深部高应力地下工程硬岩卸荷裂化机制与稳定性控制研究

Under the deep buried and high geostress conditions, the unloading excavation and mining action frequently induced the cracking behaviors of hard rock, with the characteristics of nonuniform distribution in space, step-by-step increase in time and suddenly failure process in site. Thus, taking the "hard rock" and "unloading cracking" as the key words, this program plan to: (1) Carry out the multi- scale monitoring for in-situ spatial cracking performances of hard rock under the unloading condition, and corresponding particularly laboratorial tests. These experiments' purpose is to expose the special unloading characteristics of slicing/ cracking of hard rock, and the cracking mechanism of hard rock during its crack's appearing, growing and extending; (2) Some theoretical expression methods then will be developed to describe the crack initiation, degradation of equivalent mechanical parameters and post- failure norm for the hard rock' cracking performance, based on the Oda's tensor method and fracture mechanics principle; (3) What' more, a simple index will been presented to identify the cracking depth and cracking degree for the hard rock based on the path analysis in 3D stress and strain space, and a mechanical constitutive model and corresponding programs will be edited for analyzing the unloading cracking stability and failure risk for underground engineering based on the large common finite element platform; (4) After detail theoretical check and comprehensive engineering practice, some controlling measures for hard rock's crack will be suggested from two ways, i.e. optimization of the excavation scheme for reducing the cracking risk, and reasonable supporting design for hold-up the extension of secondary cracks. The produced achievements in this programs can provide some meaningful academic guidelines and useful technical accumulations for the safe construction and disaster prevention in deep underground engineering during implementation of the national " the Belt and Road" strategy.

在深部高应力环境下，地下工程开挖/开采经常性导致硬岩发生空间非均匀分布、时间渐进发展的卸荷裂化行为及其快速灾变失稳现象。围绕“深部硬岩卸荷裂化”问题，项目拟采用试验测试→理论研究→工程实践密切结合的研究方案，首先开展硬岩开挖卸荷下渐进裂化及灾变的现场多尺度立体监测和原位取样的室内精细试验，揭示强卸荷下硬岩板/片状裂化的独特力学特征和发生、发展机制；然后基于Oda张量方法和断裂力学原理，建立硬岩渐进裂化的起裂应力判据、等效力学参数蜕变和后继屈服的理论描述方法；进而，通过分析单元在三维应力-应变空间中路径演变建立硬岩裂化定量评价指标和力学本构模型，并借助大型有限元平台开发卸荷裂化分析计算程序；最后基于抑制次生裂纹扩展的思路出发，在现场验证与应用实践基础上，从开挖方案和支护手段两个角度提出减小和避免硬岩卸荷裂化危害的实用防治技术。成果可为我国深部地下工程安全建设和灾害防治提供理论指导和技术储备。

深埋高应力环境下地下工程硬岩卸荷裂化及其诱发工程安全灾害是深部岩石工程建设中无法回避的难题之一。本项目通过试验研究、理论推演、数值分析和工程应用实践密切结合的研究方法，深入研究了深部围岩卸荷裂化及其破坏的演化机制、分析理论与控制技术，取得如下主要研究进展与结果：.（a）基于硬岩卸荷破裂原位多元、多物理量、多维综合观测技术与室内基于3D打印物理模拟试验技术，揭示了高应力下硬岩深层破裂与片帮破裂机制；.（b）建立基于断口力学分区化的硬岩渐进裂化的起裂应力判据、改进Oda的等效变形张量、等效力学参数非一致蜕变和后继屈服的理论描述方法，实现高应力下硬岩裂化的理论表征和计算分析；.（c）建立高应力下硬岩裂化的张拉/剪切破裂机制的定量评价指标，构建考虑岩体时效裂化演进的劣化力学本构模型及其程序实现，支撑深部高应力地下工程硬岩变形破坏的预测分析；.（d）研究成果成功服务了白鹤滩水电站地下厂房洞室群、金川深部巷道、硬粱包水电站地下厂房洞室群的稳定性评价、工程开挖与支护优化，一定程度上减小或避免一些安全事故，取得了较好的经济和社会效应；.本项目已在国内外主流学术期刊发表学术论文18篇（SCI论文12篇、EI论文6篇），授权中国发明专利5项，参编行业标准3部，获全国性学术大会优秀论文1篇，做学术报告6次（其中特邀报告4次），培养博士毕业生3人、硕士毕业生1人。