Effects of hanging wall and footwall on demand of structural input energy during the 2008 Wenchuan earthquake

Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated,focusing on the influence of these differences on structural input energy based on the elastic and inelastic energy responses of structures.A comparison of the input energy spectra between the hanging wall and the footwall reveal that the structural input energy on the hanging wall is not amplified due to the short duration and low peak ground velocity to acceleration ratio（V/A）.However,the larger demand of structural input energy on the footwall in the range of medium and long periods is observed and the demand increases up to 50% relative to the average level of structural input energy for rupture distances larger than 30 km.The importance of considering the footwall effect on structural input energy when comparing ground motions in the range of medium and long periods is recognized.

Effects of the hanging wall and footwall on peak acceleration during the Jiji (Chi-Chi), Taiwan Province, earthquake

The M=7.6 Jiji (Chi-Chi) earthquake, Taiwan Province, on September 21, 1999 (local time) is a thrust fault style earthquake. The empirical attenuation relations of the horizontal and vertical peak ground accelerations (PGA) for the Jiji (Chi-Chi) earthquake are developed by regression method. By examining the residuals from the Jiji (Chi-Chi) earthquake-specific peak acceleration attenuation relations, it is found that there are systematic differences between PGA on the hanging-wall and footwall. The recorded peak accelerations are higher on the hanging-wall and lower on the footwall. The clear asymmetry of PGA distribution to the surface rupture trace can also be seen from the PGA contour map. These evidences indicate that the PGA attenuates faster on the hanging-wall than on the footwall. In the study of near-source strong motion, seismic hazard assessment, scenario earthquake and seismic disaster prediction, the style-of-faulting must be considered in order that the attenuation model can reflect the characteristic of ground motion in various seismic environmental regions.

Geometric effects resulting from the asymmetry of dipping fault:Hanging wall/ footwall effects

Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rupture distance Drup and the seismogenic distance Dseis. Then, using Drup, Dseis and Drms, the hanging wall/footwall effects on the peak ground acceleration (PGA) during the 1999 Chi-Chi earthquake are evaluated by regression analysis. The logarithm residual shows that the PGA on hanging wall is much greater than that on footwall at the same Drup or Dseis when the Drup or Dseis is used as site-to-source distance measure. In contrast, there is no significant difference between the PGA on hanging wall and that on footwall at the same Drms when Drms is used. This result confirms that the hanging wall/footwall effect is mainly a geometric effect caused by the asymmetry of dipping fault. Therefore, the hanging wall/footwall effect on the near-fault ground motions can be ignored in the future attenuation analysis if the root-mean-square distance Drms is used as the site-to-source distance measure.

Preliminary analysis of the hanging wall effect and velocity pulse of the 5.12 Wenchuan earthquake

A preliminary study of the PGA attenuation, hanging wall effect and velocity pulse characteristics from the 2008 Wenchuan earthquake ofMS -8.0 is described in this paper. The study was carried out through analyses in the time and frequency domains of main earthquake records. In the PGA attenuation study, records from 316 stations less than 1000 km from the surface rupture of the fault were used as a database and attenuation relationships were developed and compared with some existing relationships that are widely used in China's Mainland, Chinese Taiwan and the US. At the same time, records from 28 stations less than 100 km from the fault were used to study the hanging wall effect and velocity pulse characteristics of this earthquake based on the distribution of PGA, PGV, spectral acceleration, and the velocity pulse peak, and the results are compared with the 1999 Chi-Chi earthquake. In addition, the large PGAs of the UD components observed in this event are also discussed in this paper. From the results of the preliminary study, some conclusions are developed and suggestions for further research are proposed.

Rupture directivity and hanging wall effect in near field strong ground motion simulation

A random synthesis procedure based on finite fault model is adopted for near field strong ground motion simulation in this paper. The fault plane of the source is divided into a number of sub-sources, the whole moment magnitude is also divided into more sub-events. The Fourier spectrum of ground motion caused by a sub-event in given sub-source, then can be derived by means of taking the point source spectrum, attenuation with distance, energy dissipation, and near surface effect, into account. A time history is synthesized from this amplitude spectrum and a random phase spectrum, and being combined with an envelope function. The ground motion is worked out by superposition of all time histories from each sub-event in each sub-source, with time lags determining by the differences between the triggering times of sub-events and distances of the sub-sources. From the example of simulations at 21 near field points in a scenario earthquake with 4 dip angles of the fault plane, it is illustrated that the procedure can describe the rupture directivity and hanging wall effect very well. To validate the procedure, the response spectra and time histories recorded at three near fault stations MCN, LV3 and PCD during the Northridge earthquake in 1994, are compared with the simulated ones.

