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In order to estimate the stability of slopes with geological defects during blasting excavations, the dynamic responses of a rock slope with a fault subjected to blasting seismic waves are studied. The SV-component of blasting seismic waves is considered and the fault is simplified as a semi-infinite crack in an unbounded space. In the background of an iron mine in central China, the relation between the stress field and the PPV of the incident wave is analyzed and the function of PPV threshold is deduced using both deterministic and probabilistic methods to evaluate the slope stability. Results show that the PPV threshold increases monotonically with the increasing frequency and reaches the lowest point at around γ1 = 14°, which should be proposed as the PPV threshold. The PPV threshold is with an about 50% failure probability when the mean values of mechanical parameters are taken. On the safe side, a more rigorous PPV threshold with only 5% failure probability is determined as 2.25 cm/s for f ≤ 10 Hz, as 2.25 cm/s-5.02 cm/s for 10 Hz 50 Hz. A through structural surface is likely to occur inside the northern slope once the PPV exceeds the proposed threshold.

The construction and long-term operation stage of the rock slope with argillaceous interlayer will be subjected to intermittent dynamic loads, such as blasting and earthquake. For the argillaceous interlayer in the rock slope, its rheological properties are not only related to the initial stress state caused by the gravity of the overlying rock mass but also affected by intermittent dynamic loads. In order to investigate the rheological properties of argillaceous intercalation under the combination of static and intermittent dynamic shear loads, the rheological tests of argillic intercalated soil samples under static shear, static and cyclic dynamic shear, and static and intermittent dynamic shear were carried out, and the rheological deformation characteristics of soil samples under different shear conditions were analyzed. The results show that when the soil specimens in the static shear rheological process are disturbed by intermittent dynamic shearing load, the intermittent dynamic disturbances might have no remarkable influence on the rheological deformation of the specimens if the initial static shearing stress and intermittent dynamic shearing stress were comparatively low. However, low-intensity intermittent dynamic disturbances might accelerate the rheological deformation process of the specimens remarkably if the initial static shearing stress state was close to their shearing strength. There was a stress threshold when the soil specimens failed under the static and cycling dynamic shear and static and intermittent dynamic shear, which is determined by the sum of static shear stress and dynamic shear stress peak. For rock slopes controlled by rheological weak structural planes and influenced by long-term blasting vibrations, the transient and long-term dynamic stability should be comprehensively analyzed.

Large strain self-weight consolidation is widely used for the management of the dredged material (DM) in dredged material disposal sites. A multilayer vacuum extraction method, which consists of a ...

Blasting is an efficient method for demolishing high-rise buildings and structures. If the collapse scope of a building to be blasted is insufficient controlled building implosion technology is preferred. However, for the conventional implosion, there is a lot of pre-weakening work that has to be done, and it is almost impossible to demolish the high-rise thin wall structures such as reinforced concrete (RC) chimneys. Therefore, a folding implosion method is proposed. In this method, several wedge-shaped notches should be blasted out in the high-rise building or structure, then these notches will turn to “plastic hinges”, meanwhile, the building or structure will turn to a folding kinematic chain, and the segments will overlap each other after falling down. For this method, some design criteria for the main parameters such as the position, initiation sequence, and initiation time delay of blast notches are proposed. The multi-body dynamics models for bi-folding implosion and tri-folding implosion are deduced to analyze the folding motions and rationality of the blasting plans. In two implosion cases, the design criteria and kinematics models are validated.

One of the most significant current discussions in safety assessment about the buried high-pressure gas steel pipeline was the dynamic response of steel pipeline subjected to ground surface explosion, which played a key role in anti-explosion safety protection of steel pipeline engineering. In this paper, the typical burial conditions of gas steel pipeline in Chinese cities was selected as a case, and explosion tests of full-scale model with different scale explosive charge have been employed to verify the reliability of the 3D numerical model, specially, the strain hardening for the steel has been considered to increase the accuracy of the numerical model. Meanwhile, the parametric analysis was also conducted to discuss the effects of internal pressure of the steel pipeline, ground surface explosives charge, inner diameter of the steel pipeline, and the buried depth of the steel pipeline on the buried gas steel pipeline's peak particle stress (PPS). At last, combined with the dynamic stress yield criterion of the steel pipeline, the anti-explosion safety factor of the steel pipeline was fully discussed. The results showed that the decrease of internal pressure and the inner diameter of the steel pipeline can improve the anti-explosion performance of steel pipeline, and when the ground surface explosive charge was 10 kg, to prevent steel pipeline failure by ground surface blasting load, the inner diameter of steel pipeline should be less than 1 m, and the internal pressure of steel pipeline should not be greater than 2.0 MPa.

Blasting demolition is the preferred method for safely and efficiently demolishing high-rise buildings, and numerical simulation is very helpful for the design of complicated blasting schemes. In simulations of demolition projects, the explosion processes and blast loadings are usually ignored to save computer time. However, the stress transients of blasted columns at the bottom of buildings are important boundary conditions, which may affect the accuracy of simulation results. Yet, few works have investigated it and provided a detailed model. To investigate the features of stress transients of reinforced concrete (RC) columns, an experiment was conducted in the present study. In a 56-m-high frame structure demolished by controlled blasting technology, a 1000 mm × 700 mm × 4100 mm column was blasted. The collected data include strain-time histories and failure mode of the column. The study shows that explosion-induced stress-time history curves far from the blastholes are jagged-triangular, which may have multiple peaks because of the delay time errors of detonators. After detonation of explosives, the bearing capacity of the column gradually decreases, which takes several milliseconds. When the bearing capacity reduces to less than the initial axial compressive stress in the column, the initial stress releases linearly, which also takes several milliseconds. The movements of the concrete fragments bent the longitudinal reinforcement bars, which induces a strong tensile stress in the residual column; their stress-time history curves are triangular. Based on the experiment results, a stress transient concept model is proposed to detailly describe the stress state of blasted RC columns in demolished high-rising buildings, which can be applied in the numerical simulation of demolition blasting.