Abstract:The coupled masonry wall is a joint member that connects two independent walls and limbs together and forces together. It is the middle link from member to structure in masonry research. Most of the existing bi-limb wall tests use specimens consisting of two rectangular vertical wall limbs to compare the crack failure law and bearing capacity of complex vertical bi-limb wall with that of the single wall. It is of great significance to study seismic performance at the structural level. Based on the single masonry wall test, this paper designs three typical facade double limb masonry walls for low cycle repeated load test, compares and analyzes the seismic performance differences of each double limb wall, such as hysteretic loop and bearing capacity; combined with the test phenomenon, the mechanical model of masonry wall rotating failure along the inclined crack is established, and the calculation method of horizontal bearing capacity of "L" facade masonry wall is proposed, and compared with the test data. The results show that when subjected to loading in different horizontal directions, the seismic ability of masonry wall with asymmetric facade shape has obvious directional characteristics, and the crack development law and failure mode of the double limb masonry wall are basically consistent with that of the single limb wall; the calculation method of the horizontal bearing capacity proposed in this paper has a good correspondence with the actual failure mode of the wall, and has a clearer physical meaning than the inclined crack failure of the wall between windows. The calculation results of the horizontal bearing capacity are in good agreement with the experimental values of the single wall and the double limb wall.

Abstract:Due to the low redundancy of the traditional beam string structure, it is easy to cause a continuous collapse of a structure when the lower string prestay cable is broken by accident. A new type of beam string structure is proposed by improving the traditional tensioned beam spars, lower chords and the connection forms among members. Based on ANSYS/LS-DYNA program platform, some new beam string structure models with different spars crossover angles and spars numbers are analyzed for continuous collapse resistance by using the instantaneous unloading method of the equivalent load in the initial state. The results show that after reasonable design, the cross strut will replace the lower chord at the failure to provide a spare force transmission path for the structure when any section of the lower chord fails，and the new beam string structure will not progressive collapse, but the lower spar internal force will increase suddenly, the large bearing allowance shall be reserved for the design of the lower brace. And also show that the closer the brace cross node is to the bottom chord, the more obvious the effect of the vierendeel truss of the remaining structure and the better the load carrying capacity. The more cross brace groups, the higher the structural redundancy, and the better the progressive collapse resistance of the new beam string structure.

Abstract:In order to research the resistance ability to progressive collapse of steel frame structure under the long-term effects of atmospheric environment, a time-dependent corrosion model of steel structure is developed to predict the changes of cross-sectional area and mechanical properties of the members. A classical multi-story steel frame structure in a Class Ⅲ atmospheric corrosion environment is studied and the Pushdown analysis is performed at different stages of its service time. The first peak load factor, the ultimate load factor and the ultimate deformation are used as evaluation indexes for the collapse resistance ability of the structure. The influences of different material parameters on the evaluation indexes are obtained by sensitivity analysis. The variation rules of evaluation indexes with volume loss rate are obtained based on regression analysis. The results show that corrosion causes degradation of the bearing capacity and ductility of the steel frame structure, especially ductility degradation. The degradation of bearing capacity is mainly attributed to the reduction of material strength and cross-sectional area of the members. The degradation of ductility is attributed to the decrease in steel elongation. There is a strong linear relationship between the evaluation indexes and the volume loss rate, which can be used to qualitatively predict the degradation of structural performance.

Abstract:The high strength of steel structure is the main trend. At present, the high yield ratio is the problem of the high strength steel, which limits the application of high strength steel in the seismic design of structures. A new type of high strength steel with a low yield ratio Q620E has been developed in HBIS Group by improving the material properties of low alloy high strength structural steel. In order to study the seismic performance of it, box-section columns with different cross-sectional dimensions were designed according to classes width-to-thickness ratio of steel columns. Low-cycle reversal tests were performed on box-shaped columns of high strength steel with nominal axial compression ratios of 0.2 and 0.35. The seismic performance of steel columns was investigated in terms of bearing capacity, ductility, energy dissipation performance and damage index by observing the damage modes, extracting hysteresis curves and skeleton curves of the specimens and comparing the seismic performance with that of Q690D ordinary high-strength steel columns. The test results show that the designed high-strength steel columns have good hysteresis performance and plastic deformation capacity; width-to-thickness ratio has a significant effect on the bearing capacity and ductility of the members; the larger width-to-thickness ratio is, the faster the stiffness dissipation capacity of the member decreases and discontinuous damage development occurs; compared with Q690D ordinary high-strength steel, Q620E steel shows greater advantages in mechanical properties and seismic design of the member, which can be considered for high-strength steel structures.

