China has witnessed an unprecedented expansion in tunnel and underground engineering over the past decades.However,the persistent occurrence of collapse-related accidents continues to challenge construction safety and emergency management systems.In scenarios where rapid disaster response directly determines survival windows,improving the operational reliability of large-diameter rescue drilling systems becomes critically important.Against this backdrop,this paper investigated the mechanical response of drilling tools and the disturbance behavior of surrounding rock during penetration through complex collapsed masses.Particular emphasis was placed on identifying key factors governing drilling stability and risk evolution under heterogeneous geological conditions.To realistically reproduce the internal structure of soil-rock mixed collapse bodies,a numerical simulation framework was developed.Rock blocks were randomly generated and spatially distributed based on Monte Carlo principles,while irregular three-dimensional block morphologies were constructed to capture geometric randomness and surface roughness.This approach was a more faithful representation of both the spatial distribution and morphological characteristics of discrete blocks within the collapsed mass.A coupled"casing-drill rod"penetration model was subsequently established in Abaqus.Numerical results were validated against field drilling data obtained from the FS120CZ large-diameter rescue drilling rig.Building upon the validated model,a parametric sensitivity analysis was conducted,focusing on drilling speed,collapse body height,and rock block content.The results indicate that drilling speed can serve as the dominant control parameter.When the penetration rate increases from 1.0 to 4.0 m/h,drill rod torque rises by 49.05%,while casing resistance increases by 63.47%.More importantly,load fluctuations intensify in a nonlinear manner with increasing speed.This amplification effect can be attributed to the compounded enhancement of frictional interaction and cutting resistance at the drill-collapse interface under high-speed penetration conditions.In contrast,under shallow burial conditions,the height of the collapsed mass exerts only a limited influence on load magnitude.However,in rock-containing collapse bodies,force-time curves exhibit pronounced"serrated"oscillations,reflecting intermittent block engagement and release.Such instability can significantly increase the likelihood of slippage and sticking incidents.Overall,drilling speed and rock block content emerge as the primary parameters controlling rescue drilling safety.These factors should therefore be prioritized in operational planning and equipment regulation.Considering the strong force fluctuations induced by rock blocks,a pre-treatment strategy involving targeted removal of large blocks along the drilling trajectory is recommended.This measure can effectively reduce peak loads and load variability,thereby enhancing drilling continuity and operational safety.
The complex structure of the bottom of a high-speed train is an important source of train aerodynamic drag. Thus, improving the bottom structure is of great significance to reduce the aerodynamic drag of the train. In this study, computational fluid dynamics (CFD) based on three-dimensional steady incompressible Reynolds-average Naiver-Stokes (RANS) equations and Realizable k-ε turbulence model were utilized for numerical simulations. Inspired by the concept of streamlined design and the idea of bottom flow field control, this study iteratively designed the bogies in a streamlined shape and combined them with the bottom deflectors to investigate the joint drag reduction mechanism. Three models, i.e., single-bogie model, simplified train model, and eight-car high-speed train model, were created and their aerodynamic characteristics were analyzed. The results show that the single-bogie model with streamlined design shows a noticeable drag reduction, whose power bogie and trailer bogie experience 13.92
Employing a combination of field measurements and numerical simulations, this study initially evaluates the impact of simplifying wheel-rail profile wear on the calculation results of vehicle performance indicators. Subsequently, it investigates the influence of time-varying wear of wheel-rail profiles on the vehicle's dynamic response, along with an analysis of change law in wheel wear depth and range under different wheel-rail profiles. The finding indicates that simplifying wheel-rail profile wear notably affect the accuracy of predicting wheel wear, with potential maximum prediction errors of up to 84 % compared to actual conditions. Furthermore, changes in the wheel-rail profile resulting from wear significantly impact the vehicle's straight-line running performance and curve negotiation performance, particularly in the early and later stages of wheel-rail wear. Moreover, profiles in the mid-term wear stage significantly exacerbates wheel wear depth, demonstrating a maximum increase 4.33 times higher than that of the standard profile.
