高水位隧道堵水限排围岩与支护相互作用分析

为了保护环境并尽可能降低衬砌结构所受的水压力,提出高水位山岭隧道应采取“以堵为主,限量排放”,即“堵水限排”的防排水设计原则。但对于堵水限排情况下衬砌结构的设计,目前尚没有规范可依,这是目前隧道设计施工亟待解决的问题。在隧道力学和渗流力学的基础上进行理论分析,研究渗流应力耦合作用下围岩的力学特性,利用特征曲线法分析了不同排放量下围岩与支护的相互作用,并与数值方法计算结果进行对比。计算结果表明：不同排水量下围岩特性曲线不同,支护阻力也不同,不同排水条件下围岩有效切向应力和有效径向应力的变化很明显,排水对围岩应力以及支护体系受力的影响是不容忽视的。另外,传统隧道设计方法在全排水时完全不考虑水的作用是不安全的。所得结论可为堵水限排衬砌结构设计提供理论依据。     

河北省李家沟公路隧道施工设计

李家沟公路隧道采用短台阶及全断面开挖;钢筋骨架网衬砌模注砼及初期锚喷砼支护,采用水泥裹砂半湿式喷砼法,衬砌分２序进行;采用光面控制爆破。     

探地雷达检测隧道衬砌中的几个问题

介绍了用探地雷达对几十座隧道做衬砌质量检测的经验及典型图像,提出了目前雷达检测定性定量解释的几个问题及进一步解决的办法.指出应实事求是地评价和宣传目前工作及方法的优点和缺点.     

祁南矿东风井冻结温度场时空演化规律分析

煤矿井壁破损透水事件时有发生,给地下空间利用和矿产资源开采构成重大威胁。为了弄清井壁破损过程承压地下水存在的影响以及透水通道形成机制,采用相似理论设计模型试验并结合流固耦合数值模拟技术开展研究。结果表明,井壁与压力水直接接触不利于其承载变形能力的发展,具体体现在破坏时屈服点位置提前出现,峰值强度及峰值应变降低,宏观裂纹分布更广,这是由压力水渗入井壁混凝土时诱发的渗流场应力场相互耦合作用引起的。对照模型试验结果开展数值仿真分析,获得一套适用于流固耦合状态下井壁破损数值计算参数。基于此开展0.05、0.10、0.20、0.40 MPa孔隙水压影响下井壁破损透水全过程细观数值分析,发现孔隙水压增大使井壁承受的临界侧向荷载依次降低5.88%、17.65%、23.53%,屈服强度附近试件内部裂纹发展明显加速,裂纹不断扩展、贯通,最终形成沟通井壁内外侧壁的透水通道。0.40 MPa孔隙水压下透水通道率先出现,相对于其他3种孔隙水压提前了2.67、2.53、1.67倍计算步,说明孔隙水压越大裂纹扩展速率越快,裂纹扩展路径先径向后环向。声发射监测表明井壁破损透水前夕,事件数量先逐步增大再持续保持高位,破损后应力得到释放,声发射事件频率及数量骤降,该信号特征可作为现场井壁破损透水监测依据,为井壁突水预防和治理提供依据。

     

基于监控量测的公路隧道二次衬砌受力分担比例

依托垫江至邻水高速公路铜锣山及明月山隧道,对公路隧道二次衬砌受力分担比例进行研究。通过围岩压力实测值与普氏理论、太沙基理论和公路隧道设计规范深埋围岩压力公式计算值进行对比,结果表明: Ⅲ级、Ⅳ级和Ⅴ级围岩压力计算值比较符合实测情况。通过对围岩压力、初期支护与二次衬砌的接触压力现场量测数据进行分析,得出Ⅲ级( 深埋) 、Ⅳ级( 深埋) 、Ⅴ级( 深埋) 和Ⅴ 级( 浅埋) 围岩二次衬砌受力分担比例分别为29. 20%、35. 28%、41. 38% 及32. 17%。研究成果对于公路隧道结构设计有着理论指导作用。     

