【作者】 聂文波；

【导师】 唐辉明； 晏鄂川；

【作者基本信息】 中国地质大学 ， 岩土工程， 2003， 硕士

【摘要】 边坡是人类生存的重要环境,人类在从事生产和建设过程中，不可避免的要对岩石圈表层进行改造，其中，高速公路修建和山区城市建设等人类工程活动对岩体的挖掘，往往形成众多的岩石工程边坡。将岩石开挖工作减至最少和预测岩石边坡的安全度和极端状态，无论对公路、铁路、坝基还是露天矿，都是土木、地质工程师共同的课题。如果斜坡陡峻，安全问题又很重要，或者边坡设计明显地影响工程费用的话，岩石边坡的合理设计就显得尤为重要。对岩石边坡的治理设计一直以来都是沿着两条思路进行，即主动锚固和被动支挡。主动锚固的主要手段是锚杆；被动支挡的主要手段是抗滑桩。文章结合高速公路边坡和三峡库区城市边坡的工程实例从四个方面展开论述：第一，论述锚杆锚固机理及锚杆正交优化设计，第二，论述抗滑桩的桩土作用机理、计算方法，第三，论述抗滑桩的优化设计，第四，对抗滑桩和边坡体系进行了三维有限元分析。通过研究得到了如下创新性研究成果：1、目前边坡工程中锚固参数的确定多以经验和规范为主，各参数之间的匹配也有不尽合理的地方。正交设计方法作为处理多因素试验的一种科学的试验方法，用这种方法只要少次数的试验就可判断出较优的试验条件，若再对试验结果进行统计分析，还可以更全面、更系统的掌握试验结果，做出试验因素对评价指标的正确判断。引用统计学中正交设计原理对京珠高速公路大悟段某边坡锚固参数进行了优化设计，优化结果表明以边坡水平变形量为评价指标，主要锚固参数对错固效果的影响显著性依次为：锚杆长度＞锚杆间距＞混凝土喷层厚度，得出的最优参数方案为锚杆长度3.0m、锚杆间距2.0m、凝土喷层厚度100mm。2、对抗滑桩桩土作用机理从室内外试验、数值计算方法等方面进行了深入的探讨和总结，指出了试验在对抗滑桩桩土作用机理的认识方面具有其他方法不可比拟的作用。3、抗滑桩的设计推力的取法有三种：一种是直接将剪出口的推力差值P1作为设计推力，目前抗滑桩设计中多采用此法；一种是将设桩处的推力差值P2作为设计推力； 一种是将设桩处的推力差值P2与剪出口的推力差值P1比较取其大者作为设计推力。实际上这三种设计推力的取法都不科学。因为取P1作为设计推力没有明确的力学上的根据，取P2作为设计推力由于没有考虑桩前岩土体的抗力，往往偏小。抗滑桩的设计推力要大于设桩处推力差值P，因为推力P有部分向下传递，设ξ为传递系数（0<ξ<1），则实际设计推力应为P/（1-ξ）。4、抗滑桩的锚固深度原则上是由地层的容许侧向抗压强度及桩基底的容许承载力确<WP=6>定，一般在抗滑桩中以桩侧岩土层的容许侧向抗压强度确定。利用刚性桩侧应力所必需遵循的原则分析确定锚固深度的简化表达式为： 或 。5、分散布置的抗滑桩是通过桩间土拱将滑坡推力传递到桩上，再通过桩传递到下部稳定地层中。引用结构力学知识得到了桩间距的表达式为： 。6、由于地下工程的隐蔽性使得精确的滑坡推力方向的确定有很大的人为性，在这种情况下，采用圆形截面抗滑桩治理边坡有巨大优势，因为采用圆形截面抗滑桩不需要非常精确地确定滑坡推力作用的方向,这不但施工方便还有利于施工安全。但是圆形截面抗滑桩配筋计算方法繁琐，不利于其推广应用，本文给出了两种配筋计算方法，黄金分割算法和近似等代法。7、应用大型有限元分析软件ANSYS对单根抗滑桩分析表明： 对于配箍量一定的抗滑桩,如纵向钢筋配置较多,破坏时,纵向钢筋不发生屈服，而随着纵向钢筋量的减少,纵筋受力减少较小。桩身混凝土受压区高度变化不大,临界斜裂缝的倾角变化很小。通过临界斜裂缝的箍筋能够绝大部分、甚至全部屈服,桩呈剪切破坏形式。纵向钢筋数量对抗剪承载力影响较小,破坏时纵向钢筋发生屈服,随着纵筋量的减少,纵筋内力按比例减小,其混凝土受压区高度显著减少,临界裂缝的倾角明显增大,而且通过斜裂缝的箍筋已不能够全部屈服,甚至不屈服。桩的抗剪能力急剧下降,桩呈弯曲破坏形式,箍筋数量对抗剪承载力影响较大。所以,设计时可以综合考虑纵筋量和箍筋量对抗滑桩的影响。 8、ANSYS对抗滑桩—边坡系统分析表明：围岩的Es越大，抗滑桩所能承受的滑坡推力就越大。在同样大小的滑坡推力作用下，围岩的Es越大，桩的埋深就越小。对于滑坡推力分布形式的模拟可得出这样的结论，对于同样大小的滑坡推力，矩形分布荷载桩较三角形荷载分布形式所得结果要偏安全。更多还原

