Study of main body element of crustal strain and its relationship with moderate-strong earthquakes

In this paper, progress in strain study of blocks and faults by GPS data are discussed, and the concept that active structures between blocks are the main body of crustal strain is clarified. By energy transfer principle of elastic mechanics, the relation between strain around faults and tectonic force on fault surfaces is set up and main body element model of crustal strain is constructed. Finally, the relation between mechanical evolution of model and seismogenic process of Kunlun earthquake （Ms=8.1） is discussed by continuous GPS data of datum stations. The result suggests that the relatively relaxed change under background of strong compressing and shearing may help to trigger moderate-strong earthquakes.

The Statistical Relationship between the Maximum Amplitude of the Body Strain Record and the Surface-wave Magnitude and Epicenter Distance

Based on the body strain record of Tiantanghe station from 2008 to 2014,we make a statistical analysis of the relationship between the maximum amplitude of the body strain record and the surface-wave magnitude,epicenter distance of the earthquakes,which occurred in the Chinese mainland and its surrounding areas with MS≥6. 0 and the rest of the world with MS≥7. 0. According to statistical results,we propose a statistical formula between the surface-wave magnitude of earthquake and the maximum amplitude of the body strain record,the epicenter distance: M_S~*= 0. 37 ln A_max+ 0. 57 ln D + 0. 07. We can also derive a theoretical estimation formula for the maximum amplitude: A_max=e^(2. 7(M_S^*-0. 07))D^(-1. 54). This demonstrates that the maximum amplitude of the body strain record increases exponentially with the increase of the surface-wave magnitude, and decreases with the increase of the epicenter distance,and shows a negative correlation with their product. We further discuss the necessity of adding instruments with high frequency sampling to earthquake monitoring, and dicuss the prospects for precise earthquake prediction in future.

A FINITE ELEMENT METHOD FOR STRESS ANALYSIS OR ELASTOPLASTIC BODY WITH POLYGONAL LINE STRAIN——HARDENING

In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity. Thus, the finite element equation with the solution of displacement is derived. The assemblage elastoplastic stiffness matrix can be obtained by adding something to the elastic matrix, hence it will shorten the computing time. The determination of every loading increment follows the von Mises yield criteria. The iterative method is used in computation. It omits the redecomposition of the assemblage stiffness matrix and it will step further to shorten the computing time. Illustrations are given to the high-order element application departure from proportional loading, the computation of unloading fitting to the curve and the problem of load estimation.

Analysis of Sacks Body Strain Interference at Beida No.200 Station in Changping and Earthquake Case Study

The relationship between Sacks body strain deformation at Beida No. 200 station in Changping and tidal solids,atmospheric pressure and water level is analyzed in this paper. Sacks body strain deformation data before the M_S8. 0 Wenchuan earthquake is studied based on the analysis of the interference. The short-impending anomaly of the body strain deformation is considered to be reliable. The anomaly characteristics conclude:( 1) The trend anomaly as extensional change of the body strain deformations on a quasi 1 year time scale before the Wenchuan earthquake was recorded, and the accumulative amount was about 4000 × 10^(-9). Correspondingly,the short-term precursor of earthquake was manifested as an extensional abrupt change.( 2) The extensional intermittent anomalous abrupt change was recorded by body strainmeters between March1 and May 7 in 2008.( 3) Four compressional abrupt changes were recorded in the intermittent distortions recorded between April 13 and May 11.( 4) High frequency components were increased in the distortion process in May 1 to 3,5,7,and 9 to 12,caused by slow earthquakes before the Wenchuan earthquake according to wavelet analysis. The abnormal phenomena are summarized and the mechanics discussed in this paper. Strain solid tide distortions in body strain observations,the continuous repeated extensional and compressional abrupt changes accompanying these distortions,and the increase of high frequency components can be regarded as the index of short term and impending earthquake prediction,based on analysis of interference factors such as air pressure and water level.

