兖州矿区第四系厚松散层沉降特性研究

发布时间：2018-06-30 11:13

  本文选题：第四系厚松散层 + 流变特性　； 参考：《西安科技大学》2015年博士论文

【摘要】：地层沉降是一种世界性地质问题,严重时将成为地质灾害。90%的地面沉降是由于大量开采地下资源(包括地下水、石油、天然气和煤炭等)和进行地下工程不当引起的,如过度地下水开采引起的地层沉陷、城市地下工程(如地铁)引起的基础沉降、矿山开采引起的覆岩和地表塌陷等。我国华东矿区开采以立井为主,立井井筒穿过深厚的第四系松散地层,在煤矿生产过程中立井井筒变形破坏是该地区煤矿安全生产的主要灾害之一,这种地质灾害严重影响了矿井的安全生产。井壁破裂的跟本原因是厚松散层的失水压缩沉降,防治厚松散层压缩沉降变形是预防井筒重复破裂的根本。光纤传感技术在松散层沉降监测中的应用为研究松散层沉降特征,计算和预测松散层沉降变形量提供了可能。对兖州矿区力学特性、变形机制和沉降特征进行研究,为厚松散层因底部疏排水引起的厚松散层主压缩层位及岩性的判定提供了理论基础和工程依据,对于华东矿区厚松散层沉降变形的准确防治、事前预防理井筒破裂具有重要意义。本文针对兖州矿区第四系厚松散层底部疏排水引起的沉降压缩问题,结合厚松散层地质构造、水文动态特征及松散层沉降光纤传感监测,对松散层不同岩性土体的流变特性、沉降机制和松散层沉降特征的相关问题进行了研究,主要开展了以下几个方面的工作:(1)通过兖州矿区第四系厚松散层砂土、黏土、砂质黏土三种岩性土体高压固结试验及砂土粒径筛分试验,研究了厚松散层沉降变形机理。对厚松散层砂土、黏土及砂质黏土蠕变特性进行了研究,建立了不同岩性松散层应力-应变-时间的非线性流变模型,试验反应了松散层具有瞬时弹性和黏滞性,单次加载中弹性变形占总变形比例最大的为砂土、其次为砂质黏土、最小的为黏土,砂质黏土具有明显的弹性后效流变特性;研究了不同应力历史对蠕变特性的影响,土体施加荷载低于预加荷载时的变形速率小于施加荷载高于预加荷载时的变形速率;研究了兖州矿区第四系厚松散层砂土层沉降变形机制,是受颗粒破碎和颗粒滑移的共同作用。(2)采用自主研制的松散层沉降变形物理模型试验装置,实现了注、失水条件下厚松散层分布式沉降变形特征的试验研究。研究了厚松散层注水条件下的沉降特征,获得了松散层注水减沉的相关参数;研究了厚松散层底部疏排水条件下的沉降特征;研究了松散层失、注水下的有效应力增量-应变关系;基于松散层非线性流变本构及应变量模型建立了松散层沉降的经验预测模型,完善了长期以来厚松散层通过“水位降-沉降量(应变)”经验拟合模型对松散层沉降变形特征的部分性表述。模型试验研究表明:注水可以有效改善松散层的应力状态;注水层上部影响高度约为注水水头的0.024倍;注水层下部影响区自底部向注水层位依次发生回弹变形,随注水量增大回弹变形增大;注水层深度应选择受压缩层位以下位置;松散层失水时应力状态由拉应力状态向压应力状态转变;垂向压缩随水位持续降由下组含水层向中组黏土隔水层扩展,不同岩性松散层交界处及注水层位以上区域易产生拉、压应力集中区;松散层注水过程应力-应变曲线呈非线性,失水过程初期黏土层经历1~2 kPa应力松弛。(3)理论推导研究了松散层沉降钻孔植入式光纤光栅监测的应变传递,并通过现场实测进行了松散层应变监测温度补偿。提出了适用于钻孔封装的光纤光栅传感器应变传递假定条件,建立了考虑钻孔半径、封孔材料弹性模量的钻孔植入式的光纤光栅传感器松散层应变传递模型;研究了松散层应变传递与钻孔半径、钻孔封装材料的关系。研究表明:封孔材料弹性模量在8~15 GPa的范围内时可以得到较高应变传递率。(4)以理论及室内试验研究为基础,实测研究了不同水位变化条件下兖州矿区第四系厚松散层沉降变形特征。分析了松散层应变随时间变化关系;研究了厚松散层水位动态与对应层位应变变化关系;研究了厚松散层垂向沉降特征,越靠近基岩松散层压应变越大;提出了厚松散层主压缩层位的判定和预测方法,厚松散层主压缩层位应综合考虑层厚、变形速率及单位变形量因素,以层位沉降值对总沉降量贡献比例为标准进行判定。研究结果表明:松散层具有明显的回弹延后和压缩滞后现象,中组砂质黏土层长期处于蠕变变形阶段,少量水位升引起的回弹变形不能抵消长期蠕变变形;下组黏土层和中组下段砂质黏土层为现阶段主压缩层,研究结果扩展了以往认为华东矿区厚松散层沉降位于下组或下组底含的认识,应重视中组沉降对井筒变形的影响;厚松散层中组下段砂质黏土层和下组底含将是松散层沉降的主要贡献层位;应重视发生蠕变松散层对应深度处井筒的监测和维护。
[Abstract]:Stratigraphic settlement is a worldwide geological problem, and the ground subsidence of.90% is caused by a large amount of underground resources (including groundwater, petroleum, natural gas and coal) and improper underground engineering, such as the subsidence caused by excessive groundwater exploitation, and the foundation of Urban Underground Engineering (such as the subway). Subsidence and mining caused by mining, such as overlying rock and surface subsidence, and so on. The East China mining area is mined mainly with vertical wells, and the shaft shaft passes through the deep Quaternary loose strata. The deformation and damage of the neutral well bore in the production process of the coal mine is one of the main disasters in the safety production of the coal mine in this area. This kind of geological disaster seriously affects the safety production of the mine. The heel of the shaft wall rupture is the compression settlement of the thick loose layer, and the prevention and control of the compression and settlement of the thick loose layer is the basis of preventing the repeated rupture of the wellbore. The application of optical fiber sensing technology in the subsidence monitoring of the loose layer provides the possibility for the study of the subsidence characteristics of the loose layer, the calculation and prediction of the deformation of the loose layer, and the mechanics of the Yanzhou mining area. The characteristics, deformation mechanism and settlement characteristics are studied, which provide the theoretical basis and engineering basis for the determination of the main compression strata and lithology of thick loose layers caused by the bottom drainage in the thick loose layer. It is of great significance for the accurate prevention and control of the settlement deformation of the thick loose layer in the East China mining area, and it is of great significance to prevent the fracture of the well barrel in advance. This paper is aimed at the Yanzhou mining area. The problem of subsidence and compression caused by sparse drainage at the bottom of the Quaternary thick loose layer, combined with the geological structure of the thick loose layer, the dynamic characteristics of the hydrology and the optical fiber sensing monitoring of the loose layer settlement, has been studied on the rheological characteristics of the soil with different lithology in the loose layer, the settlement mechanism and the characteristics of the settlement of the loose layer, and the following aspects are mainly carried out. The work is: (1) through the high pressure consolidation test of three types of clay and sandy clay in the Quaternary thick loose sand soil in the Yanzhou mining area, the mechanism of the settlement and deformation of the thick loose layer is studied. The creep characteristics of the thick loose sand soil, clay and sandy clay are studied, and the stress strain of different lithologic loose layers is established. The experimental results show that the loose layer has instantaneous elasticity and viscosity. In the single loading, the elastic deformation is the largest in the sand, the second is the sandy clay, the smallest is clay, the sandy clay has the obvious elastic aftereffect rheological