【作者】 贺桂成；

【导师】 丁德馨；

【作者基本信息】 中南大学 ， 矿业工程， 2013， 博士

【摘要】 摘要：目前,随着矿产资源的大量开采和地下水资源的过度抽取,导致地表出现了大面积的沉降,给当地的环境和人们的生命财产造成了巨大损害。石膏是一种埋深浅、矿体薄、分布广的缓倾斜层状矿体,具有遇水膨胀、软化等特点,开采此矿体极易诱发地表沉降和塌陷事故。但由于其价格低,人们对其开采沉陷的研究成果较少。因此,开展此项研究具有十分重要的理论意义。本文采用室内试验、理论分析、相似模拟、现场测试和数值模拟相结合的研究方法,对石膏矿的力学特性、采空区顶板的破断机理及其上覆岩层的移动规律,以及开采沉陷的预测方法和控制措施进行了研究,得到了如下研究成果：(1)采用RMT-15OB岩石力学试验机,对自然状态和水饱和状态的石膏试样,以及自然状态下不同高径比的石膏试样的瞬时力学特性进行了试验研究。研究结果表明：水饱和状态的石膏试样的抗压强度是其自然状态的79.94%；根据试验结果分析,得到了石膏试样强度与尺寸效应的理论模型及其参数。(2)采用SAW-2000岩石力学试验机,对自然状态和水饱和状态的石膏试样进行了分级加载的流变试验。试验结果表明：自然状态和水饱和状态的石膏试样均表现出了很好的流变特性,且其流变全过程曲线符合粘弹性流变特征；自然状态和水饱和状态的石膏试样的长期强度分别为其峰值强度的77%和68.8%,且后者的长期强度为前者的55%。(3)根据弹性-粘弹性相应原理,采用粘弹性薄板弯曲理论,建立了采空区顶板粘弹性薄板弯曲的力学模型,得到了采空区顶板的临界荷载及其挠度吐线的表达式,建立了采空区顶板破断的判据,确定了合理的采空区长度、矿房跨度、直接顶厚度等采场结构参数。利用FLAC3D中的伯格斯蠕变模型对采空区顶板蠕变变形和不同高跨比的矿柱承载能力进行了数值模拟。数值模拟结果表明：在0-60d时,采空区顶板缓慢下沉、逐渐离层、开裂形成薄板弯曲结构；在180d时,采空区顶板离层现象十分明显,顶板开始破断失稳,此时地表也出现了明显的沉降；到达360d时,采空区顶板已整体垮落失稳,地表沉降值逐渐增大,最终形成整体塌陷；当石膏矿柱的跨度小于4m时,其已被压坏而不能支承上覆岩层的围岩压力,导致采空区顶板及上覆岩层破断而垮落。(4)采用相似理论,建立了相似模拟模型试验。相似模拟试验结果表明：当矿房跨度大于10m时,采空区顶板开始产生竖向裂隙和离层裂隙；随矿房跨度的增大,其竖向裂隙和离层裂隙逐渐增大而产生弯曲、下沉、破断以及整体垮落；当矿房跨度为164m时,采空区上覆岩层的垮落带高度为55m,为采空区高度的18.3倍,导水裂隙带发育高度为94.5m,为采空区高度的31.5倍,地表沉降的最大值为115cm,下沉系数为0.38。(5)根据理论分析、相似模拟、数值模拟的结果,建立了考虑采场结构参数的地表沉降和顶板竖向位移预测的ANFIS模型,分析了其拟合性能和预测性能,对衡山某石膏矿的采空区地表沉降和顶板竖向位移进行了预测,同时还对其进行了实测。研究结果表明：建立的采空区地表沉降和顶板竖向位移预测的ANFIS模型的拟合精度分别达96%和98%以上,预测精度分别达97%和96%以上；采用该模型预测的衡山某石膏矿的采空区地表沉降值和顶板竖向位移值与实测结果吻合良好；矿房跨度为10m,矿柱跨度为4m是该地区石膏矿最合理的采场结构参数。(6)采用RMT-150B岩石力学试验机,对7种配合比的黄土-废石胶结充填体在不同龄期的抗压强度进行了测试,利用龄期为28d的黄土-废石胶结充填体的力学参数对试验采场进行了充填法回采的FLAC3D数值模拟,根据数值模拟结果选用C组配比的黄土-废石胶结充填体对该矿试验采场进行了充填,同时还对其进行了应力测试。研究结果表明：龄期为28d的C组黄土-废石胶结充填体的抗压强度大于2MPa；选用C组配合比的黄土-废石胶结充填体的试验采场的应力测试结果与数值模拟结果吻合良好,能有效地控制该试验采场的地压。(7)采用C组黄土-废石胶结充填体的力学参数对石膏矿采空区进行充填开采的FLAC3D数值模拟,分析了5种充填开采方案对采空区顶板岩层的竖向位移和地表沉降的影响。数值模拟的结果表明：采用最优充填开采方案能有效地减小地表沉降、采动影响范围和下沉系数,其值分别为未充填时的65.1%、56%和64.6%,达到了控制开采沉陷的目的。图127幅,表37个,参考文献256篇更多还原

