考虑卸荷扩容影响的柱状节理岩体各向异性渗流模型研究

Columnar jointed rock mass is a kind of typical structural rock mass involved in the development of hydropower in Southwestern China, and the flow anisotropy under unloading condition has been one of the key scientific problems that must be solved in the columnar jointed rock mass projects such as dams, rock slopes and underground caverns. However, few research results on this aspect have been reported up to now. Herein, normal unloading tests on basalt specimens containing a single columnar joint are firstly performed, and the normal deformations of a single columnar joint under unloading conditions are obtained, on the bases of which the corresponding constitutive model is established. Then simulated columnar jointed rock mass specimens are prepared by using 3D printing technology and similarity theory, and laboratory unloading experiments and corresponding numerical simulations on these specimens are conducted. From the experimental results, an anisotropic constitutive model for describing the dilatancy behavior of columnar jointed rock mass under unloading condition is set up. Then, laboratory flow tests under unloading conditions and corresponding numerical simulations on simulated columnar jointed rock mass specimens are performed, from the results of which the influences of unloading volume, unloading direction and dilatancy on the permeability of columnar jointed rock mass are analyzed and an anisotropic flow model for columnar jointed rock mass is proposed. Finally, a discrete element model of in-situ typical columnar jointed rock masses is established and numerical flow tests under unloading conditions are performed to verify the proposed anisotropic flow model. The research results will not only provide reasonable models for analyzing the flow problems in columnar jointed rock mass projects such as dam, rock slopes and underground cavern excavations, but also promote the progress of researches on flow in rock masses.

柱状节理岩体是西南地区水力水电开发涉及的一类典型结构岩体，其在卸荷条件下的各向异性渗流特性是大坝、边坡和地下洞室等岩体工程必须解决的关键科学问题之一，目前关于该方面的研究成果鲜见报导。本项目先通过含柱状节理玄武岩试件的法向卸荷试验，研究柱状节理在法向卸荷条件下的变形规律，建立相应的法向卸荷本构模型；在此基础上结合3D打印技术和相似理论制备模拟柱状节理岩体试件，综合其室内和离散元数值卸荷试验结果，建立柱状节理岩体卸荷扩容各向异性本构模型；然后通过模拟柱状节理岩体试件室内和离散元数值卸荷渗流试验，分析卸荷量、卸荷方向和扩容变形对其渗透系数的影响，建立考虑卸荷扩容影响的柱状节理岩体各向异性渗流模型，并通过实际柱状节理岩体的离散元数值卸荷渗流试验结果对渗流模型进行验证和完善。研究成果可为大坝、边坡和地下洞室等柱状节理岩体工程的渗流分析提供合理的理论模型，也对完善岩体渗流理论有积极的推动作用。

柱状节理岩体是西南地区水利水电开发工程涉及的一类典型结构性岩体，其在卸荷条件下的各向异性渗流特性是大坝、边坡和地下洞室等岩体工程必须解决的关键科学问题之一。本项目针对不规则柱状节理岩体，采用理论分析、室内物理实验和数值分析相结合的方法开展其在卸荷条件下的渗流各向异性特性。首先针对单一柱状节理，通过对其开展法向卸荷直剪试验，揭示了单一柱状节理的卸荷扩容特性并提出剪胀角参数进行定量表征；在现场调研不规则柱状节理岩体柱列横截面几何特征的基础上，以柱列横截面多边形占比为控制参数建立了基于voronoi图生成原理的不规则柱状节理二维网络随机模拟方法，在此基础上利用CAD和Solidworks软件对不规则柱状节理二维网络进行处理可得到不规则柱状节理网络三维模型，再综合利用3D打印技术和相似理论制备白水泥浆模拟不规则柱状节理岩体试件，对其开展单轴和常规三轴压缩试验研究加载条件下不规则柱状节理岩体力学各向异性特性，在此基础上开展不规则柱状节理岩体常规三轴卸荷物理试验和离散元数值试验，揭示了不规则柱状节理岩体卸荷扩容特性并提出综合剪胀角进行定量表征；采用离散元数值模拟方法建立不规则柱状节理岩体卸荷-渗流数值分析模型，分析了不规则柱状节理岩体渗流流量的影响因素，结合卸荷条件下不规则柱状节理岩体扩容特性和破坏模式归纳了其在卸荷条件下的渗流模式及各向异性特性。研究成果可为大坝、边坡和地下洞室等柱状节理岩体工程的渗流分析提供理论依据。