Similarity criteria and coal-like material in coal and gas outburst physical simulation

Coal and gas outburst is one of the main gas hazards in coal mines. However, due to the risks of the coal and gas outburst, the field test is difficult to complete. Therefore, an effective approach to studying the mechanism and development of outburst is to conduct the similar physical simulation. However, the similarity criteria and similar materials in outburst are the key factors which restrict the development of physical simulation. To solve those problems, this paper has established similarity criteria base on mechanics model, solid-fluid coupling model and energy model, and presented high similar materials. Combining with three groups of similar number, and considering similar mechanical parameters and deformation and failure regularity, the similarity criteria of outburst is determined on the basis of the energy model. According to those criteria, we put forward a similar material consists of pulverized coal, cement, sand, activated carbon, and water. The similar material has high compressive strength and the accordant characteristics with the raw coal, include density, porosity, adsorption, desorption. The new research is promising for preventing and controlling gas hazards in the future.

Physical simulation of rock burst induced by stress waves

The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material proper-ties, stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, the number and the length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway. When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was reduced to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the sur-rounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be avoided to some extent by pre-venting the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation.

A Physical Simulation Test for the RockBurst in Tunnels

According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model to simulate rockburst phenomena in tunnels. The prototype model comes from a typical section of diversion tunnels in Jinping Hydropower Station in China. The simulation of excavating tunnels is carried out by opening a hole in the model after loading. The modeling results indicated that under the condition of normal stresses in the model boundaries the arch top, spandrel and side walls of the tunnel produced an obvious jump reaction of stress and strain and the acoustic emission counts of the surrounding rock also increased rapidly in a different time period after the "tunnel" excavation, showing the clear features of rockburst. The spalling, buckling and breaking occurred in the surrounding rock of model in conditions of over loading. It is concluded that the modeling tunnel segment in Jinping Hydropower Station is expected to form the tensile rockburst with the pattern of spalling, buckling and breaking.

灵东煤矿上分层综放开采型煤相似材料模拟试验研究

以灵东煤矿为研究对象,采用室内试验、物理相似模拟、现场监测方法,选取了石膏+石子+水作为型煤相似材料,优化了材料配比,验证了相似材料的合理性。研究结果表明,石膏∶石子=1∶5,石膏∶水=0.6∶1,石子粒径为3~5 mm时,材料强度与原煤强度基本一致;选用该配比制作型煤时,模拟试验与现场监测的基本顶平均周期来压步距分别为11.3、12.2 m,误差仅为7.38%,表明该配比制作型煤进行物理相似模拟试验时可以反映现场覆岩真实变化规律。

煤层采动底板突水物理模拟试验研究进展与展望

【目的】底板突水受特定地质构造、水-岩-应力及采掘扰动等因素叠加作用影响,具有复杂性、隐蔽性、突发性等特点。【方法】物理模拟试验能较好地还原底板岩层与承压水赋存环境、直观展现采动底板裂隙扩展及突水路径演化全过程、实时获取灾变各阶段多源数据信息,因而在底板突水研究方面具有独特优势。【结果和结论】对底板突水经典理论、标准规范、模拟试验及工程实践等方面的研究成果进行了回顾,重点梳理了试验加载装置及水压模拟方式、相似材料研制及其特性指标、监测技术及其观测系统设计3个方面的研究进展,其中在模拟水-岩-应力耦合环境下的三维模型底板突水全过程信息捕捉方面有较大突破。面对数智化研究大背景,分析当前底板突水物理模拟试验领域存在的不足,并据此指出未来应重点关注大型三维底板突水综合试验平台研制、基于标准化的多特性相似材料配比数据库建立、多相多场多维耦合监测预警系统构建、人工智能等数智化技术融合应用研究等发展方向。提出的思考有助于从装置、材料、技术等方面提升未来物理模拟试验水平,从而更好支撑煤矿底板水害数智化防治基础研究工作高质量发展。

