高压岔管首次充排水过程是影响衬砌裂缝产生和扩展规律、渗透规律以及长期受力特性的关键因素,亦是关乎结构安全与围岩稳定的重要工况。以阳江抽水蓄能电站钢筋混凝土高压岔管为工程背景,基于流固耦合方法,采用离散单元法(PFC2D)研究了首次充水裂缝开展位置与初始地应力的关系;然后,利用有限差分法(FLAC3D)分析了衬砌起裂过程和贯通临界压力,明确了首次充排水至平衡状态的衬砌渗透特性以及梯级排水条件下衬砌稳定性;最后,研究了钢筋和锚杆对衬砌结构力学特性的影响,并提出限裂设计参数优化方案。结果表明:内水压力2.8 MPa为衬砌起裂临界压力,继续增至4 MPa时衬砌结构裂缝贯通;裂缝是高压岔管充水期内水外渗和放空期外水压消散的重要渗流通道,衬砌结构配筋与锚杆支护是限制裂缝开度的关键措施;放空期高外水荷载作用下衬砌存在受压破坏风险,应对内水放空梯度进行严格控制。

The accurate evaluation of rock abrasiveness is the basis for the cutting tool design of tunnel boring machines and efficient tunneling. However, the conventional test method is complicated and costly, and in situ measurement cannot be obtained easily. A new digital drilling test system was developed to assess rock abrasiveness in which drilling parameters, including the thrust on bit, rotational speed, torque, and drilling displacement, can be simultaneously collected. Based on the force analysis of the drill bit and the energy conservation law, the energy dissipation per unit volume of drilling or modified specific energy was proposed as an evaluation index, and the quantitative relationship between the index and rock abrasiveness was explored and verified. The results showed that the average difference rate between the Cerchar abrasiveness indexes obtained from the digital drilling test and Cerchar test was less than 15 %, thus proving the effectiveness and feasibility of this method for evaluating rock abrasiveness. The method is easy to implement and has few requirements for sample preparation. It can also be used for the in situ testing of rock abrasiveness in engineering sites.

The construction of subway interval tunnels at a short distance from existing buildings and engineering structures in cities is often a high-risk project. This research discusses subway interval tunnels crossing a high-speed rail shield tunnel at a short distance based on numerical simulations and on-site monitoring. The deformation patterns of the interior of tunnel, ground, and shield segments are analyzed, and the principle and function of reinforcement measures for deformation control are presented. The results indicate that constructing a temporary inverted arch using bolting and shotcreting as per the bench method has higher integral stiffness, and thus, the foot-locking effect of anchor pipes to reduce strata deformation is fully utilized. The deformation of upper high-speed railway shield tunnel segments induced by the construction of subway interval tunnels primarily occurs within a distance three times the diameter of the tunnel. Thus, this is the key area to install advanced support to control tunnel deformation. A compound advanced support approach including pipe sheds and deep-hole grouting is proposed that can exert the arching effect of deep-hole grouting and beam effect of pipe sheds to control strata deformation.

