AbstractThe mechanical properties of a coal–rock body were examined through uniaxial compression tests, and the rupture process of the coal–rock body was monitored in real time using a combined acoustic emission (AE) monitoring system and a digital image correlation (DIC) full-field strain measurement system. From a comparison of the mechanical properties of coal and sandstone, clear differences are apparent regarding the uniaxial compressive strength, deformation characteristics, and damage mode; the brittle failure characteristics of the coal samples are also more evident. The change in AE energy reflects the accumulation and release of elastic energy during the rupture process, and the evolution of AE localization points under different stress levels can effectively reflect rupture propagation. Further, the DIC full-field strain measurement method can quantitatively monitor the evolution of the displacement and strain fields at the marking point and surface simultaneously, thereby overcoming the limitations of traditional empirical and qualitative rupture processes. During monitoring, the AE focuses on the internal rupture of the specimen and the DIC focuses on the surface deformation. These complement each other and reflect the rupture process more comprehensively.

In the development of mineral resources and engineering construction in the western region, sandstone is one of the main engineering geological aquifers, and the freezing and thawing environment affects the mechanical and deformation characteristics of sandstone. In order to study the deterioration and damage characteristics of mechanical properties of loaded rocks under the influence of freeze-thaw environment, red fine sandstone in Shaanxi province was taken as the research object, and freeze-thaw cycle tests and uniaxial compression tests were carried out for 0, 5, 10, 20 and 30 times, and the stress-strain curve and mechanical characteristic parameters of the whole uniaxial compression process of frozen-thawed sandstone were obtained. The mechanical characteristic parameters of frozen-thawed rocks were analyzed, and the deterioration model of rock mechanical properties under freeze-thaw environment was established. Based on the influence of freeze-thaw environment on rock damage, considering the characteristics of rock compaction stage in deformation stage, a modified statistical damage constitutive model considering compaction stage is established. The results show that with the increase of freeze-thaw cycles, the proportion of rock compaction stage is increasing, and the peak value should also increase gradually. Brittle failure occurs in the first 30 freeze-thaw cycles, and the brittleness of rock is obviously weakened after 30 freeze-thaw cycles, and the strain softening stage is obvious. The loss rate of mechanical characteristic parameters increased rapidly in the first 10 times of freeze-thaw cycle, and then slowed down obviously. After 30 freeze-thaw cycles, the peak strength loss rate is 47.27% and the elastic modulus loss rate is 60.35%. Among them, the loss rate of mechanical characteristic parameters increases linearly with the number of freeze-thaw cycles, and the mechanical properties of rocks decrease exponentially after freeze-thaw. The peak strength and elastic modulus of rocks under freeze-thaw environment can be accurately predicted by using the pore characteristics of rocks under freeze-thaw environment. The modified statistical damage constitutive model considering the compaction stage has a higher fitting degree with the test curve, and the modified theoretical model can provide reference for the deterioration of mechanical properties and damage prediction of frozen-thawed rocks.

Abstract The mechanical properties of a coal–rock body were examined through uniaxial compression tests, and the rupture process of the coal–rock body was monitored in real time using a combined acoustic emission (AE) monitoring system and a digital image correlation (DIC) full-field strain measurement system. From a comparison of the mechanical properties of coal and sandstone, clear differences are apparent regarding the uniaxial compressive strength, deformation characteristics, and damage mode; the brittle failure characteristics of the coal samples are also more evident. The change in AE energy reflects the accumulation and release of elastic energy during the rupture process, and the evolution of AE localization points under different stress levels can effectively reflect rupture propagation. Further, the DIC full-field strain measurement method can quantitatively monitor the evolution of the displacement and strain fields at the marking point and surface simultaneously, thereby overcoming the limitations of traditional empirical and qualitative rupture processes. During monitoring, the AE focuses on the internal rupture of the specimen and the DIC focuses on the surface deformation. These complement each other and reflect the rupture process more comprehensively.

采用数值分析法对云县至凤庆高速公路随带开挖工程所不同埋深岩层竖向位移变化情况进行了解,通过归纳围岩土体变形规律提出具体的应对之策.结果发现:同一监测断面内,围岩变形峰值出现在隧道拱顶中心轴线上方,围岩沉降大小与其同隧道拱顶的距离呈反相关关系,变形曲线呈W型;岩层变形量与拱顶的距离呈正相关关系,岩层变形量在拱顶上方70 m之后越来越小,表现为直线.

