新建隧道穿既有隧道的直线段单护盾盾构施工对既有隧道环境影响已有许多研究，针对曲线段双护盾TBM隧道施工效应的研究还较少。首先，开展曲线段双护盾TBM隧道上穿既有隧道变形规律监测试验，表明：双护盾TBM穿越既有隧道施工时，撑靴作用对邻近既有隧道具有一定重要影响；曲线段管片受盾位推力向外产生水平偏移，其偏移对围岩作用影响范围约距盾位向后10m内，偏移作用随与盾尾距离增大而增大。其次，分析了曲线段管片偏移与围岩相互作用，并基于Mindlin解构建了考虑卸荷应力、刀盘推力、盾壳摩擦力、撑靴支撑力、曲线段管片偏移作用及撑靴摩擦力共同作用的附加应力计算模型，基于Winkler地基模型推导了双护盾TBM新建隧道上穿既有隧道变形解析公式，并通过实例监测、有限元数值模拟的方法对解析公式进行验证及分析。此外，针对曲线段管片偏移作用、新建隧道与既有隧道净距、新建隧道推进距离等关键参数进行了既有隧道变形的影响分析。参数分析表明：直线段既有隧道的隆起变形位移关于新建隧道轴线对称，曲线段双护盾TBM隧道开挖对既有线影响区在距既有隧道轴线-1m到15m的范围内，隧道隆起变形随推进距离的增加表现为先增大后减小的规律，...

The increasing use of high-voltage transmission wires requires more and more high-voltage pylons, and sometimes, constructing pylons in mining areas is very urgent. To ensure the safe operation of pylons, coal pillars with large side lengths are usually used to provide sufficient support; however, this results in a huge waste of coal. Eight high-voltage pylons are arranged on the ground surface corresponding to the location of working face 1110 of Sima Coal Mine in Shanxi Province, China, which cannot be mined by traditional methods. Taking this as the engineering background, the failure mode of high-voltage pylon is first analyzed. Using FLAC(3D) numerical simulations, the influence of five different mining plans on ground surface deformation in working face 1110 is evaluated, and the vertical settlement and horizontal deformation in different areas of the ground surface, as well as the variation law of horizontal strain and slope are analyzed. According to the numerical simulation results, the range of thickness-limiting mining or backfill mining in working face 1110 is shown in scheme 3, and the key regions in the mining process are determined. Secondly, the strengthening scheme of high-voltage pylons is designed, that is, the four foundations of high-voltage pylons are connected as a whole with steel supports and steel connectors so as to improve the structural strength of the high-voltage pylon. Finally, the position change in the foundation of high-voltage pylons was monitored for 22 consecutive months. The results show that the maximum settlement of the high-voltage tower foundation is 3.1 m, which is consistent with the actual mining thickness; The high-voltage pylon was stably moved, and the change in transmission line tension and total length was usually less than 1.0%. The combined mining scheme and foundation strengthening scheme can ensure the safe operation of high-voltage pylons and provide a new method for the stability control of ground buildings in coal mining subsidence area.

护盾式TBM隧道管片偏移是隧道建设的难题之一。以护盾式TBM隧道回填、注浆施工阶段引起管片竖向偏移为研究背景，首先，分析了护盾式TBM施工特点和管片竖向偏移机理，基于温克尔弹性地基梁假定和分层综合法，建立了护盾式TBM碎石-围岩耦合基床系数，并推导了临时支护阶段隧道管片沉降计算公式；然后，分析了注浆引起的管片上浮机理，并将止浆环简化为隧道管片固支点，基于弹性地基梁理论建立了隧道管片上浮分析模型，推导注浆引起的隧道上浮计算公式；最后，结合临时支护阶段管片沉降解，获取管片竖向偏移总量，并对管片沉降与上浮阶段进行关键参数敏感性进行分析。研究结果表明：隧道管片竖向偏移理论计算结果与实测值能够较好吻合，可有效揭示管片沉降及上浮变形规律，以及管片上浮引起的管片弯矩、剪力变化特征；沉降阶段，管片沉降量与压缩模量、管片环向半径成正增长，与回填层厚度呈负增长；上浮阶段，浆液充填率、地层弹性系数、回填厚度对护盾式TBM隧道管片上浮比较敏感，回填层厚度大、回填密实度小、下部注浆充填量过大、过小等易导致管片竖向偏移大。

As the highest altitude and the longest plateau railway line, the Qinghai-Tibet railway passes through a large area of continuous permafrost. As the key position of the combination of roadbed and bridge, the stability and strength of the bridge approach directly affect the smoothness of the whole line. Through an indoor model test, the distribution pattern of space temperature field and the change law of temperature measuring points in the bridge approach of gravel sandwich are studied. With the increase in the depth from the subgrade surface, the influence of the temperature change in the upper atmosphere decreases gradually at the 2.5-m platform back of the subgrade center section, resulting in an obvious lag in the subgrade. By comparing the temperature measurement data of different bridge approaches of the gravel interlayer road bridge and the bridge approach of the U-shaped block gravel road bridge, it is shown that the U-shaped structure not only has a better overall cooling effect, but also the cooling effect gradually increases with the increase in the distance from the abutment back. The influence range of the road-bridge transition section on the spatial temperature field is approximately 14 m in the back of the abutment, and the influence range at 7.5 m is the most severe. The research results have important practical significance and engineering application value for the operation and maintenance of the Qinghai-Tibet railway.

