Microseism Induced by Transient Release of In Situ Stress During Deep Rock Mass Excavation by Blasting

During deep rock mass excavation with the method of drill and blast, accompanying the secession of rock fragments and the formation of a new free surface, in situ stress on this boundary is suddenly released within several milliseconds, which is termed the transient release of in situ stress. In this process, enormous strain energy around the excavation face is instantly released in the form of kinetic energy and it inevitably induces microseismic events in surrounding rock masses. Thus, blasting excavation-induced microseismic vibrations in high-stress rock masses are attributed to the combined action of explosion and the transient release of in situ stress. The intensity of stress release-induced microseisms, which depends mainly on the magnitude of the in situ stress and the dimension of the excavation face, is comparable to that of explosion-induced vibrations. With the methods of time–energy density analysis, amplitude spectrum analysis, and finite impulse response (FIR) digital filter, microseismic vibrations induced by the transient release of in situ stress were identified and separated from recorded microseismic signals during a blast of deep rock masses in the Pubugou Hydropower Station. The results show that the low-frequency component in the microseismic records results mainly from the transient release of in situ stress, while the high-frequency component originates primarily from explosion. In addition, a numerical simulation was conducted to demonstrate the occurrence of microseismic events by the transient release of in situ stress, and the results seem to have confirmed fairly well the separated vibrations from microseismic records.     

Dynamic Study on Fracture Problems in Viscoelastic Sedimentary Rocks Using the Numerical Manifold Method

The viscoelastic deformation behavior of a sedimentary rock under different loading rates is numerically modeled and investigated by the numerical manifold method (NMM). By incorporating a modified 3-element viscoelastic constitutive mode in the NMM, crack initiation and propagation criteria, and crack identification and evolution techniques, the effects of the loading rates on the cracking behavior of a sedimentary rock, such as crack open displacement, crack sliding displacement, crack initiation, crack propagation and final failure mode, are successfully modeled. The numerical results reveal that under a high loading rate (>1,000 MPa/s), due to the viscoelastic property of the sedimentary rock, not only the structural behavior deviates from that of elastic model, but also different cracking processes and final failure modes are obtained.     

超大混凝土圆环内支撑在深基坑工程中的应用

以南京新城科技园国际研发总部园深基坑围护实例为背景,分析了直径超过200 m的超大混凝土圆环内支撑系统的工程应用特点,介绍了混凝土圆环内支撑结构设计、平面布置以及竖向承重结构的布置、圆环受力情况及配筋计算,并总结了深基坑超大圆环支撑设计的相关构造节点和关键技术要点.现场实测基坑位移较小,内支撑系统内力在可控范围内,整个施工过程达到了安全可靠的目标,对保护周边环境起到很好的作用,表明这些技术措施取得了良好的实施效果,希望为今后类似的深基坑工程围护设计与施工提供借鉴.     

High-resolution profiles of iron, manganese, cobalt, cadmium, copper and zinc in the pore water of estuarine sediment

The remobilization of iron, manganese, cobalt, cadmium, copper and zinc in the pore water of estuarine sediment cores at Yingkou was assessed using diffusive equilibrium in thin films and diffusive gradients in thin films techniques. A relatively anoxic system (+33.7 to ?224.1 mV) in the sediment cores might cause the reductive release of iron, manganese and cobalt into pore water from the estuarine sediment. High-average concentrations of iron (47.85 μg ml^?1) and manganese (3.81 μg ml^?1) were observed using diffusive equilibrium in thin films on the sediment core, but the concentration of cobalt (18.02 ng ml^?1) was relatively low. A strong correlation between iron and cobalt was observed based on the vertical profiles of the metals. Manganese and iron were more readily released from the solid phase to the solution. The peak cobalt, copper and zinc concentrations were observed in the upper layer (2–4 cm) measured using diffusive gradients in thin films. However, the peak iron, manganese and cobalt concentrations were located in the deeper layer (≥7 cm). In addition, the concentration profiles measured using diffusive gradients in thin films of cobalt, copper and zinc were independent of the iron, manganese and cobalt distribution with respect to depth.     

内蒙古自治区页岩气资源远景探讨

内蒙古自治区发育有三套富含有机碳的泥页岩地层,即中-上元古界渣尔泰山群和白云鄂博群的海相含炭页岩系:晚古生界上石炭统太原组和二叠系山西组的海陆交互相含炭页岩系;中新生界的陆相含炭页岩系,页岩气主要赋存在陆相含炭页岩系中.根据煤、油气勘查成果以及页岩气评价资料,认为鄂尔多斯盆地含页岩气地层厚度大,有机质碳含量高,为好的烃源岩;在阿拉善盆地、二连-海拉尔盆地、通辽地区中生界炭质页岩、煤层及油页岩发育且厚度大,河套盆地中渐新统临河组和中新统五原组形成于潟湖相,富含有机质,为生油气的有利层位,推断这些盆地页岩气资源前景良好.依据页岩气形成条件和含页岩气地层的相关分析,提出页岩气勘查工作首先在鄂尔多斯盆地和二连-海拉尔盆地群展开,在获得一定成果的基础上,再对阿拉善盆地和河套盆地进行勘查,对通辽盆地页岩气进行野外调查.     

