地铁盾构隧道衬砌结构变形及破坏探讨

盾构隧道衬砌结构的变形与破坏模式受接头的力学性能控制,但目前国内地铁盾构隧道接头形式多样,不同形式的接头对整环结构受力性能的影响机理还不清晰。基于足尺试验,分别研究单环、多环的国内典型地铁直螺栓接头衬砌结构、弯螺栓接头衬砌结构、快速接头衬砌结构的受力性能,对比分析其正常运营状态的变形、周边扰动下的破坏模式与极限承载力。结果表明：①通缝拼装盾构隧道衬砌结构的性能由纵缝接头性能决定,提高纵缝接头延性可使结构破坏模式从接头处连接件脆性断裂转变为结构整体失稳;②错缝结构性能取决于环间相互作用强弱,随着环间相互作用的增强,结构首个塑性铰位置从纵缝接头向管片本体转移;③可通过环间、环内的协调设计,优化结构正常运营状态基本受力性能,提高结构极限承载力并使结构发生延性破坏。     

Experimental investigation of the ultimate bearing capacity of deformed segmental tunnel linings strengthened by epoxy-bonded steel plates

In order to develop an effective method to increase the load-bearing capacity of deformed segmental tunnel linings, full-scale tests concerning the ultimate bearing capacity of the linings, strengthened by steel plates, were conducted. The design of the tested linings and the loading scheme are described in this paper. In addition to the bearing capacity, the failure mechanisms of the tested linings were investigated. It was found that bonding of steel plates to the deformed segmental tunnel linings is an effective and practical method for strengthening segmental tunnel linings, thereby enhancing both their ultimate bearing capacity and their overall stiffness. The behaviour of these structures under loading is similar, no matter whether they are strengthened by full-ring or so-called semi-ring steel plates. The failure of the strengthened linings is the consequence of local failure of the bond between the steel plates and the tunnel segment. Therefore, the success of the proposed strengthening method strongly depends on the bonding capacity.     

砂土层中盾构隧道局部破坏引发连续破坏的机理研究

盾构隧道由混凝土管片拼接而成,接缝部位薄弱,在建设和运营过程中存在大量风险。国内外发生过多起因隧道管片局部损坏演变为隧道大范围破损甚至连续坍塌并导致地表沉陷等灾害。通过对隧道管片接头的受力分析,建立了接头的极限承载力M-N包络图,作为管片接头的破坏准则。以隧道联络通道施工时,隧道腰部设置洞门作为隧道局部破坏的背景,利用离散元软件PFC,通过FISH语言二次开发研究了隧道腰部管片局部破坏引发的隧道连续破坏机理。研究表明,隧道腰部局部破坏引起土体进入隧道内从而引起隧道腰部外土体松动,并且松动区外围产生的土拱的拱脚支承于隧道顶部区域,这都导致隧道内力急剧增大,直至超过管片及接头的极限承载力,隧道局部破坏发生扩展。由于隧道环间螺栓的作用,破坏环过大的变形引起邻近环横向变形增大,进而引发邻近环的破坏,破坏沿纵向传递,隧道发生大范围连续破坏。最后,初步提出并对比分析了多种隧道防连续破坏措施。     

Experimental investigation of the ultimate bearing capacity of deformed segmental tunnel linings strengthened by epoxy-bonded filament wound profiles

A new strengthening method employing epoxy-bonded filament wound profiles (FWPs) has been applied to shield tunnels subject to large deformation. Full-scale tests were conducted on the ultimate bearing capacity of linings strengthened by the new method. With consideration for secondary loading, the strengthening measures were applied when the lining deformation reached 120 mm (0.02D). The failure phenomena are described, and the main loading process results were obtained, including load-displacement curves, cracking, and joint openings. The failure mechanisms, the key performance points, and bearing capacities of the tested strengthened linings are discussed and analysed. In addition, a comparison was made between two FWP strengthening methods as well as with epoxy-bonded steel plate strengthening methods. The results show that the epoxy-bonded FWP method is effective and practical for strengthening segmental tunnel linings, which can improve both the ultimate bearing capacity and overall stiffness of the structures. The failure of the strengthened linings is primarily caused by bond failure between the FWPs and the concrete lining segments, indicating that the bonding capacity of the adhesive is of great importance when utilising the proposed strengthening method.     

