富水软岩冻结井筒涌水机理及治理技术研究

发布时间：2018-05-07 15:50

本文选题：软岩 + 冻融循环　；参考：《西安科技大学》2015年硕士论文

【摘要】：西北地区矿井建设中,多数井筒需要穿过白垩系、侏罗系巨厚岩层,该岩层具有含水量大、岩性松软等特点,普通凿井法施工难度大,多采用冻结法凿井。但是,冻结法施工成井后大部分井筒出现井壁淋水、马头门涌水等水害问题,情况严重的还可能发生淹井事故,导致井筒施工工期长,水治理费用高等问题。目前,多采用壁后注浆治理水害,但部分井筒注浆治水效果不明显,依然存在井筒涌水量过大,影响安全生产。针对上述问题,论文开展白垩系冻结法施工成井后井壁淋水机理及注浆治理技术研究,具有重要的工程应用价值和理论意义。本文以新庄煤矿为工程背景,通过室内试验和理论分析研究冻融作用对白垩系软岩微观结构影响,物理模拟冻结井筒涌水机理研究,进而探讨软岩、软岩与混凝土凝结体渗透特性变化规律,同时对模拟井筒试件进行注浆抗渗实验,主要结论有:(1)通过孔隙率测试实验数据,得出一次冻融作用下粗、中、细砂岩渗透系数比原始渗透系数分别增大了50.8%、25.5%、28.5%,二次冻融后渗透系数比原始渗透系数增加了134.9%、76.8%、64.2%。扫描电镜实验表明:一次冻融后岩石颗粒之间松散、脱离,孔隙增大;二次冻融后孔隙裂隙继续发育,并且产生较长裂隙、孔隙裂隙贯穿性好。说明冻融作用下白垩系软岩孔隙率增大,内部产生大量贯穿性裂隙,形成弱导水通道。(2)进行粗砂岩、中砂岩和细砂岩冻融前后低温氮吸附实验,进一步从微观结构分析冻融作用下软岩孔隙结构变化情况。实验表明:粗砂岩冻融循环后孔隙体积增加以大孔为主,中孔为辅,一次冻融后孔隙率增幅9.8%,二次冻融后孔隙率增幅15.0%。中砂岩冻融循环后孔隙体积增加以大孔、中孔为主,二次冻融循环后中孔增量显著,一次冻融后孔隙率增幅9.4%,二次冻融后孔隙率增幅13.9%。细砂岩冻融循环后孔隙体积增加以中孔为主,大孔为辅,二次冻融循环后中孔增量多,一次冻融后孔隙率增幅7.6%,二次冻融后孔隙率增幅14.2%。(3)自主设计并加工了模拟井筒冻结实验装置,通过室内实验验证了冻融循环对岩石与混凝土井壁接触面产生破坏,岩石与混凝土出现分界面,形成导水通道,导致岩石与混凝土组合体渗水能力增强。(4)选取普通硅酸盐水泥、超细水泥和脲醛树脂三种浆液,对冻融作用后的井筒模拟装置进行重复注浆,测量每次注浆后岩石试件的渗透系数,对测量结果进行对比分析,研究不同注浆材料及注浆压力对软岩及软岩与混凝土组合体堵水效果。分析结果:渗透系数随注浆次数增加而减小,对于同一种浆液渗透系数随注浆次数增加而减缓;对与颗粒型水泥浆液,增大水灰比、提升注浆压力都可以提高浆液可注性;超细水泥浆液注入性比硅酸盐水泥浆液好,堵水效果明显。化学浆液能够注入到水所能到达的孔隙裂隙,在低水压情况下可以完全不漏水,堵水效果特别理想。
[Abstract]:In the mine construction of northwest area, most of the shaft needs to pass through the Cretaceous and Jurassic strata, which have the characteristics of large water content and soft lithology, and the common sinking method is difficult to be constructed, so the freezing method is often used to drill the shaft. However, after the completion of freezing construction, water hazards such as well wall flooding and water gushing at Matou gate appear in most of the wellbore, and serious flooding accidents may occur, resulting in long construction period and high water treatment cost. At present, most of the water hazards are treated by backwall grouting, but the effect of grouting is not obvious in some wellbore, and there is still too much water inflow in the wellbore, which affects the safety of production. In view of the above problems, the paper carries out the research on the mechanism of well wall watering and grouting treatment technology after the Cretaceous freezing construction, which has important engineering application value and theoretical significance. In this paper, taking Xinzhuang Coal Mine as engineering background, the influence of freeze-thaw on the microstructure of Cretaceous soft rock is studied through laboratory tests and theoretical analysis, and the mechanism of freezing wellbore water gushing in physical simulation is studied, and the soft rock is discussed. The permeability characteristics of soft rock and concrete condensate are changed. At the same time, the grouting impermeability experiment is carried out on the simulated wellbore specimen. The main conclusions are as follows: 1) through the porosity test data, the coarse and middle thickness under a freeze-thaw action can be obtained. Compared with the original permeability coefficient, the permeability coefficient of fine sandstone increased by 50.8 and 25.5and 28.5.The permeability coefficient after secondary freezing and thawing increased by 134.9 and 76.8and 64.2than the original permeability coefficient respectively. The SEM results show that the rock particles are loosely