裂隙发育过程对采动裂隙椭抛带压实区的影响研究

采空区瓦斯抽采的关键是了解工作面上覆岩层裂隙的演化过程。为了研究综采工作面覆岩采动压实区演化规律,高效进行煤矿采空区瓦斯抽采工作,以神东某矿区2207工作面为原型,通过物理相似模拟实验,利用自主研发的覆岩裂隙监测系统将图像进行直方图均衡化增强和中值滤波去噪处理,获得二值化裂隙图像后利用分形理论定量描述裂隙率,对典型周期来压覆岩垮落裂隙率进行统计分析,建立了裂隙发育程度受工作面推进时间的时空函数和采动裂隙椭抛带压实区演变修正模型。结果表明:覆岩平均裂隙率变化符合DoseResp函数关系,裂隙的发育过程包括产生、扩展蔓延、压实闭合3个阶段,裂隙在产生、闭合这2个阶段发育速率较平缓,而在扩展阶段发育速率陡增。采空区上覆岩层裂隙场形成旧裂隙区、压实区和新裂隙区3个区域,裂隙发育周期的不同导致旧裂隙区与新裂隙区在发育状态、压实程度和空间形态上有着明显差异,这些差异导致了采空区覆岩非对称性下沉现象的发生。通过分析覆岩应力恢复与覆岩内部裂隙演变关系,进一步验证了采用DoseResp时间函数曲线可以很好的表现采空区上覆岩层裂隙异速演变特征。最后建立了考虑覆岩裂隙异速演变效应的采动裂隙椭抛带压实区修正模型,并结合现场工程实践,有效提高瓦斯抽取高位钻孔布置的准确性,为工作面的安全开采提供理论指导。

致密砂岩储层不同成藏环境下气水分布研究——以东胜气田十里加汗气区下石盒子组为例

中国致密砂岩气资源丰富,勘探开发潜力广阔,但已有的开发实践证明致密砂岩气藏的开发仍然面临巨大挑战,其中气水分布的精细认识是目前的主要挑战之一。为了深入揭示致密砂岩储层在不同成藏环境下的气水分布规律,本文以东胜气田十里加汗气区上古生界气藏下石盒子组1段和2+3段储层为例,在相似准则的基础上,建立宏观物理模拟实验,研究了一口水平井底部位置成藏过程中的不同充注方式、不同充注动力、不同岩心类型条件下的气水分布规律。结果表明:与连续充注相比,幂式充注下储层中的含气饱和度更高,平均比连续充注高7.95%,阶段性的充注方式使得注入气在停住期间可以进行饱和度场再分布,增大波及体积,气水分布类型主要以气水同层或含气水层为主,无边底水;充注动力研究发现,连续充注条件下强充注动力会加剧不均匀充注程度,降低充注气体的波及效率,导致致密储层中上部的大量地层水被封存,而幂式充注条件下强充注动力可以改善不均匀充注程度,改善波及区域的驱替效率,提高储层的含气饱和度;岩心类型实验显示,储层露头岩样由于其更强的非均质性,充注气体在低物性区域会绕行或充注不彻底,断裂带沟通或远离充注位置区域,充注气体未波及,形成不同规模水体。本次物理模拟实验结果与研究区测井解释结果趋于一致,研究结果对该区块不同成藏过程气水分布特征的认识具有参考意义。

榆树泉矿煤层开采覆岩破坏物理模拟试验研究

为研究煤层开采覆岩破坏情况,以榆树泉矿为工程背景,采用物理相似模拟试验,分析了煤层开采过程中覆岩的破坏规律,结合经验公式计算,确定了煤层开采覆岩导水裂隙带高度。结果显示,随着煤层开采,覆岩裂隙在纵向上的发育速度减缓,横向裂隙发育速度加快,范围扩大,且近工作面处的裂隙逐步向破碎型裂隙发展。覆岩形态在横向、纵向以及整体上呈现出先扩展延伸而后趋于稳定的特点,覆岩形态最终趋于“马鞍形”。覆岩位移量随着距煤层工作面垂直距离的增加而减小,并且位移量由两侧向中部递减。模拟导水裂隙带的发育最大高度为65 m,与经验公式计算的结果吻合,裂采比约为16。研究结果可为榆树泉矿顶板水害防治提供科学依据。