A new attenuation model of near-fault ground motions with consideration of the hanging wall effect in the Wenchuan earthquake

The hanging wall effect is an important factor that impacts the characteristics of strong ground motions in near-fault areas. Based on a residual analysis of ground motion parameters characterizing the hanging wall effect and in recognition of the nature of the effect, many models have been developed. In this study, after a comprehensive analysis of two existing models, a new model is proposed and used to model the hanging wall effect in horizontal peak ground acceleration （PGAH） and spectral acceleration （SAH） at a period of 0.1s in the Wenchuan earthquake. Finally, comparisons between the modeling results of the hanging wall effect in the Wenchuan earthquake and the results predicted by using Abrahamson and Silva＇s NGA model （AS NGA） indicate that the AS NGA model predicts a much higher hanging wall effect than the model developed in this paper. Furthermore, the AS NGA model predicts a large hanging wall effect even at great distances, while the proposed model more accurately captures the trend of the effect.

Influence of Stope Design on Stability of Hanging Wall Decline in Cibaliung Underground Gold Mine

Cibaliung Underground Gold Mine applies cut and fill mining method to optimize ore production and maintain underground stability. Existing 5 m × 5 m height and width of stope geometry has a potential new design to increase production of gold due to variety of thick ore, however serious shotcrete failures often occur in hanging wall decline. This paper aims to find out the relationship between stope design and stability of hanging wall decline. The analysis conducted in this study is based on underground characteristics and geological condition of Cibaliung area. The impact of stope design on decline stability was analyzed by using numerical methods. The impact factors such as different rock mass, size of stope, and distance between stope and hanging wall decline were used in the analysis of underground stability especially stability on hanging wall decline.

Effects of hanging wall and forward directivity in the 1999 Chi-Chi earthquake on inelastic displacement response of structures

The characteristics of the inelastic response of structures affected by hanging wall and forward directivity in the 1999 Chi-Chi earthquake are investigated. Inelastic displacement ratios （IDRs） for ground motions impacted by these nearfield effects are evaluated and comprehensively compared to far-field ground motions. In addition, the inelastic displacement responses to hanging wall and footwall ground motions are compared. It is concluded that the inelastic displacement response is significantly affected in the short period range by hanging wall and in the long period range by footwall. Although high peak ground acceleration was observed at hanging wall stations, the IDRs for structures on hanging wall sites are only larger than footwall sites in the very long period range. Forward directivity effects result in larger IDRs for periods longer than about 0.5s. Adopting statistical relationships for IDRs established using far-field ground motions may lead to either overestimation or underestimation in the seismic evaluation of existing structures located in near-field regions, depending on their fundamental vibration periods.

Xinji Wall Hanging,a Flower of Chinese Folk Art

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External application of a Nocardia rubra cell wall skeleton in the treatment of diabetic foot ulcers

Diabetic foot ulcers are one of the most severe complications of diabetes that have imposed great financial and psychological burdens on diabetic patients.A Nocardia rubra cell wall skeleton(Nr-CWS)can be externally applied to accelerate wound healing.However,its clinical application has not yet been reported.Herein,we report two patients with diabetic foot ulcers treated with Nr-CWS.After wound debridement,the wound was covered with a sterile cotton ball infiltrated with an Nr-CWS that was diluted with 2.0 mL of saline.The covers were changed every two days until complete wound healing occurred.The two wounds healed after 3 and 12 weeks,respectively.This article aims to provide a new treatment for diabetic foot ulcers,with the hope that physicians may consider an Nr-CWS as a complementary method for the treatment of chronic wounds.