The traditional methods for testing the sleeve grouting fullness of prefabricated structures generally face the technical challenges such as high detection cost and inability to detect in real-time. In order to solve these technical challenges, the detection method and instrument based on the piezoelectric testing principle were developed. Through the electrical properties tests of grouting materials and grouting-leakage cycle tests of transparent sleeves, the effectiveness of the piezoelectric method for testing grout leakage defects was analyzed. The research results indicate that measuring the voltage changes before and after the piezoelectric sensor is wrapped in the grouting slurry can effectively evaluate the sleeve grouting fullness. The voltage measured by the piezoelectric sensor is significantly reduced after the sensor is wrapped in the grouting material (full grouting). Then the voltage increases after grouting leakage (insufficient grouting), and decreases again after supplementary grouting (full grouting). Moreover, whether the piezoelectric sensor is placed horizontally or vertically, the voltage shows obvious changes, indicating that the piezoelectric method is less affected by the sensor laying mode. Considering that the vertical embedding method is more stable for piezoelectric data, it is recommended to use the vertical laying mode in engineering projects. Furthermore, through the prefabricated model tests, the threshold for judging grouting fullness using piezoelectric method was determined. The test results show that the threshold for determining the grouting fullness using piezoelectric method can be set to 0.40. That is to say, when the voltage value is less than 0.40, it can be determined as complete grouting, otherwise it can be determined as insufficient grouting. The case studies results indicate that the piezoelectric method meets the quality control requirements during the grouting process of prefabricated structural sleeves. The research results provide a new approach and practical reference for solving the quality detection problem of sleeve grouting.
Adequate station classification is of great importance for the study of passenger flow characteristics and the development of land around stations. To address the problem that it is difficult to accurately classify new stations before the opening of new lines due to unknown passenger flow data, this paper proposes a classification method for new line stations based on the mapping relationship between the built environment and subway passenger flow. First, we cluster existing stations and calculate the passenger flow characteristic intervals of each category of stations. Random forests are used to screen important built environment factors that affect the classification of categories. Second, based on the above characteristics of passenger flow and built environment, the mapping relationship between them is determined by logarithmic transformation fitting. Finally, we calculate the unknown passenger flow characteristics of new line stations according to the mapping relationship and built environment characteristics, and then realize the classification of new line stations. An example of the Beijing subway system is taken to verify the effectiveness of the method. The results show that the method can realize the early classification of station types before the opening of new lines, and has good classification effect and applicability.
This study aims to explore the impact mechanism of the vibratory compaction deterioration in high-speed railway graded gravel (HRGG) fillers, which can contribute to the control compaction quality and enhance the service performance of subgrade. Firstly, vibratory compaction experiments were conducted with HRGG fillers using the intelligent vibratory compactor to reveal the vibratory compaction deterioration from the evolution of the dry density rho d, dynamic stiffness Krd. Secondly, X-ray computed tomography (X-CT) scan tests were conducted with the fillers of different compaction stages. Then, the evolution of coarse particle shape characteristics was obtained to reveal the key controlling factor of compaction deterioration. Finally, the high-precision 3D vibratory compaction discrete element method (DEM) models were established for different deterioration degrees. The micro-indicators, such as the coordination number, contact force chains, and fabric anisotropy were investigated to explore the inherent relationship between the compaction deterioration and the key controlling factor. The results showed that the Krd gradually decreased at the compaction deterioration. Additionally, it was found that the key controlling factor for compaction deterioration was the abrasion of coarse particles. From the DEM simulations with different compaction deterioration degrees (CDDS), the dynamic stiffness Krd decreased with increasing CDDS, which was consistent with the results of the vibratory compaction experiments. Moreover, it was observed that the micro-indicators exhibited a decreasing trend with increasing CDDS, indicating a decrease in the ability of coarse particles to wrap fine particles and particles interlocking, which disrupts the ability of the particle skeleton to withstand external loads. This study not only provides a novel approach to investigate the deterioration mechanism during vibratory compaction but also establishes a new theoretical basis for the controlling compaction quality of HRGG fillers.
When a train passes over a bridge, the vibrations of the vehicles and the bridge are the result of non-stationary stochastic processes due to the time-dependent characteristics of the coupled vehicle-bridge system. The aim of this study is to generalize the frequency domain method to investigate the non-stationary random vibration of the coupled system subjected to the excitation of track irregularities with consideration of time-dependent characteristics. To illustrate the method, a three-span simply supported bridge traversed by a single railway vehicle is adopted as an example. The time-dependent frequency response function (FRF) of the coupled system is theoretically derived through solving ordinary differential equations with variable complex coefficients, and the perturbation method is adopted to improve the calculation efficiency. By combining this with Priestley's Evolutionary Spectra theory, the evolutionary power spectral density (PSD) of the non-stationary random response of the system is then derived. The transitions will occur when the wheels cross the joints between each bridge span and between the bridge and the adjacent roadway. By adopting mode shapes of the full structure, the change of states of the vehicle crossing multiple bridge spans and moving onto the roadway can be solved as a continuous process without separation. The proposed method is validated by comparisons with the Monte Carlo method, showing higher accuracy and efficiency when calculating the time-varying standard deviation of the response. It is found that the vibration of the vehicle is approximately stationary but with large variance due to the random track irregularities, while the bridge vibration follows a strongly non-stationary process with small randomness and is more related to the moving mass effect.
