【作者】 许光祥；

【导师】 哈秋舲； 张永兴；

【作者基本信息】 重庆大学 ， 岩土工程， 2001， 博士

【摘要】 地下水对边坡等岩体工程的稳定具有巨大的影响，裂隙岩体渗流主要体现为裂隙渗流，因此，岩体水力学目前研究的主要方向是裂隙渗流的基本规律、计算模型及其与应力应变的耦合本构关系等。因开挖卸荷引起的岩体变形损伤、节理连通率和张开度增大对裂隙渗流的影响，以及渗流场的变化反过来对应力场的作用，这种称之为水流与卸荷力学的相互作用研究还是岩体水力学的新领域。本文在充分认识了国内外岩体渗流研究的发展及研究现状的基础上，结合现场观测、模型试验、理论研究及数值分析等多种方法，对裂隙岩体的水力几何参数、计算模型、基本渗流规律、裂隙排水、岩体卸荷力学及其与渗流的相互作用等多方面进行了研究，取得了如下一些主要成果。1、通过现场观测及统计分析表明，三峡永久船闸区岩体结构面第一优势走向为NE-NEE，第二优势走向为NNW，所有结构面中，陡倾角占绝对优势。仰斜孔排水效果明显优于铅直孔，二者实测排水量之比与其穿越结构面的数目之比十分一致(≈2)。岩体裂隙中的地下水位基本不随降雨量的变化而起伏，船闸区岩体渗流非稳定特性不明显，基本属于稳定渗流。2、现有的裂隙渗流基本规律的研究成果中，渗流量与隙宽出现两种截然相反的关系：超立方和次立方关系；渗流量与相对粗糙度也存在两种相反的关系：正相关和负相关关系。本文首次对这两种关系进行了详细分析，并通过单裂隙渗流试验证明了这两种关系的存在。结果表明，吻合裂隙试件为次立方和正相关关系，非吻合试件为超立方和负相关关系。3、本文首次利用宽配和糙配曲线，提出频率隙宽和频率粗糙度的概念，特别是频率水力隙宽的提出，为解决现有隙宽应用中出现的局限性具有极大的帮助作用。通过现有研究成果的实例分析和随机裂隙的计算机有限元模拟，相应于水力隙宽的频率在48~50%内，即eh=e48~e50。4、通过单裂隙排水试验，建立了倾斜孔和垂直孔的排水量之比与其交界线的等效直径比之间的自然对数关系式，排水孔排水量基本随其与裂隙面的交角减小而增大；对单组裂隙排水的初步分析表明，排水孔与裂隙面的夹角在21~36°范围内排水效果最佳。同时进行的排水管影响范围试验结果表明，排水孔的水平影响半径一般不超过排水孔半径的11.6倍。<WP=5>5、本文提出将单元裂隙网络转化为等效单元渗透张量的裂隙网络转换模型(单元网络模型)，具有真正体现裂隙岩体渗流明显的各向异性和显著的非均质性、易于模拟变隙宽裂隙、基本显示岩体裂隙网络渗流的基本特点、充分利用连续介质模型雄厚的理论基础等特点。同时，提出的自由面逸出点微调方法——流量平衡法，可较准确、方便获得逸出点的具体位置，克服了现有计算方法中逸出点仅取在结点上的局限性，并通过实例计算证实了该方法的可行性和实用性。6、岩体工程存在加载、卸荷、加卸载并存和交替加卸载等多种工程力学状态，边坡工程宜采用卸荷岩体力学理论研究。卸荷岩体力学考虑了岩体动态各向异性、岩体质量迅速劣化、抗拉强度极度敏感、高度的非线性等重要特性，不能简单地模拟加载的逆过程。岩体柔度矩阵可由岩块柔度矩阵和裂隙柔度矩阵组成，通过算例分析表明，裂隙的存在可使岩体的弹性常数大幅度的降低。7、基于现有裂隙变形曲线的研究成果，建立了裂隙卸荷变形及其割线刚度的本构关系式。通过对裂隙岩体渗流与卸荷力学相互作用的分析，提出了渗透系数与卸荷应力、应变间的本构关系。8、通过工程应用计算发现，边坡开挖卸荷后，应力场的改变可使临近坡面的岩体渗透系数增加3个数量级，而渗流对应力的分布也有较大影响，其中，渗流引起最小有效主应力的减小幅度明显大于最大有效主应力的减小幅度。分析表明，采用卸荷非线性岩体力学的计算结果更符合实际。更多还原

【Abstract】 On the basis of existing studies in the field of seepage of rock mass both at home and abroad, the present dissertation has conducted a broad study in terms of hydraulic and geometric parameters, computing model, basic seepage law, fracture drainage, rockmass’ unloading mechanics and its relations with seepage. The paper is written by employing such methods as field observation, model test, theory research and numerical analysis. The main research payoffs are as follows.⑴ Field observations and measurements and relevant statistics show that the NE-NEE and NNW constitute the first and second dominant trends of the discontinuities of the rock mass in the area of the permanent shiplock in the Threee-Gorge Project. Of all the discontinuities, the steep dip takes the absolute lion’s share. In this case, drainage through upward hole is obviously advantageous over that through plumb hole. The measured ratio of drainage using the said two ways is rather similar to that of numbers going through the discontinuities (i.e. about 2). Since the underwater level is basically immune to the changes of rainfall, the seepage flow is steady on the whole.⑵ According to the existing studies of the basic law of fracture seepage, there are two sharp contrastive relations between seepage discharge and aperture: super-cubic and sub-cubic. Similarly, there are also two opposite relations between seepage discharge and relative roughness: positive and negative relations. For the first time, this dissertation has analyzed the two relations in a detailful way and proved the existence of the above two relations by means of test of single fracture seepage. The test results reveal that mating fracture trial cubes present a super-cubic and positive relationship and that non-mating fracture a sub-cubic and negative relationship.⑶ By using the aperture curve and roughness curve, the author of the dissertation has put forward the concepts of frequency hydraulic aperture and frequency roughness for the first time. Of the two concepts, the first or frequency hydraulic aperture has got some advantages of its own in the seepage analysis. By analyzing actual cases and simulating finite element of random fracture through computer, the frequency hydraulic aperture falls within 48~50%, i.e. eh=e48~e50.⑷ By doing single fracture drainage experiments, this paper has successfully presented the logarithm function relationship between ratio of drainage discharge through upward and plumb drainage hole and the ratio of their equivalent diameters. The drainage effect will be the best when the included angle between drainage hole and fracture surface is 21~36°. At the same time, experiments also show that the horizontal affecting radius of drainage hole is no <WP=7>more than 11.6 times that of drainage hole radius.⑸ In this dissertation, the author presents a model of transforming element fracture net into element equivalent hydraulic conductivity tensor. This model can effectively reflect the obvious anisotropy and non-homogeneity of fracture rock seepage and makes it easier to simulate the various aperture fissure and display the fundamental characteristics of discrete fissure net. In addition, the model is can also make the best use of the sound theoretic foundation of equivalent continuum model. At the same time, the disscharge balance method developed in the dissertation can specify the exact location of discharge point in an easier and more efficient way. In other words, the new method gets rid of the limitation of the traditional method which fixes the point of discharge at the node alone. Actual computation proves the said new method is both feasible and practical.⑹ Rock mass projects are of different engineering mechanical states including loading, unloading, coexistence of loading and unloading, alternation of loading and unloading. What is suitable in the research of slope works is the unloading rock-mass mechanics. Since the unloading rock-mass mechanics has taken into consideration the dynamic anisotropy, accelerated degradation of t更多还原