High-energy fiber-shaped calcium-ion batteries enable integrated wearable electronics for human body monitoring

Electronic textiles hold the merits of high conformability with the human body and natural surrounding,possessing large market demand and wide application foreground in smart wearable and portable devices.However,their further application is largely hindered by the shortage of flexible and stable power sources with multifunctional designability.Herein,a free-standing ZnHCF@CF electrode(ZnHCF grown on carbon nanotube fiber)with good mechanical deformability and high electrochemical performance for aqueous fiber-shaped calcium ion battery(FCIB)is reported.Benefiting from the unique Ca^(2+)/H^(+)co-insertion mechanism,the ZnHCF@CF cathode can exhibit great ion storage capability within a broadened voltage window.By pairing with a polyaniline(PANI)@CF anode,a ZnHCF@CF//PANI@CF FCIB is successfully fabricated,which exhibits a desirable volumetric energy density of 43.2mWh cm^(-3)and maintains superior electrochemical properties under different deformations.Moreover,the high-energy FCIB can be harmoniously integrated with a fiber-shaped strain sensor(FSS)to achieve real-time physiological monitoring on knees during long-running,exhibiting great promise for the practical application of electronic textiles.

Experimental Study on Dynamic Mechanical Properties of Sprayed Concrete-Surrounding Rock Combined Body

To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ages of 3,7 and 10 d.Experimental results showed that dynamic compressive strength and dynamic increase factors(DIF)of the combined bodies increase with the strain rate.With the growth of strain rate,the critical strain of the combined bodies first increases,then deceases.Furthermore,the combined bodies of 3 d reveal the plastic property and brittle property for 7 d and 10 d when the strain rate is over 80/s.The failure characteristic of the sprayed concrete changes from tearing strain damage to crushing damage as the growth of strain rate,and the failure characteristic of rock presents the tensile failure mode as demonstrated by the scanning electron microscope(SEM).

Shear stress distribution and characteristics of deformation for shear band-elastic body system at pre-peak and post-peak

The distributed shear stress and the displacement across shear band, the evolution of plastic zones, and the load-carrying capacity of rock specimen were investigated in plane strain direct shear test according to Fast Lagrangian Analysis of Continua （FLAC）. And then the shear displacement distribution in normal direction of system composed of localized shear band and elastic rock was analyzed based on gradient-dependent plasticity. The adopted failure criterion was a composite of Mohr-Coulomb criterion, that is, the relation between tension cut-off and postpeak constitutive of rock was linear strain-softening. Numerical results show that shear stress field approximately undergoes three different stages. At first, shear stress is only concentrated in the middle of top and base of specimen. Next, shear stress in the middle of specimen tends to increase, owing to superposition of shear stresses. Interestingly, two peaks of shear stress appear far from the loading ends of specimen, and the peaks approach with the increase in timestep until elements at the center of specimen yield. Finally, relatively lower shear stress level is reached in large part of specimen except in the regions near the two ends. As flow stress decreases, the analytical shear displacement distribution in shear band based on gradient-dependent plasticity becomes steeps outside the band, it is linear and its slope tends to decrease. These theoretical results qualitatively agree with that of the present numerical predicted results. Main advantage of the analytical solution over the numerical results according to FLAC is that it is continuous, smooth and non-linear （except at elastic stage）.

Influences of load carriage and physical activity history on tibia bone strain

Background:Military recruits are often afflicted with stress fractures.The military’s strenuous training programs involving load carriage may contribute to the high incidence of tibia stress fractures in the army.The purpose of this study was to assess the influences of incremented load carriage and history of physical activity on tibia bone strain and strain rate during walking.Methods:Twenty recreational basketball players and 20 recreational runners performed 4 walking tasks while carrying 0 kg,15 kg,25 kg,and35 kg loads,respectively.Tibia bone strain and strain rate were obtained through subject-specific multibody dynamic simulations and finite element analyses.Mixed model repeated-measures analyses of variance were conducted.Results:The mean±SE of the runners’ bone strain(μs)during load carriages(0 kg,15 kg,25 kg,and 35 kg)were 658.11±1.61,804.41±1.96,924.49±2.23,and 1011.15±2.71,respectively,in compression and 458.33±1.45,562.11±1.81,669.82±2.05,and 733.40±2.52,respectively,in tension.For the basketball players,the incremented load carriages resulted in compressive strain of 634.30±1.56,746.87±1.90,842.18±2.16,and 958.24±2.63,respectively,and tensile strain of 440.04±1.41,518.86±1.75,597.63±1.99,and 700.15±2.47,respectively.A dose-response relationship exists between incremented load carriage and bone strain and strain rate.A history of regular basketball activity could result in reduced bone strain and reduced strain rate.Conclusion:Load carriage is a risk factor for tibia stress fracture during basic training.Preventative exercise programs,such as basketball,that involved multidirectional mechanical loading to the tibia bones can be implemented for military recruits before basic training commences.