地铁盾构隧道纵向接缝承载能力试验研究与解析分析

当前地铁运营实践和研究表明管片接缝是盾构隧道衬砌结构的薄弱环节,接缝的受力性能直接决定了隧道结构的承载能力。依托于整环试验研究结论,以盾构隧道管片纵缝接缝为研究对象,对不同运营工况下管片接缝的承载性能进行了足尺试验研究,获得不同工况下构件挠度、接缝转角等变化规律,得到转角刚度。分析得到了纵缝接缝的破坏链条,推导了可模拟接缝受力全过程的解析模型分析了纵缝接缝的全过程受力性能及其极限承载力。并借此模型对接缝截面与全截面受力变形进行对比分析,通过试验数据与解析模型数据的对比分析验证解析模型的合理性。     

Mechanism for buckling of shield tunnel linings under hydrostatic pressure

In this paper, the effects of segmental joints, dimensions of segments, and ground conditions on buckling of the shield tunnel linings under hydrostatic pressure are studied by analytical and numerical analysis. The results show that radial joints have significant impacts on the buckling behavior: the shield tunnel linings with flexible joints buckles in a single wave mode in the vicinity of K joint, while those with rigid joints buckles in a multi-wave mode around the linings. Hydrostatic buckling strength is found to increase with the flexural rigidity of the radial joint and the thickness of segment increasing. This study shows that ground support increases the buckling strength dramatically, while earth pressure reduces the capacity to resist hydrostatic buckling. The tunnel linings during construction are found to be easier to buckle than that during operation. Meanwhile, the buckling of tunnel linings is studied by theoretical analysis of buried tube buckling.     

连接螺栓对类矩形盾构隧道结构极限承载力影响的试验研究与分析

针对类矩形盾构隧道衬砌结构纵向接缝处弯矩正负性确定的特点,对纵向接缝连接螺栓位置进行了优化。基于结构整环足尺试验结果,对比分析了优化前后衬砌结构整体变形、接缝变形和螺栓应变的发展,研究了优化前后结构设计阶段受力性能、破坏机制、极限承载力和鲁棒性的异同。研究结果表明：①螺栓位置优化对结构设计阶段受力性能影响较小;②优化后结构在带缝工作阶段的受力性能明显提升,结构整体刚度提高,极限承载力提高30%;③优化后结构破坏呈延性破坏特征,属于塑性铰机制,结构结构整体安全性得到提高。     

装配式混凝土梁柱节点抗震性能试验与数值模拟

为研究不同螺栓强度等级对新型装配式半刚性混凝土梁柱节点抗震性能的影响,分别对螺栓等级为5.6级和8.8级的梁柱节点进行了足尺试验,分析了节点的滞回曲线、骨架曲线、割线刚度、等效黏滞阻尼系数等抗震性能指标,并基于ABAQUS有限元软件对现浇节点和5.6级螺栓连接的试验节点进行了数值模拟。结果表明:基于5.6级和8.8级螺栓连接的半刚性梁柱节点均具有良好的抗震性能和耗能能力,2组梁柱节点构件的刚度均随着位移等级的增加而逐渐降低,与5.6级螺栓连接的节点相比,8.8级螺栓连接的节点刚度退化速率较快,且正向加载下5.6级螺栓连接节点的极限承载力为8.8级螺栓连接节点的85.42%,负向加载下5.6级螺栓连接节点的极限承载力为8.8级螺栓连接节点的83.68%; 有限元模拟结果具有较高的准确性,能够很好地反映节点构件的抗震性能; 与现浇节点对比发现,现浇节点在耗能能力方面比试验节点好,但试验节点的极限承载力要优于现浇节点; 所得结论可为装配式半刚性梁柱结构的抗震设计提供依据,为新型装配式梁柱节点构件的发展及应用提供参考。     

