【作者】 王丽萍；

【导师】 张嘎；

【作者基本信息】 清华大学 ， 土木工程， 2013， 博士

【摘要】 发展有效的加固土坡安全评价方法，对于治理和防止滑坡灾害、提高土坡加固工程的合理性和经济性、保证其安全性，具有重要意义。本文针对以抗滑桩加固土坡为代表的加固土坡开展研究，自主研发试验设备，主要采用离心模型试验揭示加固土坡的破坏机理和加固机理，在此基础上发展可用于实际工程的抗滑桩加固土坡安全简化分析方法。主要取得如下新成果：1.自主研发了离心模型试验超重力场中高精度模拟完整桩施工过程的入桩及加载模拟系统、只发生剪切破坏且强度可控的剪切结构桩模型。2.进行了系列化的抗滑桩等结构加固土坡离心模型试验，揭示了地震、坡顶加载和自重加载等条件下加固土坡的响应特性及主要因素的影响规律。3．基于离心模型试验揭示了抗滑桩加固土坡的破坏机理，包括：（1）根据土坡滑裂面与抗滑桩的相对位置关系划分为过桩破坏、绕桩破坏、局部破坏和复合破坏等四类破坏模式；（2）观测证实并根据“可测的变形”定量确定了抗滑桩加固土坡存在的渐进破坏过程；（3）揭示了土坡变形局部化过程、滑裂面形成过程和抗滑桩变形过程的耦变机理，这三个过程互为因果、交替发展、耦合变化；（4）抗滑桩加固土坡破坏模式的多样化和破坏特性的复杂性与不同加载条件下土坡的变形特性密切相关。4．对比分析加固土坡和素土坡离心模型试验结果，发现抗滑桩显著减小土坡变形，其影响在向坡内部传递过程中逐渐减小。揭示了土坡的抗滑桩加固机理：抗滑桩与附近土体发生相互作用并表现为增压效应占优，该效应在抗滑桩显著影响区域内向远桩的坡内部传递，在传递过程中存在着增压效应与抗剪效应的转化，并在潜在滑裂面附近主要表现为抗剪效应，从而延缓了土坡变形局部化的发展过程和滑裂面的形成，增强了土坡稳定性。5．基于地震离心模型试验揭示了抗滑桩、土工织物、土钉等结构的抗震加固机理，证实了土坡加固机理及其分析理论方法具有良好的普适性。6．提出了“等效桩土条”模型，通过几何等效和强度等效在定量上将抗滑桩的三维加固效应简化为二维问题，扩展简化毕肖普法建立了抗滑桩加固应变软化土坡稳定性的分析方法并采用离心模型试验结果验证了有效性。将该方法用于实际土坡抗滑桩加固工程的设计分析，确定了加固显著区域。更多还原

【Abstract】 It is of great significance to develop an effective safety evaluation methodof reinforced slopes for controlling and preventing landslide disasters, forimproving the economic economy and ensuring the safety level of reinforcementprojects. The stabilizing pile was selected as the representative reinforcementstructure in the investigation of behavior of reinforced slopes in this thesis.Serialized centrifuge model tests, on the basis of development of new testdevices, were conducted to reveal the failure mechanism and reinforcementmechanism of reinforced slopes. Accordingly, a simplified, practice-facedsafety analysis method was proposed to evaluate the stability of pile-reinforcedsoil slopes. The main results and new findings are as follows:1. A simulation system was developed to realize the piling process of pilesand surface loading on the top of a slope with high precision in flight of thecentrifuge at high g-levels. A new type of structual pile was produced with aunique shear failure mode and controllable shear strength.2. A series of centrifuge model tests of slopes reinforced with differentstructures such as stabilizing piles were conducted to reveal the responsecharacteristics and influencing factors of reinforced soil slopes under theconditions of earthquake, surface loading and self-weighted loading.3. The failure mechanism of pile-reinforced slope was obtained on the basisof observations of centrifuge model tests, including:(1) The failure ofpile-reinforced slopes were catagorized into four types failure modes accordingto the relationship between the slip surface and location of piles, namely slipsurface passing through the piles, slip surface passing by the pile, local failure,and composite failure.(2) The progressive failure process of the reinforced soilslopes was confirmed and quantitatively determined using the measurabledeformation.(3) The coupling mechanism of the process of deformationlocalization, the failure process of soil slopes, and response of stabilizing pileswas illustrated with the features of interaction as both cause and effect, alternate development, and coupling change.(4) The diverse failure modes weredependent on the deformation behavior under different loading conditions.4. The results of the centrifuge model tests of the reinforced andunreinforced slopes were compared to indicate that the piles significantlyreduced the deformation of soil slope and its influence gradually decreased tothe internal slope from the piles. The pile reinforcement mechanism wasconcluded as follows: The piles performed a significant interaction with thenearby soil and exhibited dominant compression effect; such an effect wastransferred to the internal slope away from the piles within the pile influencezone with a conversion of compression effect and shear effect; the shear effectbecame dominant near the potential slip surface and delayed the deformationlocalization so that the formation of slip surface was prevented; thus thestability level of the slope was increased.5. The aseismic reinforcement mechanism of different structures, includingthe pile, the geotextile, and the nail was yielded based on seismic centrifugemodel tests. The reinforcement mechanism, together with the analysis methods,was verified to be universal.6. A simplified Bishop slice method was proposed to analyze the stabilitylevel of pile-reinforced strain-softening slopes on the basis of an equivalentmodel used to capture the three-dimensional pile effect. The proposed methodwas confirmed by the centrifuge model tests. The method was applied to thereal-world design of pile reinforcement for a dyke slope, and the analysis resultswere used to determine a significant reinforcement zone.更多还原