The terminal mining is an essential part of fully mechanized mining, and the reasonable length of the flap roof during the terminal mining is an important basis for the smooth operation of the terminal mining. With the research background of the 213 working face of the Longde Coal Mine, the contribution of this study is the influence law of hydraulic fracturing on the terminal mining mechanical behavior of the working face. Four different numerical calculation models of terminal mining hydraulic fracturing are established, and the optimal hydraulic fracturing site plan is determined according to the length of the terminal mining flap top and the working resistance of hydraulic support. The effect of hydraulic fracturing construction and the law of mechanical behavior in the terminal mining stage in the field test are analyzed. The results show that through hydraulic fracturing technology, the control of the length of the flap roof of the working face during the terminal mining period has been realized. © 2024. The Author(s).

Conduction between the unique geological formation karst collapse pillar (KCP) and the fractures caused by mining in the coal seam floor can lead to catastrophic water inrush disasters in many coalmines in Northern China. It is widely recognized that seepage mutation induced by the migration/loss of KCP fillings (highly broken rocks filling the fractured rocks) happens during occurrence of the KCP-related water inrush. However, roles of fluid path (mining-induced fracture) scale and KCP filling porosity in seepage mutation evolution remain unclear. Here, we conducted seepage tests on natural KCP fillings containing rock particles of different sizes. The filling specimens were deformed to different porosities from 14 to 26% through axial compression, and small to large fluid paths were simulated by seepage plates with distinct pore sizes from 2.5 to 12.5 mm. We found that seepage mutation occurs with significant permeability enhancement by 2 orders of magnitude under a pore diameter of 12.5 mm and a specimen porosity of 26%. There is a strong linear relationship between specimen permeability and Reynolds number (Re) over seepage mutation. The mutation is caused by the sudden collapse of the specimen skeleton and subsequent quick outflow of the particles. Therefore, it is inferred that the KCP-related water inrush is more likely to happen when highly porous KCP fillings are present and mining-induced fractures are well developed.

In this work, the authors study the mixing proportions of similar materials for use in tests of models of fluid–solid coupling by using the orthogonal test on six factors at five levels. We used river sand and calcium carbonate as aggregates, white cement and chlorinated paraffin as cementing agents, and iron sand and silicone oil as regulators. The physical and mechanical parameters as well as the hydro-physical properties of similar materials were tested at different mixing proportions, and the sensitivity of the results to the influential factors was assessed by range and variance analysis. A linear regression-based analysis of 25 groups of results was then carried out on STATA software. Following this, the similar materials chosen for fluid–solid coupling based on the above tests were applied to the model test of water inrush in a karst tunnel. The results showed that the fluid–solid coupling similar materials of karst strata were prepared, the main factors influencing basic parameters variation of similar materials were obtained; a quantitative relationship between the influential factors and parameters of the materials was also constructed, and can be used to significantly improve the efficiency of testing; the similar materials developed here can satisfy the requirements of tests on models of fluid–solid coupling. This study has important reference value for research on similar materials for fluid–solid coupling in tests of models of karst tunnels. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

为探究岩溶隧道在开挖过程中处于不同倾角断续裂隙下防突结构位移、渗流场和岩溶水压的变化规律，运用三维离散元软件进行数值模拟分析研究。构建岩溶隧道断续裂隙掘进面突水计算模型，模拟分析了隧道发生突水灾害时，防突岩体的多元物理信息变化过程。结果表明：隧道掘进面的最大位移点通常位于裂隙和隧道掘进面的交界处；当裂隙倾角从20°增至45°时，水压不断增大；倾角从45°增至70°时，各位置处的水压逐渐减小；随着岩溶裂隙倾角不断增大，岩溶水在裂隙中的最大流速先减小后增加。研究结果可为岩溶隧道突水防控提供指导作用。

