Stable interfacial adsorption in melt-cast explosives relies not only on the presence of functional additives but also on the ability of their surface functionalities to facilitate the formation of stable adsorption layers under stage-specific processing-related conditions. This study established and investigated a ternary interfacial model comprising HMX, functional additives, and DNAN through molecular dynamics simulations to elucidate how surface functionalization and stage-specific processing conditions regulate interfacial adsorption. Hydroxyl-, carboxyl-, and sulfonic-functionalized additives were comparatively evaluated based on equilibrium configuration, interfacial binding energy, radial distribution characteristics, concentration distribution, cohesive energy density, and mobility-related descriptors. Among the selected additives, the sulfonic-functionalized additive demonstrated the most robust interfacial stabilization, characterized by a stronger interfacial driving force, enhanced local ordering, and a more continuous adsorption layer adjacent to the HMX surface. Using this system as a representative case, the effects of temperature, pressure, and shear were further analyzed by correlating them with the key stages of melt-cast explosive formation. The results suggest that interfacial stabilization proceeds through selective interfacial capture, adsorption-layer reorganization, and final structural retention, and that this process is strongly affected by temperature, pressure, and shear. This work offers a molecular-level foundation for screening functional additives and understanding interfacial regulation in melt-cast explosives.

A novel mix design process for self-compacting concrete (SCC) incorporating with crushed sand is proposed based on mortar properties and the thickness of the mortar film coating the coarse aggregate surface. First, by testing the rheological properties of twelve mortar mixes, the differences in rheological parameters between natural sand and crushed diabase sand at varying volume fractions (0.32-0.46) were compared, determining the rational volume fraction range of crushed sand. Subsequently, three crushed sand mortar mixes with distinct rheological properties and strengths were prepared as the matrixes of SCC based on this range. By further adjusting the mortar film thickness (1.5-2.9 mm), fourteen SCC mixes incorporating with crushed sand were designed. By testing their workability and mechanical properties, the optimal mortar film thickness range was identified and performance determination formulas were established. Finally, the applicability of the proposed design process was validated by preparing SCC with crushed granite sand. The results indicate: (1) Mortar with crushed sand exhibits higher initial yield shear stress and plastic viscosity than that with natural sand. The rational volume fraction range for crushed sand is 0.34-0.38. (2) The recommended mortar film thickness is 2.1-2.5 mm. (3) The performance of SCC can be accurately predicted (R2=0.95) based on the mortar's initial yield shear stress, compressive strength, and film thickness. (4) The successful preparation of SCC incorporating with different types of crushed sand confirms the mix design process's adaptability and potential for application to other cementitious systems and aggregate types.

The low-carbon design of steel fiber reinforced self-compacting concrete (SFRSCC) represents an ongoing pursuit in the development of the high-performance concrete industry. Based on the solid-liquid two-phase suspension system and film thickness theory of SCC, this study proposes a novel design framework for SFRSCC focusing on the low-carbon design of cementitious materials and film thickness optimization. For rapid repair applications in bridge expansion joint transition zones, an eco-friendly micro-steel fiber reinforced sulfoaluminate cement-based self-compacting concrete (MSFR-SAC-SCC) with ultra-early strength and high toughness is developed. By establishing objective functions that consider performance, carbon emissions, and cost, the optimization of the micro-steel fiber (MSF) volume ratio and mortar film thickness in MSFR-SAC-SCC is achieved. Growth models for the mechanical properties, fracture behavior, and bonding performance of MSFR-SAC-SCC as a function of curing age are established. The results indicate that the successful preparation of MSFR-SAC-SCC verifies the feasibility of the proposed low-carbon optimization design framework for SFRSCC. Based on the established multi-objective optimization functions, the comprehensive performance of MSFR-SAC-SCC is optimal when the MSF volume ratio is 3%, the blending ratio of 6 mm and 13 mm MSFs is 1:2, and the mortar film thickness is 2.2 mm. According to its performance growth models as a function of curing age, MSFR-SAC-SCC can meet the requirements for reopening to traffic in 2 h.

