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地下水渗流作用下碎石土斜坡变形破坏机理研究
Alternative TitleStudy on the Deformation and Failure Mechanism of the Debris Slope under the Groundwater Seepage
Language中文
韩培锋
Thesis Advisor孔纪名
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Abstract碎石土斜坡是指残积物、坡积物、崩塌或滑坡堆积物等土石混合体堆积形成的具结构松散的坡体,在我国山地广泛分布,也是地质灾害极易发生的一类斜坡。调查表明,地下水渗入作用是诱发碎石土斜坡失稳的主要因素,目前这方面的研究还非常薄弱。因此,对地下水渗流作用下碎石土斜坡变形破坏机理研究不仅具有理论意义,也为暴雨诱发滑坡预报研究提供基础,具有重要的现实意义。论文以内六铁路某处典型地下水渗流诱发的碎石土滑坡为研究对象,通过碎石土滑坡的实地勘察,建立地质力学模型。利用室内地下水渗流模型试验,重现地下水渗流过程中碎石土斜坡体内含水率、饱和度、孔隙水压力、坡体位移、应力和应变等的变化规律。计算斜坡体的稳定系数,建立稳定系数与含水率、孔隙水压力、湿陷沉降及坡体位移的经验公式。分析地下水渗流对斜坡破坏的机理,考虑地下水渗水应力对斜坡稳定性的影响,修正计算模型。论文取得了以下认识: (1)随着渗水时间的增长,碎石土体的含水率增长速率逐渐增大,当碎石土的含水率达到一定程度后,含水率的增长速率逐渐减小;研究发现水头压力越大,碎石土坡体变形破坏时最终的含水率越小;水头压力越大,碎石土斜坡越容易达到最大含水率状态,失稳破坏时越不容易达到饱和状态。 (2)随着地下水不断渗入碎石土坡体内部,碎石土孔隙内的气体被逐渐排出,基质吸力逐渐减小,孔隙水压力逐渐增大;地下水水头压力越大,碎石土斜坡变形失稳时的孔隙水压力值越小,斜坡变形失稳破坏需要的时间越短;孔隙水压力起始阶段迅速增长,随着输水时间的增长,孔隙水压力缓慢增长。 (3)水头压力越大,在碎石土斜坡失稳破坏时的沉降位移越小;越靠近斜坡体前缘,碎石土斜坡在地下水渗流作用下沉降量越大;水头压力越大,碎石土斜坡坡顶观测点沉降位移速率越快,并且还可以发现,随着输水时间的延长,沉降位移速率是先快速增大,随后又缓慢的降低。 (4)通过物理模型试验过程中观测记录斜坡的裂缝扩展及变化情况,总结地下水渗流过程中碎石土斜坡体的变形破坏规律,分析不同水头压力条件下斜坡的后缘主裂缝的宽度、深度随时间变化的规律,从而重现斜坡在整个渗水过程中的坡体变形破坏的变化规律。 (5)通过物理模型试验和数值模拟,建立斜坡的稳定系数与渗水时间、含水率、孔隙水压力、湿陷沉降和斜坡体的累积位移之间的经验公式。考虑地下水渗流时水的渗水应力对斜坡稳定性的影响,修正基于传递系数法的稳定系数计算公式,并对其进行简化。 论文主要创新性成果: (1)利用三轴试验分析不同含水率状态下碎石土体的粘聚力和内摩擦角,通过归纳建立了粘聚力与含水率的经验公式:c=-0.0046ω2+0.0034ω+21.116,内摩擦角与含水率的经验公式:φ=-0.2648ω+27.765,利用该公式可以有效估算不同含水状态下粘聚力和内摩擦角,从而可以计算地下水渗流过程中坡体的抗剪强度与含水率的关系。 (2)基于模型试,验建立斜坡的稳定系数与渗水时间、含水率、孔隙水压力、湿陷沉降和斜坡体的累积位移之间的经验公式如下: 稳定系数与时间的经验公式为:Fs=-At2-Bt+C; 稳定系数与含水率的经验公式为:Fs=-Aω+B; 稳定系数与孔隙水压力的经验公式为:Fs=Aμ4+Bμ3-Cμ2-Dμ+E; 稳定系数与湿陷沉降的经验公式为:Fs=-Ad3+Bd2-Cd+D; 稳定系数与滑坡体累积位移的经验公式为:Fs=-As2-Bs+C。 基于上述的经验公式,在判定地下水渗流过程中碎石土斜坡的稳定性时,可以利用其中的含水率、孔隙水压力、湿陷沉降和坡体位移等其中的一个或多个因素来估算斜坡的稳定系数,从而为碎石土斜坡稳定性判识提供参考依据。 (3)考虑地下水渗流过程中渗水应力对斜坡稳定性的影响,建立考虑完整渗水应力的稳定系数计算公式并进行验证。该公式增加了浮托力的作用,考虑了完整渗水应力对碎石土斜坡稳定性的影响,其计算得到的稳定系数更符合实际情况,从而为计算斜坡的稳定性提供参考
Other AbstractDebris slopes are made of residual soil, slope wash, debris of the collapse and landslide, its structure are loose. This kind of slope widely distributed in China's southwest mountainous area, it is easy to happen geological disasters for this kind slope. Investigation showed that the groundwater seeping is the main induced factor for debris landslides, and the research of this is still very weak at present. Therefore, studying on deformation and failure mechanism of debris slope under the groundwater seepage not only has theoretical significance, but also provides the basis theory for the heavy rain induced landslide forecast, the research has important practical significance. We established the geological mechanical model basing on the debris landslide near the railway, which was induced by groundwater seepage. We used groundwater seepage model test to research on the changing rule of the moisture content, saturation collapsibility, pore water pressure, settlement, slope displacement, stress and strain during the groundwater infiltrated in debris slope. We calculated the stability coefficient of the slope body, established