efficiency in different oxidation systems based on vacuum ultraviolet or free chlorine was investigated; The effects of pH value, free chlorine dosage, bicarbonate in water, and humic acid on the removal of CBZ by vacuum ultraviolet/chlorine system and the attenuation of free chlorine in the system were explored. Through the free radical quenching test, the main active substances that oxidize CBZ in the vacuum ultraviolet/chlorine system were further explored. The results show that when pH=6, the chlorine dosage is 8 mg/L, the initial CBZ concentration is 30 μmol/L, the CBZ removal rate exceed 99.5% after 16 minutes of reaction in the vacuum ultraviolet/chlorine system; under the same conditions, the rate constant of the vacuum ultraviolet/chlorine system to remove CBZ is 1.75 and 5.30 times that of vacuum ultraviolet system and UV/chlorine system. Vacuum ultraviolet and free chlorine have a synergistic effect on removing CBZ.Under acidic conditions, the removal effect of CBZ is better, and the optimal reaction pH value is 6; the dosage of free chlorine is an important factor affecting the degradation rate of CBZ, and the best dosage of free chlorine is 8 mg/L; while bicarbonate and natural organic matter in the water both have an inhibitory effect on the removal of CBZ; during the degradation of CBZ by the vacuum ultraviolet/chlorine system, the main free chlorine consumption is ultraviolet light excites and consumes and reacts weakly with CBZ and degradation products, the system has oxidation of HO· and Cl· and direct photolysis.

Abstract:Coal gangue is one of the biggest industrial solid waste in China, and it is widely used in the field of wastewater treatment as adsorbent. However, there are a lot of crystal water and clay mineral impurities in the natural coal gangue. If natural coal gangue is directly used to treat wastewater, there are some problems such as low efficiency, long time and large dosage. In this experiment, ZnCl₂ was used to modify coal gangue to reduce the crystal water and clay mineral impurities, increase the specific surface area of coal gangue, improve the treatment efficiency and reduce the treatment cost. Through the modification experiments under different conditions, the modified coal gangue needed for this experiment is obtained. At the same time, the structure and chemical composition of the modified coal gangue are changed compared with the original coal gangue. ZnO has replaced SiO₂ as the main chemical composition of zinc modified coal gangue, the Zn²⁺ loading on the surface of coal gangue increases the specific surface area of coal gangue, changes the internal structure of coal gangue, and improves the ability of treating phosphorus-containing wastewater with coal gangue as adsorbent. Through the adsorption treatment of 50 mg/L simulated wastewater containing phosphorus by zinc-modified coal gangue, the optimum adsorption conditions were obtained as follows:The dosage of zinc-modified coal gangue was 1 g/L, the pH was 5 and the temperature was 30℃. In addition, Ca²⁺ and Mg²⁺ can promote the adsorption of phosphate on zinc-modified coal gangue.

Abstract:For the traditional packed bed sulfur autotrophic denitrification process has the problems of large filling dosage, serious head loss, easy blockage of the reactor and so on, the nitrogen removal of simulated wastewater by contact denitrification process with sulfur coating was studied. The effects of filler filling ratio, temperature and hydraulic retention time (HRT) on the denitrification performance of the reactor were investigated. The results showed that when the influent NO₃^--N concentration was 50 mg/L, the temperature was (25±1)℃, and HRT=19.5 h, the NO₃^--N removal efficiency was significantly improved with the filler filling ratio increased from 1/10 to 1/5 and the NO₃^--N removal rate increased from 56.77% to 78.26%. Temperature has a great influence on the denitrification in the reactor. When the filler filling ratio was 1/5 and HRT=19.5 h, the average NO₃^--N removal rates were 71.05% and 98.38% at (25±1)℃ and (30±1)℃, respectively. Moreover, when HRT was reduced to 9.7 h, the average NO₃^--N removal rate was 89.29%. During the whole reaction process, the effluent NO₂^--N concentration was very low, kept within 0.4 mg/L. And the effluent pH value of the reactor was maintained between 6.8 and 8.3, which met the pH conditions required for microbial growth. The sulfur autotrophic denitrification dominant bacteria of sulfur coating contact denitrification system were Thiothrixs、Thiomonas and Sulfuritalea, with the proportions of 2.89%,1.55% and 1.35%, respectively. The result of microbial function prediction showed that sulfur and nitrogen metabolism plays a key role in denitrification of the system.

