裂隙岩体的不均匀冻胀性及其引起的隧道围岩冻胀力研究

Surrounding rocks of tunnels in cold region are mostly rock mass and thus encountered freeze and frozen rock mechanics problems very often. Non-uniform mechanical properties of fractured rock mass and its distinct directionality when freezing in tunnel together lead to non-uniform frost heave properties of surrounding rock mass, which is the main cause of frost heave force in cold region tunnel. Therefore, non-uniform frost heave properties, non-uniform frost heave model and frost heave force computation theory for cold region tunnel considering the non-uniform frost heave properties of fractured rock mass are scientific questions in frozen rock mechanics which need to be solved urgently. So in this project, experimental research combined with analytic theory and numerical simulation research will be conducted on non-uniform frost heave properties and non-uniform frost heave models of intact rock and rock mass containing connected or intermittent fractures, classification of frost heave properties and frost heave force computation to understand non-uniform frost heave properties and evolution patterns of intact rock and fractured rock mass which are under different water supplying conditions ,as well as modeling non-uniform frost heave of fractured rock mass. And after all of above, classification standard and method of fractured rock mass frost heave properties can be proposed, which will provide scientific basis for water proving and drainage and lining insulation design of cold region tunnel. Frost heave force computational theory for cold region tunnel will be developed to enable the computation of frost heave force better in accordance with engineering practice and to effectively improve the level of both tunnel frost damage prevention and tunnel design in cold region.

寒区隧道工程中因围岩主要是岩体而遇到岩体的冻结和冻岩力学问题。裂隙岩体因其力学性质的非各向同性和隧道围岩冻结时的明显方向性，导致围岩具有不均匀冻胀性，它是产生寒区隧道冻胀力的主要原因。因此，裂隙岩体的不均匀冻胀性及其不均匀冻胀模型，以及考虑岩体不均匀冻胀性的寒区隧道冻胀力计算理论是冻岩力学中迫切需要解决的科学问题。本项目以试验研究为基础、理论解析和数值模拟研究相结合，通过岩石不均匀冻胀性及冻胀模型、含贯通和非贯通裂隙岩体的冻胀性及冻胀模型、裂隙岩体冻胀性分级及冻胀力计算理论等研究，在弄清岩石和裂隙岩体在不同补水条件下的不均匀冻胀性及其演化规律、建立裂隙岩体不均匀冻胀模型的基础上，提出裂隙岩体冻胀性分级标准和分级方法，为寒区隧道的防排水和保温设计提供依据，建立考虑裂隙岩体不均匀冻胀性的寒区隧道冻胀力计算理论，以使寒区隧道冻胀力的计算更符合工程实际，有效地提高寒区隧道的设计和冻害防治的水平。

寒区隧道围岩的非各向均匀冻胀是产生隧道冻胀力的主要原因。本项目重点研究了岩体非各向均匀冻胀性及冻胀模型，以及考虑岩体非各向均匀冻胀性的寒区隧道冻胀力计算理论等科学问题。基于各向均匀冻结时岩石冻胀试验，研究了饱和岩石典型冻胀变形过程以及冻结温度对岩石冻胀性的影响规律，提出了各向均匀冻结时岩石的热力耦合冻胀模型。自行设计了岩石单向冻结试验装置，进行封闭条件下不同温度梯度时岩石单向冻结试验，探明了单向冻结时岩石非各向均匀冻胀变形规律，并引入非各向均匀冻胀系数，建立单向冻结时岩石非各向均匀经验冻胀模型。基于开放条件下不同温度梯度时单向冻结试验，探明了开放条件下岩石非各向均匀冻胀性及其冻胀变形规律，引入分凝势理论计算迁移水分凝冻胀，建立了开放条件下岩石的THM耦合冻胀模型。基于非贯通裂隙岩体、贯通裂隙岩体的单向冻结试验，探明了单向冻结时裂隙岩体的非各向均匀冻胀性以及裂隙尺寸、温度梯度等因素对裂隙岩体非各向均匀冻胀特性的影响；考虑裂隙对岩体非各向均匀冻胀性的影响，提出了考虑裂隙率、裂隙与温度梯度夹角影响的裂隙岩体非各向均匀冻胀系数计算方法。最后，提出了考虑围岩非各向均匀冻胀的冻胀力弹性解析解及弹塑性解析解，给出了围岩冻结后弹塑性状态判定方法，可根据围岩冻胀变形合理地计算寒区隧道冻胀力。上述研究为寒区隧道围岩冻胀变形及冻胀力计算提供了理论依据，在寒区隧道防抗冻设计方面应用前景可观，具有重要的理论意义和工程应用价值。