The rationally layout of connecting line is of significance for improving network efficiency and network planning. Under the background of advocating "network integration" and resource sharing, An urban rail transit connecting line planning model considering maintenance resource sharing is proposed, which minimizes the total construction cost of connecting lines and the total transfer time of trains require maintenance. A hybrid algorithm combining CPLEX and NSGA-II is applied to solving the model. The results of case study show that compared with the existing method, the proposed model achieves better effect in maintenance resource sharing based on realizing connection of all lines. Besides, key parameters of the model are discussed. The obtained results provide a consult for the layout determination of connecting lines and urban rail transit heavy repair sharing depots.
为提高高海拔地区铁路施工人员安全行为水平,探讨心理弹性对安全行为的影响机理.基于社会认知理论和人—环境交互作用理论,引入安全自我效能和高海拔环境风险感知作为心理弹性和安全行为间关系的中介变量和调节变量,构建心理弹性和安全行为关系的假设模型.首先,采用一种分阶段收集数据的方法,使用有关心理弹性和安全行为的成熟量表,以甘肃、青海和西藏在建的高海拔铁路施工区域8个项目部的一线施工人员为研究对象进行问卷调查.其次,在验证性因子分析和相关性分析的基础上运用AMOS 24.0建立结构方程模型验证假设并计算路径系数.最后,构建安全行为的因果关系图和流图,将路径系数和常量作为系统动力学(SD)模拟仿真参数,在安全自我效能和高海拔环境风险感知的干预下,运用Vensim模拟心理弹性和安全行为的变化过程.研究结果表明,心理弹性显著正向影响安全行为(安全遵守和安全参与);安全自我效能在心理弹性和安全行为(安全遵守和安全参与)影响关系中起中介作用;高海拔环境风险感知显著调节心理弹性对安全行为(安全遵守和安全参与)的影响.仿真结果表明,在安全自我效能和高海拔环境风险感知的干预作用下,心理弹性和安全行为呈现为先下降再上升的抛物线.研究成果丰富了心理学在工程实践中的应用,为安全行为研究提供了新思路,对提高企业安全管理水平提供了切实可行的建议.
为了探究实时、准确的路基不均匀沉降识别方法,以CRTSⅠ双块式无砟轨道路基沉降病害为研究对象,建立车辆-轨道-路基垂向耦合动力学模型,讨论不同路基沉降状态下的车辆-轨道系统振动规律,选取路基沉降识别敏感特征,并基于粒子群优化支持向量机算法实现对无砟轨道路基沉降病害的有效识别.研究结果表明:钢轨及道床的垂向位移对路基沉降变化较为敏感,随沉降幅值的增大而增大,随沉降波长的增大而减小,而路基沉降对钢轨及道床垂向振动加速度影响较小,利用轨道结构振动响应判断路基沉降状态可行性较低.车体、转向架及轮对垂向振动加速度随着路基沉降幅值增大而增大,其中车体、转向架对路基沉降幅值变化相对敏感,而轮对相对不敏感.随着沉降波长增加,车体与转向架垂向振动加速度先增大后减小,车体对沉降波长的敏感程度远高于转向架,故可将车体垂向振动加速度作为识别敏感特征.车体垂向加速度振动信号对无砟轨道路基沉降波长的识别准确率高于对沉降幅值的识别准确率,其中沉降幅值为20 mm时的识别准确率为84.78％,表明算法在该工况下的识别性能相对较低,但仍能保证一定的准确率,而对于无沉降和不同沉降波长工况,算法识别准确率接近100％.研究成果证明了粒子群优化支持向量机算法可实现对无砟轨道路基沉降的有效识别.