Defying Death at the Foot of the Great Wall

ON August 15, 2002, world famousescapologist Robert Gallup gave a free performance at the foot of the Badaling Great Wall. It was for the benefit of young people from China’s western regions who cannot afford to continue their education."Defying death" is Gallup’s specialty. With the help of an assistant, he is tied up, and sus-

Happy Life at the Foot of the Imperial City Wall——A Glimpse of Community Life in Dongcheng District, Beijing

Grandpa Qin, now 74, has returned to where he had lived for more than six decades in the company of his daughter. In front of him, the old dilapidated scenes have all disappeared. The former nine 1.9-meter-wide lanes have become 12 six-meter-wide roads. The former crowded courtyards, 11 stairs down the lanes, have completely changed their outlook. The only things that seem to have not changed are the old Beijing style of blue tiles and gray bricks and the imperial city walls nearby that are the witnesses to all these changes. Grandpa Qin is among the 300 households who have returned after the rebuilding project was completed. Qin’s family lived in the Nanchizi community for five generations. The big

柱脚不同连接形式钢框架-摇摆墙结构抗震性能对比分析

增设摇摆墙后框架结构地震下柱脚仍会发生一定程度的塑性损伤,将柱脚设置为铰接或提离后有望减轻上述缺陷。以三层、六层和九层钢框架为基准模型,分别建立柱脚固接、铰接及提离三种框架-摇摆墙结构模型并进行动力弹塑性时程分析,对比各结构最大侧向位移、层间位移角、峰值加速度、层间剪力、墙体剪力和弯矩等;进一步建立耗能连梁固接和铰接的对比模型,研究连梁连接方式对结构抗震性能的影响。结果表明:三层模型中柱脚固接时侧向位移、层间位移角、加速度、层间剪力及摇摆墙墙体剪力的控制效果最优,六层、九层模型中分别对应柱脚提离和柱脚铰接效果最好;摇摆墙墙体剪力图和弯矩图分别呈现“C形”和“反C形”,柱脚固接时墙体弯矩均为最小,与层数无关。柱脚固接耗能连梁两端采用固接最优,柱脚铰接和柱脚提离时耗能连梁两端采用铰接形式效果更优。此分析可为框架-摇摆墙结构进一步推广应用提供参考。

轮足复合式爬壁机器人研究综述

当前轮足复合式机器人机构主要包含轮足结合、分离复合以及变形轮足,分别能够实现不同障碍通道的移动作业、复杂未知环境的探索操作以及突发应急救援等应用。然而,针对船舶、压力储罐等金属立面环境,轮足复合式爬壁机器人必须兼具壁面适应、越障和壁面过渡的全位置自主作业能力,应用于壁面焊接、清洗、检测等作业任务。对比分析当前的国内外研究,轮足复合式爬壁机器人针对在垂直和倾斜壁面的工程应用有良好的适用性,它具备适应复杂曲面工作面的能力,并能够应对非结构化工作场景。轮足复合式爬壁结构在应对曲率变化、非结构化壁面等工作将会有良好的应用前景。

港口工程吹填区悬挂式防渗墙施工技术

为探究港口工程吹填区悬挂式防渗墙施工技术,以沙特某港口工程为工程背景。首先对悬挂式防渗墙进行了设计,并综合考虑防渗墙混凝土材料以及渗流稳定情况,对悬挂式防渗墙设计进行优化。其次对悬挂式防渗墙关键施工技术进行了详细研究和论述,结合该港口工程主要施工步骤,对施工重难点进行了分析,并提出了有针对性的控制措施。

逆断层上下盘开采扰动下断层活化响应模拟研究

为探究煤层不同开采方式下逆断层应力场、位移场演化规律和断层活化规律,通过数值模拟分析逆断层地质条件下进行上盘开采和下盘开采时断层处的正应力和剪应力演化规律、断层活化过程以及断层和覆岩的位移场变化特征。研究结果表明:随工作面逐渐靠近断层,断层上部的正应力逐渐降低、剪应力逐渐升高,断层下方的正应力逐渐升高、剪应力逐渐降低,正应力和剪应力升高或降低的速率随工作面与断层距离减小而增加;当工作面与断层距离在80 m和40 m时,断层处正应力和剪应力发生异于前期应力规律性的变化,出现大幅度增长和降低的情况;相对于上盘开采,下盘开采时断层更易受煤层开采扰动而发生活化,且活化程度和范围均大于上盘开采;随工作面不断向断层靠近,下盘开采时采空区上覆岩层下沉量和断层两侧岩体相对位移量均明显大于上盘开采。研究结果对煤层开采遇断层时围岩治理和防灾减灾具有一定科学指导意义。

