基于改进的Mogi模型对樟树盐矿采空区地面沉降的分析

樟树现代医药物流中心项目区周边采卤井引发的地面沉降是关系到项目区能否投入建设的关键问题。Mogi模型是基于半无限空间弹性理论的地面沉降预测模型,而盐矿采空区地表沉降变形的主要诱因是地下腔体体积的蠕变收缩,通过引入稳态蠕变阶段盐溶腔体积收缩解析解,对Mogi模型进行改进,并应用于项目区的地面沉降预测,利用沉降叠加的方法获得采卤井群诱发地面沉降发展趋势。结果显示：樟树医药物流中心周边卤井群蠕变引发的地面沉降及地面倾斜均在地基基础设计规范要求范围内;随着与井群距离的增大,项目区内地面倾斜呈现先增大后变小的趋势。同时,利用改进的Mogi模型得到的地面沉降和地面倾斜与相同条件下数值模拟沉降结果有着良好的相似,改进的Mogi模型为盐矿采空区及盐穴储气库的地面沉降分析提供了一种准确、快速的方法。     

厚覆盖层矿山地下开采地表塌陷机制分析

随着矿山开采深度的不断增加,厚覆盖层成为部分深部地下矿山的主要特点。以物探调查、变形监测以及理论分析为手段,对某典型厚覆盖层金属矿山地下开采初期地表塌陷的成因与机制进行了分析。结果表明,厚覆盖层中存在的大面积采空区为地表塌陷变形提供了空间,采空区顶板厚度较小为地面塌陷的发展提供了条件,采空区的存在是地表塌陷的主要原因。地表出现塌陷以后,塌陷范围以塌坑为中心继续向外扩展,受覆盖层内采空区走向,断层和岩层分界面等地质缺陷影响,塌坑向西、向南与向北三个方向上的扩展较向东快得多。降雨会增大塌坑向外扩展的速度,因为地表水的下渗加快了塌坑周围岩土体向塌坑方向的移动和下沉。     

废弃采空区裂隙带高度预测模型及应用

煤炭开采引起覆岩破断及地表下沉,覆岩及地表运移规律可反映裂隙带高度的动态演化过程。因地表下沉滞后于煤炭开采,对于废弃采空区,长期压实作用导致裂隙带高度较采动期间有所降低。基于地表点下沉速度的阶段特征将裂隙带高度的演化过程分为2个阶段,第1阶段裂隙带发育对应岩层破断逐步向上传递的过程,第2阶段裂隙带高度降低对应离层及裂隙闭合、断裂岩层受压后变形回弹及破碎岩体自然压实的过程。着眼于压实作用对裂隙带高度的影响,根据煤层采厚、垮落带和裂隙带岩层变形量及地表下沉值之间的定量关系,建立了第2阶段裂隙带高度预测模型,并结合太平煤矿实测结果进行验证,采用控制变量法分析了单一因素影响下废弃采空区裂隙带高度的演化特征。结果表明：废弃采空区裂隙带高度受控于垮落带块体强度、垮落带初始碎胀系数、采动期间裂隙带高度最大值及对应的垮落带高度、煤层埋深、地表最终下沉量等因素,太平煤矿采后15 a的裂隙带高度实测值11.36～13.00 m与理论预测值12.75 m吻合度较高,模型的可靠性得到验证。最后,应用此预测模型对武安煤矿（关停矿井）2002－2003年采空区裂隙带高度开展理论计算,结合地空瞬变电磁探测确定了地面瓦斯抽采钻孔理想的终孔位置并成功开展了地面钻孔瓦斯抽采试验。     

盐岩地下储备库引发地表沉陷事故的风险分析

在盐岩储备库的建设和运营过程中,由于腔体不断收缩而导致上覆岩层发生变形,从而引起储库上部地表发生碟状沉降变形,甚至造成地表塌陷事故是盐岩地下储备库的重要事故类型之一。针对盐岩地下储备库引发的地表沉陷事故进行分析,找出了该类事故的发生机制并建立相应的故障树模型,计算得到地表沉陷事故的14种发生模式和10个基本致因事件,并提出了相应的控制措施。并从风险分析的角度对盐岩储备库引发的地表沉降事故的后果严重性进行预测分析研究,并以湖北云应盐矿为例,假设该地区在储气库的建设或运营过程中发生地表沉降事故,采用模糊综合评价法对该类事故后果的严重性进行风险预测,得出后果为可忽略、需考虑、严重、非常严重、灾难性的概率分别为0.24、0.28、0.29、0.15、0.04。为有效预防盐岩储备库运营引发地表沉陷事故以及在事故发生前进行损失严重性预测提供了依据和方法     