Abstract:It is urgent to deal with the severe problem of heavy metal pollution in landfills using efficient remediation technology. In recent years, the potential of MICP technology to remedy heavy metals contaminated soil/water has been extensively explored. Sporosarcina pasteurii shows better urease activity and heavy metal tolerance among the indigenous microorganisms. However, few researches have explored the immobilization/removal potential of S. pasteurii to heavy metals in high concentration. Then, it is difficult to explain the immobilization/removal mechanism of S. pasteurii to different healy metals using only MICP theory. In addition, the efficiency of commonly used bioremediation processes needs to be further improved.To avoid the impact of humus and leachate in the landfill, this study took heavy metal contaminated solutions as the research object and used simple mixing methods to carry out bioremediation experiments. Based on the MICP and chemical equilibrium theory, the Visual MINTEQ software was used to simplify and simulate the bioremediation process of heary metal contaminated solutions. The results show that in the high concentration range, S. pasteurii can efficiently remove heavy metal such as Cd, Cr(Ⅲ) and Zn through biomineralization and bioaccumulation.In addition, the simple mixing method is easy to operate, the bioremediation efficiency is high, and it has the potential for engineering applications.

Abstract:This paper takes the antimony mine wastes from Xikuangshan (XKS) Antimony Mine in Lengshuijiang City, Hunan Province as the research object, and studies the leaching and releasing regularity of heavy metals from antimony mine wastes comprehensively and systematically. The content of heavy metals in antimony mine wastes and leaching solution was determined through the digestion test and semi-dynamic leaching test, and the release regularity of Sb, As and Hg in antimony mine wastes leaching solution was analyzed. The results show that the concentration of heavy metals in antimony smelting slags is relatively high. Except Pb, the concentration of heavy metals in all the three kinds of antimony mine wastes exceeds the risk screening value of Standard for Risk Control of Soil Pollution in Agricultural Land of Soil Environmental Quality(GB 15618-2018); the concentration of Sb, As and Hg in antimony mine wastes exceeds the standard background value of soil in Hunan Province.The leaching concentration of Sb, As and Hg in antimony smelting slags reached the maximum in 2-3 days of simulated acid rain leaching, and the leaching concentration of Sb, As and Hg in antimony ore waste rocks and antimony ore tailings reached the maximum on the first day of leaching, the antimony mine wastes from which the amount of heavy metals can be precipitated from the most to the least is in the following order:Antimony smelting slags > antimony ore tailings > antimony ore wastes. There is a quadratic function relationship between the cumulative leaching amount of heavy metals from antimony mine wastes and the cumulative leaching amount of simulated acid rain. The experimental results will provide some theoretical support for the prevention and control of soil-groundwater pollution by antimony mine wastes.

Abstract:The effect and mechanism of municipal sludge drying with slag-based modified material were revealed by the study of moisture content at different contents of modified material and curing times. The hydration products and microstructure of slag-based modified material and the dried sludge were characterized by using X-ray diffraction analysis, scanning electron microscopy and thermogravimetric analysis. The results showed that the moisture content of dried sludge reduced gradually with the contents of modified material and curing age. The drying effect of slag-based modified material on sludge was better than that of quick lime at the same conditions. Microscopic experimental results indicated that insoluble calcium silicate hydrate gels and ettringite crystal were formed during the hydration process of slag-based modified materials at alkaline conation, transforming a lot of free water into crystalline water in order to reduce moisture content of sludge. Meanwhile, these hydration products filled the pores of sludge, inducing to a thorough from loose agglomerate structure system of original sludge to a firmly bonded structure with different phases. It is helpful to the further resource utilization of sludge.