节段有效连接是保证预制装配桥墩正常使用的关键.锥套锁紧连接是一种新型钢筋连接形式,操作简便,连接高效,但尚无应用于预制装配桥墩的详细研究资料.以某拟建轨道交通高架桥梁预制装配桥墩为工程背景,考虑现浇连接(CIP),锥套锁紧连接(TS)和套筒灌浆连接(GS)3种方式,设计制作了3个1︰3的桥墩缩尺试验模型,完成了拟静力试验和数值仿真分析,对比了不同连接方式桥墩的破坏形式、承载能力、刚度退化和自恢复能力.研究结果表明:锥套锁紧连接应用于预制装配桥墩,其等同现浇程度显著优于套筒灌浆连接.3种连接方式的试件最终破坏形态均为典型弯曲破坏,表现为墩身与承台接缝处的裂缝贯通以及柱角区域混凝土压溃,但现浇连接和锥套锁紧连接试件的裂缝沿墩身基本呈环向均匀分布,套筒灌浆连接试件的裂缝较为集中于套筒连接区段接缝处.锥套锁紧连接试件承载能力、塑性转动能力基本等同现浇,残余位移和自恢复能力次之,耗能能力最差;套筒灌浆连接试件的承载能力和耗能能力较前二者都高,其中承载能力较锥套锁紧连接提升了34.3％,但延性系数降低了23.8％.相比于增大恒载轴压比,增大墩身纵筋配筋率可有效提升锥套锁紧连接试件耗能能力和承载能力,同时较小程度损失试件的延性和自恢复能力.研究成果为锥套锁紧连接预制装配桥墩的设计和应用提供了详细技术参考.
软土区大面积堆载极易引发桥梁桩基时效性横向变形,但其变形机理及预防措施目前仍缺乏深入研究.依托典型堆载致桥墩偏移工程案例,开展固结-蠕变试验阐明软土时效性变形特征,比选最佳描述模型.将一维KOPPEJAN模型扩展至三维形式,基于ABAQUS平台开发对应用户材料子程序,并将其应用至有限元模型中.基于已验证的有限元模型,研究桩基响应及桩侧横向附加荷载时效性变化规律,进一步考察微型隔离桩和应力释放孔对桩基偏移的主动防控效果,据此提出适用工程建议.研究结果表明:相比MESRI模型和TIME-HARDENING模型,一维KOPPEJAN模型更适合描述该场地软土时效性变形特征,改进的扩展KOPPEJAN模型可以较好地还原该工程桩基桥墩的时效性偏移过程;随着堆载时间的延长,软土侧向变形持续增大,桩侧横向附加荷载持续增加至趋于稳定,但其沿深度的分布基本不变,主要分布在软弱土层内(4.0～32.0 m);深厚软土条件下,尽管微型隔离桩能够改善该桥梁桩基的受力行为,但很难将该承台偏移量控制在8.0 mm以内;采用孔深与软土厚度相同的应力释放孔可以减小承台偏移量60％以上,达到较好防治效果,但应注意应力释放和桩顶荷载联合作用引发的反向扰曲变形,建议钻孔施工完成后及时进行回填处理.研究成果可为主动防控堆载引发的墩台偏移等病害提供理论指导.
城市轨道交通列车发生故障无法运行时需安排其他列车进行救援,制定合理的救援和运行调整方案对维持线路的服务水平具有重要意义.为应对救援过程造成停车线的长时间占用、运用车底数量减少和后序列车延误等问题,考虑采取小交路折返、车次取消和使用备车等运行调整措施并适时恢复救援列车的正常运营.以与原时刻表的偏差和列车取消停靠的车站数量最小为目标构建运行图调整的混合整数线性优化模型,采用滚动优化算法兼顾求解质量和效率.研究结果表明:详细刻画救援过程有助于提升列车救援场景下的运行图调整效果,救援列车重新投入运营能及时补充在线运营车底数量,减少加开备车数量和列车取消停靠车站的数量,目标函数优化6.8％以上.小交路折返措施有助于维持车底周转效率,避免延误列车提前下线退出运营,各断面总运力提高4.4％以上.综合优化方案的实际开行列次数量接近计划开行列次,线路的服务水平得到维持.当列车在线路中段发生故障时,后序列车正向救援方案中故障区段两侧列车调整策略选择更加灵活;当列车在靠近线路一端发生故障时,后序列车反向救援方案对非故障区段列车的正常运行影响较小.研究成果可为列车故障救援场景下救援方式和运行图调整方案的选择提供决策依据.