Validity of a noninvasive estimation of deep body temperature when wearing personal protective equipment during exercise and recovery

Background:Deep body temperature is a critical indicator of heat strain.However,direct measures are often invasive,costly,and difficult to implement in the field.This study assessed the agreement between deep body temperature estimated from heart rate and that measured directly during repeated work bouts while wearing explosive ordnance disposal(EOD)protective clothing and during recovery.Methods:Eight males completed three work and recovery periods across two separate days.Work consisted of treadmill walking on a 1%incline at 2.5,4.0,or 5.5 km/h,in a random order,wearing EOD protective clothing.Ambient temperature and relative humidity were maintained at 24℃and 50%[Wet bulb globe temperature(WBGT)(20.9±1.2)℃]or 32℃and 60%[WBGT(29.0±0.2)℃]on the separate days,respectively.Heart rate and gastrointestinal temperature(TGI)were monitored continuously,and deep body temperature was also estimated from heart rate(ECTemp).Results:The overall systematic bias between TGI and ECTemp was 0.01℃with 95%limits of agreement(Lo A)of±0.64℃and a root mean square error of 0.32℃.The average error statistics among participants showed no significant differences in error between the exercise and recovery periods or the environmental conditions.At TGI levels of(37.0–37.5)℃,(37.5–38.0)℃,(38.0–38.5)℃,and>38.5℃,the systematic bias and±95%Lo A were(0.08±0.58)℃,(–0.02±0.69)℃,(–0.07±0.63)℃,and(–0.32±0.56)℃,respectively.Conclusions:The findings demonstrate acceptable validity of the ECTemp up to 38.5℃.Conducting work within an ECTemp limit of 38.4℃,in conditions similar to the present study,would protect the majority of personnel from an excessive elevation in deep body temperature(>39.0℃).

Body Response to Local Muscular Performance of Individuals Engaged in Various Professional Occupations

We have compared 142 adult men and women of various ages, grouped by professional occupation, all the occupations involving local muscular performance. We studied heart reactions and central nervous system reactions to local muscular performance done until fatigue set in. The results suggested that adaptive body changes had a number of shared signs, namely, tachycardia, hypertension, and increased statistical figures of the heart rhythm, which were indicative of tension in central regulatory mechanisms of the heart.

抚顺与铁岭台伸缩仪同步异常特征分析

2019年抚顺与铁岭地震台伸缩仪观测值出现趋势性拉张变化,经过核实,抚顺与铁岭地震台洞体应变均认定为异常并进行跟踪。2020年两项异常开始出现恢复迹象,但自2021年6月开始,抚顺伸缩仪与铁岭伸缩仪再次出现趋势性拉张变化,且两个台站伸缩仪曲线形态具有同步性特征。因此,本文从仪器对比分析、数字滤波及周期分析以及区域长基线GNSS数据结果 3个方面进行分析。结果表明:2021年以来的拉张变化为正常的年变变化,而2019年至今的趋势拉张变化与该区域应力环境变化有关,需持续关注。