素混凝土衬砌破坏一直是灌区建筑物健康发展的难题,由于素混凝土衬砌断面厚度较大、造价较高、衬砌自身刚性与背后堤坡之间存在较大间隙,在外界荷载的作用下常常发生破坏,从而严重威胁到灌区堤坝工程的安全运行。从堤坝衬砌破坏机理出发,针对破坏的位置以及破坏现象提出一种新型材料（聚丙烯纤维混凝土）堤坝衬砌形式,并利用通用有限元软件ADINA对素混凝土衬砌与聚丙烯纤维混凝土衬砌堤坝进行了数值模拟分析,结果表明:聚丙烯纤维混凝土衬砌同素混凝土衬砌堤坝相比应变基本相同,但其韧性与抗剪性能显著特高,是一种科学实际的衬砌方法。

随着西部大开发和“一带一路”伟大战略的深入实施,我国交通和水利水电工程建设重心明显向地形地质条件极端复杂的西部山区和岩溶地区转移,越来越多“大埋深、高应力、强岩溶、高水压、大流量”等高风险深长岩溶隧道工程投入建设。钻爆法施工过程中,爆破荷载作用及由其引起的地应力瞬态卸荷效应会加剧岩溶隧道发生突水突泥灾害的风险,对隧道建设安全造成重大威胁。本文采用理论分析与数值计算相结合的方法,分别开展了静态、爆破荷载作用及爆破荷载与地应力瞬态卸荷耦合作用下隧道围岩稳定性研究,含高压水裂隙围岩在爆破荷载与地应力瞬态卸荷耦合作用下裂隙开裂扩展规律研究,以及隧道周边溶腔在爆破荷载与地应力瞬态卸荷双重动力扰动下突水演化机制研究,取得了如下研究成果:（1）深埋岩溶隧道采用钻爆法施工时,爆破荷载的强扰动作用会引起隧道开挖轮廓面处围岩初始地应力的瞬态卸荷效应,使隧道围岩稳定性下降。通过开展隧道围岩稳定性的离散元数值模拟,进一步证实爆破荷载与地应力瞬态卸荷作用能够在一定程度上劣化隧道围岩的稳定性;（2）修正和完善了含高压水裂隙围岩的裂纹扩展理论。考虑地应力瞬态卸荷作用,当侧压力系数大于1/3时,采用修正的计算公式获得的支裂纹应力强度因子大于修正前的支裂纹应力强度因子;首次揭示了隧道爆破开挖过程中裂隙围岩动态响应机制,建立了爆破荷载与地应力瞬态卸荷双重动力作用下围岩裂纹尖端应力强度因子的计算方法。理论研究发现,爆破荷载和地应力瞬态卸荷对原始裂隙的开裂与扩展起促进作用。原因在于爆破荷载对围岩强烈的冲击和拉压作用以及地应力瞬间卸荷引起的应力集中效应,加剧了原始裂隙的开裂与扩展;（3）考虑爆破荷载与地应力瞬态卸荷耦合作用影响,开展了含高压水裂隙围岩原始裂隙的开裂与扩展规律的数值模拟。结果显示,随着裂隙倾角的增大,原始裂隙的开裂与支裂纹的扩展速度呈现出增大趋势。当裂隙倾角为0°和90°时,裂隙分别沿着水平和竖直方向扩展;当裂隙倾角为15°和75°时,裂隙均沿着原始裂隙所在的斜面发生滑移错动的现象;当裂隙倾角为30°、45°和60°时,裂隙均沿着爆破荷载作用与地应力卸荷方向开裂扩展。在地应力瞬态卸荷作用的影响下,裂隙在沿着径向开裂扩展的同时,出现向切向方向偏转扩展的趋势,最终在裂隙尖端出现切向的支裂纹;（4）含高压水溶腔位于隧道上部的离散元数值模拟研究发现,增大岩层倾角,防突层的稳定性与抗突水能力逐渐降低,当倾角为0°时,其稳定性和抗突水能力最强;防突层的稳定性及抗突水能力与防突层厚度和隧道埋深呈正相关,当防突层厚度为4m、隧道埋深为800m时,其稳定性与抵抗岩溶水破坏的能力最好;溶腔位于隧道下部的数值计算结果显示,随着岩层倾角的减小、防突层厚度的增加或隧道埋深的增加,防突层的稳定性与抵抗岩溶水破坏的能力逐渐提高。当岩层倾角为0°、防突层厚度为4m、隧道埋深为800m时,防突层的稳定性与抗突水能力最强;（5）含高压水溶腔位于隧道侧部的离散元数值计算结果表明,随着岩层倾角的增加,防突层的稳定性逐渐增强,其抵抗突水的能力逐渐提高,当岩层倾角为30°时,防突层具有较好的稳定性。另外,防突层的稳定性与防突层的厚度呈现出正相关的关系,当防突层厚度为4m时,其稳定性较好。防突层的稳定性与隧道埋深并没有严格的正相关或负相关的关系,当隧道埋深为500m时,防突层的稳定性较好,其抗突水能力较高,而当隧道埋深为800m时,防突层的稳定性最差。