The prediction of machining induced microstructure is fundamental to provide guidance on process-structure-property control. However, the inconsistent surface microstructure distribution is always induced by dynamic and drastic thermo-mechanical coupling. Although existing data-driven microstructure prediction approaches have been established to predict the machining induced microstructure, they do not accommodate variation in the localized transient thermal characteristics and the induced microstructure evolution with spatial distribution due to the limitation of linking key process parameters to overall microstructure. Accordingly, the consistent microstructure is predicted across the entire machined surface with the presupposition of the constant machining thermo-mechanical loads under certain process conditions. To this end, a deep neural network (DNN) transfer learning model with stacked auto-encoder (SAE) is proposed to predict the localized microstructure of machined surfaces through transient thermo-mechanical characteristics combining magnitude and process rate information. Firstly, cutting simulations are conducted with a modified power-law constitutive model considering varied strain rate effects and JMAK model to obtain multi-dimensional datasets including localized thermo-mechanical characteristics, microstructure for pre-training and optimal structure selection of DNN model. Subsequently, the SAEs are employed to initialize DNN for optimizing weights and bias values, and experimental data is used to fine-tune the DNN model via transfer learning. The proposed method is demonstrated through a case study of Ti6Al-4V milling. The inhomogeneous microstructures are effectively predicted at various regions within machined surface under different machining conditions. The SHAP results illustrate that the temperature, heating rate and cooling rate have more significant effects on grain size in comparison with strain and strain rate.

To solve the problem of low utilisation rate of aged asphalt in reclaimed asphalt pavement (RAP) processed by cold regeneration technology, a new rejuvenated emulsion system for aged asphalt was proposed, incorporated with functional oil and epoxy resin. The microscopic rejuvenation mechanism of the emulsion on aged asphalt was analysed by infrared (IR) spectrometer, fluorescence microscope and scanning electron microscope (SEM), which was verified by the road performance of the asphalt mixtures that were completely incorporated with RAP rejuvenated by the new emulsion. The IR test showed that the carbonyl index of the aged asphalt returned to the level before the rolling thin film oven test (RTFOT) when the functional oil emulsion content was 12% of the aged asphalt. According to the fluorescence image and SEM image, when the epoxy resin emulsion was 10% of the activated asphalt, a three-dimensional network was formed. Therefore, it was determined that the optimal ratio of the functional oil/epoxy resin regeneration emulsion was 1:0.83 similar to 1:0.42. Further, through the splitting strength and stability, it was confirmed that when the content of regenerated emulsion was 3.0%, the content of moisture was 4.0% and the content of cement was 1.38%, the cold-regenerated asphalt mixture had superior road performance.

Crushed sand is becoming a main substitute for river sand in the concrete industry. The quality of crushed sand production is crucial for concrete. Fine powder refers to the particles less than 0.075 mm in crushed sand, mainly consisting of rock powder (limestone with CaCO3 as the main component) from the parent rock, and clay powder (yellow clay with Al2(Si2O5)(OH)4 as the main component) from the clay minerals. These particles possess a strong adsorption effect, significantly impacting the performance of high-fluidity concrete. This study addresses the issues of distinguishing and optimizing the content of each component in the fine powder of crushed sand used for preparing high-fluidity concrete. To this end, a method has been established to determine the content of each component based on the methylene blue value (MBV). Furthermore, rational content classifications based on MBV have been proposed through a series of tests on crushed sand mortar, including rheological properties, workability, strength, and scanning electron microscopy (SEM) analysis. Finally, a correlation has been established between the initial yield shear stress and the slump flow of mortar, which can be used to predict the workability of mortar and provide guidance for controlling the fine powder content.

The guar gum/borax-based hydrogel system was employed to rapidly consolidate waste construction slurry to form porous soft solid, which could effectively mitigate the impact of waste construction slurry on the environment. The adsorbability of porous soft solid on methylene blue from cationic dye wastewater was studied to explore new utilization way in the paper. For the methylene blue solution with the pH of 8 and concentration of 30 mg center dot L-1, when the dosage of porous soft solid was 0.15 g center dot mL(-1), the adsorption equilibrium was reached at 32 h, and the removal rate of methylene blue by the porous soft solid was up to 82.96 %. The X-ray diffraction and Fourier Transform Infrared Spectroscopy analysis indicated that both the hydrogel and clay particles in the porous soft solid were involved in the adsorption of methylene blue. The pseudo first-order kinetic equation and the Weber-Morris intraparticle diffusion equation can be used to describe the adsorption process on methylene blue by the porous soft solid.

