In water-saturated karst environments, existing shield tunnels are under external water pressure, posing potential water inrush hazards. It is an effective method to improve the permeability of the strata near the tunnel by ground grouting. However, currently, there is limited research on the impact mechanism of ground grouting on existing shield tunnels, leading to blindness and increasing risks of construction. This study investigates the mechanical response mechanisms of ground grouting to existing shield tunnels by grouting simulation systems with numerical simulation validation. Based on field tests from the subway water inrush control project, the stress and strain characteristics of the shield tunnel segments under multifactor influences were analyzed. The results indicate that the following: (1) under the action of grouting pressure, the maximum stress on the tunnel segment is observed at the intrados of the springline near the grouting pipe. The segment contracts horizontally away from the grouting pipe and expands vertically upward. (2) The segment moves horizontally away from the grouting pipe, with no vertical displacement. (3) The greater the grouting pressure, the longer the grouting duration, and the more frequent the grouting, the more significant the impact on the stress of the segment. The research findings provide theoretical guidance for practical grouting engineering.

Understanding the distribution of hydraulic parameters is essential for preventing water-related hazards in limestone mines. Tracer testing is a technique to elucidate the spatial heterogeneity of hydraulic parameters and transport properties within an aquifer. In order to estimate fluid flow characteristics and the distribution of hydrogeologic properties of the limestone aquifer, this study performed an integrated tracer-based tomographic inversion and heterogeneity characterization for the Hejing limestone mine in southwest China. The temporal moment analysis was conducted on the recorded tracer breakthrough curves (BTCs), and the swept volumes and flow geometries were estimated. Furthermore, potential flow paths for water inflow were identified by inverting the travel-time dataset via tomographic inversion using the simultaneous iterative reconstruction technique (SIRT) algorithm and the staggered grid method. The estimated high-conductivity zones estimated by travel-time tomography were consistent with areas of high mass recovery, short mean residence times, and large tracer-swept volumes. Potential paths of water inflow were confirmed to be distributed in the southeast and northeast of the limestone mine. Based on the reconstructed high-conductivity distributions, three sets of grouting curtains were designed to avoid further hazards. The groundwater levels measured during grouting demonstrated that the grouting was satisfactory. The findings of this study can provide valuable references for solving the preferential flow paths and subsurface heterogeneity in aquifers and for characterizing of subsurface heterogeneity. Future joint inversion studies based on tracer, geophysical and head data are expected to refine the outcomes on stratigraphic heterogeneity.

To address the problem on grouting control of water inflow disaster in coastal area, a caisson-type grouting experimental system of a single fracture in flowing water under tidal action was developed independently. Through the tide simulation system, the tidal action of different intensity and frequency was effectively described. Tide simulation system, fracture system, grouting system, water supply system and information monitoring system were combined to realize the visualization of the whole grouting process under tidal action. Furthermore, the grouting experiments of a plate fracture under different tidal action were developed and the blocking mechanism under tidal action was revealed. The conclusions were as follow: 1) Under constant water head, the slurry had three typical diffusion patterns, which were circular distribution, double U-shaped distribution and elliptical distribution respectively. 2) Under tidal action, the pressure showed a periodic fluctuation growth, and the growth rate slowed down with the increase of fracture aperture. 3) Strong tidal action would promote the diffusion of and increased the outflow amount of slurry, which was not conducive to grouting. Based on the water inflow treatment project of limestone mine in Guangxi, Through the field grouting tests, the 2# water inflow point was blocked. The research results have a certain reference value for the technology optimization of grouting engineering in coastal areas.

Due to the complex geological structure and abundant groundwater system in karst areas, the gushing water disasters of mines in karst areas are characterized by large flow rate, high velocity and frequent occurrence, which have become an unavoidable social problem, further caused huge economic losses and casualties. In this paper, a novel treatment method and construction technology were summarized and put scientifically forward a set of management procedure for karst gushing water treatment to guarantee security production during mine construction in karst region. The construction procedure includes safety assessment policy, precise exploration method, collaborative grouting mode, curtain closure technology and effectiveness inspection system, furthermore the precise exploration method, grouting material, construction steps and effectiveness check for the karst gushing water treatment are introduced in detail. Finally, the engineering application was successful conducted using the karst pipeline gushing water procedure in treatment object of water inrush of mine belonged to China Resources Cement (Pingnan Country) limestone mine co., which the total quantity of gushing water reached to 117700 m3/d. The engineering trial demonstrates the applicability of this treatment process and accumulated for the similar projects so as to further perfect the treatment method and technology of water inrush in karst conduit.