Exploring the phenomenon of surface cracks and the abnormal phenomenon of ground behavior during coal mining under gully landforms, laboratory physical similarity simulation models were established to study the movement characteristics and ground behavior laws of working faces of different mining methods under gully landforms. The results indicate that in cases when a roadway is situated below the top of the slope, the corresponding deformation of the surrounding rock of the roadway is aggravated by the mining stress. Furthermore, when a roadway is located below the base of the gully, it is less affected by mining; thus, it could remain relatively stable. The ground behavior laws of working faces in gully geomorphology areas are associated with the position of the working face and the direction of working: when mining towards the gully, the ground behavior appeared relatively gentle and the surface slipped towards the gully; when mining away from the gully, the ground behavior appeared intense, the pressure was sudden and short, and with the increase in overburden thickness, the interval distance periodically decreased. When a working face passes through a gully, dumping of the hydraulic support should be prevented in the section of mining towards the gully; in sections of mining away from gully, the support strength should be strengthened to prevent the support and other equipment from being crushed. In actual mining, mining towards a gully should be adopted as much as possible in the stoping of the working face. In this way, the ground behavior is gentle, the interval distance periodical weight is longer, and the advance abutment pressure is small.

Due to advantageous sensitivity to low resistance and noncomplicated operation, transient electromagnetic methods are the most widely used geophysical methods for advanced detection of coal-mining-disaster water bodies. To realize real-time imaging, we developed a wireless antenna attitude angle measuring instrument based on an electronic compass, which measures antenna attitude angle real-time. According to attitude angle information sent through WiFi to the host of transient electromagnetic real-time imager instruments, current transmission, signal acquisition, and antenna rotation angle information are achieved for real-time imaging. We studied the direct algorithm of the apparent resistivity of the whole-space transient electromagnetic field in overlapping loop mode based on double-logarithmic-transform piecewise least-squares fitting, which not only ensures accuracy but also accelerates calculation. On-site detection was carried out in a coal mine, and the detection results are generally consistent with the drilling results.

以云县至凤庆高速公路隧道开挖工程为研究对象,采用数值分析和相似模拟相结合的手段,对其处于不同埋深岩层围岩变化规律展开研究.为保证隧道开挖施工安全,分别对隧道拱顶围岩压力、拱腰围岩压力以及上方围岩压力进行监测.基于监测数据分析围岩应力变化规律,明确了隧道开挖对其拱顶上部岩层影响程度和拱腰不同位置岩层应力在应力释放阶段所表现形式.研究表明,拱腰围岩竖向应力在左右隧道开挖整个施工阶段,应力变化曲线主要可分为3种类型,逐渐增大最终趋于稳定型、先增加后快速下降再缓慢增加型和先增加后快速下降至0型;根据拱顶及拱顶上方岩层竖向应力曲线,可将隧道拱顶上方岩层分为3种状态,拱顶上方0～50 m应力释放"高影响区",拱顶上方50～150 m岩层属于应力释放"次影响区",拱顶上方150 m以上岩层属于应力释放"缓影响区".

以云县至凤庆高速公路隧道工程为背景,提出采用现场监测和数值分析结合的可行性研究方案.通过数值分析与实际工程对掌子面的位移进行研究.详细分析不同开挖进尺情况下掌子面前方不同位置处的岩层位移变化规律后,发现掌子面开挖进尺与掌子面前方岩层变形规律,开挖进尺越大,对其掌子面的稳定越不利,同时发现掌子面岩层可以提供一部分阻力,阻止掌子面前方岩体朝掌子面移动,以及掌子面上方岩层的重力势能作用.提出红线开挖进尺的确定方法和现场实际开挖进尺的确定准则;讨论了施工过程中掌子面前方岩层存在的挤出现象,表明采用红线开挖进尺乘以安全系数更能保证现场的施工安全.

