锁固束口形滑坡天然土拱效应作用机理研究

发布时间：2018-10-05 14:13

【摘要】：四川地区地处我国西南山区,因具有多山地和丘陵这一地貌特征,受降雨、地震及人为活动等影响常常发生各类地质灾害,其中边坡问题十分突出。在一般性边坡治理工程中,抗滑桩具有施工方便、阻滑能力强等显著优点,在实际工程中被广泛应用,且采用抗滑桩进行坡体支护时,桩间形成的土拱作用对坡体稳定性具有重要影响。对具有锁固束口形特殊地形特征的一类滑坡进行治理时,锁固束口形地形会限制滑坡的滑动,坡体束口段产生的土拱作用可充当部分阻滑力,对滑坡整体稳定性具有巨大影响。本文以锁固束口形滑坡为研究对象,以滑坡中的天然土拱效应作用机理为研究目的,基于弹性理论建立力学概化模型证明束口形滑坡中天然土拱现象的存在;以李子乡束口滑坡为真实算例运用FLAC3D模拟研究分析,采用理论研究和数值分析方法对束口形滑坡中天然土拱效应展开探讨分析。主要完成如下工作:(1)基于束口形滑坡力学概化分析模型推导出束口形一类滑坡中窄口段后部土体任意一点的土拱应力解析表达式通解,证明束口滑坡天然土拱效应的存在。土拱效应的变化规律表明,滑坡束口状地形在一定的开阔程度才会出现明显的土拱现象,在颈缩角α介于20°～40°间具有明显应力集中现象,形成显著土拱效应,一旦开阔程度超过范围,土拱现象会迅速减弱直至消失;(2)推挤压力P、摩阻力q的增大对束口地形段产生的土拱应力会产生较大的影响,当推挤压力P在200kPa～400kPa,摩阻力q不超过300kPa时,滑坡中产生的天然土拱作用可显著提高坡体稳定性;(3)相比桩-土间土拱作用产生的圆形土拱形状和抛物线土拱形状,束口滑坡中土拱作用产生的土拱形状具有较大不同。随坡体深度及窄口段地形界限的逐渐改变,拱形不断变化调整以适应上部不断变化的应力,土拱形状整体呈现"不规则马蹄形",是束口滑坡天然土拱一大显著特征;(4)束口滑坡内部土拱效应的有效作用深度介于z=69m～z=61m之间,土拱效力整体呈稳定状态,超过这一范围后土拱效应对坡体稳定性的影响会逐渐减弱。李子乡滑坡中土拱的作用区域为x向80m～140m、y向20m～80m处,这一范围内天然土拱作用对滑坡的稳定性至关重要,在后期束口形一类滑坡灾变防治时可充分利用滑坡自身所形成的土拱作用效力,为工程实践提供指导。基于上述结论,研究成果对束口形滑坡防治具有一定的理论价值和工程应用前景。
[Abstract]:Sichuan is located in the southwest mountainous area of China. Because of its mountainous and hilly features, various geological disasters often occur under the influence of rainfall, earthquakes and human activities, among which the slope problem is very prominent. In general slope treatment engineering, anti-slide pile is widely used in practical engineering because of its advantages such as convenient construction and strong anti-slide ability, and when anti-slide pile is used to support slope body, The soil arch between piles has an important effect on the stability of slope body. In the treatment of a kind of landslide with special landform characteristics of locking beam-shaped, the clamped beam-shaped topography will limit the slide of landslide, and the soil arch produced by the beam-mouth section of slope body can act as part of the anti-slip force, which has a great influence on the overall stability of landslide. In this paper, the mechanism of natural soil arch effect in the landslide is studied. Based on the elastic theory, the existence of the natural soil arch phenomenon in the bunch-shaped landslide is proved. The natural soil arch effect in the bunch-shaped landslide is analyzed by theoretical and numerical methods, taking the Zhukou landslide as a real example and using FLAC3D simulation analysis. The main works are as follows: (1) based on the generalized mechanical analysis model of bunched-shaped landslide, the analytical expression of soil arch stress at any point in the back of narrow section of a beam-shaped landslide is derived, which proves the existence of natural soil-arch effect in Zhukou landslide. The variation rule of soil arch effect shows that the soil arch phenomenon appears only in a certain open degree in the bevel topography of landslide, and the stress concentration phenomenon is obvious in the necking angle 伪 between 20 掳and 40 掳, which forms a remarkable soil arch effect. As soon as the open degree exceeds the range, the earth arch phenomenon will decrease rapidly and then disappear. (2) the increase of the push extrusion force Pand friction Q will have a great influence on the stress of the soil arch in the beam-mouth terrain section. When P is at 200kPa400 KPA and the friction Q is less than 300kPa, the natural soil arch in landslide can significantly improve the stability of slope body. (3) compared with the shape of circular soil arch and parabolic soil arch produced by pile-soil arch interaction, The shape of soil arch caused by soil arch is different in Guankou landslide. As the depth of the slope and the boundary of the narrow section of the slope gradually change, the arch is constantly changed to adapt to the changing stress of the upper part. The shape of soil arch presents "irregular horseshoe shape" as a whole, which is a significant feature of natural soil arch in bunchou landslide. (4) the effective depth of soil arch effect is between z=69m~z=61m and the effectiveness of soil arch is stable. Beyond this range, the influence of soil arch effect on slope stability will gradually weaken. The action area of the earth arch in the Lizixiang landslide is in the x direction of 80mg / 140mt / y direction 20m~80m, which is very important to the stability of the landslide, in which the natural soil arch action is very important to the stability of the landslide. The earth arch effect formed by the landslide itself can be fully utilized in the prevention and treatment of landslide in the late stage, which can provide guidance for engineering practice. Based on the above conclusions, the research results have certain theoretical value and engineering application prospect for the prevention and control of Bundle mouth landslide.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.22

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