separated and the pores increase after the first freeze-thaw, and the pore fractures continue to develop after the secondary freezing and thawing, and long cracks are produced, and the pore fractures are permeable well. The results show that the porosity of Cretaceous soft rock increases under freezing and thawing, and a large number of penetrating cracks are formed in the inner part of the soft rock, forming a weak water conductivity channel. The coarse sandstone and fine sandstone are tested for nitrogen adsorption at low temperature before and after freezing and thawing. The change of pore structure of soft rock under freezing and thawing is further analyzed from microstructure. The experimental results show that the pore volume of coarse sandstone increased mainly by large pore, supplemented by mesopore, increased by 9.8 percent after primary freezing and thawing, and increased by 15.0 by secondary freezing and thawing. After freeze-thawing cycle, the pore volume increases mainly in large pore and middle pore. After secondary freeze-thaw cycle, the increment of mesopore is remarkable, the increase of porosity after primary freezing and thawing is 9.4, the increase of porosity after secondary freezing and thawing is 13.9. After freezing and thawing cycle, the pore volume of fine sandstone increased mainly in mesopore, supplemented by large pore, and increased after secondary freeze-thaw cycle. After freeze-thawing, the porosity increase of 7.6% and the increase of porosity after secondary freezing and thawing 14.22%. 3) the experimental device of simulating wellbore freezing has been designed and processed independently. Through laboratory experiments, it has been verified that freezing and thawing cycle has destroyed the interface between rock and concrete shaft wall. The interface between rock and concrete formed a channel of water conductivity, which led to the enhancement of permeability of rock and concrete.) three kinds of slurry, ordinary Portland cement, ultrafine cement and urea-formaldehyde resin, were selected. The borehole simulation device after freezing and thawing is repeated grouting, the permeability coefficient of rock specimen after each grouting is measured, and the measured results are compared and analyzed. The effects of different grouting materials and grouting pressure on soft rock and the combination of soft rock and concrete are studied. The results showed that the permeability coefficient decreased with the increase of grouting times, decreased with the increase of grouting times for the same kind of slurry, increased the water-cement ratio and raised the grouting pressure to increase the injectability of the same kind of slurry, and the permeability coefficient of the same kind of slurry decreased with the increase of the number of grouting times, and the increase of water-cement ratio to granular cement slurry, the increase of grouting pressure. The injectability of superfine cement slurry is better than that of Portland cement slurry, and the water plugging effect is obvious. The chemical slurry can be injected into the pore fissure which can be reached by water, and can not leak completely under the condition of low water pressure, so the water plugging effect is very ideal.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD745

【参考文献】