In order to further investigate the impacts of the water environment on the mechanical properties of rocks for an engineering project, taking the water-rich conditions in a coal mine as the engineering background, a series of tests were conducted, including the uniaxial compression test, the conventional triaxial compression test, and the constant axial pressure test on the cementitious sandstone. This was conducted along with the establishment of a multi-linear strain softening constitutive model. According to the tests, the following conclusions can be drawn. Firstly, as the water content increases, the weakening effect of water on the rock mass was obvious. Under various stress paths, the water weakened the rock body to various degrees. In other words, the weakening effect of water on the rock mass was either inhibited or promoted under different stress path conditions Secondly, under various stress paths, the turning point strength and strength variance rate of the rock mass’ mechanical properties decreased linearly with the increase of water content. This further proves that water has a weakening effect on the rock mass, showing that the failure of the specimen changes from brittleness to ductility. Thirdly, the test sample demonstrated different types of damages including the tensile failure, transformation from tensile-shear composite failure to shear failure, and expansion failure under three stress path conditions. In addition, the unloading process demonstrated some dynamic failure characteristics. The research aims to provide some foundational insights for the scientific design and safe construction of the mine and other underground engineering, especially rock mass engineering in the multi-water environment.

A large amount of data would be generated during the process of microseismic monitoring, and data transmission with the cable has some shortcomings such as poor anti-interference, time-consuming, laborious, high cost, and low construction efficiency. On the other hand, the influence of signal diffraction and the multipath effect will greatly cut down the energy of the signal during the wireless transmission in the complex mountainous area. The wireless transmission system based on Wi-Fi is designed in this paper, which includes the base station and data transceiver. The maximum distance and transmission rate at point-to-point communication of the base station are up to 1000 m and 150 Mbps, respectively, and it provides the communication backbone line for the network. The data transceiver adopts the network protocol based on Ad Hoc, and the transmission distance is up to 200 m at the condition of complex topography and lush mountains. We have applied the system to in-site microseismic monitoring with 28 geophones of the coalbed methane fracturing in South Chongqing. It achieved a good performance with a transmission rate of 1.2 Mbps, a time delay of 1.95 ms, and a signal strength of up to −52.3 dBm for real-time data transmission in the field. The results show that the system has the advantages of low BER, fast transmission speed, long communication distance, and stable and safety hardware and has a great value for more applications of microseismicity in complex topography.

以楚雄段施工6标倒虹吸交通洞施工支洞区间隧道工程为背景,提出隧道爆破振动现场监测试验的可行性研究方案.通过现场试验对爆破振动速度和震率变化规律进行研究.详细分析了现场试验爆破点距离监测点距离处最大振动速度变化规律,发现爆破振动速度和震率符合M.A.萨道夫斯基地振动最大速度经验公式.

微震监测技术是目前预测岩体损伤最有前景的探测技术之一.为提升微震监测技术的准确性,以云县至凤庆高速公路隧道开挖工程为背景,现场进行了微震监测,并对爆破、打炮眼、电气干扰及岩石破裂信号进行了分析.结果表明,可以根据体变势、频谱最大频率、视体积及视应力大小等特征来区分不同信号.其中爆破信号的体变势、视体积和视应力的数值最大,频谱最大频率多数分布在0～10 Hz.岩石破裂产生的微震信号的体变势大多集中在0～10 m3,数值较大,频谱最大频率多数分布在50～60 Hz和180～200 Hz.研究结果对剔除干扰信号和指导现场微震监测具有重要意义.

井下瞬变电磁随掘探测技术是探测掘进面前方致灾水体的有效方法,从硬件方面评估仪器对致灾水体的分辨能力,是仪器能够在井下正确使用的重要手段.通过比较二次场绝对差和仪器分辨率、叠加后背景噪声之间的大小关系,分析含水致灾体识别的硬件条件和评估依据;提出从硬件方面评估井下瞬变电磁对致灾水体分辨能力的计算方法:根据致灾水体结构建立三维地质模型,推导梯形波关断与负阶跃波关断二次场感应电压的关系,在GPU上采用全空间三维有限差分并行算法计算了致灾水体二次场响应;测量某瞬变电磁仪的关断时间和综合噪声,根据致灾水体的硬件分辨依据,从硬件方面评估井下瞬变电磁仪对导水陷落柱、充水采空区的分辨能力.为井下瞬变电磁探测仪器的研制和现场准确探测提供技术参考,具有重大的研究意义.

