Wuqiang Cai 蔡武强

• Doctor of Engineering
• Tongji University

Mineral grains serve as the basic units of rocks. Understanding rock materials at the grain-scale level allows us to unveil the underlying fundamental mechanisms, thereby facilitating the development and innovation of engineering solutions. This is especially significant amidst the current energy and sustainability transition, where many geomechani...

The Generalized Zhang and Zhu (GZZ) strength criterion is one of the three-dimensional criteria suggested by the International Society for Rock Mechanics and Rock Engineering (ISRM), and it has been widely used and validated. However, the shape of GZZ criterion is non-convex and non-smooth on the π-plane, limiting its implementation into the numeri...

The elastic perfect plastic model (EPP) fails to accurately capture the strain-softening mechanical behaviors of rock masses, while the post-peak constitutive model of elastic strain softening (ESS) has great application limitations in practical engineering for complex numerical algorithms. In this paper, an EPP constitutive approximation of rock m...

The difficulty in the 3D analysis of a circular tunnel excavation lies in the selection of a reasonable softening equation for the out-of-plane stress (σz) in the plastic zone. This study developed and compared the semi-analytical solutions of a circular opening considering different approaches for obtaining σz, and the results were verified by the...

The dilation angle is the most commonly used parameter to study nonlinear post-peak dilatancy (PPD) behavior and simulate surrounding rock deformation; however, simplified or constant dilatancy models are often used in numerical calculations owing to their simple mathematical forms. This study developed a PPD model for rocks (rock masses) based on...

Fracture diameter is an important factor to evaluate rock mass quality accurately, while there is a lack of effective methods to estimate three-dimensional diameter of multiple groups of fractures by observation data. The study proposes a density-based multi-level clustering method to cluster the two-dimensional outcrop fracture data according to b...

深部卸荷岩体表现出显著的三维、非线性力学特征，浅埋隧道的设计分析方法和工程经验不适用于深埋隧道工程。传统计算模型未反映深部岩体力学特征，参数主要通过室内试验或位移反分析确定，缺乏实时、准确获取岩体参数并进行深埋隧道动态诊断的设计分析理论和方法。本文综述和研究了GZZ岩体强度三维连续分析的理论基础、参数原位取值方法及对深部岩体工程的适用性；考虑深部岩体三维强度和峰后剪胀效应的非关联塑性流动法则及弹塑性本构关系得到了岩石真三轴试验、模型试验、现场监测数据的验证；基于数字化原位测试获取岩体力学参数，可实现隧道工程三维正分析和动态设计，克服了传统位移反分析设计方法的局限；揭示了深埋隧道开挖面三维挤出变形规律和应力主轴旋转力学机理，阐明了中间主应力和三维应力状态对深埋隧道稳定的力学影响机制；探讨了“应...

博士学位论文摘要： 向地球深部进军是必须解决的战略科技问题，深部岩体隧道的智能建造是当今隧道工程建设的重要发展趋势，采集精细化、分析精确化、控制精准化是智能建造的核心内容，也是制约深埋隧道高效、安全建造的主要瓶颈。传统计算模型没有反映深部岩体力学特征，模型参数主要由室内岩石力学试验或现场位移反分析确定，缺乏实时、快速、动态获取岩体参数并进行三维正分析和动态设计的方法；同时，现有的隧道工程设计分析思路主要是基于对变形的目标控制(变形控制)，忽略了深埋隧道开挖过程中卸荷岩体应力分布和转移的过程调控(应力控制)机制。综合采用理论分析、数值模拟和试验测试等手段，研究高应力和复杂应力环境下深部岩体三维、非线性强度特征和力学行为，基于数字化原位测试获取岩体参数并进行三维(正)分析和动态设计，形成深埋岩体...

The semi-analytical method based on finite difference method is widely used in the study of the mechanical response of surrounding rocks in a circular tunnel. The core of the three-dimensional (3D) mechanical analysis of the plastic zone is to solve nonlinear equations with a complex yield criterion, which leads to a long iterative solution time an...

Deep rock tunneling exhibits a significant three-dimensional (3D) space effect. The complex stress path and extrusion deformation during excavation are the most significant and decisive factors in the stability and construction safety of a deep tunnel. 3D and forward numerical analyses based on generalized Zhang–Zhu (GZZ) strength criterion are per...

The mechanical behavior of a deep rock mass cannot be precisely evaluated with the traditional theory and model used for shallow tunneling. Moreover, the deep rock mass parameters are primarily determined from laboratory rock tests or field displacement-based back analysis. There is still a lack of a real-time, rapid, and dynamic forward analysis m...

The design experience and the shallow tunnel theory, which emphasize the plane strain assumption, two-dimensional (2D) strength theory, and indoor or back analysis-based parameters of rock mass, should not be directly adopted for deep tunnel design. This paper reports the development of a digital acquisition technique to quickly, automatically, and...

Deep rock tunnels are often in complicated true triaxial stress state and the mechanical behavior of the surrounding rock is significantly different from that in shallow tunnels, resulting in that the commonly applied strength criteria and tunnel design methods obtained from shallow tunnels cannot meet the requirement of the refined rock stability...

The generalized Zhang–Zhu (GZZ) strength criterion has a high associated fitting accuracy for true triaxial test data. It makes direct use of the parameters of the Hoek–Brown criterion and has become one of the strength criteria recommended by the International Society for Rock Mechanics (ISRM). In this study, a new version of the GZZ criterion is...

The damages of different drilling modes to reservoirs are different in types and degrees. In this paper, the geologic characteristics and types of such damages were analyzed. Then, based on the relationship between reservoir pressure and bottom hole flowing pressure corresponding to different drilling modes, the experimental procedures on reservoir...

Laboratory compressive experiments are regarded as the most accurate method to obtain the strength parameters of rock, and the rocks used for experiments are often dry. However, in geotechnical engineering, the rock masses are often under different hydraulic environments because of which rock strength decreases by varying degrees; consequently, the...

When it comes to ultra-deep wells drilling, there are multiple difficulties to be considered: over-pull and blockage during tripping because of swelling of shale and clay, instability, and costly maintenance of traditional water-based drilling fluid in high temperature. In order to solve these problems, a completely cationic drilling fluid system w...

At the front of a working coalface, the stress state can differ significantly across different zones. This seriously affects the permeability of the coal seam. In this study, we adopt a discrete element method to study the coal permeability under different stress states. The results indicate that an increase in stress causes the permeability to de...

Johnson-Holmquist (J-H) constitutive model has been widely used to study the dynamic failure process of rock. But for the reason that J-H constitutive model contains many parameters and determining these parameters requires a lot of experiments, J-H constitutive model for describing the dynamic mechanical properties of rocks is lack of accurate and...

During the development of oil field, well operation fluids will inevitably invade the formation, and insoluble is produced when contaminant ions contained in operation fluids react with formation fluids, which will easily plugs the pores, consequently affecting the flow of formation fluids. It is of remarkable significance for formation damage eval...

We developed a new model for fluid movement around the wellbore by introducing a Dirac function, which simplifies a water-injection well as a point source. The effect of porosity on the reaction and diffusion of contaminant ions is also taken into account in the model, making it more reliable in theoretical prediction.

The effect of the borehole pressure on the rock fragmentation of a bit has been studied extensively. However, its basic mechanism remains controversial. In the study a discrete element method is used to study the rock fragmentation process of single, double bit-teeth indentation under different borehole pressures. The results show that the borehole...