地层沉降条件下可缩性钻井井壁受力机理的试验研究

针对地层沉降条件下煤矿立井井壁的破坏机理,提出了一种新型可缩性钻井井壁结构。通过模拟试验表明:在地层沉降条件下,这种井壁结构能随之压缩,从而可使作用在井壁上的竖向附加力(即负摩擦力)得到相应衰减,使井壁达到安全使用。由此提出了可缩性钻井井壁竖向承载力的设计方法。研究成果已在淮北矿区的4个井筒中得到了成功应用。     

双立板可缩性井壁接头优化设计分析

为了解决因负摩阻力过大而导致的井壁破坏的问题,文中研究并提出一种新型的可缩性井壁接头方案。并以祁南矿北风井的可缩性井壁接头为优化对象,通过理论计算和数值模拟相对比的方法对该接头方案进行优化。ANSYS数值模拟的结果表明,井壁接头的水平和竖向承载力极限值分别为28、22.4MPa;在增加弧形板后,井壁接头的外立板的厚度相比优化前减小了10mm;该双立板可缩性井壁接头优化设计方法明显节省了材料成本,提高了井壁接头的安全系数,可以为后续类似井壁接头设计提供参考。     

井壁竖直附加力变化规律模拟试验研究

利用大型竖井模拟试验台,对冲积层疏排水过程中立井井壁受到的竖直附加力的变化规律开展了模拟试验研究。试验结果表明:竖直附加力随含水层降压量的增大而线性增加,随深度增大而增大,随土层中粗颗粒含量增多而增大。分析计算表明:应采用竖向可缩新型井壁结构防止井壁因冲积层疏排水而破坏。     

考虑层间效应的钢纤维混凝土隧道单层衬砌#br# 受力特征模型试验研究

为探究考虑层间接触效应的钢纤维混凝土隧道单层衬砌内力分布规律,自行设计考虑层间效应的单层衬砌模型并研制竖向油压5MPa和侧向压力1.5MPa作为逐级施加的卧式加载试验台架,开展不同荷载作用下的钢纤维混凝土隧道单层衬砌受力特征模型试验。研究结果表明：不考虑层间接触特征的单层衬砌与考虑接触特征的单层衬砌在拱腰和墙角处的安全系数均为最低,最容易出现弯矩和轴力突变;考虑层间接触特征的单层衬砌最大弯矩与最大轴力均出现在拱脚处,层间接触面存在明显黏结力,结构的轴力增加和弯矩减小,内力变得均衡,结构的整体安全性高于不考虑层间接触面,相对不考虑层间效应,受力最不利的左右拱脚处的安全系数分别增加143.7%、149.4%;当竖向油压达到3MPa、侧向油压值达到0.9MPa时,仰拱周围层间接触面压力增长速度显著加快,仰拱处混凝土由线弹性转变为塑性,竖向油压达到4MPa,侧向油压值达到1.2MPa时,仰拱、拱角与拱顶层间接触面应力值有减小或反向增长的趋势,仰拱、墙角等界面发生破坏;钢纤维在单层衬砌裂缝扩展在30%~70%之间阻裂效果最好。     

冻结施工立井井壁受力分析

本文阐述了冻结施工立井井壁在井筒施工期间、冻结壁解冻后和矿井投产后的受力情况。分析了冻结施工立井井壁在矿井投产后受到破坏的主要原因。提出了防止立井井壁破坏的途径。     

侧向荷载作用下公路隧道衬砌损伤演化分析

为了研究侧向荷载作用下隧道衬砌的损伤演化机制,采用1∶10相似模型试验分析了隧道结构在侧向荷载下的受力变形特征、破坏形式和损伤过程,基于试验结果利用数值计算反演分析了衬砌结构刚度衰减规律。研究表明:侧向荷载下隧道受力变形过程分为4个阶段:弹性受力阶段、拱腰开裂阶段、保护层局部破碎剥离阶段、结构软化破坏阶段;结构破坏模式表现为拱肩位置的斜剪破坏,关键部位破坏顺序为“拱腰开裂—拱肩脆性剪坏—拱腰延性破坏”,破坏时形成三铰拱可变体系。衬砌结构刚度在拱腰开裂后快速衰减,结构丧失承载力时刚度衰减幅度为84%;考虑隧道安全性评价,以结构技术状况评定值为界,结构在无破损、轻微破损、中等破损、严重破损、危险状态下的刚度折减系数分别为0.95、0.57、0.33、0.21、0.16。     