Abstract:To solve the problems of uncontrolled damage to prefabricated frame joints and the difficulty of post-earthquake repair, a new type of prefabricated steel-concrete composite frame joint based on an artificial plastic hinge connection is proposed. which has the characteristics of simple structure, good performance of bearing capacity and energy dissipation, easy assembly, and so on. To further clarify the mechanical performance of the new joint, the nonlinear finite element model of the joint was established through ABAQUS. Taking the axial compression ratio, flange connecting plate thickness, and diameter of the shear damper as parameter variables, the effects of different parameters on the failure mode, stress mechanism, and moment rotation curve of the joint were studied, and the stiffness of the joint was also evaluated. The results showed that the failure mode of the new joint was a flexural failure at the beam end, and the artificial plastic hinge plays a key role in the internal force distribution and transmission of the joint. With the increase in axial compression ratio, the bearing capacity, and ductility coefficient of the joint showed a trend of first increasing and then decreasing. The flange connecting plate thickness had a great influence on the bearing capacity and ductility. The diameter of the shear energy dissipation rod had little influence on the bearing capacity but had a great influence on the ductility deformation of the joint. The new joint belongs to the hinge connection and full-strength connection.

Abstract:To study the seismic behavior of concrete-filled square steel tubular column to U-shaped steel-concrete composite beam joints with separated internal diaphragm, four joint specimens were tested under cyclic loading. The test parameters are the diaphragm type and the connection forms at the beam-column interface. The hysteric behavior, ductility, energy dissipation and deformation were analyzed and suggestions the designing the reinforced plate were provided. Test results indicate that the beam bending failure occurred in all specimens, and the hysteric curves show an inverted S-shape, with an obvious pinch effect. The displacement ductility coefficient ratio is between 2.3-3.1, the elastic limit of inter-story drift rotation is between 1/68-1/53, the elastic-plastic limit of inter-story drift rotation is between 1/28-1/19, and the equivalent viscous damping coefficient is between 0.12-0.16, indicating that the specimens show good deformation and energy dissipation capacities. Changing the type of diaphragm has little effect on the load-carrying capacity of the specimen, but compared with the traditional internal diaphragm joints, the energy dissipation capacity of the weak axial internal diaphragm joints is decreased. Strengthening the beam-column connection can alleviate the stiffness degradation and effectively improve the bearing capacity and energy dissipation capacity of the joints.

Abstract:Five joint specimens were manufactured in this study based on the criterion of strong column and weak beam in order to investigate the seismic performance of the endplate-bolted joint of concrete filled square steel tubular with a high-strength core-to-steel beam. A pseudo static test was conducted to investigate the failure mechanism of joints and the effects of axial compression ratio, FRP thickness and the presence of high-strength core on the seismic performance. The behavior of joints before and after replacing steel beams were compared. The test results showed that all specimens eventually failed due to the formation of plastic hinges at the steel beam ends. The joints showed a high bearing capacity, good energy consumption capacity and ductility under this failure mode. The joint encasing the high-strength core exhibited a higher bearing capacity but smaller ductility. The initial stiffness and energy dissipation capacity of the joints were improved as the FRP tube thickness increased. Compared with the original specimen, the energy dissipation capacity, ductility and initial stiffness of the beam replacing specimen were smaller. The deformation analysis results showed that the composite column in the panel zone of the joint mainly undertook the bending deformation, whereas the shear deformation of the joint was mainly carried by the beams. The joints were classified as rigid joint according to the initial stiffness.

Abstract:In this paper, H-shaped steel is embedded in simple concrete-filled steel tubular composite columns to form a new type of composite structural columns. In order to study the mechanical behavior of the new composite structure columns, the experimental studies are carried out under four working conditions: pure bending, compression-bending, torsion-bending and compression-bending-torsion. In order to meet the loading needs during the test, a set of loading devices suitable for multi-working condition simulation is designed and made. In the loading of complex load, the axial compression ratio is 0.24 for the condition with axial compression, and the torsion-bending ratio is 0.34 for the condition with torsion. Through the loading tests of four specimens, the indexes such as torque-torsion angle hysteresis curve, moment-displacement hysteresis curve, torque-torsion angle skeleton, moment-displacement skeleton, mechanical characteristics and stiffness degradation are analyzed. The results and mechanism are analyzed in depth, and the results show that the mechanical performance is good under complex loads, and the basic suggestions for using this new structure in engineering practice are put forward.