Failure mechanism of tunnel lining joints and bolts with uneven longitudinal ground settlement

To simulate the failure mechanism of tunnel segmental lining joints and longitudinal bolts under uneven longitudinal ground settlement, a numerical model with 3D lining rings and bolts was established. The loads were divided into two parts: the soil pressure around the tunnel just after construction and a displacement loading according to field measurements of uneven longitudinal ground settlement. The interactions between the lining tenons, bolts and their holes, were determined. The results indicated that the deformation of the circumferential joints consisted of opening and dislocation, but the dislocation was dominant. The progressive failure of bolts and waterproofing measures were also revealed. The evaluation of structural integrity of circumferential joint and the mitigate measures were proposed in order to ensure the operational safety of a metro tunnel.     

外伸式端板连接蜂窝钢梁-混凝土柱组合节点抗震性能试验研究

通过7个1∶2比例外伸式端板连接蜂窝钢梁-混凝土柱组合节点的低周反复加载试验,研究不同螺栓数目、直径及排列方式的外伸式端板连接蜂窝钢梁-混凝土柱组合节点在各受力阶段的抗震性能和合理的节点构造形式。基于试验数据,分析了节点在反复荷载作用下的破坏形态、滞回曲线、骨架曲线、刚度退化、延性和耗能性能等。试验结果表明：试件的破坏形态和变形与螺栓数目、直径及排列方式有关,外伸端板螺栓连接中螺栓数目多、直径大的节点连接形式的承载力高,抗震性能较好;8个端板螺栓4行2列的排列形式为最合理的抗震节点形式;外伸端板螺栓数量为8个时的延性和耗能性能都能满足抗震的要求。     

盾构隧道管片接头抗弯承载力计算模型研究

盾构隧道管片接头承载力的计算是管片设计和服役性能评估的重要部分和关键部分,针对形式相同而细部构造不同的管片接头,提出一套适用于其抗弯承载力计算的理论方法十分重要。鉴于此,文章基于接缝面的不连续特征将接缝面进行适当分区,建立盾构隧道管片接头抗弯承载力计算模型,并给出对应的求解算法。将理论模型的计算结果与接头足尺试验结果进行对比分析,验证理论模型的正确性,然后采用该计算模型对管片接头抗弯承载力进行分析与讨论。结果表明：管片接头抗弯承载力曲线具有明显的非线性特征,随着轴力的增大,接头极限弯矩呈先增大后减小的趋势。混凝土强度对于接头抗弯承载力的影响较为显著,而螺栓强度和螺栓直径对于接头抗弯承载力的影响程度受轴力控制,轴力较小时,上述两参数的增大对于接头抗弯承载力的提升效果明显,轴力较大时效果逐渐减弱,当轴力高于某一阈值后,螺栓对于接头抗弯承载力无影响。文章所提出的抗弯承载力计算模型与研究结果以期为盾构隧道结构设计、试验和性能评估提供重要参考。     

铝合金板式节点平面外受弯滞回性能试验研究

为研究节点板厚度、节点板材质、是否设置抗剪键以及加载模式对铝合金板式节点滞回性能的影响,完成了4组共计8个试件平面外受弯的拟静力试验,对其变形特征、破坏模式、承载能力、延性以及耗能能力等进行了分析。结果表明：板式节点在平面外往复弯矩作用下的受力过程可以分为5个阶段,即弹性阶段、螺栓滑移阶段、孔壁承压阶段、承载力退化阶段和破坏阶段;通过破坏后试件的形态特征可归纳出节点的两种破坏模式分别为杆件破坏和节点板块状拉剪破坏,且破坏模式与节点板厚度和杆件翼缘厚度密切相关;由于螺栓滑移的影响,节点的滞回曲线不够饱满;综合对比试件的骨架曲线、位移延性系数和能量耗散系数,节点板较厚的铝合金板式节点具有更好的承载能力、变形能力和耗能能力。     