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。     

巨厚冲积层钢筋钢纤维高强混凝土井壁试验研究

针对550～700m巨厚冲积层中煤矿立井井筒的支护难题,提出采用钢筋钢纤维高强混凝土的井壁结构。通过模型试验,对这种井壁结构的力学特性和破坏特征进行了深入研究。结果表明:在相同条件下,采用钢筋钢纤维高强混凝土可显著地提高井壁的承载力,并可改善普通高强钢筋混凝土井壁延性差的缺陷,具有良好的塑性特征,且提高了井壁结构的工程可靠性。最后,根据理论分析和试验结果推导出了钢筋钢纤维高强混凝土井壁承载力的计算公式,从而为该种新型井壁结构的工程应用提供了设计依据。     

铁路隧道管片衬砌承受高水压分界值研究

铁路隧道一般位于山岭或水下的复杂地质环境中,面临着地下水的威胁,国内工程界对于管片衬砌所能承受的高水压一直没有明确的分界值。针对管片衬砌结构型式的特点,从接缝防水及结构受压承载能力两方面对高水压分界值展开研究。提出了管片衬砌结构高水压限界的定义及判定方法,求解了不同围岩级别、不同管片设计参数（混凝土强度等级、厚度）条件下的管片衬砌高水压承载能力。最后通过大比例尺模型试验对衬砌受水压作用的力学特征进行分析。研究结果表明：管片接缝在允许的张开量和错位量的前提下,同时考虑设计材料的应力松弛与老化,密封垫设计承受的最大水压能力约在 0.8 ～ 1.0 MPa 之间;管片环不同位置处的受压承载能力安全系数近似呈正弦曲线分布,拱顶及拱底位置为衬砌结构受力控制点,提高混凝土强度等级或加大管片厚度可以显著增加管片衬砌的受压承载能力;高水压条件下结构呈受压破坏,低水压条件下呈受拉破坏,一定范围内提升管片的外水压力,衬砌结构的轴力值增加明显,弯矩值变化幅度不大,对于结构受力是有利的。     

层状围岩中管片衬砌受力特征的模型试验研究

深部层状围岩结构强度具有各向异性特点,此类地层中修建盾构隧道,管片衬砌易受偏压作用,对结构安全构成挑战。开展层状围岩与盾构管片衬砌相互作用关系的相似模型试验研究,研究不同层理倾角下管片衬砌壁后围岩压力、管片衬砌内力和变形分布规律。研究结构表明:管片衬砌受力和变形特征受层理面控制明显,管片衬砌受力极不均匀,弯矩、轴力和变形呈现非对称分布;管片衬砌壁后围岩压力最大值集中在强度最弱的层理面法线方向,该方向上管片衬砌的弯矩最大,轴力最小,变形最大;层理倾角对管片衬砌的受力和变形影响显著,层理倾角不仅影响管片衬砌壁后围岩压力分布形状还影响其量值大小;均质地层中,管片衬砌裂缝主要出在封顶块接头处和其他环向接头处,层状地层中管片衬砌裂缝出现位置受接头位置影响减弱,而受层理倾角影响明显,管片衬砌裂缝出现位置主要集中在层理面法向。研究结果对层状围岩中修建盾构隧道的支护结构型式设计具有一定参考价值。     

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.     

深厚表土层中的井壁破裂与治理

在介绍了深厚表土层中的井壁破裂现象及特征基础上 ,分析了竖直附加力对井壁破裂的影响 ,展望了对破坏井筒及新建井筒的破裂治理及预防破裂的方法与技术 .     

盾构隧洞双层衬砌接头相互作用模型

简要介绍了双层衬砌接头荷载试验原理及结果。在此基础上，根据双层衬砌接合面结构处理方式的不同，提出了双层衬砌相互作用的三种模型：讨论了内衬混凝土受拉开裂后内衬刚度降低的模拟方法，并用试验结果对模型的合理性进行了验证，研究表明：用弹性铰单元来模拟混凝土开裂后构件刚度的降低是合理的，考虑混凝土开裂后内衬刚度降低的计算结果与试验结果更吻合。     