The cold recycling technology of asphalt pavement has great economic benefits, is friendly to the environment and has a good development prospect. But the reclaimed asphalt pavement (RAP) is used as the "black aggregate," and the aged asphalt has not been fully utilized. Therefore, activating and reusing the aged asphalt in RAP is one of the key problems to be solved. By using artificially aged asphalt instead of naturally aged asphalt, this work reports a new technique for activating asphalt of RAP by functional oil emulsion. The functional oil emulsion was prepared by phase inversion method, and the asphalt regeneration effects were studied in detail. The optimum results showed that the solid content of the functional oil emulsion was 50% and the average particle size was 2.17 mu m. The storage stability of 1 day and 5 days were 2.2% and 4.8% respectively, and the demulsification time at 20 degrees C and 40 degrees C were 2 hours and 1 hour respectively. By studying the penetration, ductility and softening point of recycled asphalt under different dosages of functional oil emulsion, it is found that the parameters of the recycled asphalt recover to more than 94% at 12% content of functional oil emulsion.

Waste construction slurry is a by-product of engineering construction, and the realization of eco-friendly disposal and resource utilization of waste construction slurry is an urgent problem to be solved in the engineering field. In this study, a new method for preparing water and fertilizer retention by chemical cross-linking of the waste slurry was proposed, which can achieve low-energy, rapid disposal of waste slurry in situ and obtain a planting matrix with slow-release and water-retention effects. The detailed study of the microstructure, slow-release performance, and biological toxicity of the slurry soft consolidation product proves that this method can effectively treat and utilize the waste slurry produced in the construction process. The test results show that the three-dimensional networks in soft consolidation product can effectively lock the slurry's water molecules and solid particles and avoid outflow pollution. Meanwhile, the mixed fertilizer can be evenly distributed in the soft consolidation product. Under simulated rainwater, the nutrient release rate in 25 days is 44.47

To alleviate concrete performance deterioration caused by disturbance, it is proposed in this paper that nano cellulose can be used to enhance the anti-disturbance capacity of concrete. Macroscopic strength, mesoscopic pore structure, microstructure, and acoustic emission characteristics were considered simultaneously to analyze the anti-disturbance capacity of nanocellulose concrete, and then to reveal the anti-disturbance mechanism. The research shows that the nanocellulose can induce the growth of C-S-H gel, form a bridge structure between hydration products, and then improve hydration products' compactness, optimize concrete pore structure, and enhance the anti-disturbance performance of concrete. The research also shows that acoustic emission parameters of nanocellulose concrete with disturbance do not show significant changes, which is consistent with pore structure characteristics of the concrete, confirming the excellent anti-disturbance capacity. Moreover, the evolution law of the b-value obtained by the acoustic emission test indicates that the first peak reversal of the b value in time-series can be used to evaluate the concrete sensitivity to disturbance, and the time when the b-value and its first peak appear can characterize the anti-disturbance performance of concrete.

Compared to river sand, crushed sand is characterized with higher irregularity of fine aggregate with size 0.075-4.75 mm and rock powder content with size <0.075 mm, which makes it is difficult to meet application requirements only by its sieving gradation. In the case of meeting the limitations of continuous gradation sand, the packing void fractions n and fineness modulus M of the continuous-graded crushed sand were proposed together to characterize fine aggregate gradation, which should vary with 41.8-45.0 % and 2.9-3.2 respectively to guarantee the prepared mortar with better strength and workability, while the rational rock powder content was 6-9 %. It was also found that there was a significant correlation between the yield shear stress tau 0 of the mortar prepared with continuous-graded crushed sand and its slump flow SF, while the plastic viscosity eta has a significant correlation with the its segregation resistance SR. Finally, the predicting formula of slump flow SF was obtained, which could be used to optimize the sand gradation further, and the plastic viscosity eta should be not less than 17 Pass to ensure good anti-segregation.

