Chen Hong-kai

Method to calculate fatigue fracture life of control fissure in perilous rock

Rupture and safety of perilous rock are dominated by control fissure behind perilous rock block. Based on model-I and model-II stress strength factors of control fissure under acting of weight of perilous rock, water pressure in control fissure and earthquake forces, method to calculate critical linking length of control fissure is established. Take water pressure in control fissure as a variable periodic load, and abide by P-M criterion, when control fissure is filled with water, establish the method to calculate fatigue fracture life of control fissure in critical status by contributing value of stress strength factor stemming from water pressure of control fissure in Paris’s fatigue equation. Further, parameters (C and m) of sandstone with quartz and feldspar in the area of the Three Gorges Reservoir of China are obtained by fatigue fracture testing.

RESEARCH ON ABRASION OF DEBRIS FLOW TO HIGH-SPEED DRAINAGE STRUCTURE

As one weak topic in research of debris flow, abrasion of debris flow shortens obviously application life of control structure composed of concrete. High-speed drainage structure, one of the most effective techniques to control giant debris flow disaster, has shortened one-third application life due to abrasion by debris flow. Based on velocity calculation method founded by two-phase theory, research of abrasion mechanism of debris flow to high-speed drainage structure was made. The mechanism includes both abrasion mechanism of homogeneous sizing and shearing mechanism of particle of debris flow to high-speed drainage trough structure. Further abrasion equations of both sizing and particle were established by Newton movement theory of debris flow. And abrasion amount formula of the high-speed drainage trough structure is set up by dimensional analysis. Amount to calculating in the formula is consistent with testing data in-situ, which is valuable in design of high-speed drainage structure.

Global composite element iteration for analysis of seepage free surface

As one of the most difficult topics in rock mass hydromechanics, seepage free surface plays an important part in slope stability researches. Based on analysi of numerical methods to solve seepage free surface, global composite element iteration (GCEI) is presented in this paper. FEM program is made by using CGEI Calculation shows that not only the program is simple using GCEI, but also the tolerance is higher after 5 iterations

Research on equivalent processes of rock mass parameters with anchor piles

Using normal and shear rigid coefficients of intact rock and fracture plane, rigidly normal, shear equivalent rigid coefficients of fissure rock mass are conducted. On the basis of hypotheses of small displacement of rock mass, principle of superposition, irrelevance of strength parameters C and ϕ and Coulomb theory, formulas to calculate equivalent strength parameters C and ϕ of equivalent continuous mass from fissured rock mass with anchor piles are given. The achievement is extremely valuable in integral stability analysis of the rock mass slope and important in promoting the research of the rock masss constitutive relation.

Experimental analysis on physical and mechanical properties of thermal shock damage of granite

The purpose of this study was to explore the changes of mechanical and physical properties of granite under different thermal loading effects. Uniaxial compression experiments studying the rules of the influence of temperature load on mechanical properties of granite were carried out. After high-temperature heating at above 600 °C, granite tended to have stronger ductility and plasticity as well as declined peak stress and compressive strength. Thermogravimetry - differential scanning calorimetry (TG-DSC) analysis results showed that, thermal load at different temperatures induced reactions such as water loss, oxidation and crystallization in the microstructure of granite, which led to physical changes of granite. Hence it is concluded that, heating can significantly weaken the mechanical performance of granite, which provides an important support for the optimization of heating assisted processing of granite. It also reveals that, heating assisted cutting technique can effectively lower energy consumption and improve processing efficiency.

Notice of Retraction Numerical simulation of rockfall impact force in the case of oblique impacting

The impact force by rockfall events is the main loads for structure design such as tunnel entrances and rockfall passive mitigation measures. But the impact force formula are empirical or theoretical calculation methods in the case of positive impact. To solve the impact force calculation problem in case of oblique impact, by systematically comparative analysis between numerical simulation and formula calculation method in case of different impacting speed, different buffer layer thickness and different rockfall size, the authors found that numerical analysis and formula calculated results changed in the same way. And the numerical differences are within 10%. It si proved that by speed decomposition, extending the positive impact force calculation method to the the oblique collision is feasible. But also for calculation of rockfall impact force beyond the scope of the formula, numerical simulation is a feasible way.