管道修复用管状纺织复合材料的力学性能

管状纺织复合材料用于修复管道的内衬管,受到管道内输送介质的压力作用,其承压性能直接影响修复效果。为此基于对管状纺织复合材料特殊力学性能的要求及其自身结构特点,通过对其拉伸性能进行测试,建立了计算管状纺织复合材料拉伸断裂强力/宽度与破裂压强间关系的数学模型。通过实验证实,该数学模型精度较高;当待修复管道管径发生变化或腐蚀孔尺寸发生变化时,可计算管状纺织复合材料的耐压性能,对管状纺织复合材料的应用具有实际指导意义。

Rock burst laws in deep mines based on combined model of membership function and dominance-based rough set

Rock bursts are spontaneous, violent fracture of rock that can occur in deep mines, and the likelihood of rock bursts occurring increases as depth of the mine increases. Rock bursts are also affected by the compressive strength, tensile strength, tangential strength, elastic energy index, etc. of rock, and the relationship between these factors and rock bursts in deep mines is difficult to analyze from quantitative point. Typical rock burst instances as a sample set were collected, and membership function was introduced to process the discrete values of these factors with the discrete factors as condition attributes and rock burst situations as decision attributes. Dominance-based rough set theory was used to generate preference rules of rock burst, and eventually rock burst laws analysis in deep mines with preference relation was taken. The results show that this model for rock burst laws analysis in deep mines is more reasonable and feasible, and the prediction results are more scientific.

Dynamic compressive strength and failure mechanisms of microwave damaged sandstone subjected to intermediate loading rate

To investigate the influence of microwave heating on the dynamic behavior and failure mechanisms of rock,dynamic compression tests were conducted on microwave-irradiated sandstone specimens using a modified split Hopkinson pressure bar(SHPB)system.Experimental results show that microwave radiation can effectively weaken the compressive strength of sandstone.Rock specimens show three different failure modes under impact load:tensile failure,tensile−shear composite failure and compressive−shear failure.The dynamic Poisson’s ratio,calculated using the measured P-and S-wave velocities,is introduced to describe the deformation characteristics of sandstone.With the increase in microwave power and heating time,the Poisson’s ratio declines first and then increases slightly,and the turning point occurs at 244.6℃.Moreover,the microstructural characteristics reveal that microwave radiation produces dehydration,pore expansion,and cracking of the rock.The damage mechanisms caused by microwave radiation are discussed based on thermal stress and steam pressure inside the rock,which provides a reasonable explanation for the experimental results.

Research on experiment and calculation of foam bursting device

This research presents experimental data on mechanical foam bursting device,based on the high speed of air fluid impinging insidethe foam bursting device,foam bubbles disrupted as a consequence of pressures changed very quickly as shear force and their impact forces.Experimental data on foam-bursting capacity have been presented.Designed device can provide effective foam bursting on collapse foam.

Numerical investigation on the sensitivity of jointed rock mass strength to various factors

The mechanical properties of jointed rock masses, such as strength, deformation and the failure mechanism, can be understood only by studying the sensitivity of jointed rock mass strength (both the peak and residual strengths) to the factors that affect it. An orthogonal design of uniaxial compression tests was simulated on eighteen groups of jointed rock specimens having different geometric and mechanical properties using RFPA2D (Rock Failure Process Analysis) code. The results show that the peak strength is controlled by the geometric parameters of the joints, but that the residual strength is controlled by the mechanical prop- erties of the joint interfaces. The failure mode of jointed rock specimens is mainly shear failure. Joint quantity, or density, is the most important index that affects jointed rock mass strength and engineering quality.

Fracture Characters and Seismogenic Fault of the Yajiang Earthquake Sequence with M_S6.0 in Sichuan in 2001

The Yajiang earthquake sequence in 2001, with the major events of M S 5.1 on Feb. 14 and of M S 6.0 on Feb.23, are significant events in the Sichuan region during the last 13 years. Eighty-eight earthquakes in the sequence with at least 5 distinct onset parameters for each recorded by the Sichuan Seismic Network in the period of Jan. 1 through June 30, 2001 were chosen for this study. The events are relocated and the focal mechanism is derived from P-wave onsets for 13 events with relatively larger magnitudes. The focal depth of all earthquakes fall between a range of 2km to 16km, with dominant distribution between 9km to 11km. The foreshocks, the M S5.1 earthquake and the M S6.0 earthquake and their aftershocks are all located close to the Zihe fault and the dominant epicentral distribution is in NW direction, identical to that of the fault. The fracture surface of the focal mechanism is determined in accordance to the mass transfer orientation in the recent earth deformation field in the Yajiang region. The P axes of the principal compressive stress in focal mechanism solutions of the 13 events show bigger vertical components, and the horizontal projection trending SE. The earthquakes are of left-lateral, strike-slip normal, and normal strike-slip types. The rupture surface of most earthquakes strike NW-SE, dipping SW. Based on the above information, we conclude that the Zihe fault that crosses the earthquake area, striking NW and dipping SW, is the seismogenic fault for the Yajiang earthquake sequence.