Abstract:This paper proposes a reasonable method for calculating the horizontal seismic action of precast concrete floors. This method can be used to ensure the integrity of these kinds of floors to transfer the horizontal force caused by earthquakes. Firstly, a typical 5-story frame structure model is built for further analysis. The acceleration values obtained by the elastoplastic time-history analysis are larger than those calculated using the equivalent lateral force (ELF) method or empirical amplification (EA) method which was proposed by ASCE 7-10. Therefore, both the ELF and EA methods underestimate the horizontal acceleration (i.e., horizontal seismic action) of the floors, which would lead to unsafe design in engineering practice. Secondly, the modal superposition (MS) method is proposed, in which the key parameters specified by ASCE7-16 were employed and modified to coordinate with the requirements of the seismic design codes in China. The MS method is employed for calculating the accelerations of the 5-story model in different seismic intensity areas. Lastly, the analysis results were compared with those obtained from the elastoplastic time-history analysis, which indicates that the amplification coefficients of the floor acceleration (k) have a similar distribution trend along with the building height. Moreover, the precast concrete floors designed using the MS method could meet the seismic performance objective “Keep elastic under moderate earthquake and unyielding under rare earthquake”.

Abstract:A series of resonant column tests were conducted on coral sand taken from the Nansha Islands, South China Sea with different grain gradations. The small-strain shear modulus G₀ of the coral sands with various void ratio e with the confining stress of 20~300 kPa was obtained. The influence of coefficients of uniformity C_u, mean particle size d₅₀, and fines content F_c on G₀ of coral sand was investigated, and the G₀ formulation for coral sand was established. For the constant effective confining pressure σ0', the curve of G₀-e moves downward as the increasing C_u, and moves upward as the increasing d₅₀. The G₀ firstly decreases and then increases as the increasing F_c, and the G₀ reaches the minimum value for F_c of about 20%. The G₀ prediction equations of terrigenous sandy and gravelly soils will obviously underestimate the G₀ value of coral sand. The influence of F_c on G₀ essentially results from the change of C_u and d₅₀ for coral sand with various F_c. The G₀ prediction equation of coral sand related to C_u and d₅₀, which implies the influence of F_c on G₀, was proposed, and the correction factor A' related to the morphology and mineralogy of the particle form of coral sands was incorporated in the proposed G₀ prediction equation. The validity of the G₀ prediction equation was verified by comparing the measured and predicted G₀ values of coral sands from different seas.

Abstract:Using the mixture of waste tires and soil as building materials in the field of civil engineering is one of the most promising measures to deal with waste tires. In order to study the effect of waste tire rubber particles on improving silt, taking the mixed soil of rubber particles and silt as the research object, the soil-water characteristic curve of rubber silt was measured by filter paper method, and the effect of different moisture content and rubber content on the soil-water characteristic curve was analyzed. The results show that at the same rubber content, the matrix suction of the mixed soil decreases nonlinearly with the increase of moisture content, showing a typical three-stage characteristic; at the same moisture content, the matrix suction increases at first and then decreases with the rubber particle content. When the rubber content is 20%, the matrix suction of the mixed soil is the largest. The soil-water characteristic curve model of mixed soil is established based on the Van Genuchten model. Based on the particle contact theory and considering the different specific gravity of particles, the contact state model of mixed soil is established, and the skeleton void ratio is constructed to describe the unsaturated characteristics of mixed soil. the matrix suction of mixed soil increase at first and then decrease with the increase of the skeleton void ratio.

Abstract:In order to study the propagation pattern of vibration wave generated by urban subway operation in buildings adjacent to the metro and provide guidance for engineering practice, this paper takes adjacent buildings along the subway line as the research object and refer to the range of actual quantities to establish the general finite element numerical model of subway train-rail-tunnel-ground-building system. The transmission distribution and spectral characteristics of vibration response of the same floor and different floors in the building are studied. The results show that the vibration excitation of the building caused by subway operation is mainly in the range of 1~50 Hz; The greater the room area, the more the natural vibration frequencies of the floor are located in the dominant frequency range of the excitation load, and the more prone it is to cause floor resonance; The vibration intensity of floor span midpoint is usually greater than that of corner point, and the vibration of corner point will exceed floor span midpoint in low frequency band of 1.25~2.0 Hz; The vibration acceleration response in three directions presents a fluctuating distribution trend with the rise of the floor. Through the calculation of several examples, the influential characteristics of running speed, tunnel burial depth and horizontal distance between building and tunnel are analyzed.