碳纤维复合材料板与钢板胶-螺混合双搭接接头拉伸性能试验研究

对双层搭接的碳纤维复合材料板与钢板胶-螺混合连接在单调受拉伸荷载下的拉伸性能展开试验研究;考察其极限承载力、应变分布以及破坏模式;并与螺栓连接、纯胶连接方式比较;同时还考虑制作工艺对混合连接的影响。结果表明,混合连接承载力稳定。两种工艺制作的固定尺寸的混合节点中,先胶结再钻孔的节点在一定数量范围内增加螺栓数会使承载力上升,但过多使用螺栓承载力反而下降;先钻孔再涂胶的节点螺栓和胶层协同工作性能好,但制作工艺要求更高。     

Numerical investigation into the composite behaviour of over-deformed segmental tunnel linings strengthened by bonding steel plates

Bonding steel plate has been used as a strengthening approach to repair disrupted segmental lining of operational tunnels. This paper introduces numerical investigation into the composite behaviour of the initially deformed segmental tunnel linings strengthened by bonding steel plates using finite element modelling. Cohesive zone modelling was used to simulate the interface bonding behaviour between the segmental linings and steel plates. The full history of the tunnel behaviour before and after strengthening were simulated, where the segmental tunnel lining is initially loaded to create some deformation, then after bonding steel plate, the strengthened tunnel is reloaded until failure occurs. By comparing the results with experimental data from the literature, the proposed model was proved to be capable of simulating the strengthened lining behaviour and able to capture the strengthening failure process in terms of the interface debonding. Subsequently, the segmental lining response and interface shear stress distribution and propagation were analysed to interpret the interaction and failure mechanism of the steel plate strengthened segmental linings. The influence of the initial deformation and the steel plate thickness were investigated and discussed in terms of the strengthened stiffness and capacity. It has been found that the interface shear stress concentration occurred at the positions of the segment joints, where bond damage first initiated. The ultimate failure of the steel plate strengthening happened suddenly once a local debonding zone close to the segmental joint was formed. In addition, the predicted results indicate that a delay in strengthening would result in an increase in strengthened capacity but a decrease in strengthened stiffness. By using thicker steel plates, the strengthened stiffness was improved, while the strengthened capacity could be improved only if the thickness was relatively thin.     

T形柱框架节点延性及承载力的试验研究

对10根T形柱节点进行了低周反复荷载作用下的试验研究,着重分析了T形柱节点的承载能力和破坏特点,梁、柱主筋和核心区箍筋应力变化;实测梁端的荷载-位移滞回曲线,研究轴压比、配箍率对节点核心区受剪承载力和延性性能的影响。并把试验结果与混凝土规范中矩形柱节点计算公式进行了比较。     

高强钢芯筒-螺栓连接钢管柱框架节点抗震性能试验研究

为解决现有单边螺栓容易拔出、钢管柱壁板撕裂等锚固不足问题,提出高强钢板-螺栓组合连接副,用于钢管柱框架节点。为研究该类节点的抗震性能和破坏模式,设计4个足尺比例的高强钢芯筒-螺栓连接钢管柱框架节点试件,变化参数为螺栓规格和钢梁端板厚度,分别进行单调加载静力试验和循环加载拟静力试验,考察节点破坏模式、转动能力、连接系数、耗能能力及螺栓拉力。研究表明:M20-20、M24-25两种钢板螺栓组合连接节点可达到抗震规范的节点承载力连接系数限值要求,为半刚性节点;单调和循环两种加载方式下节点的破坏模式相近,节点域应变和变形都较小,对节点转动角度影响可以忽略;循环加载下节点的破坏位移明显较单调加载的小,梁端受弯承载力略有提高,芯筒端部钢管柱应变显著增长,M24-25节点的耗能能力较M20-20的高约10%;循环荷载作用下的螺栓最大实测拉力大于单调荷载作用下的螺栓最大拉力,组合连接副承载力的设计方法有待进一步研究。     