For the large-flow and high-speed dynamic water sealing problem in karst pipelines, the dynamic water sealing mechanism under flow-control speed-down conditions is researched systematically by numerical calculation, model test and engineering application. Firstly, numerical simulation for the dynamic water turbulent flow in the pipeline is conducted under different water heads and flow rates. The change laws of flow velocity and pressure are analyzed during the flow-control speed-down. Secondly, the flow-control speed-down test for dynamic water in the pipeline is carried out using the self-developed karst pipeline model test system. The functional relation between the value opening and the flow velocity after flow-control in the pipeline is deduced, and the numerical results are supplemented and verified. Finally, the proposed dynamic water sealing method of flow-control speed-down is successfully applied to the water gushing treatment project of the China Resources Cement (Pingnan) Riverview Limestone Mine. The results show that: (i) As the degree of flow-control speed-down increases, the flow velocity in the pipeline decreases gradually and the pressure increases gradually. (ii) The flow-control speed-down test effectively reduces the flow velocity and increases the slurry retention rate in the pipeline. (iii) The large-flow and high-speed water inrush at the construction site is effectively treated, and the validity and applicability of the proposed method are verified, which have important guiding significance for the disaster treatment of large-scale water inrush in karst areas.

Our proposed integrated evaluation method for the grouting effect in karst areas is based on the cloud model (CM), the analytic hierarchical process (AHP), and a fuzzy comprehensive evaluation system. Our method fully considers the fuzziness and randomness of the evaluation indices, and bridges the gap between qualitative information and a quantitative evaluation value. The evaluation index system for the grouting effect is established by integrating metrics related to the construction technology, apparent parameters, and observational data from inspection holes and geophysical exploration techniques. First, the weight of each index is calculated using the AHP, which has been modified by the CM. Then, we calculate the cloud model membership degree for each index. Finally, we determine the comprehensive evaluation level by examining the similarity measures between the various cloud models. In this case study, we use our integrated method to evaluate the initial results of the grouting treatment project in the China Resources Cement (Pingnan) Limestone Mine. Our results are validated by subsequent monitoring results for this project. This study provides valuable insight into the treatment of water inflow in karst areas.

The visualization and analysis of massive, mull-source, mull-dimensional, heterogeneous, dynamic, and complex spatial data is playing an increasingly important role in 3D scene and geological modeling. There are great differences in various research fields regarding data acquisition techniques, morphological descriptions, and application purposes of spatial objects. Therefore, based on an existing three-dimensional visualization technology and analysis program of spatial data, an integrated processing method for the effective fusion and analysis of mull-source complex spatial data is proposed. This method combines a massive point cloud model with a digital elevation model, in addition to combining the complex stratum with fault modeling technology. The structural grid and geological grid are effectively combined to realize the unified modeling and visualization of natural and artificial objects. This method was then applied to a 3D modeling scene of deeply buried mines and a geological construction model for open pit mines. The comprehensive and effective utilization of multi-source geological data is realized by using this modeling method. Finally, the challenges of spatial data visualization from the aspects of the difficulties in spatial data acquisition, the complexities of the spatial structure, the constraint relations of geological bodies, and the complexity of the 3D modeling process are discussed in this study. Three specific suggestions are proposed. This study enhances the application efficiency of multi-source spatial data modeling technologies already in practice and provides reference for future applications and developments.

For the sealing problem of water gushing in karst pipelines, the sealing mechanism and method are investigated by numerical simulation, laboratory experiment and engineering application. The process of flow-control speed-down in large-flow and high-speed karst pipeline is simulated, and the change laws of flow velocity in the pipeline are analyzed. The modified construction solid waste cement-water glass grouting material is developed for plugging the water gushing in karst pipelines. The grouting sealing effect under different flow-control conditions is analyzed by grouting sealing tests. The results show that: (i) The flow velocity in the pipeline is effectively reduced by the flow-control speed-down. The greater the degree of flow-control, the more obvious the effect of speed-down. (ii) When the proportion of the modified construction solid waste cement-water glass grouting material in liquid a and liquid b is 1:1 and the mixing amount of waste red brick powder is 40-60%, the grouting sealing performance is the best. (iii) The slurry retention rate can be increased by the flow-control speed-down of dynamic water in the pipeline. The primary and secondary relationship of various factors affecting the grouting sealing effect is as follows: grouting quantity > initial flow velocity of the dynamic water > slurry type > water cement ratio > pipeline curvature. Research results are successfully applied to the water gushing treatment project of China Resources Cement (Pingnan) Riverview Limestone Mine, which have certain reference significance for the treatment of karst water gushing. (C) 2020 Elsevier Ltd. All rights reserved.