Abstract:Based on the project of GRS-IBS in Taihang No.1 Tourism Road K43+175 in Shanxi Province, a series of dynamic triaxial tests of reinforced sand with different reinforcement spacings were carried out. To provide reference for deformation prediction and condition evaluation during design process of GRS-IBS, the influence of the reinforcement spacing on the dynamic response characteristics such as dynamic strength, dynamic shear modulus, damping ratio and cumulative plastic strain were analyzed respectively. The evolution patterns of dynamic response characteristics were also discussed. The results show that the type of dynamic stress-strain curve changes from hyperbolic to linear with the increase of the number of reinforced layers, and the peak as well as dynamic strength and dynamic modulus are also improved; the denser the reinforcement, the greater the increase would be. Increasing the confining pressure or the number of reinforced layers can reduce both the dynamic shear strain and the damping ratio but increase the dynamic shear modulus. The axial plastic strain can be inhibited effectively by increasing the number of reinforcement layers under the cyclic loading, so that the reinforcement spacing in GRS-IBS structure should be controlled to raise the cyclic stress ratio and maintain the long-term dynamic stability of the reinforced soil.

Abstract:Based on the slurry shield engineering of Xinjizhou water supply corridor project in Nanjing Yangtze River, the applicability of reusing waste sand as shield synchronous grouting materials was studied, which was produced by slurry shield construction in silty fine sand layer and rock stratum. Through changing the particle size distribution of abandoned sand in sandy soil layer, its influence on the performance of mortar was examined; furthermore, the influence of the particle shape of rock stratum waste sand on the performance of mortar was investigated, and the proportioning optimizing of synchronous mortar prepared from rock stratum waste sand was discussed. The results indicated that the sand layer waste sand can be used to replace the original sand directly, and the rock stratum waste sand can also satisfy the engineering requirements by adjusting the proportion; the fluidity of mortar improves with the increase of fineness modulus and sand content of sand layer waste sand, but excessive clay content results in decreased fluidity, shorter setting time and lower strength of mortar; the rougher the surface of rock stratum waste sand particles, the worse the fluidity and shorter the setting time. The waste sand of shield construction can be used for synchronous grouting under the appropriate proportioning, but the mortar proportioning should be adjusted appropriately with the change of particle size distribution and particle surface shape of waste sand.

Abstract:Vacuum preloading combined with electro-osmosis is one of the most commonly used method to treat dredged slurry, but there are problems such as blockage of drainage boards, serious electrode corrosion and high energy consumption which results in its limited use in engineering practice. In order to overcome the shortcomings of vacuum preloading combined with electro-osmosis method, this paper proposes a vacuum preloading- step-by-step energy dynamic compaction combined with electro-osmosis. Through five groups of laboratory model contrast tests, the pore pressure dissipation ratio (PPDR) was used to determine the dynamic compaction start-up time, and the optimal value was studied. During the tests, the pore water pressure, drainage volume, surface settlement and in situ strength of soil were monitored. The water content, vane shear strength and anodic corrosion were measured before and after the test. The test results showed that: compared with the test group of vacuum preloading combined with electro-osmosis method, the dynamic compaction in the vacuum preloading stage can crack the soil column caused by silting and effectively improve the drainage efficiency. After dynamic compaction, the cracks on the soil surface were reduced and the soil sample was more flat. The amount of anodic corrosion and energy consumption in the process of electro-osmosis consolidation were decreased. The drainage increased the most and the increase of settlement was the greatest and the shear strength after treatment reached 65 kPa when PPDR was 70%, under which a better treatment effect was obtained.

Abstract:Microbially induced calcium carbonate precipitation (MICP) is a new green ground improvement technique in geotechnical engineering and has a promising prospect in reinforcing granular soils. The uniformity and the mechanical performance of MICP-treated sands are important issues in the MICP method. To optimize the MICP-treatment scheme and improve the overall performance of MICP-treated sands, a comparative experimental study on different MICP-treatment schemes for sands was carried out. Firstly, the MICP-treatment schemes, including the conventional two-phase method, the pH method and the temperature-controlled method, were introduced in detail. Then, a series of MICP-treatment experiments on sand columns were conducted, following the three different schemes, respectively. Finally, the three different schemes were compared in terms of the distribution of CaCO₃ in the post-treatment specimens, the utilization rate of reaction solutions and the unconfined compressive strength of the post-treatment specimens. Under the testing conditions in this paper, the conventional two-phase method has the worst performance in the three aspects; the pH method and the temperature-controlled method generally perform well; in comparison with the pH method, the temperature-controlled method has a higher utilization rate of reaction solutions and a higher strength under high-treatment conditions; the temperature-controlled method has the best overall performance.

