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碎石土滑坡结构特征探测及岩土体地物参数和抗剪强度的相关性分析
Alternative TitleThe detection of structure characteristics and analysis on the coupling relationship between geophysical parameters and shear strength of rock and soil in a gravel landslide
Language中文
徐兴倩
Thesis Advisor苏立君
2015
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword碎石土滑坡 剪切波速 微动 结构特征 抗剪强度
Abstract滑坡体结构特征和滑动面的几何形态、埋深及岩土体的力学参数是评价滑坡稳定性、开展滑坡防护和治理工作的基本依据。地震边坡岩土体受地震作用后,坡体结构发生不同程度的变形、损伤和破坏,地震灾区存在着严重的安全隐患问题,严重威胁着人民的生命和财产安全。震后即时排除这些安全隐患的前提是如何快速获取边坡岩土体地质结构特征和力学性能。传统的边坡地质结构特征获取方式主要是人工开挖或机械钻取岩芯难度巨大、费用高昂、对坡体有损伤。而岩土体力学性能的获取主要是将各岩土样本送回实验室测定,室内土工试验相对准确,但却很耗时,却都不满足快速的要求。因此,在一定程度上限制了对滑坡岩土体地质结构特征和物理力学性能及稳定性评价研究的深入开展。 假设能充分利用地球物理技术快速、经济、无损和安全的特点,快速探测坡体结构,通过岩土体地物参数标定力学参数,就能达到及时评价滑坡稳定性的目的。为证明上述假设,本文以四川省阿坝州理县通化乡西山村滑坡为研究对象,基于该滑坡前期的野外调查和工程地质勘察结果,采用多种原位物探技术、室内土力学试验和滑坡地物模型试验相结合,以快速的探测滑坡体地质结构特征,建立起碎石土滑坡岩土体地物参数和力学参数之间的耦合关系。初步探寻快速标定坡体力学参数的新方法,进而达到快速评价坡体稳定性的目的。该研究有望为震后滑坡潜在失稳隐患的排查和灾后安置点选择及重建选址工作提供参考依据。 论文的主要研究内容和研究成果如下: (1)对碎石土滑坡浅层裂缝的地物敏感性特征进行了类比研究。基于地震法、电法和电磁法,探测了四川汶川地震灾区碎石土滑坡浅层裂缝,发现由于碎石土的破碎特征,地球物理方法对碎石土滑坡浅层裂缝的探测深度是有限的,最可靠的深度范围是2m。碎石土滑坡中存在大量尺度不等的大块石或孤石,在钻孔覆盖密度小的情况下,尤其是对于浅层结构,钻探结果精度明显低于地球物理探测结果。在大于2m的深度范围内,剪切波速对裂缝最为敏感,电阻率和电磁波衰减相对次之,多通道瞬态面波法(MASW)最适合于碎石土滑坡浅层裂缝的深度演化特征研究。 (2)双源型面波(DDSW)勘察方法的提出有效地提高了滑坡结构探测的分辨率。为了获取碎石土滑坡内部结构,我们融合了主动震源瞬态多通道面波法(MASW)和被动震源微动勘察法(MSM),对面波数据和微动信号分别利用频域波数法(F-K)和空间自相关法(SPAC)进行处理。双源型面波分析方法(DSSW)能最大限度的兼顾滑坡体结构特征探测的深度和分辨率,满足坡体软弱夹层、破碎带、潜在滑动面及大块石或孤石的探测。在探测深度、尺度及经济程度方面都优于钻探技术,更适合于大范围、高密度的滑坡勘察。 (3)开展了地球物理方法在碎石土滑坡结构特征探测上的优化组合方式研究。滑坡岩土体的地物参数(剪切波速、电阻率值和电磁波衰减特性)能为滑坡水文地质结构特征研究提供有效的参考依据。瞬态面波法(MASW)和地质雷达法(GPR)相互搭配能定性和定量的获取滑坡体浅部堆积层厚度和起伏变化。电阻率层析成像法(ERT)最适合于碎石土滑坡水文信息和地下水渗透路径的定位。瞬态面波法(MASW)和微动勘察法(MSM)相互结合最适合于深层滑坡的地质结构特征、基岩和基岩风化层及潜在滑动面埋深及起伏形态的调查。 (4)归纳总结了碎石土滑坡的发育特征和治理方法。地球物理勘察结果显示碎石土滑坡中地下水“树枝状”的管网渗流系统发育,坡体中的管道尺寸各异,地下水渗流具有不均匀性和集中渗流的特征,地表水入渗是影响碎石土滑坡稳定性的主要因素。渗透功能的强弱直接决定着碎石土滑坡的稳定性,此类滑坡的治理应主要以排水截流为主要措施。地球物理技术的综合应用对于碎石土滑坡地下水渗透路径的原位识别非常有用,能为工程治理过程中排水槽或沟等位置选取提供有效的参考依据。 (5)探讨了含水量和粒径级配对碎石土地物特征的影响。利用室内水槽模型试验获取了碎石土体的地物参数,发现随着含水量和细粒土含量的增加,碎石土电阻率值和剪切波速值都呈现逐渐减小的趋势,线性关系明显。含水量对地物特征的影响在含水量19%(塑限)附近较为明显,级配对其影响主要集中于细粒土含量在45%附近。 (6)分析了碎石土地物参数和抗剪强度之间的耦合关系。基于水槽模型试验和大直剪实验的结果,发现在相同含水量条件下,碎石土剪切强度随着剪切波速和电阻率值的增加而增加,分别在90m/s和80Ω.m 附近变化最为明显,幅度范围约为30~125KPa。同时,粘聚力随着电阻率和剪切波速的增加而逐渐减小,内摩擦角则逐渐增大。相对来说,电阻率对剪切强度的敏感性差于剪切波速。因此,碎石土滑坡岩土体地物参数可以作为其活动性监测和稳定性评价的参考指标。
Other AbstractThe structural characteristics of landslide, the geometry and depth of the slipping surface, the mechanical parameters of rock and soil are the fundamental basis of landslide stability evaluation, protection and governance. Landslide structure deformation, damage and destruction happened under earthquake action, following the serious safety problems in seismic disastrous area where a serious threat to the safety of people’s life and property. The premise of excluding these security risks immediately after the earthquake was how to quickly acquire the structural characteristic and the rock-soil mechanical properties. For the structural characteristic of a landslide, the traditional manual excavation or mechanical drilling was difficult and costly, and a certain degree of damage on the slope. The result of laboratory soil test was relatively accurate for rock-soil mechanical parameters, but it is time consuming, and both