experience formula between the stability coefficient and moisture content, pore water pressure, collapse settlement, slope displacement. The paper analysis of mechanism of slope destruction under the groundwater seepage, considered the influence of slope stability by the water seepage stress and then corrected calculation model. The main research contents and results are as follows: (1) As the time growth of the groundwater seeps through debris soil, the moisture content of debris soil gradually increase, when the moisture content of debris soil reaching to a certain extent, the growth rate of moisture content reduced gradually; The study found that the greater of head pressure, the final moisture content of debris slope is smaller when the slope deformation damage; The greater of head pressure, the debris slope more easy to achieve maximum moisture content condition and is not easy to reach saturation when slope failure. (2) With the groundwater infiltrating in debris slope, gas gradually out of the pore in the slope, the matrix suction decreases slowly, the pore water pressure increases gradually; the greater of pore water pressure, the value of pore water pressure is smaller when the debris slope failure, the instability and failure of slope needed shorter time; at the beginning, the pore water pressure growing rapidly, the pore water pressure growth slowly with the time growth of groundwater seepage time. (3) The greater of pore water pressure, the value of settlement displacement is smaller when the debris slope failure; The closer the slope in front of slope, the greater settlement displacement gravel soil slope under the action of groundwater seepage settlement is larger; Head pressure, the greater the gravel soil in the settlement of the instability and failure of slope displacement is smaller; The closer the slope before body, gravel soil slope under the action of groundwater seepage settlement is larger; Head pressure, the greater the gravel soil slope top settlement observation point displacement rate faster, and you can also found that with the extension of water delivery time, the subsidence displacement rate is rapid increase first, then slow down. (4) We observed and recorded crack propagation and changing during the whole process of groundwater seepage through the physical model experiment, studied on deformation and failure law of debris landslide under the groundwater seepage, analyzed the changing of width and depth of main cracks with time changing near the rear platform area of landslide under different head pressure, then reappear the deformation and destruction law in the whole groundwater seepage process. (5) The paper established experience formula between the stability coefficient and moisture content, pore water pressure, collapse settlement, slope displacement through physical m
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7886
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
韩培锋. 地下水渗流作用下碎石土斜坡变形破坏机理研究[D]. 北京. 中国科学院研究生院,2014.
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