Abstract:The installation of polystyrene geofoam (EPS) inclusions between the rigid retaining wall and backfill can reduce the earth pressure acting on the retaining wall. To date, there is a lack of the calculation method for the earth pressure on rigid retaining walls with EPS inclusions. In this study, the compression from geofoam inclusions is equated to the displacement of the backfill, and the soil arching behind the retaining wall is considered. Based on the displacement-dependent earth-pressure model (DDEP), the iterative method is introduced for the convergence calculation, and then the theoretical solution is obtained to calculate the earth pressure on the rigid retaining wall with EPS inclusion. The advantage of the proposed method is that it can be used to solve the earth pressure when the EPS compression modulus is not provided. A series of FLAC3D numerical models is established to verify the proposed method and analyze the load reduction effect of EPS inclusions. The proposed theoretical solutions based on the DDEP model and iterative method are in preferably consistency with the numerical results. Effect of EPS on reducing the earth pressure increases with increase of the thickness of EPS inclusions when EPS elastic modulus is constant, and decreases with increase of the elastic modulus of EPS inclusions while EPS thickness is constant.

Abstract:Soil-bentonite barrier is one of the most important means to isolate contaminated sites, which has been widely used in engineering practice. Adding hydroxypropyl methylcellulose (HPMC) to the soil-bentonite barrier can effectively make up for the attenuation of its anti-seepage performance in heavy metal environment. A series of experiments including free expansion, scanning electron microscope, permeability, one-dimensional compression and direct shear strength for the destruction of bentonite structure by copper ion, the improvement mechanism of HPMC and the barrier mixing HPMC with different ratios are conducted under high ion concentration (50 mmol/L) environment. The results show that HPMC can reduce the agglomeration of copper contaminated bentonite, keep the continuous structure of bentonite and as HPMC mixing ratio increases, the damage degree of barrier gets lower and the anti-seepage performance becomes better. The mechanical properties of barrier such as the compressibility increases, but shear strength decreases slightly with higher HPMC mixing ratio.

Abstract:Using pre-absorbent low active slag as internal curing material instead of fine aggregate, the autogenous shrinkage and resistivity variation of low active slag internal curing mortar were studied, and the relationship between them was revealed. The results show that with increase of low active slag content, the early strength of mortar decreases greatly, with the extension of age, the strength reduction in the middle and late stages of mortar is smaller than that in the early stage. It is suggested that the appropriate content of low-activity slag is 15%-25% of the fine aggregate quality. The internal curing of low active slag has obvious influence on the resistivity development of mortar. Before setting hardening, the resistivity of mortar increases with the increase of low active slag content. After it, the slurry resistivity decreases with the increase of low active slag content. The internal curing of low active slag can effectively inhibit the autogenous shrinkage at various stages of the slurry, especially in the rapid shrinkage stage and transient expansion stage. At the same time, the resistivity after 36 h has a good correlation with autogenous shrinkage, and the change of autogenous shrinkage can be predicted by the development trend of resistivity.

Abstract:Electrolytic manganese residue (EMR) occupies a lot of land resources and may result in potential heavy metal pollution. In order to solve these problems, electrolytic manganese residue-based cementitious materials, initial electrolytic manganese residue and medium-coarse sand were employed to fabricate the filling material self-cemented with electrolytic manganese residue used for mine backfilling. The fluidity, compressive strength and leaching toxicity of hydration slurry of the filled composite were tested to evaluate the performances of the synthetic material, and the microstructure was characterized with X-ray diffraction and scanning electron microscopy. The results showed that the fluidity of the filling material slurry reached 200 mm, meeting the needs of technical requirements of filling; the compressive strength of the solidified body of the filling material could reach 1.5 MPa or more after curing for 28 days, meeting the conditions of the filling body strength for mining site; the leaching toxicity of the filling material significantly reduced with the main heavy metals including Mn and Co fully solidified and stabilized, meeting the national groundwater quality standard. The results of XRD and SEM analysis make it clear that the hydrated calcium silicate, ettringite and other crystals generated by the hydration of the filling material are the main reasons why the strength of the solidified body was stable and the heavy metals were solidified. All these findings indicated that this method could effectively solidify/stabilize electrolytic manganese residue and reduce the risk of environmental pollution.