岩盐水溶开采沉陷新概率积分三维预测模型研究

开采沉陷的准确预测是减小和杜绝开采沉陷灾难发生的前提，传统概率积分法难以应用于岩盐水溶开采复杂条件下的地表沉陷预测。因此，充分考虑上覆岩层在复杂地质条件下可能表现出来的各向异性、岩盐溶腔的不规则性，建立了新概率积分三维预测模型；并从力学角度，对三维预测模型的参数进行了研究，获得了模型参数与上覆岩层力学参数之间的关系。该模型能够对复杂地质条件和不规则采空区引起的地表沉陷进行较为准确地预测。     

Analysis of surface subsidence mechanism and regularity under the influence of seism and fault

Surface subsidence with various formation mechanisms possesses varied and complex influencing factors. Thus, studying surface subsidence mechanism and regularity under different special geological conditions is important in implementing disaster prevention and reduction programs. This paper focuses on goaf surface subsidence under the influence of the interaction between seism and fault, taking the Changping Expressway surface subsidence as the case study. In the full investigation of the engineering geological conditions in research area, the graphic method and numerical simulation method FLAC3D are adopted to study surface subsidence mechanism and regularity, after which the influence of seism and fault on surface subsidence is explored. The results show that the Changping Expressway surface subsidence is caused by earthquake-induced reactivation of the old goaf. Under the influence of geological fault, the maximum surface settlement significantly increased, the location of the maximum surface subsidence became close to the fault side, and the subsidence deformation showed an apparent discontinuity near the fault.     

Prediction of sub-surface subsidence movements due to underground coal mining

Summary The theoretical model of the relationship between sub-surface and surface subsidence movements proposed earlier by the authors of this paper is briefly described and further tested against another case history example. Using this model, the magnitudes of the maximum subsidence, tilt and horizontal strain at sub-surface horizons between the ground surface and seam level are predicted in terms of the magnitudes of the corresponding components at the surface due to the extraction of subcritical panels with a wide range of width-depth ratios and the results presented in the form of nomographs and tables. These graphs and tables could be used to estimate the maximum subsidence, tilt and horizontal strain at any chosen sub-surface horizon associated with the extraction of a subcritical panel from the known corresponding maximum values at the surface.The proposed theoretical model can also be used to predict sub-surface subsidence components at any point within the zone influenced by the extraction of a panel from the corresponding surface subsidence components which may be obtained from field measurements or pre-calculated using any existing method of surface subsidence prediction. As an example, the profiles of surface and sub-surface subsidence at various horizons between the ground surface and the seam level resulting from the extraction of an assumed sub-critical longwall panel are predicted using the theoretical model together with the empirical method of surface subsidence prediction. The pattern of sub-surface subsidence movements in the strata overlying the panel is examined.     

宁东煤炭基地金凤煤矿GPS地面变形监测研究

掌握采空区地面变形规律是科学预防和治理地面塌陷的前提与基础,是煤矿地质环境动态变化的重要监测内容。以宁东煤炭基地金凤煤矿为例,在收集、了解金凤煤矿0110202和011805工作面开采时间、开采深度、开采煤厚、工作面长度、工作面宽度、工作面走向等参数的基础上,建立工作面地表自动化GPS监测点,将工作面开采进程与地面变形时间、空间统一起来,研究工作面地面变形时间和变形量的规律。结果表明,金凤煤矿011202工作面地面变形一般在采后13个月左右进入变形活跃阶段,从开始变形到地面开始稳定的持续时间为16～19个月,最大累积变形量约为3300mm;011805工作面采空区地面变形一般在采后10～11个月进入变形活跃阶段,从开始变形到地面开始稳定的持续时间为13～16个月,最大累积变形量约为2600mm。研究结果为金凤煤矿后续工作面开采地表变形规律及类似开采条件下采空塌陷的预防与治理提供了定量化的依据。     

大面积堆载作用下滨海吹填软土地基变形特性研究

通过在大面积堆载场地设置地表沉降监测仪器,进行历时3年的现场监测,对大面积堆载作用下滨海吹填软土地基的沉降变形特性进行了分析研究,揭示了大面积堆载作用下软土地基变形特性不同于常规荷载作用下软土地基变形特性的规律,总结了大面积堆载条件下软土地基变形沉降的规律,利用数值计算方法模拟了地基沉降变形规律,分析了地基破坏模式,数值计算结果与现场监测结果有着较好的一致性,在400 kPa堆载力的作用下,最大沉降值约为1.6m。     

