【作者】 赵勇；

【导师】 冯世进；

【作者基本信息】 同济大学 ， 土木工程， 2022， 博士

【摘要】 近年来,我国隧道及地下工程建设发展迅速,不可避免地对邻近建(构)筑物产生影响。我国当前已有上万座在役填埋场,为节省土地资源、降低建设运营成本,部分隧道工程不可避免地会下穿填埋场。目前,下穿填埋场隧道施工引发环境岩土工程灾害的相关研究很少。本研究以深圳坂银通道鸡公山隧道下穿下坪固体废弃物填埋场工程为例,综合地应力智能反演分析、隧道爆破振动与开挖变形现场实测、隧道爆破振动与损伤动力数值模拟、渗滤液分布综合现场探测、流固全耦合渗流数值模拟等多种方法,研究填埋场与下穿爆破施工隧道之间的相互作用机制与控制措施。研究所得下穿填埋场隧道区域地应力综合智能反演分析方法、下穿隧道爆破施工对填埋场影响机制与评价准则、填埋场深部基岩渗滤液分布综合探测方法、填埋场渗漏与下穿隧道施工对渗流场影响机制等研究成果,可以为下穿填埋场隧道工程提供理论与技术支撑,对隧道施工引发环境岩土工程灾害问题的研究具有重要参考价值。主要研究内容与创新工作如下:(1)针对下穿下坪填埋场隧道区域地质条件复杂、钻孔测试难以实施等情况,结合多源信息分析、多元线性回归、人工智能算法等方法搭建了地应力综合分析框架,开展了隧道地应力宏观特征分析、地应力局部状态分析以及地应力关键因素智能反演优化,揭示了坂银通道下穿填埋场隧道区域地应力分布特征,为后续研究提供了地应力条件。该方法可合理考虑多种影响因素,方法内部可以形成相互支撑和验证。分析结果表明,下穿填埋场隧道区域水平构造应力显著,水平应力范围为2.5～5.5 MPa,地应力状态为σH>σh>σV,当前侧压力系数范围为1.0～2.5,上覆垃圾会对填埋厚度较大区域的下部基岩竖向应力产生较大影响,但不会改变三向应力状态。(2)针对隧道钻爆施工对填埋场下部区域的影响机制,从环境振动和岩体损伤两方面开展研究。在环境振动方面,结合现场实测与动力数值模拟,研究了隧道爆破引发围岩振动的传播规律及关键因素的影响;在此基础上,提出了下穿隧道爆破荷载下填埋场底部衬垫系统破坏判据。结果表明,爆破荷载作用下可将填埋场衬垫系统HDPE 土工膜与土工布界面的峰值抗剪强度作为临界破坏值,针对当前垃圾堆填高度,爆破荷载下衬垫系统临界剪切破坏值230 kPa,临界峰值振速12 cm/s,坂银通道隧道爆破施工不会影响下坪填埋场衬垫系统安全。在岩体损伤方面,建立了耦合修正D-P模型和Yang-Liu损伤模型的岩石弹塑性损伤本构模型,该模型能够准确考虑爆破荷载作用下岩体的受拉损伤特性;模型应用于下穿下坪填埋场隧道爆破施工数值模拟中,结果表明,在考虑软弱破碎夹层的最不利工况下,隧道围岩最大损伤深度为6.1 m,远小于填埋场底部到隧道36 m的距离,故正常施工条件下,下穿隧道爆破引发围岩损伤对填埋场的影响较小。(3)针对填埋场服役时间长、内部渗滤液分布和底部潜在渗滤液渗流通道不明等情况,提出了隧道下穿填埋场渗滤液分布综合探测方法。综合运用高密度电阻率法、地震波反射法、瞬变电磁法等地球物理无损探测方法,同时结合超前地质钻孔和取水化验,揭示了填埋场内部渗滤液分布以及底部潜在渗流通道,为后续研究提供了水文地质边界条件。该方法不影响填埋场运营安全,多种探测结果可以相互验证,对同类工程具有重要参考价值。结果表明,当前测试区域渗滤液水位在填埋场表面以下15～20m深度,衬垫系统基本完好,无大规模渗滤液下渗风险。填埋场底部存在两条连通至隧道区域的潜在渗流通道,宽度20～40 m,但尚未有渗滤液和填埋气下渗进入隧道。(4)针对填埋场渗漏和隧道开挖对渗流场的影响机制,考虑了垃圾体和岩土体的非饱和渗透特性,建立了渗流-应力全耦合条件下隧道下穿填埋场全区域渗流分析数值模型,对填埋场渗漏、隧道开挖及两者共同作用下的渗流场演化规律与隧道防排水优化措施进行了研究。分析结果表明,发生渗漏后,隧道区域围岩将在45 d左右达到孔压峰值。渗漏路径倾角、渗流通道宽度和渗漏区域范围均对渗流场演化规律有一定影响,其中渗流通道宽度的影响最大。当下穿填埋场隧道开挖后,隧道附近孔压先上升,后经历三阶段下降,最后随着衬砌封闭逐渐回升。隧道爆破引发围岩损伤对渗流场有显著影响,填埋场渗漏与隧道开挖的时序不会影响最终孔压值。下穿隧道施工与运营过程中,若填埋场发生超过直径40 m的大规模渗滤液下渗时,隧道拱底孔压将超过衬砌混凝土 P8抗渗等级,需采取相应优化措施。因此,从注浆封闭、衬砌抗渗性能、隧道排水措施、分区防水措施四个方面对隧道防排水原始方案进行了评估分析,优化了下穿填埋场隧道防排水方案与渗滤液填埋气渗漏应急管理措施。更多还原

