【作者】 李群；

【导师】 唐辉明；

【作者基本信息】 中国地质大学 ， 岩土工程， 2007， 硕士

【摘要】 边坡稳定性是岩土工程中十分重要的研究课题之一，随着社会经济的发展，人类工程活动日益频繁，大规模的基础建设活动逐渐从平地向山区转移，边坡稳定问题越来越突出，支挡加固工程作为边坡防治的有效方法而备受关注。格构梁是近年来快速发展的一种新型支挡结构，它与锚杆（索）相结合，能够提供足够大的抗滑力，同时较其他形式的结构美观，在许多行业得到广泛应用，但是其设计理论落后于实际应用。本文引入双参数地基模型，并通过对土压力分布系数的合理假设得到了模型需要的参数，通过算例对比分析说明双参数模型的合理性；并采用FLAC^3D对格构梁进行了数值模拟，研究在水平地基及边坡上地基对梁荷载的反应及梁内力分布规律，最后介绍了双参数法在实际工程中的应用。通过研究，主要取得以下成果：1．分析了格构梁的受力特点，得出梁的控制方程：E_bI_b（d⁴y）／（dx⁴）=q（x）-p（x），分析了三种典型的计算方法：倒梁法、Winkler法和弹性半无限空间法。分析结果表明：倒梁法简单地将地基反力假设为均布，只适合于梁与基础相对刚度大、地基岩土体分布均匀、荷载均匀、对称且荷载间距不大时的情况；Winkler法假设土体为弹簧，荷载处的地基反力与位移成正比，没有考虑应力在地基中的扩散，只适合于坡体较破碎、强度低、无良好弹性的情况；弹性半无限空间法把地基看作均质、连续、弹性的半无限体，根据静力平衡和位移协调条件求出地基反力，该方法在计算土质地基上梁内力时差别较大，适合于岩质地基。2．引入双参数地基模型计算格构内力，从地基一点的应力应变入手，并根据z方向平衡条件，通过变分法得出了由两个参数控制的地基控制方程：-κ_H▽²ω（x，y）+κ_vω（x，y）=q（x，y），κ_v、κ_H分别为反映竖向压力σ_z及剪应力τ_xz、τ_yz影响的地基反力系数和地基侧向系数。根据地基应力分布系数的特点，对其进行合理假设，获得了计算模型参数的方法，提高了理论与工程实际的联系程度，并最终推导出格构梁的解析解。经与Winkler法、弹性半无限空间法、室内试验和现场试验的对比，表明双参数法计算的结果更接近试验数据，且应用范围更广。3．利用FLAC^3D进行格构梁数值模拟。分析了pile结构单元模拟地基梁的机理。通过模拟，分析了单根梁在水平地基及边坡上的内力特点和地基的应力、位移分布特点，以及格构框架在边坡上的内力特点、地基对框架作用的反应。模拟的主要结果有：单根格构梁在水平地基与边坡上的内力不同，在边坡上的内力要比水平地基上的小约10％；地基应力的扩散特点也有差别，导致这些差别的原因是由于边坡上的梁与坡面存在着摩擦力，以及边坡自重应力场与水平地基应力场的差别。在纵梁间加上横梁组成格构框架时，横纵梁同时受力，梁的内力减小，梁底地基的应力集中程度也显著降低，同时应力的扩散也更均匀范围更大，治理效果更显著，因此在实际工程中应尽量设计成框架梁。4．通过对三峡库区秭归一边坡治理的设计，详细介绍了双参数法的实际应用；通过与倒梁法、Winkler法、弹性半无限空间法结构设计的比较可知，根据双参数法的结构设计能够在保证安全的情况下，在一定程度上降低工程造价，值得推广。更多还原

【Abstract】 Slope stability is one of very important research subjects in geotechnical engineering. With the development of economic and society, large scaled infrastructure move to mountains, which lead to the slope stability becoming more and more significant, and great attention was payed to reinforcement project as an effective method to prevent destroy. It can supply enough anti-slide force when Lattice frame was applied combining with anchor-rope, and more beautiful than other structure. So it applied widely in diversified fields, but its design theory lags behind the practice.Two-parameter foundation model was introduced to calculate the force of lattice frame. By means of rational hypothesis on distribution coefficient of soil stress, the parameters was acquired. Several examples were calculated to prove the model’s rationality, and FLAC^3D was carried out to demonstrate the reaction of horizontal foundation and slope toward load and the internal force distribution law of beam, finally the application of two-parameter method model was introduced. Results are as follow:1. Force of lattice frame is analyzed to derive the control equation: E_bI_b（d⁴y）/（dx⁴）=q（x）-p（x）·Three typical calculation methods were analyzed, which including inverse beam method, Winkler method and semi- infinity elastic space mehtod. The result indicates that inverse beam method, which simply based on hypothesis of distributed load, is suitable for the situation that beam and base have relative great stiffness, the homogeneous foundation and symmetrical load in proper space only. Winkler method ignores the stress diffuseness in foundation, it is applicable to cracked, low strength and less elasticity foundation. Semi-infinity elastic space mehtod regards the foundation as homogeneous, consecutive and stretchy semi- infinity body, the contact pressure can be calculated according to static equilibrium and deformation compatibility, and ordinary suitable for rock foundation.2. Two-parameter foundation model was applied to calculate the force of lattice frame. Beginning with the stress and strain state of foundation, the manipulative equation of the beam was achieved under the help of equilibrium conditions on z axes, the expression of the equation is -k_H▽²ω（x,y） + k_vω（x,y）=q（x,y）, it was controlled by two parameters k_v and k_H, which respectively representate contace presure modulus and lateral modulus influenced by vertical stressσ_z and shearing strengthτ_xz,τ_yz . Rational hypothesis on characteristic of foundation stress distribution coefficient helps to infer calculation method and analytic solution of lattice frame. Comparing to Winkler method, semi- infinity elastic space mehtod, indoor test and field test, the result indicates that two-parameter method is closer to test data and it is of more comprehensive application.3. The numerical simulation is carried out by FLAC^3D. The mechanism of SEL-pile is analyzed. The characteristic of internal force of single beam on horizontal foundation and slope were anaylzed, so did the distribution of stress and displacement. The principal result of simulation includes difference between internal forces brought by single beam on horizontal foundation and slope, which internal force on slope is 10% smaller than that on horizontal foundation. Likely there is difference between strain diffuseness characteristics, owing to friction of slope girder to sloping face and difference in gravity strain field of slope and strain field of horizontal foundation.when lattice frame is composed with beam and carling they bear the load at the same time, which reduces the internal force of beam as concentration degree of strain at the bottom of beam foundation and average the strain diffuseness to enlarge its extent, therefore the design of lattice flame has prior consideration in actual project depending on its notable effect.4. Taking the slope in the Three Gorges Reservoir area of Zigui as an example, the application of two-parameter was detailedly introduced. The beam structure was designed by inverse beam method, Winkler method, semi- infinity elastic space mehtod and two-parameter method, the compared result indicated that the structure which based on two-parameter method could save investment at a certain extent.更多还原