The morphology of sand particles strongly influences mortar rheology properties. A characterizing method for the morphology indicator of graded sand particles was proposed by morphology testing and analyzing. Then, taking sand volume fraction as the weight of the morphology indicator of the graded sand particles, the morphology impact factor was put forward to characterize the comprehensive effects of morphology and quantity of graded sand particles on the mortar performance. The effects of morphology impact factor on mortar rheology properties, workability and strength were explored by rotational rheometer, slump flow, anti-segregation and strength testing. The results show that the proposed morphology impact factor is capable of characterizing morphology effects of graded sand particles, well correlated with yield shear stress and slump flow of the mortar, and the slump flow can be predicted in terms of the yield shear stress of the fresh mortar; when the morphology impact factor is between 0.86 and 1.08, the fresh mortar possesses good fluidity and anti-segregation performance. This research, based on rheology, contributes a new way to the mortar and concrete design manner.

为了研究悬索桥实测挠度的温度效应分离,进一步分析悬索桥实测挠度与温度之间的关联性,采用了变分模态分解(variational mode decomposition,VMD)方法对挠度信号进行处理.通过经验模态分解(empirical mode decomposition,EMD)和VMD对仿真信号的对比分析,发现VMD较EMD对噪声有更好的鲁棒性,解决了EMD所存在的模态混叠现象,但仍存在端点效应.提出采用3段交叉信号分解消除VMD分解所存在的端点效应,考虑模态个数、惩罚因子对VMD分解的影响,形成了基于优化VMD的温度效应分离方法.利用优化VMD方法将输入挠度信号分解成一系列具有不同尺度的本征模函数(intrinsic mode function,IMF).根据各个分解模态的中心频率,结合实际温度变化的周期性判定对应的挠度组分,对由温度引起的挠度分量进行组合,研究了悬索桥不同截面挠度与温度的关联性,相关系数均达到0.9以上.结果表明,该方法能有效地分离信号中不同的频率组分,同时还能提取出挠度信号中的趋势项,通过分析各个模态与实测温度的关联性,证明温度效应主要集中在低频段,悬索桥挠度变化主要受温度影响;在模态个数的选择过程中,发现随着模态个数的增大,低频信息的中心频率逐渐趋于稳定,高频信息被分解得更加精细.验证了该方法可用于桥梁长期健康监测的数据分析及桥梁损伤识别.

灌浆法加固技术具有经济实惠、实用性强、安全性高等特征,将其应用到桥梁施工中,有助于,延长桥梁的使用寿命,提升桥梁结构稳定性.因此,应当坚持统一性与针对性的原则,实现灌浆法加固技术的科学运用.

将新拌自密实混凝土(self-compacting concrete,SCC)视作砂浆和粗骨料两相悬浮体系,研究砂浆流变特性以及砂浆膜厚(粗骨料的理论计算裹浆厚度)对SCC性能的影响.设计不同强度等级的SCC配合质量比,采用旋转流变仪优化SCC砂浆中粉煤灰质量分数和砂的体积分数,通过改变SCC中粗骨料体积分数设计不同砂浆膜厚混凝土配合质量比,测试不同砂浆膜厚下新拌混凝土筛出砂浆(新拌自密实混凝土通过5 mm标准筛后自由流出的砂浆)的流变特性、工作性以及其硬化混凝土的抗压强度.结果表明,基于SCC砂浆流变参数进行砂浆组分优化得到的粉煤灰取代质量分数范围为25％ ～35％,砂的体积分数范围为0.40 ～0.42;当砂浆膜厚大于2.1mm后,新拌混凝土的工作性满足SCC要求,筛出砂浆流变参数和硬化混凝土抗压强度趋于稳定,新拌混凝土坍落扩展度与其砂浆屈服剪切应力和密度相关,并给出了预测公式.

将微细钢纤维自密实混凝土(MSFRSCC)视作由满足一定填充能力和抗离析性能要求的基础自密实混凝土(SCC)与微细钢纤维净浆组成.在此基础上提出了采用基础SCC和钢纤维净浆制备MSFRSCC的二次配合比设计方法,并通过坍落扩展度和纤维特征值来确定该方法的适用范围,获得了MSFRSCC基本力学性能随纤维特征值变化的规律.结果表明:基于基础砂浆流变参数制备基础SCC,同时基于净浆平均裹浆厚度确定钢纤维净浆用量来最终制备MSFRSCC的方法,能够满足对MSFRSCC强度和工作性的预期;当纤维特征值不大于70.0％时,二次配合比设计方法能保证MSFRCC的工作性要求,且MSFRSCC的力学性能与纤维特征值线性相关度较高,可以基于基础SCC来预测其力学性能.