页岩气作为一种非常规天然气资源,我国的页岩气资源分布范围广泛,其储量丰富开采潜力大.页岩气储层渗透率超低,气体赋存状态复杂多变导致其开采率相对较低,开采难度大.目前,页岩气的开采通过压裂增透技术,已经实现了长期稳定生产,极大提高了开采效率.为了检测压裂影响范围,检验裂缝发育状况,国内的科研单位引进了多种型号的微震仪,并开展了相关的科研工作.本文提出了一种设计方案,可实现微震检测仪数据无线传输.在重庆等地的多个页岩气压裂施工现场,开展了压裂微震监测试验,验证了无线传输的自组网技术的性能.

页岩气储层渗透率超低,气体赋存状态复杂多变,采用常规天然气抽采方法显然不能实现持续、充足的开采量.目前,页岩气的开采通过压裂增透技术,已经实现了于长期稳定生产,极大提高了开采效率.为了检测压裂影响范围,检验裂缝发育状况,国内的科研单位引进了多种型号的微震仪,并开展了相关的科研工作.设计了一种无线传输的微震检测仪,介绍了微震检测统的原理与仪器各部分的组成.在西南地区页岩气压裂施工现场,通过大量的野外实验,验证了本款无线微震检测仪的各项性能.

针对南方煤矿安全生产火灾风险管理评估的问题,选取东林矿火灾事故(煤层自燃倾向性等级均为Ⅱ类)为分析对象.列出了矿井火灾事故风险目录并采集煤矿火灾事故风险信息;建立了矿井火灾事故人、机、环、管耦合的事故模拟情景,计算矿井火灾事故风险损害后果和风险可能性,绘制矿井火灾事故风险矩阵图,得出事故风险等级值;根据矿井火灾事故风险评估的结果,形成动态事故风险监测机制,提出火灾事故风险的管理标准、技术措施、管理措施和应急准备.

以开展煤矿事故风险管理工作为需求,以中梁山北矿8大类主要煤矿事故中的瓦斯事故为分析对象,开展煤矿事故风险评估工作.列出了“煤矿瓦斯事故风险目录”;用“煤矿瓦斯事故风险采集表”计算了“煤矿瓦斯事故风险损害后果”和“煤矿瓦斯事故风险可能性”,绘制“煤矿瓦斯事故风险矩阵图”,得出煤矿瓦斯事故风险等级值;根据煤矿瓦斯事故风险评估的汇总结果,提出采用综合分析和历史比对方法,形成动态煤矿瓦斯事故风险动态监测机制.并提出风险的管理标准、技术措施、管理措施和应急准备.该研究为重庆市典型煤矿瓦斯事故风险管理提供一个应用示范案例.

The water accident in the 8 major coal mine accidents in Donglin Mine(the maximum water discharge is 1 950 m3/h)is taken as the object of analysis,and the "six tables and one chart of Chongqing Municipality′s Emergency Risk Management Operation Guide(Trial)"as the core framework to carry out coal mine accident risk assessment.First of all,listed the "coal mine water accident risk catalog","coal mine water accident risk collection table";secondly,calculated "coal mine water damage accident risk damage"and "coal mine water accident risk possibility",then drew"coal mine accident risk matrix,and the risk grade value of the accident of water damage in coal mine was obtained.According to the summary results of risk assessment of coal mine water disaster,the manage-ment standard,technical measure,management measure and emergency preparedness plan were put forward.Through the research of this paper,it has provided a typical example of the risk of coal mine accident in Chongqing.

选取东林矿8大类主要煤矿事故中的运输事故为分析对象,开展煤矿事故风险评估研究.列出"煤矿运输事故风险目录"、"煤矿运输事故风险采集表";计算了"煤矿运输事故风险损害后果"和"煤矿运输事故风险可能性",绘制"煤矿运输事故风险矩阵",得出煤矿运输事故风险等级值;根据煤矿运输事故风险评估的汇总结果,提出风险的管理标准、技术措施、管理措施和应急准备方案.通过研究,为典型煤矿运输事故风险管理提供一个应用示范案例.

为了查清岩层中含水层发育情况,为矿井施工和开采提供安全保障,采用井液电阻率测量技术,利用井液电阻率曲线随时间变化产生的离差现象,绘制离散曲线,通过分析计算,查明地下水运动状态,判别含水层类型,并确定含水层位置和涌水量.实例测量结果表明,该方法能有效查明含水层发育情况,可为矿井设计、施工提供防治水技术参数.