沙尘天气下输沙率的野外观测与分析

2014年7月—2014年8月借助风速仪、微梯度集沙仪,通过野外监测系统获取的试验数据,对塔中地区2014年7月—2014年8月沙尘天气过程中贴地层输沙率进行分析,得出:0～85 mm高度内,随着风速的增大,35～85 mm无论是绝对的输沙量还是相对的输沙量都减少。0～85 mm高度内,各层输沙率最大值均出现在风速为8 m·s-1左右,波动较为显著;最小值出现在6.5 m·s-1左右,波动不明显;沙尘天气中,输沙率最大值出现在5～15 mm高度,最小值出现在35～85 mm高度。扬沙天气中,风速9.2 m·s-1时,输沙率最大值在0～5 mm处。沙尘暴天气,拐点风速为7.5 m·s-1,7.5 m·s-1时,输沙率增加不显著,7.5 m·s-1时,输沙率增加显著。通过微梯度集沙仪获得的上述试验数据是风沙工程设计的一个极重要工程参数,具有重要的实践意义。     

MICAPS3.0的本地化和二次开发

MICAPS3.0系统的主要用途是为预报员提供一个天气分析显示的工作平台。气象预报和服务人员通过此平台检索各种气象数据,显示气象数据的图形和图象,对各种气象图形进行编辑加工,诊断分析气象条件,进行中期、短期、短时天气预报制作。     

保德区块中低阶煤层压裂施工砂堵原因分析及技术对策

针对保德区块中低阶煤储层压裂过程中容易出现砂堵影响储层改造效果的问题,根据研究区块的地质条件,结合水力压裂时裂缝在煤层中的扩展规律,分析了保德区块煤层水力压裂出现砂堵的4类主要原因,分别为煤储层裂隙相对发育造成压裂液滤失量增加、压裂沟通高渗透性的顶底板、煤储层本身有效厚度大滤失量增大及多层合压造缝不充分。在此基础上,提出了相应的技术对策,使用清洁压裂液、适当提高并稳定施工排量及优化压裂施工设计,为现场的水力压裂施工和提高煤储层改造效果提供重要指导。     

Reversal of monthly East Asian winter air temperature in 2020/21 and its predictability

在全球变暖的背景下,近年来东亚冬季气温存在复杂的季节内变化.本文研究了2020/21年东亚冬季气温的月际转折及可预测性.结果 表明,2020/21年东亚冬季气温前冬(2020年12月-2021年1月中旬)偏冷,后冬(2021年1月中旬-2月)偏暖.西伯利亚高压强度在前冬和后冬也出现转折变化.在前冬,由于2020年9月巴...     

Comparing Simulations of Rising Flux Tubes Through the Solar Convection Zone with Observations of Solar Active Regions: Constraining the Dynamo Field Strength

We study how active-region-scale flux tubes rise buoyantly from the base of the convection zone to near the solar surface by embedding a thin flux tube model in a rotating spherical shell of solar-like turbulent convection. These toroidal flux tubes that we simulate range in magnetic field strength from 15 kG to 100 kG at initial latitudes of 1^° to 40^° in both hemispheres. This article expands upon Weber, Fan, and Miesch (Astrophys. J. 741, 11, 2011) (Article 1) with the inclusion of tubes with magnetic flux of 10²⁰ Mx and 10²¹ Mx, and more simulations of the previously investigated case of 10²² Mx, sampling more convective flows than the previous article, greatly improving statistics. Observed properties of active regions are compared to properties of the simulated emerging flux tubes, including: the tilt of active regions in accordance with Joy’s Law as in Article 1, and in addition the scatter of tilt angles about the Joy’s Law trend, the most commonly occurring tilt angle, the rotation rate of the emerging loops with respect to the surrounding plasma, and the nature of the magnetic field at the flux tube apex. We discuss how these diagnostic properties constrain the initial field strength of the active-region flux tubes at the bottom of the solar convection zone, and suggest that flux tubes of initial magnetic field strengths of ≥?40 kG are good candidates for the progenitors of large (10²¹ Mx to 10²² Mx) solar active regions, which agrees with the results from Article 1 for flux tubes of 10²² Mx. With the addition of more magnetic flux values and more simulations, we find that for all magnetic field strengths, the emerging tubes show a positive Joy’s Law trend, and that this trend does not show a statistically significant dependence on the magnetic flux.