冷弯方钢管柱-H型钢梁外伸端板单向螺栓连接节点性能试验研究

为研究冷弯方钢管柱-H型钢梁外伸端板单向螺栓(hollo-bolt)连接节点的静力性能,对3个足尺寸的边柱节点进行了静力加载试验,试验研究参数为端板厚度和柱壁厚度。通过分析试验现象得到了不同端板厚度、柱壁厚度下单向螺栓连接节点的静力性能及破坏机理等,绘制了弯矩-转角曲线,对节点核心区各组件的应力-应变曲线进行了详细的分析。研究结果表明:随端板厚度增加,节点承载力不断增加,当端板厚度达到16mm后,端板厚度不再是节点承载力控制的主要因素;在其他条件不变的情况下,柱壁厚度对节点承载能力及转动能力有显著影响,柱壁厚度增加可有效提高节点刚度和承载能力。节点的极限转角较大,节点具有良好的变形能力,破坏形态主要有端板弯曲变形、单向螺栓套筒剪断和柱壁鼓曲变形破坏3种。     

地铁车站预制装配式结构注浆式单榫#br# 短接头抗弯承载性能试验研究#br#

文章基于注浆式单榫短接头在偏心受压条件下的承载性能试验研究,分析单榫短接头的M-θ曲线特征、裂缝发展规律、混凝土和钢筋应力特性,明确短接头的破坏形态,提出主要承载阶段的占比关系;同时对不同注浆材料和不同荷载条件下短接头的抗弯承载表现进行分析,得到不同因素对短接头抗弯承载的影响;并通过与单榫长接头在承载特性、裂缝发展及接缝变形等方面进行对比研究,揭示短接头的承载机理,明确短接头的应用条件。     

钢板攻丝高强螺栓连接钢框架节点力学性能试验研究

对采用钢板攻丝高强螺栓连接的钢框架节点分别进行了高强螺栓拉伸及剪切试验、钢柱法兰连接节点静力及拟静力试验、梁柱半刚性连接静力试验.基于试验数据对节点连接的承载能力、失效模式以及刚度特征等关键问题进行了分析.研究结果表明:由自攻螺纹钢板及高强螺栓构成的连接形式具有良好的抗拉、抗剪性能,以螺杆断裂为最终破坏模式;钢柱法兰连...     

型钢混凝土L形柱-混凝土梁框架节点滞回性能试验研究

为研究型钢混凝土L形柱-混凝土梁框架节点的滞回性能,以柱截面配钢形式、轴压比、水平加载角度及 有无楼板参与工作为变化参数,进行4个平面和7个空间L形柱-混凝土梁框架节点的拟静力试验;比较分析试件的 破坏形态、滞回曲线、承载能力、刚度退化、耗能能力、位移延性以及层间位移角等抗震性能指标。研究结果表 明：平面节点和空间节点的破坏形态分别为核心区发生剪切破坏和梁端出现塑性铰,带楼板工作的钢筋混凝土梁 柱空间节点出现板的弯曲破坏以及梁底出现塑性铰的破坏模式;配实腹式型钢试件的滞回曲线比配空腹式型钢试 件的饱满;平面节点的承载能力比空间节点的大,但耗能能力、位移延性及抗倒塌能力均不及空间节点;楼板的 存在对节点承载能力的提高和维持刚度的稳定均具有有利作用;轴压比可提高节点的承载力和初始刚度;L形柱 框架节点的层间变形能力大于规范规定的层间位移角限值。通过引入加载角度,提出了型钢混凝土L形柱-梁空间 节点受剪承载力计算模型,其能较好地反映节点核心发生剪切破坏的传力机制。