【Abstract】 Slope is important environment for mankind and an important component of engineering construction. The surface of lithosphere can be inevitably transformed in the course of the production and construction of human beings. Specially, many human being engineering activities such as rebuilding high way and constructing cities in mountain area often cause so many rock slope. Minimuming the load and forecasting the safety degree and the critical state are the common study focus for geologists and engineers whether it is road or railway, dam base. The design is very important if slope is steep and safety degree can’t be overlooked. Or slope design is tightly connected with engineering expense.Two methods are used all the way for the design to harness rock slope. The methods are anchoring and retaining. The anchoring measure is anchoring bolt and the retaining measure is slide-resistant pile. It is an aim to study the mechanism and the optimum design of anchoring bolt and slide-resistant pile in harnessing rock slope in the paper. The major content is demonstrated from two sides in the paper. Firstly, anchoring mechanism and orthogonal and optimum design of anchoring bolt are demonstrated. Secondly, the formal mechanism between pile and soil of slide-resistant pile, the calculating methods and the optimum design of its system are demonstrated. The mechanism and the optimum design of anchoring bolt and slide-resistant pile are demonstrated on the base of two engineering examples in the paper. The two examples are high way slope and city slope in Three Gorges. The conclusions are as follows:1.The parameters of anchoring bolt are very important for anchoring effects. The length and the interval of anchoring bolt are main parameters and must be decided in engineering design. Study shows that the effect of anchoring will be greatly reduced if its length is too long. So, selecting its length is very significant to fully play its role and get economical and rational anchoring result. 2.Anchoring parameters of slope of Dawu section in Jingzhu high way are best selected using orthogonal design principle. The results show that the effects of anchoring parameters are different and remarkable according to horizontal deformation of slope. The order of the difference is : the effect of anchoring bolt length > the interval of anchoring bolt > thickness of sprayed concrete. The optimum parameters are obtained. They are: its length is 3m, its interval is 2m and the thickness of concrete is 100mm.3.Slide-resistant pile bears down-sliding force that slide mass generates. One part is transferred to stable stratum under the sliding plane through pile. The other is transferred to slide mass in front of the pile.4.The designed thrust is greater than the thrust difference P where pile is placed. In fact, the designed thrust is P/(1-ξ) because one part of P is transferred down.. The ’ξ’ is transferring<WP=8>coefficient and it is between 0 and 1. ξ is decided according experience analogy method if there are no test data.5.The anchoring depth of slide-resistant pile theoretically is decided according to permissible sided compressive strength of stratum and permissible bearing load of the base of pile. Commonly, it is decided according to permissible sided compressive strength of rock stratum in the side of pile. The formula of anchoring depth is established using the principles that sided stress of stiff pile must abide by. The formula is or .6. For scattered piles, thrust is transferred to slide-resistant pile through soil arch between piles. Then, the thrust is transferred to stable stratum through pile. The formula of pile interval is obtained by structure mechanics: .7.Decision of more accurate direction of thrust is random because of concealed underground engineering. In view of it, slide-resistant pile whose section is round is exploited in harnessing slope. For slide-resistant pile whose section is round, more accurate direction of thrust isn’t necessary. Thus, its construction is convenient更多还原