【Abstract】 In recent years,great development has been taken place in tunneling and undergournd space technology in China.At the same time,more than ten thousands of landfills have been built in our country.Some tunnels might be inevitabley designed to cross underneath the landfill because of financial or technology reasons.At present,researches on the environmental geotechnical engineering hazards induced by tunnel construction have rarely been reported.In this paper,the project of the Jigongshan Mountain Tunnel excavated under the Xiaping landfill in Shenzhen was taken as an example to study the interaction mechanism between the landfill and the underlying tunnel.Multiple methods including intelligent back analysis,field tests and numerical simulation were employed to identify the characteristics of the stress and seepage field in the study area.The research results,including the integrated intelligent back analysis method of the stress field under the landfill,the influencing mechanism and evaluation criteria of the underlying constructing tunnel on the landfill,the integrated detection method of the leachate in and under the landfill,and the influencing mechanism of the landfill leakage and the underlying tunnel on the seepage field,could be valuable either for the project of the Jigongshan Mountain Tunnel,or for similar researches on the environmental geotechnical engineering hazards induced by tunnel construction.The main content and innovation were as follows:(1)An integrated strategy comprising multisource information analysis,multiple linear regression and artificial intelligence algorithm was developed to predict the initial ground stress for tunneling under the Xiaping landfill.The distribution of the initial ground stress was studied and the influence of the landfill was considered by geological analysis,rock sample analysis,field measurements and intelligent back analysis.This new strategy could consider the effects of tectonic movement,rock and fault parameters and landfill load on ground stress simultaneously.It was revealed that the horizontal tectonic stress,with a range of 2.5-5.5 MPa,was significant in the tunnel region under the landfill.The state of the three principal stresses is σH>σh>σV,and the range of the lateral pressure coefficient is 1.0-2.5 at present.The landfill load would chiefly influence the vertical stress under the landfill,but would not change the original 3D state of stress.(2)The influence of tunnel excavation on the landfill was studied from two aspects of environmental vibration and rock damage.As for the study of environmental vibration induced by tunnel excavation,field measurements and numerical simulation were combined to identify the vibration propagation law and influence factors.The failure criterion of landfill bottom liner system was established,and the peak shear strength of the geomembrane/geotextile interface,230 kPa for the current landfill height,was selected as the critical index.The relevant critical PPV of the landfill liner was calculated as 12 cm/s.The results showed that the landfill liner system was safe under the blast induced by tunnel excavation.As for the study of rock damage induced by tunnel excavation,the modified Drucker-Prager model coupled with Yang-Liu damage model was established to consider the characteristics of tensile damage for surrounding rock under blasting load.This elastoplastic damage model of rock was employed in the dynamic numerical simulation of tunnel construction.It was found that the largest damage depth was 6.1 m when considering the effects of weak intercalated layer.Compared to the vertical distance between the landfill and the tunnel,the effects of rock damage induced by blast on the landfill could be neglected.(3)With no intrusion into the landfill liner system,an integrated geological and geophysical investigation,including electrical resistivity tomography(ERT),tunnel geological prediction(TGP),transient electromagnetic method(TEM),geological drilling,and sample analysis,was carried out on the ground and in the tunnel under the Xiaping Landfill.The geological conditions under the landfill were ascertained,and the leachate distribution and potential leakage paths were identified.It was proved that the proposed integrated detecting system was of high precision,and would not affect the operating safety of the landfill.The results showed that the leachate level was 15-20 m below the landfill surface.Two possible leachage pathways from the landfill to the tunnel were found,and the width was 20-40 m.The leachate was well confined by the landfill liner system,and the probability of remarkable leachate leakage was low.(4)The unsaturated hydrologic-mechanical coupled numerical simulation was performed to study the influence of landfill leakage and tunnel construction on the seepage field.The anisotropy and evolution of the landfill and the rock were also taken into consideration.It was identified that the pore pressure would reach the peak in 45 d after the landfill leakage.Factors affecting the evaluation of the seepage field included dip angle and width of the leakage path and the size of the leakage point,among which the effect of the path width was the largest.After the excavation of the tunnel under the landfill,the pore pressure in the tunnel region would rise,and then fall in three steps.It would re-rise with the completion of the lining construction.The effect of rock damage induced by blast on the seepage field was significant,and time order of landfill leakage and tunnel construction would not change the final pore pressure.The safety of the tunnel waterproof and drainage system could not be ensured when large-scale leakage with the diameter of over 40 m occurred in the landfill.Therefore,the original scheme of tunnel waterproof and drainage was analyzed and evaluated from four aspects as grouting,lining impermeability,drainage measures and partition waterproofing system.Finally,suggestions of tunnel waterproof and drainage optimization were given,and emergency measures of leachate and landfill gas leakage were proposed.更多还原