全断面隧道掘进机（TBM）施工法具有机械化程度高、掘进速度快、作业环境好、生态扰动小以及综合效益优等特点,已成为了目前国内外隧洞工程的重要施工手段。但由于TBM对工作地质条件适应性差这一特殊性,使得现有应用于传统钻爆法施工的围岩探测技术不能直接应用于TBM施工。因此,如何快速、准确地超前获取TBM施工洞段岩体基本物理力学特性,尤其是岩石强度和耐磨性参数,是保证TBM施工安全与提高掘进效率亟需解决的问题。应用多功能数字钻进测试系统,进行不同类型砂浆与岩石试样的室内数字钻进试验以及物理力学性质试验。研究了数字钻进参数与岩石物理力学特性的相关性,提出了岩石数字钻进参数与其物理力学参数的关系模型,揭示了岩石钻进过程中随钻参数与其物理力学特性之间的内在联系,并基于能量守恒原理,获得了数字钻进参数与钻进效率的数学模型。（1）成功利用多功能数字钻进测试系统,初步实现了岩石钻进过程中随钻参数的实时监测和精确采集。基于岩石数字钻进测试结果,研究数字研磨钻进过程运行参数与响应参数之间的响应关系,验证了多功能数字钻进测试系统结构的合理性及有效性,为深入探讨数字钻进参数与岩石物理力学参数的相关性奠定了设备基础。（2）基于能量分析方法,提出了岩石研磨钻进过程的数学模型,定义了岩石单位研磨能ηe以及推导出其理论表达式,建立了数字钻进参数与岩石强度参数UCS的关系模型,并利用岩石数字研磨钻进试验结果验证了模型的合理性。（3）根据室内岩石物理力学性质试验分析结果,包括岩石单轴压缩试验、Cerchar磨蚀性试验和矿物成分分析试验,分别得到了岩石矿物成分石英含量（Q）、等效石英含量（EQC）、矿物加权硬度（H）、单轴抗压强度（UCS）参数以及岩石磨蚀性指数（RAI）与Cerchar磨蚀性指数（CAI）之间的数学关系式。结合岩石数字研磨钻进试验计算结果,利用岩石单位研磨能ηe,建立了数字钻进参数与岩石耐磨性参数CAI的关系模型,并验证了模型的合理性。（4）考虑到岩石旋切钻进过程中的破碎特征,利用能量守恒原理构建了岩石旋切钻进过程的数学模型,从而建立了数字钻进参数与钻进效率的关系模型。基于正交试验原理,开展了基于花岗岩的数字旋切钻进原位试验,获得了数字钻进参数对钻进效率的敏感性规律。

高压水作用下水工隧洞衬砌开裂难以避免,透水衬砌设计关键是确定衬砌与围岩联合承载条件下的钢筋混凝土衬砌结构受力特征和裂缝控制标准。本文基于压力隧洞衬砌裂缝起裂和扩展特点,分析了传统裂缝计算公式及以数值仿真计算方法的工程适用性,并针对衬砌的主要设计参数进行了裂缝宽度敏感性分析;通过裂缝控制标准解析、数值仿真及工程实际量测的结果对比,提出了衡量衬砌裂缝控制标准的关键依据。研究结果表明,尽管实测裂缝宽度往往大于限裂标准,但多数工程仍正常运行,现行国内外规范的裂缝控制标准过于苛刻,降低了支护结构材料的利用效率,应建立与工程实际相符合的裂缝宽度控制标准。兼顾压力隧洞的工程安全与经济效益,较合理的混凝土衬砌配筋率接近0.9%,衬砌厚度接近800 mm,裂缝宽度控制标准增加至0.35～0.5 mm。

快速准确地超前获取岩体力学参数是指导岩体工程安全施工的重要前提。利用自主研发的多功能数字钻进测试系统,进行了不同强度等级完整试样的室内数字钻进试验及单轴压缩试验研究。根据试验分析结果,基于岩石研磨钻进过程中金刚石钻头的受力特点,利用力学极限平衡与能量守恒原理,定义并推导出了岩石单位体积研磨能的理论解,获得了数字钻进参数与岩石单位体积研磨能的数学方程式,进而建立了岩石数字钻进参数与单轴抗压强度的定量关系,即RDP-Rc预测模型,并进一步验证了该模型的可行性与有效性。研究方法与结果可以为工程岩体强度参数的实时原位测定提供一种新的途径。

Soil particle size distribution (PSD) is critical for assessing the potential for internal instability of sand-gravel soils, mainly because particle migration in sand-gravel soils owing to seepage forces affects almost all soil hydraulic properties during internal erosion processes. Therefore, a reliable PSD analysis is essential for revealing the mechanism of particle migration and internal instability of sand-gravel soils. At present, however, PSD is commonly calculated by manual interpretation methods and cannot be continuously and nondestructively analyzed during internal erosion processes. Those methods are lacking, however, in that it results in a failure to continuously determine the internal erosion condition. In this paper, a new approach with the ability to continuously predict the PSD changes in sand-gravel mixtures is introduced based on one-dimensional laboratory suffusion tests in a non-destructive nuclear magnetic resonance (NMR) system over a range of suffusion times. The results show that pore expansion and particle migration are an interactive process that controls suffusion development in sand-gravel mixtures. The proposed method is verified through experimental data measured by sieve analysis, and has potential to retrieve PSD information at different suffusion times. (C) 2020 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.