为解决深部软岩巷道大变形、返修率高等问题,在前人研究基础上研发了一种新型高预应力增阻大变形锚杆,该新型锚杆主要由托盘、夹片、杆体1、杆体2、连接套、锥形套、滑移套管等组成,可以施加不低于120 kN的高预应力,让压点可控为180～ 240 kN,变形量可在150～1 000 mm内灵活调节,锚杆的破断力可达到350 kN左右,且在变形的过程当中能保持较高的渐增支护阻力;室内静力拉伸特性试验结果表明,该新型锚杆与传统锚杆相比,具有“先抗后让再抗,防断增阻”的优良特性;为进一步研究新型锚杆的力学支护机理,在建立该锚杆杆体轴向力学特性曲线的基础上,采用Fish语言编程对FLAC3D数值模拟软件CABLE单元进行了相应二次开发,数值试验获得的试验结果与室内试验结果基本完全一致,高精度模拟了大变形锚杆的轴向拉伸力学行为;典型深部大变形软岩巷道-金阳煤矿-500 m疏水巷变形机制研究表明,围岩强度低、地应力高以及锚杆初始预应力低是导致其变形的主要因素,采用传统等强螺纹钢锚杆支护已经无法解决三者之间的突出矛盾,必须设法加强支护强度降低围岩的变形速率,同时提高支护构件适应围岩大变形的能力,才能保持巷道围岩的稳定;为验证该新型锚杆的支护效果,提出了以该新型高预应力增阻大变形锚杆为核心的新“锚网喷”支护技术,数值模拟及现场监测结果表明,该支护方案可有效提高锚杆受力状态,降低围岩变形量,与原支护方案相比,围岩最终变形量减少了近60％,取得了良好的支护效果,具有重要的推广应用价值.

The intelligent identification of and information extraction from discontinuities in fractured rock masses is crucial for the construction of a 3D fracture network model. A Deterministic-Stochastic Identification and Modelling (DSIM) method for use with discrete fracture networks is proposed using laser scanning technology. The identification of and information extraction from discontinuities is carried out using point cloud data processing by analyzing the outcrop characteristics of the joints and bedding planes visible on the surfaces of the rock mass. For joints, their orientations are extracted using a region growing algorithm, while their sizes are fitted using the Gauss function. For bedding planes, their orientations and sizes are extracted from the 3D point cloud and real image data in a semi-automatic manner. Afterwards, a constrained circle algorithm is applied to restrict the spatial size and shape of the polygonal fractures. In this way, the DSIM method is developed, which conforms to the outcrop characteristics of the bedding planes and joints. From the perspectives of the geometry and geostatistics of discrete fractures, complex discontinuities in 3D space are grouped and spatial density distribution functions are formulated. A corresponding program is compiled to identify and model discrete fracture networks. Finally, a case study was carried out in the Hejing Limestone Mine, Guangxi, China. The proposed DSIM method was validated with real site data and numerical verifications. In addition, the case study also demonstrates that the DISM method can effectively reduce the uncertainty in the identification and modelling of discrete fracture networks (DFN).

在系统研究巨野矿区某深井矿山胶带巷断层高压涌水特征的基础上,提出并实施了"疏水降压+浅部加固+深部截源"的治理方案.依据物探及水文地质分析,施工泄压钻孔进行疏水降压,使巷道周围含水层水压降至合理范围,结合中空螺旋注浆锚杆进行巷道浅部围岩加固,最终进行深部注浆封堵水源.为确定合理的疏水降压值,基于COMSOL有限元分析,建立渗流场-应力场耦合模型进行数值试验,模拟不同降压值情况下孔隙水压力以及围岩应力、位移的相应变化,数值试验优选最佳疏水降压值为3 MPa.现场实施后,有效封堵了巷道断层高压涌水,减水率达91％,且治理后巷道围岩稳定,满足了安全生产需要.

The characteristics of transient electromagnetic field in detecting shallow karst was studied focusing on the engineering and environmental problems caused by karst collapse. The shallow karst was generalized to be two types of geophysical models. The method of three dimensional finite difference in the time domain was used to simulate the transient electromagnetic responses. The resistivity，the karst size and the buried depth were selected as the comparison parameters. The numerically calculated differences of responses are bigger when the filled karst has the low resistivity and large size. The responses from the karst are mainly in the early stage. The transient electromagnetic field can identify nicely both the filled and half-filled shallow karsts. A field experiment was used to verify the numerical results in Guangxi. The transient electromagnetic profile revealed the known karst and found the unknown karst. The numerical and field experiments indicated that early observation and short time for turn off were better for small loop transient electromagnetic survey for shallow karst.

The effect of bolt length and the initial anchorage force in the secondary support of coal mine tunnel was studied. 18 computing conditions were established with parameters of the bolt length and initial anchorage force through the finite element method (FEM) program of ABAQUS, and the ef-fect of each parameter in the secondary support of coal mine tunnel was studied in a qualitative way, which was examined in the field test in a coal roadway. The research results have shown that 1) Com-pared against support completed at one time, the secondary support reduces the hoop stresses in the roadway surrounding rocks and lower the tendency of cracking in the surrounding rocks; 2) Increasing the bolt length and bolt initial anchorage force can improve the secondary support bolting effect; 3) From the perspective of cost and effect, increasing the bolt initial anchorage force plays a more efficient role in improving the secondary support bolting effect than increasing the bolt length.