properties, and the influence of different stress history on the creep characteristics is studied. The deformation rate of the applied load is lower than that of the pre loaded load. The deformation mechanism of the sand layer in the Quaternary thick loose layer of Yanzhou mining area is studied. (2) the physical model test device for the settlement and deformation of the loose layer is realized by the self developed experimental device for the settlement and deformation of the loose layer. The characteristics of the distributed settlement deformation of thick loose layer under the condition of water loss are studied. The characteristics of the settlement under the condition of water injection in thick loose layers are studied. The related parameters of water injection reduction in the loose layer are obtained. The settlement characteristics of the bottom of the loose layer under water drainage are studied, and the loss of the loose layer and the effective stress increment under the water injection is studied. Based on the nonlinear rheological constitutive model and the strain model of the loose layer, the empirical prediction model of the settlement of the loose layer is established, and the partial expression of the characteristic of the loose layer settlement deformation has been perfected for a long time through the empirical fitting model of the "water level drop settlement (strain)". The model test study shows that water injection can effectively improve the looseness. The stress state of the layer is about 0.024 times as high as the head of water injection. The impact zone of the lower part of the water injection layer occurs in turn from the bottom to the water injection layer, and the springback deformation increases with the increase of water injection; the depth of the water injection layer should be under the position of the compressed layer, and the stress state of the loose layer is from the tension stress state to the pressure stress state when the loose layer loses water. State transformation, vertical compression with the water level continuous drop from the lower group of aquifers to the middle group of clay aquifers expansion, the boundary of different lithology and the water injection layer above area is easy to pull, pressure stress concentration area; the stress strain curve of the loose layer water injection process is nonlinear, the initial clay layer experience 1~2 kPa stress relaxation in the initial stage of water loss. (3) theory push The strain transmission of the implantable fiber Bragg grating monitoring in the loose layer settlement is studied, and the temperature compensation of the strain monitoring in the loose layer is carried out through the field measurement. The assumption conditions for the strain transfer of the fiber Bragg grating sensor suitable for the borehole packaging are put forward, and the implantable fiber with the borehole radius and the elastic modulus of the sealing material is established. The strain transfer model of the loose layer of the grating sensor is studied. The relationship between the strain transfer of the loose layer and the radius of the drill hole and the package material is studied. The study shows that the elastic modulus of the porous material can be higher in the range of 8~15 GPa. (4) based on the theory and laboratory test research, the measured conditions are studied under the conditions of different water levels. The deformation characteristics of the Quaternary thick loose layer in the Yanzhou mining area are characterized. The relationship between the strain of the loose layer and the time variation is analyzed. The relationship between the water level of the thick loose layer and the strain change of the corresponding layer is studied. The characteristics of the vertical settlement of the thick loose layer are studied, the greater the pressure is closer to the loose laminates of the bedrock, the determination and prediction of the main compression layer of the thick loose layer are put forward. The results show that the loose layer has obvious springback delay and compression lag, and the sand clay layer in the middle group is in the stage of creep deformation for a long time and a small amount of water in the middle group. The rebound deformation caused by the position rise can not offset the long-term creep deformation; the lower group clay layer and the sandy clay layer in the lower part of the middle group are the main compression layers. The results extend the understanding that the subsidence of the thick loose layer in the East China mining area lies in the lower or lower group bottom, and should pay attention to the effect of the settlement of the middle group on the wellbore deformation; the lower part of the thick loose layer should be attached to the lower section of the thick loose layer. The sandy clay layer and the bottom formation will be the main contribution zones for the settlement of the loose layer; attention should be paid to the monitoring and maintenance of the shaft at the depth corresponding to the creep loose layer.
【学位授予单位】：西安科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD327
，

本文编号：2086090