特大采空区上覆岩层地压与地表塌陷灾害监测研究

大红山铁矿采用无底柱分段崩落法开采形成了3个规模巨大的采空区,采空区上覆岩层移动与地表开裂塌陷将导致露天采场发生滚石地压灾害、井下采场产生空气冲击波次生地质灾害、地表与井下发生泥石流地质灾害等。针对上述问题,采取了多通道微震监测、非接触式岩移实时监测、基于手持式GPS仪的地表开裂范围监测和基于全站仪的地表沉降与水平移动监测的多种综合地压监测手段,对上覆岩层崩落高度、上覆岩层下沉变形量、地表开裂范围和地表沉降与水平移动等进行了监测,通过两年的监测获取了大量的监测数据,经分析表明,采空区上覆岩层崩落高度约在+1 090⁺1 060 m,上覆岩层+1 090 m平巷内观测点累计沉降量为1 350 mm,地表开裂范围位于以岩移角为75°划定的地表岩移范围内,地表测点最大累计沉降与水平移动量为1 779与948 mm,上覆岩层与地表的变形移动活动处于稳定渐进可控的状态,目前不会发生上述地压地质灾害。     

采动覆岩分布式光纤感测模型试验及沉降预测方法研究

煤层采动覆岩沉降提前于地表,可作为地表稳定性的预警指标。针对煤层开采引起的覆岩沉降预测问题,采用分布式光纤感测技术,通过制作大柳塔煤矿采动覆岩相似材料试验模型,研究了煤层开采引起的覆岩变形特征,基于灰色理论和Knothe时间函数,建立了基于实测应变的采动覆岩沉降预测模型,探讨了预测精度,并取得了如下研究成果：有关分布式光纤感测技术的覆岩应变分布,准确反映了垮落带和导水裂缝带的发育特征,基于GM(1, 1)模型和新陈代谢模型的覆岩沉降预测精度较好但限于短期预测;当相对残差最大值与相对残差和均取最小值时,Knothe时间函数中获得较为准确的参数c值和τ值并提高了预测精度,建立了大柳塔煤层覆岩动态沉降预测模型的表达式,其预测模型适用于覆岩沉降的前期阶段和后期阶段。     

Analysis of the behavior of large underground oil storage caverns in salt rock

The storage of petroleum products above ground surface has many constraints and limitations. A viable alternative is to excavate large underground spaces in rock to provide a safer way for oil storage. Soft rock formations such as salt domes provide suitable conditions from environmental and operational aspects. The potential for high volume storage and low permeability are among advantages of oil storage in caverns excavated in salt rocks. The complicated shape of oil storage caverns, complex behavior of salt rock, and boundary conditions associated with large underground openings are major challenges in the design of salt caverns excavated for oil storage purposes. In this study, the deformation mechanism and stability of salt caverns were investigated. A comprehensive 3D numerical study was carried out to investigate the effects of cavern size and depth, salt rock deformation modulus, and ground in‐situ stress regime on the behavior of large salt caverns. The stress field and deformation mechanisms were studied numerically aiming at shedding lights into the design aspects of salt caverns for oil storage. The analysis results show that the cavern safety factor is reduced as a function of cavern depth and storage volume. Also, with decrease in k (ratio of horizontal to vertical in‐situ stress), the stability of salt caverns will increase; however, with increase in salt rock young modulus, the sensitivity of cavern stability to k ratio is reduced. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigating the effects of lateral stress to vertical stress ratios and caverns shape on the cavern stability and sidewall displacements

Effects of lateral stress to vertical stress ratio on behavior of a cavern in various geomechanical and geometrical conditions were studied. Results indicated that the range of one to two lateral stress to vertical stress ratios was the best condition for cavern stability. The ranges causing tension and compressive failure were specified as well. Two-dimensional stability analyses were carried out by using Phase². Key point location on the cavern side wall was investigated and determined using an equation based on a large number of numerical analyses. Subsequently, in order to predict the elasto-plastic displacement and elastic displacement on a side wall key point, two equations were fitted based on various cavern cross sections considering four basic factors, i.e., rock deformation modulus, overburden depth of caverns, heights of the caverns, and the lateral stress to vertical stress ratio. The proposed equations were utilized to predict displacement at the key points of 10 projects subsequent to which the computation results were compared to in-site measuring results and back analysis results. Finally, using key point displacement as a stability factor, the effects of three different shapes of caverns including mushroom, horse shoe, and elliptical were investigated on cavern stability. The most optimum shape was elliptical in a vast range of lateral stress to vertical stress ratios; mushroom and horse shoe shapes were preferred in uniaxial stress fields concerning the rock quality.     

煤矿采空区场地地基稳定性及适宜性分析

结合一煤矿采空区场地作为新建高层住宅小区场地,通过开采条件、地表移动变形综合确定煤矿采空区的稳定性;采用工程类比法、采空区特征判别法、活化影响因素分析法、地表剩余变形判别法等判别采空区场地工程建设适宜性;建议采空区场地采取吸收地表沉陷变形的柔性措施和抵抗地表沉陷变形的刚性措施来确保拟建建筑物的安全.     