非均匀充填采场上隔离矿柱安全回采关键参数研究

针对崩落采场和充填采场之间设置的水平隔离矿柱在后期回采中引发的安全问题,以大冶铁矿-170 m隔离矿柱为工程背景,基于弹性力学理论,考虑隔离矿柱下非均匀充填体影响,通过分析采场巷道底板应力应变特征,构建充填体上隔离矿柱分析模型,采用数值模拟的方法,研究充填体上巷道底板的位移分布,得出3种不同类型底板上巷道间距和巷道尺寸对采场稳定性的影响规律。综合考虑,建议隔离矿柱崩落开采巷道沿用当前工程3.6 m×3.2 m的巷道尺寸;巷道间距采用10 m时,巷道均可针对上分段脊部残留矿柱,回采率高,但需增加底板安全控制措施;采用15 m时,巷道均位于底部矿房或矿柱中间,相互影响小,支护成本低。为有效回采隔离矿柱,建议采用“3.6 m×3.2 m的巷道尺寸+10 m的巷道间距+二步骤采场矿柱顶、底部分段1∶4胶结充填”的回采方案。

硅压阻式压力敏感芯体应变电阻失效分析

通过对硅压阻式压力敏感芯体内部应变电阻失效故障的排查及定位分析,确立了应变电阻缺陷造成传感器失效机理,总结激发应变电阻缺陷暴露的检测方法,确定对压力敏感芯体进行1200 h常温电老炼的筛选方案。筛选试验结果表明:增加1200 h常温电老炼后,可剔除由于应变电阻缺陷造成敏感芯体输出漂移的失效元件。

基于多模干涉的光纤冰体应变传感器

基于“单模-无芯-单模”光纤传感器对冰体进行应变测量研究。传感器以“分层冰冻”的方法植入冰体,冰体应变变化导致传感器干涉光谱波长偏移,通过监测光谱波长实现冰体应变测量。对于实际环境中已经存在的冰体,对“分层冰冻”方法进行优化,通过在冰面上铺设光纤,之后注水冰冻的方式,实现光纤在已有冰体中的植入。利用光谱相邻波谷温度灵敏度相近的特点,将相邻波谷波长差应用于应变测量,可以不受冰体温度变化影响。实验结果显示,冰体承载力大于500 g时,其应变显著增加,当承载力大于600 g时,冰体出现脆性断裂,传感器有效提取了该区间内冰体“韧-脆”转变过程中的应变信号。融化实验显示,传感器可以监测到冰体自然融化过程中完整的应变变化过程,测量结果不受冰体内部温度变化的影响。

高聚物胶凝戈壁土的动残余变形特性试验研究

高聚物胶凝戈壁土是将高聚物与戈壁土按一定比例拌合而成的,可有效提高戈壁土的力学性能。为研究高聚物胶凝戈壁土的动残余变形特性,采用中型动三轴试验研究了高聚物质量比、围压、固结比和动应力比等对高聚物胶凝戈壁土残余剪应变和残余体应变的影响。结果表明:高聚物胶凝材料能有效降低戈壁土的动残余变形,高聚物胶凝戈壁土在经受30次循环荷载后产生的残余剪应变为天然戈壁土的15.0%~18.8%,残余体应变为天然戈壁土的12.1%~22.2%;掺入高聚物质量比为3%和12%时,残余剪应变的减小幅度为85.0%、95.2%,残余体应变的减小幅度为87.9%、95.5%,且高聚物质量比越大,减小幅度越大。采用投影寻踪回归(projection pursuit regression,PPR)分析了各影响因数对残余变形的影响权重,得出高聚物胶凝戈壁土动残余剪应变和残余体应变的影响权重依次为高聚物质量比、围压、动应力比和固结比。采用指数函数对高聚物胶凝戈壁土的残余变形与振次的关系进行拟合,建立了能反映高聚物质量比影响的高聚物胶凝戈壁土的修正残余变形模型。