基于相似原理的基板玻璃铂金通道澄清物理模拟试验研究

玻璃液澄清作为基板玻璃生产关键工艺环节,其运行环境温度高且有耐火材料包覆,包括一系列物理与化学反应,过程非常复杂,无法进行在线研究。为实现对基板玻璃澄清排泡过程的研究,基于相似原理,构建铂金通道澄清物理模拟试验模型,借助澄清物理试验模型对玻璃液澄清排泡过程进行试验验证,为大流量下铂金本体设计和澄清工艺探究提供参考依据。

煤矿开采二维物理相似模拟试验平台

提出了一种煤矿开采二维物理相似模拟试验平台。该平台具有可模拟煤矿开采1000 m埋深以内的地应力、可调角度、可做垂向及两侧地应力模拟加载、可模拟煤层开采等功能,并经有限元分析验证了其强度和刚度。该平台可以为煤矿开采的安全和高效提供重要的技术支撑。

煤矿井下切顶卸压成巷及围岩控制方案的应用分析

以五矿切顶留巷为研究对象,利用UDEC数值模拟、物理相似模拟分析及工业实验验证的方法对切顶卸压成巷特性及控制方案进行了研究。通过UDEC数值模拟可知,当切顶的高度为7 m时,采空侧的巷道顶板无法切断,导致顶板出现离层情况;当切顶的高度为9 m时,基本顶可以沿着预裂切缝跨落,基本顶中的应力可以降低到19~24 MPa;当切顶高度继续增加时不会再影响应力分布。通过物理相似模拟分析可知,当切顶高度为7 m的时候,基本顶的断裂线处于实体煤帮侧,井下巷道围岩会受到破碎岩层的挤压,造成顶部的离层、垮塌;当切顶高度为9 m的时候,巷道基本顶会顺着预裂切缝断裂,此时在采空区跨落的岩层不会对巷道围岩产生挤压,具有明显的卸压作用;当切顶高度继续增加到12 m时,基本顶可以顺着预裂切缝跨落,但对卸压效果并没有明显的增加。根据现场工业试验验证可知,在切顶高度为9 m的情况下,采用高强锚索补强支护+单体柱支撑+U型钢+金属网挡矸支护能够显著提升围岩稳定性。

Physical simulation experiment and numerical inversion of the full life cycle of shale gas well

The ultra-low porosity and permeability,as well as complex occurrence and transport state of shale reservoir make it possess special L-type production characteristic curve and complicated shale gas flow mechanism.To solve the difficulty of collecting complete production data due to short production time and operation discontinuity,a full-diameter core physical simulation experiment on the full lifecycle production process of shale gas well depletion is conducted with the purpose of obtaining many important production data including complete pressure and daily gas output in the simulated production process of shale gas well.The experimental results show the production characteristic from simulation is consistent with those from gas well.Based on the simulation data,the critical desorption pressure(12 MPa)of core,free gas production(3820.8 mL),adsorbed gas production(2151.2 mL),the proportion of the daily gas production between free and absorbed gas under different time and formation pressure,as well as the production time and final recovery rate corresponding to abandoned pressure,can be determined accurately.Numerical inversion is carried out to calculate the production performance curve of shale gas well and predict the development effect of gas well based on well testing and similarity analysis of the dimensionless time between core experiment and gas well production.Finally,the permeability and the fracturing effect(fracture network density)as the keys to the effective development of shale gas reservoirs are proposed.The permeability is the fundamental factor and the fracturing technology is the major means.

榆神府矿区双煤层开采覆岩破坏及地面沉降特征研究

为研究双煤层开采条件下浅埋煤层覆岩破坏特征及地表沉降规律,以榆神府矿区典型浅埋煤层地质条件为基础,采用数值模拟方法,分析了6种不同工况下双煤层开采时覆岩破坏与地表沉降特征,并用物理相似模拟实验加以验证。结果表明:浅埋煤层覆岩破坏方式为全厚切落,留煤柱开采时隔水层中采动破坏呈现“泥盖效应”,不留煤柱开采时采空区两侧形成离层裂隙发育区,裂隙沿采空区两侧上方呈约45°发展;煤层开采时地表呈台阶式下沉,随着工作面推进,地表沉降中心不断前移,隔水层重量对地面沉降的影响逐渐减小,煤层厚度与地表沉降值呈正相关性;煤层开采过程中存在应力集中现象,上覆岩层中垂直应力沿煤层开采方向依次出现应力集中区、应力卸压区和应力集中区。