钢纤维混凝土隧道衬砌力学行为模型试验研究

文章通过相似模型试验,研究了钢纤维混凝土材料应用于隧道支护结构的力学行为。试验通过千斤顶逐级加载的方式,得到支护结构整个力学行为过程中与围岩之间的接触压力、变形发展规律及其裂后承载能力。通过与传统素混凝土支护结构相比,钢纤维混凝土具有良好的承载和变形能力,是一种理想的柔性支护材料。     

Numerical simulation on the cracking and failure law of compacted clay lining in landfill closure cover system

According to the mass conservation equation of solid phase, water transport, air migration and enthalpy balance equations in a deformable and unsaturated porous medium, and the mechanics model, a thermal‐hydro‐mechanical (THM) coupling mathematical model is developed in order to accurately predict the crack propagation of the compacted clay lining (CCL) in a landfill closure cover system. Numerical simulation analysis of the cracking and failure of the CCL in a landfill closure cover system under complex conditions (landfill gas pressure, variation of soil surface temperature, moisture loss of coverage soil, and uneven settlement of landfilled MSW (municipal solid waste)) is performed. The results show that the cracks are discovered firstly on the soil surface and then extend to the deeper cover system and became bigger. The cracks had broken through the closure cover system at 30 days. Over the depth range of 0.06 m, the change rate of settlement is found to be the highest because of the strong influence of temperature. The rise of temperature around the cracks is fast when the CCL is broken through by the cracks. There is a hollow area near the cracks over the depth range from 0.15 to 0.7 m, and the temperature stabilize at around 11°C without any obvious reduction. Under the condition of evaporation, the main crack in the CCL is similar to a pumping well, which causes more rapid moisture content reduction around the cracks. Vertical deformation increases linearly with depth in the process of deformation and cracking of CCL induced by uneven settlement of landfilled MSW. Copyright © 2014 John Wiley & Sons, Ltd.     

声波无损检测技术在南昆铁路隧道检测中的应用

文章简要地介绍了声波检测技术检测隧道衬砌质量的基本原理及应用实例     

Effects of tunnelling on existing support systems of perpendicularly crossing tunnels

The interactions between perpendicularly crossing tunnels in the Sydney region are investigated using a full three-dimensional (3D) finite element analysis coupled with elasto-plastic material models. Special attention is paid to the effect of subsequent tunnelling on the support system, i.e. the shotcrete lining and rock bolts, of the existing tunnel. The results of the analysis show that in a region such as Sydney, with relatively high horizontal stresses, installation of the new tunnel causes the shotcrete lining of the existing tunnel to be in tension in the side facing towards the tunnel opening and in compression at the crown and invert. The pre-stressed rock bolts are usually tensioned more in the sections closest to the tunnel opening. For this particular study, if a new tunnel is driven perpendicularly beneath an existing tunnel, significant increases are induced in the bending moments in the shotcrete lining at the lateral sides of the existing tunnel and in the axial forces at its crown and invert. The increase in side bending moments causes further tensile cracking but the crown and invert stresses remain within the thresholds for both compressive failure and tensile cracking for shotcrete lining of typical concrete quality. Moreover, the driving of the new tunnel causes the tensile forces in the existing side rock bolts to increase and those in the existing crown rock bolts to decrease. In contrast, if the new tunnel is driven perpendicularly above the existing tunnel, compressive failure of the existing shotcrete lining is induced at the crown of the deeper tunnel for concrete of typical capacity and a significant tensile force increase of the existing rock bolts around the crown. It is concluded that in order to ensure the stability of the existing tunnel, local thickening is needed at the sides of the existing shotcrete lining if the shallow tunnel is installed first and local thickening is needed at the crown if the deep tunnel is installed first.     

控量分段孔底注浆法在煤田涌水钻孔中的应用

河南省平顶山煤田郏县煤预查区某钻孔,在179.09～269.64m出现了18次涌水,最大涌水量为200t/h。从控量分段孔底注浆的原理出发,详细介绍了该方法在注浆方案的设计、注浆材料的选择、注浆量的计算、注浆压力的控制和注浆效果检验方面的实际应用。透孔检查显示,该孔的注浆堵漏止涌的成功率为100%,达到了预期目的。