Abstract:Given the problems of oil refinery slag sludge containing a large amount of dirty oil, complex composition, and challenging to deal with, the pretreatment test of slag sludge produced by oil refinery of Sinopec Jinling Branch was used by ultrasonic means.The influence of ultrasonic power, ultrasonic temperature, ultrasonic time, and ultrasonic frequency on the decontamination rate of slag sludge was analyzed by L₁₆ (4⁴) orthogonal test method. Error analysis was carried out by SPSS 25.0, and the orthogonal experimental results were refined by using the single-factor test. The characteristics of sludge change before and after ultrasound were characterized by infrared spectroscopy, scanning electron mirror, energy spectrum analysis, and so on.The results are as follows:The orthogonal test showed that the influencing order of factors was ultrasonic power < ultrasonic time < ultrasonic temperature < ultrasonic frequency. When the ultrasonic power was 60 W, ultrasonic time was 10 min, the ultrasonic temperature was 60℃, and ultrasonic frequency was 3 times, the removal rate of petroleum substances could reach 31.13%. The infrared spectrum showed that the corresponding peak of scum oil sludge after ultrasonic treatment was significantly changed, showing that aromatics, alkanes, olefins, and other substances were decreased, indicating that the long chain of petroleum hydrocarbon was destroyed. After ultrasonic extraction, the alkanes in the extracted oil decreased and the alcohols increased, which may by that one of the hydrogen groups of alkanes was replaced by hydroxyl group to produce corresponding alcohol. Compared with alkanes, alcohols were more easily degraded by microorganisms. Scanning electron microscope (SEM) analysis showed that after ultrasonic treatment, the gap between the particles increased, the viscosity decreased, and the texture became loose.The mechanism of petroleum hydrocarbon in scum oil sludge by the ultrasonic method was as follows:through mechanical effect, cavitation effect and thermal effect, the long chain of petroleum hydrocarbonin scum oil sludge was destroyed, the viscosity between particles was reduced, the voids between particles were increased, the three-phase separation of oil, mud and water was promoted, and the petroleum hydrocarbon was decomposed and separated, thus reducing the content of petroleum substances in scum oil sludge. Energy dispersive spectrum analysis(EDS) showed that the proportion of carbon and oxygen elements in the oil sludge after ultrasound did not significantly decrease, indicating that the ultrasonic thermal effect did not occur obvious gaseous oxidation reaction. As a result, the ultrasonic method is a physical method, with no additional chemical drug, and the treatment method is simple. It can be used as a composite treatment process pretreatment means.

Abstract:Solidification/stabilization technology is widely used in remediation of heavy metal contaminated sites. Carbon dioxide carbonation can change the chemical dissolution behavior of pollutants in heavy metal contaminated clayey soil solidified. Taking the lead-contaminated soil as the research object,the relationship between lead concentration and pH value in leaching solution was measured by acid/alkali titration test and pH related dissolution test. Five fractions of chemical occurrence of lead were determined by sequential extraction procedures. The change of chemical dissolution characteristics of cement solidified heavy metal contaminated clay and the relationship between the dissolution of heavy metal pollutants and pH value under carbonization were studied. The results show that the acid/alkali buffering capacity of solidified contaminated soil decreases by 18.5%-72.4% under carbonation. The relationship between the solubility of lead and pH value shows the behavior characteristics of amphoteric substances. The solubility of lead is relatively small when the pH value is between 7 and 11, and it is larger when the pH value is less than 7 or more than 11. The chemical occurrence forms of lead in the solidified contaminated soil are mainly Fe-Mn oxides bound phase. Under the action of carbonation, the proportion of exchangeable phase and carbonate bound phase of cement stabilized soil increases by 4.3% and 3.5% respectively, while the proportion of Fe-Mn oxides bound phase, organic matter bound phase and residual phase decreases by 2.1%, 0.9% and 4.8% respectively. Under the combined action of acid rain and carbonation, lead in cement stabilized soil is more easily dissolved.