对接焊缝构造形式对高强钢梁柱节点断裂性能的影响

为研究对接焊缝构造形式对Q460高强钢梁柱节点断裂性能的影响,设计了4种不同构造形式的对接焊缝节点试件进行加载试验,采用拉卸循环加载方式,研究其承载能力、变形能力、破坏形态等性能,对比分析不同焊缝构造形式节点试件的断裂性能,对衬板双边焊缝构造形式节点试件进行了深入研究,分析了衬板双边焊缝间距对节点断裂性能的影响。结果表明:梁柱翼缘对接焊缝不同构造形式对试件断裂性能有一定影响,衬板采用双边焊缝构造形式可加强焊缝区域的强度,避免焊缝及热影响区发生断裂破坏,使试件破坏区域外移至母材区,试件的抗断裂能力较强;衬板采用双边焊缝的构造形式对试件的承载能力影响较小,对试件的变形能力影响较大,承载力及变形较衬板采用单边焊缝分别提高了3.3%,31.9%;增大衬板双边焊缝间距有利于加强焊缝区域强度,建议在构造允许的前提下,适当增大衬板宽度,降低焊缝发生开裂破坏的可能性。     

Interaction of tunnel linings and soft ground

Although soil-lining interaction is highly dependent on the tunnelling technology used, most of the available design methods for tunnel linings fail to take into consideration this important factor. During tunnel excavation, the in-situ stresses are significantly altered, depending on the tunnelling technique as well as the configuration of the tunnel and the characteristics of the soil deposits. The reduced radial stresses are the starting point of the soil-lining interaction at lining activation. This paper presents a method of lining design that considers the details of the excavation procedure and lining installation. Interaction between the tunnel lining and the ground is analysed in two stages—excavation and interaction. The excavation stage is responsible for determining the pre-lining soil deformations and the reduced in-situ stresses. The interaction stage models the soil-lining system together. Soil continuum, tunnel lining, and the interface between them are idealized in the whole system using nonlinear finite-element techniques. The deformations of the soil-lining system, as well as the lining internal forces, and equilibrium soil pressures are determined. Finally, results of the proposed analytical method as well as commonly used procedures are compared with field measurements compiled during the construction of two tunnels in which a precast segmental lining and rib and lagging lining were used.     

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.     

基岩冻结新型单层井壁施工技术与监测分析

 以鄂尔多斯市呼吉尔特矿区葫芦素副立井为工程实例,详细阐述国内首个基岩冻结新型单层井壁的施工工艺和监测方法,对井壁施工过程中的技术难点进行分析,给出井壁混凝土的质量控制指标。现场实测表明：(1) 凿井期新型单层井壁的钢筋应力和混凝土应变同时受基岩冻结压力与井壁温度的影响;(2) 井壁钢筋应力、混凝土应变的变化过程可分为OA,AB,BC,CD共4个阶段;(3) 凿井期葫芦素副立井竖向钢筋拉、压应力极值分别为35.5～70.8和－7.0～－45.0 MPa,环向钢筋则始终处于受压状态,其压应力极值为－41.7～－101.0 MPa;(4) 凿井期混凝土竖向、环向压应变极值分别为－190.5～－458.0和－590.4～－799.1 με,环向压应变极值为竖向的1.3～4.2倍;(5) 建议将竖筋悬吊的井壁高度取为12 m;(6) 葫芦素副立井井壁配筋于凿井期具有足够的安全储备,混凝土压应变处于安全范围。     

层状围岩管片衬砌配合陶粒与锚杆的联合支护技术研究

深部层状围岩中修建盾构隧道,管片衬砌易受偏压作用,对结构安全构成挑战。提出一种管片衬砌配合陶粒可压缩层与锚杆的联合支护技术,采用大比例尺相似模型试验针对联合支护技术的支护效果进行研究,进行了可压缩层配合不同长度和间距的锚杆支护效果对比研究,从管片衬砌内力、变形角度分析了联合支护效果,从可压缩层的压缩变形路径和移动特征角度分析了联合支护机理。研究结构表明:联合支护技术一定程度上改变了管片的内力分布形式,降低了围岩偏压作用,削减管片衬砌内力和形变量;锚杆的施作可以有效减小层状围岩变形,陶粒压缩层可以有效吸收围岩变形;联合支护中锚杆的长度和间距存在一个最优值,超过该最优值,锚杆的加固效果不再明显增加;联合支护的作用机理由两部分构成:陶粒压缩层的让压作用与锚杆加固作用。研究结果对层状围岩中修建盾构隧道的支护结构型式设计具有一定参考价值。