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101.
102.
A coupled chemo‐viscoplastic cap model for simulating the behavior of hydrating cemented tailings backfill under blast loading
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Although the use of blasting has become a routine in contemporary mine operations, there is a lack of knowledge on the response of cement tailings backfills subjected to sudden dynamic loading. To rationally describe such a phenomenon, a new coupled chemo‐viscoplastic cap model is proposed in the present study to describe the behavior of hydrating cemented tailings backfill under blast loading. A modified Perzyna type of visco‐plasticity model is adopted to represent the rate‐dependent behavior of the cemented tailings backfill under blast loading. A modified smooth surface cap model is consequently developed to characterize the yield of the material, which also facilitates hysteresis and full compaction as well as dilation control. Then, the viscoplastic formulation is further augmented with a variable bulk modulus derived from a Mie–Gruneisen equation of state, in order to capture the nonlinear hydrostatic response of cemented backfills subjected to high pressure. Subsequently, the material properties required in the viscoplastic cap model are coupled with a chemical model, which captures and quantifies the degree of cement hydration. Thus, the behavior of hydrating cemented backfills under the impact of blast loading can be evaluated under any curing time of interest. The validation results of the developed model show a good agreement between the experimental and the predicted results. The authors believe that the proposed model will contribute to a better understanding of the performance of cemented backfills under mine blasting and contribute to evaluating and managing the risk of failure of backfill structures under such a dynamic condition. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
103.
本文基于高炉钻孔切割工程的需求,对精密三维工业测量的过程给予详细阐述,以飨类似工程的需求。 相似文献
104.
地震记录中小爆破的识别与判据研究 总被引:6,自引:5,他引:1
主要研究小当量爆破(即矿山爆破)与小震级地震事件的识别与判据。我们利用北京遥测地震台网的短周期模拟记录资料作过一些研究(傅等,1997),取得了一定的进展,在此基础上,又利用北京遥测地震台网的DAPS(模拟信号台网中心数字化地震记录)系统进行了较为深入、定量的研究。主要根据两者在波形记录特征、ML与MD震级差别、频谱分析中卓越周期与拐角频率方面的不同,使得地震与爆破的识别取得了较高的概率。 相似文献
105.
Damage in the form of cracks is predicted to assess the susceptibility of a tunnel to failure due to a blast. The material‐point method is used in conjunction with a decohesive failure model as the basis for the numerical simulations. The assumption of a cylindrical charge as the source for the blast allows the restriction of plane strain and two‐dimensional analyses. In the simulation, a further restriction of a single pressure pulse is used as the source of stress waves that are reflected and refracted after reaching the free surface of the tunnel wall. Three critical zones of significant cracking in the vicinity of a tunnel are identified as potential contributors to tunnel failure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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108.
采用自行设计的高温抗压强度在线测定装置,研究了氧化球团矿在不同气氛下的高温强度变化规律,并对高温下强度变化的机理进行了分析和探讨.实验结果表明:球团矿在中性气氛和氧化性气氛下的高温强度变化规律基本一致,表现为在低于800℃的温度范围内,球团矿强度随着温度的上升而增大,但在800~900℃球团矿强度有个明显的下降,900~1100℃球团矿强度随温度的升高略有回升,1100℃以后强度急剧下降,到1200℃时已基本失去强度;中性气氛下的球团强度整体高于氧化性气氛下的强度;在还原性气氛下,球团矿强度随着温度和还原度的提高而降低,至1100℃时强度基本消失. 相似文献
109.
A three‐phase soil model is proposed to simulate stress wave propagation in soil mass to blast loading. The soil is modelled as a three‐phase mass that includes the solid particles, water and air. It is considered as a structure that the solid particles form a skeleton and their voids are filled with water and air. The equation of state (EOS) of the soil is derived. The elastic–plastic theory is adopted to model the constitutive relation of the soil skeleton. The damage of the soil skeleton is also modelled. The Drucker–Prager strength model including the strain rate effect is used to describe the strength of the soil skeleton. The model is implemented into a hydrocode Autodyn. The recorded results obtained by explosion tests in soil are used to validate the proposed model. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
110.
Alexander Belousov 《Bulletin of Volcanology》1996,57(8):649-662
On 30 March 1956 a catastrophic directed blast took place at Bezymianny volcano. It was caused by the failure of 0.5 km3 portion of the volcanic edifice. The blast was generated by decompression of intra-crater dome and cryptodome that had formed
during the preclimactic stage of the eruption. A violent pyroclastic surge formed as a result of the blast and spread in an
easterly direction effecting an area of 500 km2 on the lower flank of the volcano. The thickness of the deposits, although variable, decreases with distance from the volcano
from 2.5 m to 4 cm. The volume of the deposit is calculated to be 0.2–0.4 km3. On average, the deposits are 84% juvenile material (andesite), of which 55% is dense andesite and 29% vesicular andesite.
On a plot of sorting vs median diameter (Inman coefficients) the deposits occupy the area between the fall and flow fields.
In the proximal zone (less than 19 km from the volcano) three layers can be distinguished in the deposits. The lower one (layer
A) is distributed all over the proximal area, is very poorly sorted, enriched in fragments of dense juvenile andesite and
contains an admixture of soil and uncharred plant remains. The middle layer (layer B) is distributed in patches tens to hundreds
of metres across on the surface of layer A. Layer B is relatively well sorted as a result of a very low content of fine fractions,
and it contains rare charred plant remains. The uppermost layer (layer C) forms still smaller patches on the surface of layer
B. Layer C is characterized by intermediate sorting, is enriched in vesicular juvenile andesitic fragments, and contains a
high percentage of the fine fraction and very rare plant remains which are thoroughly charred. Maximum clast size decreases
from layer A to layer C. The absence of internal cross bedding is a characteristic of all three layers. In the distal zone
(more than 19 km from the volcano) stratigraphy changes abruptly. Deposit here consists of one layer 26 to 4 cm in thickness,
is composed of wavy laminated sand with a touch of gravel, is well sorted and contains uncharred plant remains. The Bezymianny
blast deposits are not analogous with known types of pyroclastic surges, with the exception of the directed blast deposits
of the Mount St.Helens eruption of 18 May 1980. The peculiarities of deposits from these two eruptions allow them to be separated
into a special type: blast surge. This type of surge is formed when failure of volcanic edifice relieves the pressure from
an inter-crater dome and/or cryptodome. A model is proposed to explain the peculiarities of the formation, transportation
and emplacement of the Bezymianny blast surge deposits.
Received: 19 December 1994 / Accepted: 12 December 1995 相似文献