冲击扰动下充填承压溶洞围岩渗压动态瞬增效应与诱导突泥机理

Mud gushing from filling confined karst caves, a complex dynamic geological disaster, is an important issue to be solved for mining, tunnels and other underground engineering. At present, most of the researches on the mechanism of mud gushing from karst caves are limited to the category of static mechanics and fail to consider the dynamic disaster factors such as blasting impact. The research will be performed around the two key scientific problems,i.e.the dynamic response characteristics of muddy water seepage field in surrounding rock of filling confined karst caves and the critical disastrous conditions of the mud-resistant rock plug under impact disturbance. The laws of dynamic transient increase of muddy water seepage pressure in rough rock fractures, and rock crack propagation under impact disturbance will be captured by the experimental study. The dynamic response characteristics of the seepage, stress and displacement fields of the surrounding rock and the precursor rules related with mud gushing will be studied by the physical simulation. In the proposed project, by means of theoretical and numerical methods, the propagation and attenuation of stress wave in the surrounding rock with rich mud，and the dynamic stress field-dynamic seepage field coupling mechanism under impact disturbance will be discussed. Dynamic evolution of various physical fields induced by impact disturbance and energy release law of mud during mud gushing will be clarified. Moreover, the project will focus on how to determine the reasonable minimum safety thickness of mud-resistant rock plug for filling confined karst caves under impact disturbance. This study will provide a theoretical basis for the prevention and control of mud gushing from karst caves, and has important theoretical significance and application value to prevent mud from outbreaking from filling confined karst caves.

充填承压溶洞突泥作为一种复杂的工程地质动力灾害，是采矿、隧道等地下工程亟待解决的重要课题。目前对于溶洞突泥机理的研究大多局限于静力学范畴，未能考虑爆破冲击等动力致灾因子。本项目围绕冲击扰动下充填承压溶洞围岩泥水渗流场的动态响应特性和阻泥防突岩塞动力失稳的临界灾变条件这两个关键科学问题开展研究。通过试验研究捕获冲击扰动下粗糙岩石裂隙泥水渗压的动态瞬增效应和裂纹扩展特性，通过物理模拟研究冲击扰动下充填承压溶洞围岩渗流、应力和位移场的动力响应和突泥前兆规律；采用理论与数值分析研究应力波在富泥水围岩中传播与衰减规律、冲击扰动下围岩裂隙动应力场－动渗流场耦合作用机理，阐明冲击扰动诱导溶洞突泥过程中各物理场动力学演化和突泥体能量释放规律，回答冲击扰动下充填承压溶洞阻泥防突岩塞最小安全厚度的问题。该研究成果可望为充填承压溶洞突泥的防治提供理论依据，对于抑制充填承压溶洞突泥灾变具有重要理论意义与应用价值。

项目组围绕冲击扰动下充填承压溶洞围岩渗压动态瞬增效应与诱导突泥机理相关科学问题，在冲击扰动下裂隙岩体流变-断裂行为及渗流试验、充填承压溶洞围岩破断失稳的扰动机制与数值研究及承压溶洞阻泥防突岩塞动力失稳诱导突泥方面取得了一些重要的进展。（1）完成了泥水混合物时滞突出的物理模拟试验，揭示了泥水混合物突出过程中的孕育、渗出、非稳定突出和稳定突出四个阶段的泥水突出规律；完成了常规三轴压缩试验和循环加卸载流变试验，率先提出了采用分级增量循环加卸载的试验方法识别、标定和量化岩石黏弹塑性应变，建立了黏弹塑性应变分离的非线性流变理论；完成了常规三轴压缩条件下岩石渗透性试验，得到不同围压，孔隙水压下茅口灰岩的全应力-应变曲线与渗透压差ΔP的变化曲线，分析全应力-应变下茅口灰岩的渗流、强度以及破坏特征；完成了岩石的断裂韧度和亚临界裂纹扩展试验，获得亚临界裂纹扩展速率与应力强度因子的关系；完成了不同法向应力作用下岩石节理的直剪试验，并建立了一种新的天然岩石节理剪切强度模型。（2）研究了岩石在泥浆和水环境中的动态特性，发现粘土填充圆柱形厚壁花岗岩试件的动态抗压强度( DCS )随应变速率线性增大的规律，揭示其岩石裂隙泥水渗压的动态瞬增效应；考虑泥水渗流压力、裂隙岩体的初始损伤和裂隙演化引起的累积损伤，建立了泥水-力耦合下裂隙岩体损伤模型。（3）深入剖析泥水-力耦合效应，研究了裂隙岩体渗流-损伤耦合机理，并提出了一种包含等效连续和离散裂隙介质的双重介质模型，并用工程实例进行验证；采用岩石流变学和断裂力学，研究了岩石裂隙的流变断裂行为，并构建了岩石裂纹流变断裂的等效Burgers模型；研究了梯度应力场中的围岩对动应力加载的响应，分析了圆形洞口处的梯度应力分布，并推导了一维应力波在梯度应力场中的传播，采用LS-DYNA程序中的隐式-显式求解方法，研究了梯度应力场中岩石的动态力学行为。（4）针对承压溶洞防水岩柱失稳破裂及留设厚度量化表征的瓶颈问题，提出一种全新的流固耦合-强度折减联动算法，实现冲击扰动下岩溶泥水突出-岩柱失稳破裂全过程的三维数值再现，构建承压溶洞防水岩柱工程留设厚度的新计算法则，回答了冲击扰动下充填承压溶洞阻泥防突岩塞最小安全厚度的问题。项目出版学术专著1部，发表学术论文72篇，获得授权发明专利12项，研究成果获湖南省自然科学奖、绿色矿山科学技术奖和中国煤炭工业协会科学技术奖三项。