水泥基3D打印材料基础配合比试验与质量评价

水泥3D打印技术在土木建造工程和类岩石力学行为模拟中日渐推广,其水泥基3D打印材料方面却一直面临流动性、收缩性、可加工性等质量与成型控制方面的挑战和基础性配方缺乏的不足。首先针对水泥基3D打印实体质量评价的问题,建立了一套考虑成型全过程的6指标评估体系及其质量分级方法,包括流动性、挤出性、凝结时间、可建造性、密实性以及变形率,从打印过程、堆积成型、实体精度三方面实现对3D打印实体模型的质量评价;进而采用不同阈值范围的两阶段正交设计与打印测试进行了水泥基3D打印材料的基础性配合比试验优选,获得了一种综合打印性能较好的基础性配合比;最后对其打印成型水泥基3D实体模型进行单轴压缩试验,并评估了其类岩石力学特性,从而得到一种新型的类岩石水泥基3D打印基础性配合比,可为采用水泥基3D打印材料的工程建造和岩石工程物理模拟试验奠定基础。

废弃工作面遗留煤层气扰动储层空间划分——以屯兰煤矿12501工作面为例

废弃矿井扰动空间精确划分是遗留煤层气资源评价和开发利用的重要基础,以山西西山矿区屯兰煤矿2号煤12501工作面为例,采用应力场数值模拟、裂隙场数值模拟和物理相似模拟的方法,综合研究了采动过程中及采空区稳定后的应力场、裂隙场的分布规律。研究结果显示:物理相似模拟与数值模拟吻合度高,综合以上3种方法,最终将12501废弃工作面遗留煤层气扰动储层空间划分为底板裂隙区、重新压实区、导气裂隙区和承压区。底板裂隙区位于煤层中工作面的正下方,整体采动裂隙发育区域呈现出靠近开采煤层为底面的倒梯形台,裂隙场数值模拟结果显示其垂向深度为22.3 m,其深度为开采煤厚的5.58倍。承压区位于工作面四周的未开采煤储层,在工作面倾向的边界起分别向外延伸70 m,在工作面走向的边界起分别向外延伸100 m的位置上,数值模拟结果显示承压区煤储层垂向应力峰值为远大于煤层原始状态的应力数值,但小于垂层煤样的平均抗压强度。导气裂隙区主体位于开采煤层工作面边缘区域,底部为高度约为13.2 m的岩层垮落带,紧邻垮落带上部为高约33.6 m的岩层断裂带,断裂带内竖向裂缝不断扩展贯通离层裂缝。导气裂隙区整体形状为梯形台,其高度为开采煤厚的11.7倍。重新压实区主体分布于开采工作面采空区的中间部分,倾向宽度为110 m,走向长度为1 268 m。此区域主要为弯曲垮落的覆岩构成,整体形状为梯形台,位于导气裂隙区内部。导气裂隙区为遗留煤层气资源的开发有利区。

大巷煤柱回收工作面覆岩破坏及应力演化规律研究

以赵家梁煤矿大巷煤柱回收为研究背景,用物理相似模拟实验和现场监测等方法,对大巷煤柱回收工作面覆岩破坏及应力演化规律进行研究。结果表明:3101工作面采空后,靠采空区侧保护煤柱应力峰值为5.12 MPa,距采空区7 m;3102工作面采空后,靠采空区侧保护煤柱应力峰值为5.2 MPa,距采空区8.5 m;大巷煤柱回收工作面回采完成后,保护煤柱上方应力分布呈马鞍形,两侧采空对大巷煤柱回收工作面影响较小。现场实测数据与物理相似模拟实验所得数据相符,验证了相似模拟实验用于类似问题研究的可行性。

Experimental study on the movement law of overlying rock non-pillar coal overhead mining