On the basis of systematic study of the characteristics of fault lagging water inrush in the mining face 13301 of Wanglou coal mine, its seepage-flowing conversion mechanism was deeply ana-lyzed. Then the double-stage theory model of "mining disturbance-penetration weakened" is put for-ward. The stage of the fault permeability weakening is further divided into three stages: unsaturated seepage stage, slow and stable full seepage stage, and fast saturated seepage stage. Based on the com-mon characteristics of flow pattern changes in the process of water inrush, the mathematical and physi-cal model of each stage was established through Richard equation, Darcy's law, and Brickman equation respectively. Then finite element model for the coal mining faces was established, which realized the complete description of the process for the internal groundwater flow in the fault group from unsaturat-ed to saturated, from slow to fast in water flow speed, from weak to strong in permeability. The water inflow amount calculated through the model basically tallies with the reality.

In the tunnel surface-borehole configuration, the receiver is put into the borehole based on the advanced drilling on the tunnel face. With the data acquired in different depths in the borehole,the depth to time profile of transient electromagnetic responses can be obtained to determine the position of the water bearing structures. The physical modeling results show that no valid signals are observed in depth with a small magnetic moment excitation,while the acquired electromotive force are direction reversal in deep and late time with a large magnetic moment excitation. This phenomenon can be used to identify the abnormal bodies. The acquired profiles are obvious different on amplitude value and the reversal time with high or low resistivity target exist. This method will have no additional cost with existing borehole and is very fast in acquiring data. It can improve the accuracy in identifying the disaster sources.

Based on metal diaphragm’s radial tensile properties and according to the principle of matching the soil medium and the soil pressure sensor,a miniature Bragg grating soil pressure sensor was designed.The sensor leveraged the metal flake by external pressure resulting from the maximum strain.The theoretical pressure sensor sensitivity was 2.337 6 nm/MPa.Using AN-SYS to build up the finite element model of metallic flake could obtain the result that the model’s pressure sensitivity was 2.332 0 nm/MPa by extracting the radial displacement of the flake’s center. Using the pressure calibration platform which was formed by a desktop air pressure source,fiber grating demodulation instrument and other devices could calibrate the sensor.In the measurement range of 0.3 ~ 1 MPa,test shows that the sensor’s pressure sensitivity is 1.962 9 nm/MPa,representing an increase of 654 times than bare grating.Its linearity was 99.4%.The sensor has characteristics of low chirp and high stability.

针对深部高应力回采巷道在开挖支护后围岩所表现的变形量大、收敛速率快、持续变形时间长的特点,以某矿3309工作面煤巷为研究背景,详细分析了该巷道破坏特征及破坏机制,并针对此类巷道提出了“改善围岩力学性质”及“提高支护结构耦合性”的控制对策.结果表明,采用新支护技术方案对比原支护能有效抑制围岩塑性区的发展,降低围岩变形量.

山东省菏泽市彭庄煤矿西翼-500 m水平行人大巷属于典型中深部软岩巷道,由于支护对策不合理导致围岩变形破坏剧烈.为了得到围岩的变形规律及破坏机制,进行矿压监测、松动圈探测、围岩物理力学参数测试、地应力测试等研究,并提出2次耦合支护方案.为进一步研究2次耦合支护力学机制,对初次支护和2次支护后围岩塑性区与应力分布特点以及初次支护后10～60 d内进行2次支护围岩变形规律进行数值模拟分析.研究结果表明:2次耦合支护能有效控制围岩塑性区的发展,改善应力分布状态,最佳2次支护时间为巷道初次支护后的30～40d.2次耦合支护能有效控制围岩稳定,减小围岩变形,能为类似软岩巷道支护工程提供一定的参考.

The west track roadway in Pengzhuang coal mine is a typical soft rock roadway, which is buried more than 700 meters underground, and is frequently passing through the weak fractured mud-stone layers. To better master the deformation and failure mechanism of the surrounding rock, based on field monitoring, borehole camera and geological radar detection, rock physical mechanics test, in-situ stress test and 25 kinds of numerical comparison experiments were carried out respectively in this paper. The results show that the deformation of the surrounding rock can be effectively reduced by the com-bined support scheme of high strength and pre-stressed anchor (bolt) & bolt-grouting, and the support-ing structure integrity and bearing capacity can also be effectively improved. As a new supporting method of deep soft rock roadway, the supporting effect of the combined support scheme has significant advantages comparing with the traditional supporting method.