Effects of two kinds of microsteel fibers were employed in reinforced concrete (RC) with different fiber volumes fraction. The RC beam was partially reinforced by microsteel fiber reinforced concrete (MSFRC) based on the idea of gradient design. Flexural performances were specially investigated. Results show that microsteel fiber highly strengthened and toughened the concrete matrix. With the same fiber volume content, the concrete reinforced by Type I fiber was generally better in strength compared with that of Type II, while the bending toughness was substantially improved. The bending strength of the concrete reinforced by microsteel fiber in partial section of tensile region was comparable to that in whole section. Based on the traditional strength theory, the critical MSFRC layer depth of in the partially reinforced RC beam was about 0.3 times of the beam depth, which possessed the same crack resistance ability with the beam composed of MSFRC in the whole section. Compared with that of the reference beam, the cracking load of the partially reinforced beam was enhanced by 119%, and the ratio of the cracking moment to ultimate moment improved by 91%. Moreover, the width and height of the cracks in the partially reinforced beam developed much slower than those in the reference beam, and the steady state in which all cracks emerged appeared later; meanwhile, the crack spacing in the pure bending region was smaller, and the number of cracks in the bending-shear region was less, which means that the partially reinforced beam is of excellent properties to resist cracking and bending. Finally, the calculation formula of the bearing capacity of the partially reinforced beam was proposed, which was in good agreement with experimental results.

为提升混凝土与钢筋之间的黏结性能,充分发挥高强钢筋的强度特性,选用直径0.2 mm的镀铜微钢丝钢纤维制备一种纤维体积掺量高达6％,工作性和强度兼备的高体积率微钢丝钢纤维混凝土,研究其与高强钢筋的黏结性能.参考已有的钢筋-混凝土黏结性试验规程相关建议,设计了高强钢筋-混凝土中心拉拔试验,分别研究高强钢筋与高体积率微钢丝钢纤维混凝土和普通混凝土对比组的黏结破坏过程,获得其典型破坏模式、 加载端荷载位移曲线和极限黏结强度,进而得到加载端荷载-位移关系模型,并采用数值模拟方法对试验结果进行验证.试验结果表明,高强钢筋-高体积率微钢丝钢纤维混凝土拉拔试件破坏模式由普通混凝土对比组的混凝土劈拉破坏转变为高强钢筋的受拉屈服破坏,黏结强度较普通混凝土对比组试件提高125.5％以上,充分发挥了高强钢筋的强度特性,黏结性能显著改善,数值分析与试验结果较吻合.

通识教育和专业教育相结合的人才培养制度符合中国高等教育的基本国情.在分析土木工程专业未来发展趋势的基础上,探讨未来土木工程师的人才属性和培养要点,阐述土木工程专业和通识教育的结合方式,介绍重庆交通大学基于“回归工程”教学理念在课程教学改革、学业导师岗位职责、面向实际工程的毕业设计改革和课外实践活动等方面的探索.

An elastic-plastic analysis of the mode III crack surface vicinity was performed in an infinitely wide elastic-perfectly plastic plate, in which a pair of anti-plane forces applied at an arbitrary point on the crack surface. The crack line analysis method was used without the traditional small-scale yield condition. The plastic zone length, the plastic zone shape, and the elastic-plastic stress field in the vicinity of the crack surface were obtained analytically. Moreover, the plastic zone lengths in the vicinity of the crack surface and crack line were compared, and it was found that under a pair of anti-plane forces applied at an arbitrary point on the crack surface, the plastic zone length in the vicinity of the crack surface reached its maximum faster than that in the vicinity of the crack line under the same conditions, which indicates the stress state near the crack surface region is more detrimental than that near the crack line region. The variation of plastic zone length with the load position was also studied, and it was shown that when the point forces were closer to the crack tip, the plastic zone length was smaller and the stress state of the crack was more disadvantageous.