露天地下楔形转接过渡诱导冒落控制边坡岩移危害技术研究

露天地下楔形转接过渡模式的安全管控是利用崩落法开采挂帮矿形成的塌陷坑阻止边坡岩移威胁露天采场,但地采扰动下的高陡边坡破坏过程不易控制,因而制约了楔形转接过渡模式在大型深凹露天矿山中的应用。针对上述问题,结合极限平衡分析方法,揭示出崩落法开采扰动下的高陡边坡渐进破坏规律,提出了边坡滑移体体积计算方法,以及通过调控回采顺序控制边坡滑移进程以实现塌陷坑完全承接边坡滑移体的边坡岩移危害控制技术。研究表明:边坡岩体不会随挂帮矿向下开采而发生持续破坏,只有当挂帮矿开采至关键分段时,边坡岩体受力状态超过极限平衡状态才发生滑移破坏,可通过滞后回采关键分段上盘三角矿延缓边坡滑移,以及通过滞后回采关键分段下盘矿体和采用下向阶梯状回采工作面增大塌陷坑容积,最终实现塌陷坑有序承接边坡滑移体。研究成果完善了大型深凹露天矿楔形转接过渡的安全管控方法,提高了楔形转接过渡模式的适用性。

深凹露天矿山挂帮矿安全回采工艺研究及实践

为充分回收挂帮矿资源,根据攀西某深凹露天矿山挂帮矿赋存条件及内排土堆排情况,本文提出“内排土连续回填、挂帮矿分步回采”工艺。利用内排土修筑临时道路至回采平台,为回采工作创造设备运转空间;同时连续回填采坑,缩短挂帮矿回采完成后边坡暴露时间。采用靠帮预裂爆破,控制单响起爆药量在250 kg以下,使用等效载荷加载于回采区域,经计算,边坡最大振动速度1.6 cm/s,满足边坡安全速度要求。建立边坡三维模型,计算了回采工艺全过程中边坡位移变化情况,回采完成后边坡整体位移均小于0.5 cm,不会出现大范围边坡失稳。经现场实际应用,累计采出矿石超过58.34万t,且边坡稳定。为矿山下一步全面回采挂帮矿资源提供技术支撑,可供类似矿山参考借鉴。

边帮煤井工开采边坡变形失稳规律及控制技术研究

从边帮煤井工开采覆岩运移、边坡变形破坏、失稳滑移及控制角度出发,综合运用力学分析、物理模拟、数值模拟及现场工业性实测和应用等手段,对采动边坡变形破坏特征和失稳滑移规律等内容开展了系统研究,提出了针对关键岩块B回转的边坡失稳滑移控制技术。结果表明:采动边坡变形破坏经历了表生改造、结构改造和时效变形3个阶段,呈“横三区”和“竖二带”分布,1 360和1 400平盘移动趋势指向露天矿坑,且存在剪切滑移带生成,在关键岩块B回转形成水平推力作用下采动边坡1 360平盘局部发生失稳滑移;基于此,提出了控制关键岩块B回转的逆坡开采局部充填和回填压脚两种边帮煤安全、高效回收技术,并对其进行了对比分析,得出两种控制技术均能有效降低边坡内部覆岩的变形破坏程度、改变1 360平盘的移动方向及抑制剪切滑移带的生成,但回填压脚的控制效果要优于逆坡开采局部充填,基于此进行了工程应用和验证。

基于Simulation的薄壁桶搬运过程的形变研究

桶料的搬运方式主要有托底式、夹取式和挂取(吊取)式,文中针对薄壁桶的搬运方式进行模拟分析,通过模拟分析的具体数值来进行合理的选择。主要对挂取(吊取)和夹取2种薄壁桶的搬运方式进行模拟分析,基于Soildworks中的Simulation进行计算,并得出具体数值,选取合理的薄壁桶搬运方式。模拟分析表明:在同等桶壁厚的情况下,夹取式桶料搬运形式薄壁桶的变形程度较大,主要体现在薄壁桶的夹持部位,如特定场景需夹持薄壁桶的桶身进行搬运时,还需适当加厚薄壁桶的桶壁来抵抗夹持板的夹持力,使薄壁桶不会产生较大的形变量。