高速列车在行驶过程中,其滚动轴承的工况往往会发生变化,如转向架的轴箱轴承转速变化等,在此情况下,传统的基于非平稳信号分析的滚动轴承故障诊断技术很难对故障进行有效检测.为了在变化的工况下实现故障类型的自适应识别,基于深度迁移学习的滚动轴承智能故障诊断技术逐渐被应用于轴承故障诊断领域中.然而,深度迁移学习智能故障诊断技术在工程应用中仍存在模型复杂度高的问题.此外,传统领域适配方法在进行迁移诊断时主要进行整体领域差异的对齐,忽略了不同域下同一故障状态的子域特征分布,导致模型的泛化能力差.同时,领域适配在滚动轴承智能故障诊断中的应用主要集中在单源领域,当源领域和目标领域数据分布差异过大时,单个源领域学习到的数据特征有限,可能无法达到较高的可迁移性.为改善上述问题,提出一种稀疏性多源完全领域适配迁移诊断方法,为验证所提算法的有效性,采用不同的故障数据建立不同的故障诊断场景并进行分析.结果表明,该方法中提出的周期循环稀疏设计模式使得卷积层和全连接层的权重矩阵包含大量规则排列的零权重参数,能够有效降低模型的复杂度.同时,该方法在进行数据特征的迁移时,考虑了全局和局部差异的对齐,能够一定程度改善模型的泛化能力.此外,通过不同数目源领域的试验验证分析,表明多源领域适配方法具有较好的迁移诊断效果,对于迁移诊断技术的实际应用具有一定的指导意义.
地面突发堆载诱发运营期内地铁隧道病害的案例屡见不鲜,广州地区地铁隧道建设中常遇洞身上部为软土、砂层,下部为硬岩的土岩复合地层.目前对于局部超载作用下,土岩复合地层中盾构隧道变形与破坏特征并不明确,现行加固标准对于该种特殊地层的适用性也亟待验证.通过1︰5的土箱模型试验,探究不同硬岩比的土岩复合地层中隧道在正上方局部超载作用下的变形规律和破坏模式.试验结果表明:地层硬岩比对局部超载下盾构隧道的位移发展及其分布影响显著,结构的临界失稳荷载等级随着硬岩比增大而提高,结构破坏椭圆度随之减小,硬岩比的增大加强了结构外部围岩的约束作用,显著地控制了隧道椭变,但约束的加强也使结构呈现脆性性状,位移发展速率出现明显突变点;硬岩限制了其范围内管片的内力发展,且土岩交界面上部邻域管片产生应力集中现象,结构首先在此区域发生破坏,且常以贯穿式裂缝形式发展,随着硬岩比增大,结构呈崩角、劈裂等脆性破坏形式;隧道拱顶附加土压力会随结构失稳进入下降阶段,且随着硬岩比增大,软土压缩对地表超载的分散效应减弱,进而导致隧道拱顶附加土压力对地表超载更加敏感;将试验数据与现行加固标准对比分析,发现现行加固标准不适用于高硬岩比土岩复合地层中盾构隧道.研究成果可为加固标准结合地层因素优化提供理论支撑.
装配式建筑作为建筑工业化和信息化深度融合的产物,近年来发展势头迅猛.为满足日益增长的装配式混凝土(PC)构件的市场需求,需要科学布局PC构件厂使其形成规模化效应,为此提出一种PC构件厂的选址优化方法.首先,基于市场供求理论,通过灰色预测模型和二次指数平滑法构建PC构件需求量综合预测模型,以江西省为例,对未来6 a构件需求量进行预测,避免造成PC构件产能过剩,预测结果显示江西省未来3 a内对PC构件的需求量将会急剧上升,亟需增设新的PC构件厂.其次,调研现阶段PC构件厂布局等情况,并利用Python获取城市建设用地、交通网络、水网、学校、医院、旅游景点、政府机关、高密度居民区等地理信息数据,在PC构件厂选址原则的约束下,通过地理信息系统(GIS)平台对所获取的空间信息数据等进行叠置分析和擦除分析,得到初步选址点.最后,建立最优运输成本模型,基于模型假设和约束条件进行求解,确定PC构件厂的选址位置.结果表明:采用选址优化模型,能够将624个初步选址点优化为80个最佳选址点,验证了选址优化模型的有效性,形成了PC构件厂的优化布局方案.研究结果可为PC构件厂选址提供一定的参考,有助于装配式建筑产业的进一步发展.