Abstract:WWTPs (Wastewater Treatment Plants) produce a large amount of daily primary sludge. The composition of primary sludge is complex. The inorganic content is high while the settleability is poor. Isoelectric point pretreatment can effectively destroy the flocculation state of the primary sludge. Free nitrous acid can effectively destruct bacterial structure and promote the hydrolysis of organic matter, the pre-treated primary sludge is more conducive to its fermentation, recycling, final treatment and disposal. The effect of isoelectric point pretreatment by free nitrous acid on primary sludge was studied in this study. Experimental results showed that the settling property of primary sludge is improved. The CST reduced from 203.10 s to 101.65 s. Organic matter is retained to the maximum extent in the solid phase. The COD in supernatant decreased from 1 246.59 mg/L to 1 048.80 mg/L. The metal pollutants in the sludge were released efficiently. The secondary pollution in transport and disposal was prevented and reduced. However, this condition also promoted the dissolution of nitrogen and phosphorus pollutants after 300 mg/L NO₂^--N was added for pretreatment, SCOD dissolution increased, but the release of nitrogen and phosphorus pollutants was significantly reduced. After pretreatment, NH₄⁺-N was only 118.88 mg /L and PO₄^3--P was 6.91 mg /L. These results showed that the best pretreatment condition for primary sludge is 300 mg/L NO₂^--N for 1 h.

Abstract:In this study, a fixed-bed biofilm reactor using hybrid zeolite and plastic bio-carriers was constructed, in which successful enrichment of glycogen accumulating organisms (GAOs) under oscillating filling (anaerobic) - draining (aerobic) conditions was achieved. Associated with zeolite chemical adsorption, anaerobic removal of COD by GAOs and ammonia by zeolite was achieved. The hybrid carrier bioreactor was fed with synthetic wastewater with COD and ammonia concentration of (508±19)mg/L and (40±3)mg/L, respectively, and operated under periodical cycles of anaerobic (6 h) and aerobic (6 h). The removal rates of COD, ammonia nitrogen, and total nitrogen (TN) by single-stage treatment were 89.2%, 57.5%, and 57.5%, respectively. The removal rates of COD, ammonia nitrogen, and TN by the two-stage reactors were 93.1%, 84.9%, and 70.8%, respectively. By reducing the HRT by 50% (anaerobic/anoxic 3 h + aerobic 3 h), the TN removal rate in the two-stage reactors was increased to 81.7%. The results of 16S rRNA high-throughput sequencing showed that the relative abundance of Candidatus Competibacter (GAOs) increased by 30.43 times (0.46% → 14%) on the surface of the plastic carrier, while it only increased by 14.35 times ( 0.46%→6.60%) for the zeolite carrier, indicating that the surface of the plastic carrier is more favorable for the enrichment of Candidatus Competibacter.

Abstract:The presence of emerging contaminants in the raw water puts forward new challenges to drinking water treatment process. The chlorination of typical sulfonamides antibiotic sulfadimethoxine (SDM) in the sodium hypochlorite disinfection process was studied. The chlorination effects, including the initial concentration of residual chlorine, the pH value of the solution, ammonia concentration, and the inorganic anions, were also investigated. The mechanism of SDM chlorination was explored and the ecological risk was further assessed. The results showed that, under the conditions of the initial SDM concentration 15 μmol/L, the initial concentration of residual chlorine 60 μmol/L, the SDM removal reached high up to 95.9% in 120 s. The degradation process conformed to the pseudo-second reaction kinetics. The constants of degradation rate decreased with the increasing ammonia concentration, and increased with the initial concentration of residual chlorine. Background anions Cl^-, NO^3-, SO₄^2- had marginal effects on the reaction while HCO₃^- and CO₃^2- had inhibition effects on the reaction. SDM chlorination can be improved under neutral conditions. Nine degradation intermediates are identified by using high-resolution mass spectrometry HRMS Orbitrap. The degradation process covers chlorination, demethylation and hydroxyl addition reactions. The complete removal of SDM does not imply an effective reduction of ecological risk during disinfection process which poses a potential risk to the safety of drinking water quality.