Pillarless coal mining technology is a new practical technology.Based on the compensating mechanical behavior of the Negative Poisson’s Ratio(NPR)anchor cable on the roof,the roadway was successfully retained by the top cutting and pressure relief technology.This study utilizes the Digital Speckle Monitoring(DIC monitoring),stress-strain monitoring,and infrared thermal imaging systems to conduct physical model experiment of similar materials from the displacement,stress-strain,and temperature fields to investigate in depth the fracture change law of the overlying rock.In addition,it uses FLAC3D numerical simulation to invert the surface displacement settlement.The results show that the non-pillar overhead mining under the 110 mining method has little influence on the rock crack in the middle of the coal seam,and the crack development area is mainly concentrated in the overlying rock mass of the upward coal seam.The compensatory mechanical behavior of NPR anchor cable and the dilatation characteristics of rock mass have a good effect of retaining roadway along goaf,and can also reduce surface settlement.The 110 mining method provides a scientific basis for ecological environment protection and the development of other kilometer deep soft rock high ground stress underground projects.

厚土层区煤层开采红土隔水稳定性评价

为评价薄基岩厚土层地质结构下煤层开采后红土层隔水稳定性,以某综采工作面为研究对象,通过钻探法和物理相似模拟研究了导水裂隙带高度,采用孔组抽水和水化学分析法评价了上覆红土层隔水稳定性。结果表明,综采放顶煤采煤条件下采厚9.57 m时,实测导水裂隙带高度为92.01~101.17 m,裂采比9.61~10.57,与临近矿区实测值相比,明显偏小。物理相似模拟预测结果为136.61 m,导水裂隙带高度位于红土层顶界,与实测值相比结果偏大。抽水试验和水质评价表明,采空区第四系松散含水层和直罗组风化基岩之间水力联系较弱,煤层开采对红土层的隔水稳定性影响较小。红土层对导水裂隙发育存在抑制作用,是薄基岩区保水开采的重要保障。

CO_(2)驱不同注采模式提高采收率实验研究

非均质、黏性指进是决定CO_(2)驱开发效果的关键因素,而调整注采方式是控抑气窜、扩大波及的有效手段。目前该方向的研究以数值模拟为主,亟需开展CO_(2)驱不同注采方式的物理模拟研究,以进一步明确CO_(2)驱连续气驱、轮换开采和注采耦合等模式的动用机制、开发特征和油藏适应性。通过CO_(2)驱相似物理模拟实验,对比CO_(2)连续气驱、轮换开采和注采耦合模式的开发特征差异,并分析CO_(2)驱不同注采模式的适用性。实验结果表明:连续气驱模式下不同渗透率区域开发效果差异大,低渗透率区域见气后的增油潜力较低,适合相对均质油藏开发;轮换开采模式通过采油井交替开启,改变注采井间主流线方向,有效改善非均质储层中低渗透率区域的开发效果,适合强非均质油藏或气窜后的开发调整阶段;注采耦合模式利用注采交替引起的压力场交替变化,可以较均衡的提高全区波及范围,提高难动用边角区储量动用率,适合弱非均质油藏或前期开发阶段。

地面压裂坚硬顶板对矿山压力显现影响的实验研究

地面压裂是控制煤矿坚硬顶板减少矿山压力灾害的一种新方法。但该方法的有效性以及地面压裂形成的水压裂缝的产状对矿山压力显现的影响尚待进一步研究论证。通过物理相似模拟实验,在模型中坚硬顶板内分别不预制裂缝、预制水平裂缝和预制垂向裂缝并模拟煤层开采,研究了采动过程中顶板的周期垮落、坚硬顶板的破断和工作面的矿压响应。结果表明:随煤层开采覆岩呈“■”型垮落规律,即先垮落采空区上方A区域,然后沿工作面推进方向垮落与A临近的B区域,再垮落A、B上方的C区域,间隔一定周期B、C区域同时垮落;受水平裂缝影响,顶板周期垮落步距平均缩短23.08%;受垂向裂缝影响平均缩短19.23%;含水平裂缝和垂向裂缝的坚硬顶板均提前破断,平均破断步距缩短10.23%;工作面推进至裂缝影响区时,覆岩作用在开切眼煤壁附近的矿山压力和工作面超前支承压力降低,表明压裂坚硬顶板可降低工作面矿压。研究成果对于揭示覆岩垮落规律、地面压裂控制矿压显现规律和矿山压力灾害防治具有重要意义。