大规模压气储能洞室稳定性和洞周应变分析

地下储气构造物是压气储能(CAES)电站选址的决定因素,其中人工开挖的硬岩洞室因其受地质构造限制小、适应范围广而备受关注。针对压气储能地下洞室方案选型和密闭性要求,选择了典型的洞室埋深(200、300、500 m),考虑不同的洞室形式(隧道式和大罐式)和洞室尺寸,采用Abaqus有限元软件计算出高内气压下压气储能洞室围岩的塑性区和洞周应变。通过分析开挖后和充气后两个工况下围岩的受力和变形特征,获得合适的洞室形式。当围岩级别为Ⅱ级、内压为10 MPa的情况下,埋深为300 m的圆形洞室和大罐式洞室稳定性较好,该埋深下6 m直径圆形洞室最大洞周应变为7.55410??,容积为5 310 m大罐式洞室最大洞周应变为5.54410??,以上值都在一般橡胶类高分子密封材料的正常工作范围内,这为密封材料在不同温度下的延伸率和耐久性研究提供了基础数据。     

榆林某煤矿采空区地表移动变形预测及其工程分区

根据已有类似条件下的地表沉降监测资料,采用工程类比、典型曲线法、概率积分法及有限差分数值分析等多种手段和方法,对榆林某煤矿未来采空区地表移动变形规律进行预测。划定采动影响区为开采边界以外316m,最大下沉值为5760mm。结合建(构)筑物所能承受的允许变形值,将采动影响区根据工程需要划分为严重影响区、一般影响区和轻微影响区。为差别化利用土地资源、降低工程建设投资风险、充分利用煤炭资源提供科学依据。      

盐穴储气库破坏后地表沉陷规律数值模拟研究

地下盐穴储气库在天然气调峰和保障供气安全上具有不可替代的作用。地下盐穴储气库达到设计年限后,将报废而逐步垮塌,必然引起严重的地表沉陷。因此,对盐穴储气库破坏后地表沉陷规律进行研究具有十分重要的意义。考虑到目前的数值分析软件进行地表沉陷分析的不足,开发了用于盐穴储气库破坏后地表沉陷数值模拟的有限元专用软件-2D-Sink,该软件具有处理破碎岩块的能力。应用2D-Sink对盐穴储气库破坏后引起的地表沉陷规律进行了系统的研究,共建立了6种模型进行数值模拟,分别研究了地表沉陷层理效应、地表沉陷的岩层倾斜效应、地表沉陷的断层效应和多盐穴地表沉陷规律。对多溶腔地表变形曲线与单溶腔叠加的地表变形曲线进行比较,验证了地表沉陷叠加原理的正确性。研究成果为盐穴储气库报废后地表沉陷灾害控制提供了理论基础。     

广东英德沙口镇岩溶地面塌陷发育特征及形成机理分析

近年,广东省粤北山区隐伏区岩溶地面塌陷日益增加,直接影响人民生产生活。英德市沙口镇某村地质环境复杂,第四系覆盖层厚度薄,底部卵石层与下覆天子岭组灰岩直接接触,溶洞与断层破碎带发育,溶洞与溶洞间连通性较好,岩溶地面塌陷地质灾害严重。在综合分析沙口镇某村地质环境条件基础上,从内、外两方面因素,对岩溶地面塌陷发育特征及形成机理进行分析,认为在长期地下水位波动、潜蚀及淘蚀等作用松散盖层土体颗粒流失形成土洞,地表水与地下水强烈交替形成正负压力等作用下,土洞上部盖层发生塌陷。研究结论为科学制定岩溶地面塌陷防治方案提供依据。     

采空场覆岩变形数值模拟与相似模拟比较研究

用有限元数值计算尝试了离层模拟,并分别采用数值模拟与相似模拟的方法研究了木架山矿区143剖面倾斜采空场处理时的地表移动与覆岩破坏规律。研究发现,随着矿柱的崩落,覆岩跨度不断增加,引起的地表移动范围也不断增大,地表垂直沉降范围大致为跨度的1.5～1.7倍,垂直沉降曲线始终对称于最大沉降点;水平移动的范围大于垂直沉降的范围,最大水平移动量大约为最大沉降量的40 %,且水平移动不对称。另外,当覆岩发生整体下沉时离层主要存在于跨度两端,离层由层理剪切破坏引起。     

概率积分法在大柳矿井11采区开采地面塌陷预测中的应用

根据大柳矿井11采区上覆岩层的实际情况,采用概率积分法对煤层开采后的地表变形情况进行了预测,绘制了地表下沉等值线图,分析了地表沉陷对周围环境的影响程度和范围,并提出了防治措施,为区内开展类似研究工作和大柳矿井未来生产沉陷的防治提供了参考依据。