规模牛场牛病毒性腹泻-黏膜病流行病学调查

[目的]掌握病毒性腹泻-黏膜病(BVD-MD)在规模牛场3个品系牛间的感染状况,了解不同品系间BVDV感染是否存在差异。[方法]选择新疆师市范围内的19个规模牛场,分别饲喂中国荷斯坦奶牛(以下简称荷牛),弗莱维赫乳肉兼用牛×荷斯坦奶牛杂交代乳肉兼用牛(以下简称弗荷牛),挪威红牛×荷斯坦奶牛杂交代乳肉兼用牛(以下简称挪荷牛);共计采集血清样品7 965份,分别使用牛病毒性腹泻(BVD)实时荧光RT-PCR检测和牛病毒性腹泻ELISA方法检测抗原和抗体阳性率。[结果]实时荧光RT-PCR阳性总检出率为1.72%,荷牛阳性检出率为1.73%,弗荷牛阳性检出率为1.35%,挪荷牛阳性检出率为2.05%;场群阳性检出率为68.42%;3个品系的犊牛、青年牛、后备牛、成母牛均检测到BVDV,3个品系牛之间抗原阳性率差异不显著;牛病毒性腹泻ELISA方法检测阳性总检出率为36.69%,荷牛阳性检出率为37.11%,弗荷牛阳性检出率为36.74%,挪荷牛阳性检出率为34.02%,场群抗体阳性率为100%,3个品系牛之间抗体阳性率差异不显著。[结论]师市规模牛场3个品系牛均存在BVDV感染,且不同品系间BVDV感染率差异不显著。

温泉体应变观测数据不同频段影响因素及特征

定点形变观测值序列包含的信息有来自地球内部的应力积累和来自地球外部的因素影响,数学物理内涵丰富。基于形变测值序列综合性与可分性的特点,将温泉体应变、气温、水位、气压进行频域分析,然后将时间序列值分解,研究温泉体应变不同频段的影响因素,结果表明:(1)气压对温泉体应变的影响主要有2~4小时和1~2个月之间的月波两个频段;(2)水位为温泉体应变年周期频段的主要影响因素,且它们之间的相位差约为29天;(3)固体潮为影响温泉体应变半日波、日波频段的主要因素。

基于物联网的滑坡下管道应力监测及预警方法研究

我国地质环境复杂,长输管道在敷设过程中不可避免地穿越滑坡等地质灾害频发区域,在滑坡的推拉作用下埋地管道易发生大位移变形,导致管道变形失效,甚至引发泄漏、爆炸等事故。以滑坡为研究背景,研究了地质灾害引发管道破坏失效的影响规律,以滑坡体内、外段对滑坡区管道划分不同区段,通过迭代计算完成整体应变力学分析,基于极限应变准则对管道可能发生的不同尺度滑坡位移进行模拟计算和风险评估,开发了基于物联网的地质灾害下管道应力应变及周围土压力、地层变形等监测技术及相关硬件设备,建立地质灾害下管道本体安全监测软件系统,实现了现场监测数据的自动采集、上传、数据分析和报警等功能。开发的硬件设备及软件系统在某输油管道开展现场应用,实现了滑坡灾害易发区管道本体安全性的在线实时分析与评价预警。

某山谷贮灰场坝体静动力分析

燃煤发电的余灰一般都会堆放在灰场,随着堆灰高度的增加,灰场底部灰体和地基的应力会逐渐变大,部分灰体和地基土会进入塑性区域,且随着塑性区的加大会直接威胁到灰场的安全,因而高坝在安全方面的风险也随之加大,发生滑坡的可能性及滑坡造成的危害也会明显增加。根据规范要求,山谷干灰场最终贮灰高度超过100 m时应作专题研究。以龙王庙灰场为例,开展了灰场坝体的有限元静动力分析,得出了各工况下坝体的应力场和位移场,确定了坝体动剪应力、水平加速度和相对位移的分布规律,对同类工程有一定的参考价值。

基于自发熵增的静态物体系的超重失重分析与判断

该文由一个简单实验导出了有趣的物理现象,物体系外观“静止”状态下可产生超重和失重。实验设计的简易物体系(盛水容器+水+气球),浮体重量和浮体与水的相互作用力不等。借助浮力和水压变化引起气球或气体热力学状态改变,进而反过来引起浮力变化,导致物体系对支撑物(台秤)的压力改变,从而产生超重和失重现象。针对浮体上下运动,从非平衡态到平衡态的自发状态改变,将熵变拓展应用到宏观物体运动。孤立系统宏观熵变增加意味着状态变化的自发性,以及运动物体和水的相互作用力大小与运动物体本身重量大小不等,由此可判断超重和失重。同时,详细分析物体受力状态的变化对于如何分析复杂物体系状态变化和受力起到示范作用。