Cui Zhendong

Institute of Geology and Geophysics Chinese Academy of Sciences

The load versus load point displacement (LPD) curve is significant for the nonlinearity corrections for the mode-I fracture toughness of chevron bend (CB) specimens. The testing fixture plays a crucial role in measuring load versus LPD curves. To better measure the LPDs of CB specimens, we developed an improved fixture system consisting of an under...

Reused roadways are increasingly adopted in fully mechanized coalfaces with large mining heights because of the ventilation and gas drainage problems. However, the forced mechanism and grouting control technology of the reused roadway was seldom studied. Hence, in this paper, field monitoring and numerical simulation were undertaken to investigate...

In order to accurately test the KIC of the vertical stratification direction of shale, a semi-circular bending specimen with a linear chevron notch ligament (LCNSCB) was designed. The minimum dimensionless stress intensity factor (Y*min) of the LCNSCB specimen was calculated by the finite element method and the slice synthesis method, respectively....

Water level monitoring data from 5 deep wells on the North China Platform are used to study how two large earthquakes impact deep aquifers. After the passage of seismic waves from earthquakes, a subset of these wells shows changes in the phase shifts of water level responses to lunar diurnal (O1) and semidiurnal (M2) tides. We fit a model for the t...

Damage mechanics play an important role in the analysis of rock deformation and failure. Numerous damage variables have been proposed and the corresponding continuum damage models were suggested. Knowing how to apply these theoretical models appropriately in numerical simulations is the key to whether they can be adopted to solve practical problems...

The bedding planes of unconventional oil and gas reservoirs are relatively well developed. Bedding planes directly interfere with hydraulic fracture expansion. Determining how bedding planes influence hydraulic fractures is key for understanding the formation and evolution of hydraulic fracturing networks. After conducting X-ray diffraction analysi...

Even when the maximum stress is less than the peak stress under conventional loading, fatigue failure of rock is likely to occur, thereby showing its unique characteristics. The present study summarized the factors affecting rock fatigue life from the perspective of phenomenology and studied the fatigue damage process of rock from the microscopic p...

Weak bedding planes are considered the main cause of en echelon cross-layer cracks in layered rocks. This study aimed to determine why and how weak bedding planes affect the development of cross-layer crack paths under three-point bending conditions. A contrast test of tight sandstone and shale specimens was conducted to confirm the unique role of...

A common problem in cold regions is the influence of freeze–thaw damage on the stability of rock engineering. Therefore, a series of uniaxial compression tests of sandstone after freeze–thaw treatment was carried out in this study. The purpose was to express the initial damage of rock after freezing and thawing treatment more quantitatively and to...

Rock fracture toughness is an important parameter for the engineering geological design. In this present study, chevron straight-notched semi-circular bend (CSNSCB) specimens with wide-flat liner chevron ligament (Type-A) and long-narrow liner chevron ligament (Type-B) were designed and prepared using wire cutting method. Mode-I fracture toughness...

When the shale gas reservoir is fractured, stress shadows can cause reorientation of hydraulic fractures and affect the complexity. To reveal the variation of stress shadow with perforation spacing, the numerical model between different perforation spacing was simulated by the extended finite element method (XFEM). The variation of stress shadows w...

Trying to reveal the mechanism of gas seepage in coal is of significance to both safe mining and methane exploitation. A series of FEM numerical models were built up and studied so as to explore the mesoscale mechanism of seepage in coal fractures. The proposed mesoscale FEM model is a cube with micron fractures along three orthogonal directions. T...

Producing a sufficient volume of multiscale crack networks is key to enhancing recovery of shale gas. The formation of crack network largely depends on initiation and propagation of microcracks. To reveal the influence of different loading methods on the propagation of mineral-scale microcracks, this study used the Voronoi tessellation technique to...

The Brazil disk test is carried out for thin layered rock with different thickness by numerical simulation method, with the load and AE data of samples analyzed.The following are some findings: (1) When the thickness of a single layer of layered rock increases, its tensile strength does not simply increase. Instead, they roughly show a U-shaped rel...

In order to accurately test the mode I fracture toughness(KIC) of shale, three point bending loading experiments are carried out using notched semi-circular bend(NSCB) and cracked chevron notched semi-circular bend(CCNSCB) samples under three types of prefabricated notches (splitter, arrester and divider), respectively. According to statistical res...

To better understand the formation and evolution of hierarchical crack networks in shales, observations of microscopic damage, and crack growth were conducted using an in situ tensile apparatus inside a scanning electron microscope. An arched specimen with an artificial notch incised into the curved edge was shown to afford effective observation of...

Rock engineering applications require a more efficient and dependable approach to estimating mode-I fracture toughness (KIC) than is currently available. Herein, we develop an empirical relation between mode-I fracture toughness and tensile strength according to data from laboratory tests and previous researches on several kinds of brittle rocks. T...

Acoustic emissions (AE) and stress–strain curve analysis are accepted methods of analyzing crack propagation and monitoring various failure stages, including crack closure and the crack initiation level, during rock failure under brittle rock loading. This study designed a series of three-point bending tests and shear fracture tests to investigate...

Karst is a potential geological disaster threatening urban construction. However, the existing methods for evaluating the stability of karst foundations are qualitative. This makes it difficult to propose reasonable and practical suggestions for optimal treatment measures in engineering projects. This paper presents a set of quantitative comprehens...

Three-point bending tests on specimens with different offset notches are widely used to study the propagation of mixed cracks. This paper adopts the experimental scheme that makes the loading direction perpendicular to the existing crack to investigate the Ⅰ-mixed cracks. Ⅲ Load-displacement curves of different offset notch positions (L=20mm, 30mm)...

The geomechanical stability of caprock is critical to the long-term safety of geologic storage of CO2 in depleted oil reservoirs. Based on the theory of rock fracture mechanics in deep formations, we propose a quantitative assessment framework for the resistance of caprock to hydraulic fracturing due to CO2 injection and storage in a sand lens rese...

The Rosedale Fault System (RFS) bounds the northern margin of the Gippsland Basin on the Southern Australian Margin. It comprises an anastomosing system of large, Cretaceous-age normal faults that have been variably reactivated during mid Eocene–Recent inversion. A number of large oil and gas fields are located in anticlinal traps associated with t...

The influence of dip directions on the main deformation region of layered rock around tunnel is studied using a 3D distinct element code called 3DEC. We learn that the main deformation regions around tunnels are regularly changeful along with different intersection angles between dip direction and advancing direction of the tunnel. The specific def...