methods could not meet the rapid requirements. Thus, the further development of research on geology structure, mechanical characteristics and stability evolution of landslide were limited. The hypothesis was proposed that it was feasible to detect landslide structure and assess the landslide stability quickly if we could calibrate the rock and soil mechanical parameters with geophysical parameters, and take advantage of the rapid, economic, security and non-destructive features. To prove the above assumptions, we have selected Xishan village landslide as research subject located in Tonghua Town, Li County, Aba Zang & Qiang Autonomic State, Sichuan province, China. Base on preliminary engineering geological survey, our study intended to combine the geophysical techniques, in-situ test and laboratory soil test to build the relationship between geophysical parameters and mechanical parameters for evaluating landslide stability quickly after earthquakes. The study was expected to provide a reference for potential slope instability hazard investigation, the selection of post-disaster resettlement site and post-disaster reconstruction site. The main research content and research results are as follows: (1) Based on sensitivity analysis of the fissure distribution along depth in a gravel landslide with geophysical techniques including electrical method, electromagnetic method and seismic method in Sichuan seismic disastrous region. Geophysical detecting depth of fissures on the landslide surface was limited due to the broken characteristics of gravel soil. The shallow fissure depth range of 2m depth was most reliable. In the case of small borehole covering density, geophysical techniques as an effective tool to improve the drilling success rate had higher precision than boreholes as a result of many large rubbles and solitary stones in a gravel landslide, especially for shallow landslide structure. Shear wave velocity was more sensitive to fissures than resistivity value and electromagnetic wave attenuation in the credible range of 2m~4.5m along depth. MASW was most appropriate choice to delineate the surface fissure depth for a gravel landslide. (2) To obtain the shear wave velocity structure of landslide, we have combined initiative source multichannel analysis of surface wave (MASW) method and passive source microtremor survey method (MSM). The surface wave records and microtremor were processed with frequency wave number method (F-K) and spatial auto correlation method (SPAC), respectively. We have proposed a new method Dual-source Surface Wave (DSSW) method, which could simultaneously assure both the exploration depth and resolution for the structure characteristics of landslide, including weak intercalations, broken zone, large solitary stones and potential sliding surface in gravel landslide. This technology is more effective than drilling in terms of delineating depth, survey scale and expenditure, and it was more suitable for large scale and high density survey of a gravel landslide. (3) The optimiz
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/15052
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
徐兴倩. 碎石土滑坡结构特征探测及岩土体地物参数和抗剪强度的相关性分析[D]. 北京. 中国科学院大学,2015.
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