高速磁浮作为一种高速度、高舒适性的便捷公共交通方式已成为公共交通的重要组成部分.目前高速磁浮方式整体上处于技术研发为主,商业运营仍处于起步阶段,特别是针对车站能力的研究较为缺乏.基于高速磁浮列车的运输组织要求,对高速磁浮车站的列车作业优化和能力利用问题进行研究.通过将高速磁浮车站到发线与径路一体化考虑,从车站径路运用和车站径路分段解锁的层面着手,在时间-空间双重约束下建立给定时刻表下高速磁浮车站作业安排优化模型.根据问题特性,将遗传算法的全局搜索性能和模拟退火算法的局部搜索性能相结合,设计遗传模拟退火算法.通过高速磁浮车站算例得出总延误为0的车站作业安排优化方案,并对车站能力利用状况进行分析.设计基于列车作业紧凑安排的车站能力启发式算法,通过压缩给定时刻表下车站接发车作业的间隔时间,计算特定的车流构成类型和比例下的高速磁浮车站通过能力.对比分析不同运行图场景下的高速磁浮车站通过能力,探索其一般规律.分析得出不停站通过列车、始发终到列车、停站通过列车、立折列车对车站通过能力利用效率依次降低的规律.该研究从列车车站列车作业组织角度丰富了高速磁浮技术,可为高速磁浮车站的作业安排和能力利用提供借鉴.
转向架构架是高速动车组的重要承载部件,对其关键结构精确分析及优化能保障列车安全平稳运行.为提高转向架构架设计优化的精度和效率,提出一种子模型技术与径向基函数-改进快速非支配排序遗传算法(RBF-CLNSGA-Ⅱ)相结合的多目标优化方法.首先,通过分析转向架构架的结构强度,确定等效应力最大的位置,利用子模型技术对该区域构建子模型并进行相对灵敏度分析,然后构建其RBF神经网络,提高计算和拟合效率.其次,提出CLNSGA-Ⅱ算法,通过引入Circle混沌映射、自适应交叉变异概率、Levy飞行策略及动态更新拥挤度比较算子,提高NSGA-Ⅱ算法Pareto解集分布的均匀性和稳定性,同时增强全局搜索以及局部开发能力.最后,构建以结构相关参数为设计变量、最大等效应力和质量最小为目标、变量区间及材料屈服极限为约束的多目标优化模型,利用CLNSGA-Ⅱ算法对基于子模型技术的RBF神经网络进行多目标优化,得到Pareto最优解.研究结果表明:子模型技术和RBF-CLNSGA-Ⅱ算法相结合,不仅能够解决大型复杂结构拟合困难、运算周期长的问题,而且研究过程相比传统方法,针对性更强,求解精度更高,结果稳定性更好.优化后的构架子模型最大等效应力降低了4.603％,质量减少了2.922％,该方法对大型复杂部件的设计优化具有重要工程实用价值.
将自密实混凝土(SCC)与普通混凝土(OC)组合应用于连续梁桥0号块,可以解决底腹板混凝土振捣困难问题,还可以节约施工成本.为探究SCC与OC分层浇筑时2种混凝土界面的黏结力学性能及耐久服役性能,厘清SCC与OC组合应用于连续梁桥0号块的可行性.确定了力学性能与收缩性能相近的SCC的配合比,在此基础上,研究了界面含水率对SCC-OC分层浇筑试件的界面劈裂拉伸强度、直接剪切强度及氯离子渗透性的影响,模拟了冷热循环、干湿循环和冻融循环3种服役环境对界面黏结力学性能的影响.结合MIP及SEM多手段分析SCC-OC黏结界面处的孔隙结构特征及界面微观形貌,揭示了界面含水率对SCC-OC组合构件黏结力学及耐久性能的影响机理.结果表明:SCC与OC分层浇筑时需要确保界面含水率不能过低,界面含水率的降低会引起SCC-OC组合试件的孔隙率提高、微裂缝增大,导致黏结力学性能与抗氯离子渗透能力的降低.且界面含水率越低,SCC-OC组合试件在不同的环境下服役后产生的损伤越大.不同的服役环境对SCC-OC黏结界面的损伤程度不同,冻融循环对SCC-OC试样的黏结最不利,冷热循环引起的损伤最小.SCC中掺加减缩剂可以减少SCC内部水分的蒸发,对SCC-OC的黏结耐久性能具有一定的益处.