【Abstract】 Abstract:The area of mining subsidence increasing with groudwater overdrafting and mineral resources excessive mining, at present, is serious threats to the human life and property and the surrounding environment. The gypsum is a gently inclined bedded ore body that is characterized by shallow burial, narrow forebody, wide distribution, watered expanding and softening, and mined out the gypsum ore bady is easily to cause the events of mining subsidence. There is little research results on the mechanism of mining subsidence because of the lower price, it is very important to study on the mechanism of mining subsidence. This paper combined use laboratory test, theory anlysis, similar simultion, field test and numerical simulation for analyzing the characters of gypsum ore body, broken mechanism of goaf roof and deformation law of overlying strata, and control measures and prediction method. The main results are as follows:(1) The instantaneous mechanics characteristics of the gypsum standard sample in a natural state and saturated state and the gypsum with six different ratios of height to diameter in a natural state by using RMT-150B rock mechanics testing machine. The laboratory test results show that, the compressive strengths of the gypsum standard sample in a saturated state is79.94%of the gypsum in a natural state, the laboratory test ruesults were used for establishing the theoretical model between strength and dimension effect and its parameters.(2) The rheological mechanics characteristics of the gypsum in a natural state and in a saturated state under step loading by using SAW-2000rock mechanics testing machine. The laboratory test results show that, the stress-strain full curve of the gypsum under step loading is in good agreement with viscoelastic creep curve, the long-term strength of the gypsum in a natural state and in a saturated state is77%and68.8%of its peak strength, and the long-term strength of the gypsum in a saturated state is55%of the peak strength of the gypsum in a natural state.(3) The elastic-viscoelastic correspondence principle was used for establishing the viscoelastic plate mechanics model for analysing critical loading and the formula of the flexural function of the goaf roof, and establishing the brocken criterion of the goaf roof. The suitable room length and interval room span and immediate roof thickness of the mining stope of the gypsum mine are determined. The Burges creep model in FLAC3D programe was used for simulating the creep deformation of the goaf roof and overlying strata, and simulating the bearing capacity of the gypsum pillar at different height to span ratios. The simulate results show that, the subsidence of the goaf roof is slowly grew, gradually separated strata, forming a thin plate bending structure with the time increasing after60days of the ore body mined out, and the goaf roof and overlying strata begin to brocken and the surface appear subsidence at the same time after180days of the ore body mined out, and the goaf roof and the surface begin to collapse as an integrity after360days of the ore body mined out. The gypsum interval pillar begin to brocken and don’t support the surrounding rock pressure as the interval pillar span is less than4m.(4) The similar simulation model was estalished based on similarity theory. The simulation results show that, the immediate roof start to produce the vertical fracture and bed separated fissures when the room span is more than10m, the goaf roof and overlying strata begin to separated strata, bent, sunk, brocken and collapsed as an integrity with room span increasing, and the height of the collapse and the height of the transmissive fractured belt of a stope is56m and94.5m, that is18.7times and31.5times of the height of the goaf, and the maximum of the surface subsidence is115cm, and the subsidence coefficient is0.38as the room span is164m.(5) FLAC3D was used for simulating the surface subsidence of the old goaf with different structural parameters and analyzed the factors which is influencing the surface subsidence. The simulating results were used for establishing the ANFIS (adaptive neuro-fuzzy inference system) model for predicting the surface subsidence and the vertical deformation of the roof of the goaf and the fitting and predicting capabilities were analyzed. The ANFIS model was used for predicting the surface subsidence and the vertical deformation of the roof of the goaf of a gypsum mine in Hengshan and the practical surface subsidence and vertical deformation of the roof were measured. The results show that, the accuracies of the fitting results of the surface subsidence and the vertical deformation of the roof by the established ANFIS model amount to96%and98%, and the accuracies of the predicting results of the surface subsidence and the vertical deformation of the roof by the established ANFIS model amount to97%and96%, respectively, and the predicted results of the surface subsidence and the vertical deformation of the roof of the goaf of a gypsum mine by the established ANFIS model and he measured results are in good agreement. The interval pillar span and room span are suitable to4m and10m for the mining stopes of the gypsum mine in Hengshan.(6) The compressive strengths of the backfills of the cemented waste rock with cement and loess with seven different mixture ratios at different solidification durations were measured by using RMT-150B rock mechanics testing machine. In addition, the mechanical parameters for the backfills of the cemented waste rock with cement and loess at the solidification duration of28days were used to simulate the mining and filling processes of test stop by using FLAC3D. Based on the simulation results, the backfills of the cemented waste rock with cement and loess with type C mixture ratio was used to filling in the test stope, and the stress measurements were conducted for the backfills and surrounding rocks. The results show that the compressive strength of the backfill of the cemented waste rock with cement and loess with type C mixture ratio at the solidification duration of28days was larger than2MPa. The stress measurements of the backfills and surrounding rocks in the test stope are in good agreement with the simulation results, which means that the backfills of the cemented waste rock with cement and loess with type C mixture ratio can be used to effectively control the ground pressure in stope mining.(7) FLAC3D was used for simulating the influence of the sufface subsidence and the vertical deformation of the roof with five different backfilling schemes for backfilling the gaof of the gypsum used the cemented waste rock with cement and loess with type C mixture ratio. The simulate results show that, the sufface subsidence and the affected areas and the subsidence coefficient by mining with optimal scheme to backfill the gaof of the gypsum is65.1%and56%and64.6%that the unfilled gaof of the gypsum.更多还原