Analytical investigations of in situ stress inversion from borehole breakout geometries

This study aims to investigate the feasibility of deriving in situ horizontal stresses from the breakout width and depth using the analytical method.Twenty-three breakout data with different borehole sizes were collected and three failure criteria were studied.Based on the Kirsch equations,relatively accurate major horizontal stress(sH)estimations from known minor horizontal stress(sh)were achieved with percentage errors ranging from 0.33%to 44.08%using the breakout width.The Mogi-Coulomb failure criterion(average error:13.1%)outperformed modified Wiebols-Cook(average error:19.09%)and modified Lade(average error:18.09%)failure criteria.However,none of the tested constitutive models could yield reasonable sh predictions from known sH using the same approach due to the analytical expression of the redistributed stress and the nature of the constitutive models.In consideration of this issue,the horizontal stress ratio(sH/sh)is suggested as an alternative input,which could estimate both sH and sh with the same level of accuracy.Moreover,the estimation accuracies for both large-scale and laboratory-scale breakouts are comparable,suggesting the applicability of this approach across different breakout sizes.For breakout depth,conformal mapping and complex variable method were used to calculate the stress concentration around the breakout tip,allowing the expression of redistributed stresses using binomials composed of sH and sh.Nevertheless,analysis of the breakout depth stabilisation mechanism indicates that additional parameters are required to utilise normalised breakout depth for stress estimation compared to breakout width.These parameters are challenging to obtain,especially under field conditions,meaning utilising normalised breakout depth analytically in practical applications faces significant challenges and remains infeasible at this stage.Nonetheless,the normalised breakout depth should still be considered a critical input for any empirical and statistical stress estimation method given its significant correlation with horizontal stresses.The outcome of this paper is expected to contribute valuable insights into the breakout stabilisation mechanisms and estimation of in situ stress magnitudes based on borehole breakout geometries.

Numerical simulation on borehole breakout and borehole size effect using discrete element method

Estimation of horizontal stress magnitudes from borehole breakouts has been an attractive topic in the petroleum and mining industries,although there are critical research gaps that remain unfilled.In this paper,numerical simulation is conducted on Gosford sandstone to investigate the borehole breakout and its associated borehole size effect,including temperature influence.The discrete element method(DEM)model shows that the borehole breakout angular span is constant after the initial formation,whereas its depth propagates along the minimum horizontal stress direction.This indicates that the breakout angular span is a reliable parameter for horizontal stress estimation.The borehole size effect simulations illustrated the importance of borehole size on breakout geometries in which smaller borehole size leads to higher breakout initiation stress as well as the stress re-distribution from borehole wall outwards through micro-cracking.This implies that the stress may be averaged over a distance around the borehole and breakout initiation occurs at the borehole wall rather than some distance into the rock.In addition,the numerical simulation incorporated the thermal effect which is widely encountered in deep geothermal wells.Based on the results,the higher temperature led to lower breakout initiation stress with same borehole size,and more proportion of shear cracks was generated under higher temperature.This indicates that the temperature might contribute to the micro-fracturing mode and hence influences the horizontal stress estimation results from borehole breakout geometries.Numerical simulation showed that breakout shape and dimensions changed considerably under high stress and high temperature conditions,suggesting that the temperature may need to be considered for breakout stress analysis in deep locations.

Inversion of breakout data from inclined boreholes for stress state of the upper crust in Jizhong depression

The forward and inverse problems of studying crustal stress state from breakout data of inclined boreholes are concisely stated. direction of the maximum horizontal principal stress (compressive) and relative magnitudes of the horizontal stresses to the vertical stress in the upper crust in two regions of the Jizhong depression, the North of China, are obtained by analyzing the breakout data of 6 inclined wells. To get stable results in the analysis wesearched for the unknown parameters both forwardly and inversely. The results show that the maximum azimuths of the horizontal Principal compressive stresses in the central and southern part of the Jizhong depressionare N86°E and N77°E, respeCtively, while the relative magnitudes of the three principal stresses in the uppercrust (about 1000-4000 m) of the depression are variable. In the centra; part of the Jizhong depression we havefound SH : Sv: SK= 1. 38: 1. 00: 0. 57, where SH, SV and Sh are the maximum horizontal, vertical and minimum horizontal stress, resistively. This indicates that the present stress regime in this area is of strike-slipfaulting type. In the southern part of the depreSSion we have obtained SH: Sv: Sh=0. 80: 1. 00 1 0. 62, indicating a normal faulting stress regime in the shallow Part Of the crust.

Research on the anti-disturbance issues of the breakout prediction system in continuous casting

This paper introduces the function, structure and alarm principles of the breakout prediction system installed for continuous casting in Baosteel＇ s No. 2 Steelmaking Plant. It elaborates on four parameters in the alarm logic,including the temperature changing rate, temperature difference, temperature fluctuation and temperature match of thermocouples. This paper also explains the causes of different disturbances within the breakout prediction system, and the methods used to prevent and eliminate disturbances from radiation, earth, crosstalk, temperature drift and time drift. Finally, the paper summarizes some potential applications of the above technology.

Progress of breakout prediction technique for slab casters at Baosteel

Breakout prediction is one of the important techniques of continuous casting. The software and hardware of the breakout prediction system have been upgraded and revamped time after time since slab casters were put into operation at Baosteel, and its performance and technical indexes have been improved remarkably. This paper reviews the development of the breakout prediction technique of the No. 1 Steelmaking Plant at Baosteel. The newly developed BBPS ^Ⅱ is introduced, and the mould mapping system of the No. 4 slab caster is described. The breakout prediction technique is playing an important role in increasing production capability, improving slab quality and decreasing breakout events.

Study on tectonic stress of Zhongyuan oil field with wellbore breakout data

Recording curves of four-arm caliper logs obtained from 36 wellbores in Zhongyuan oil field have been processed and analysed with computer programs. Orientations of principal stress axes in Dongpu seg,where theZhongyuan oil field is located, are inferred from dominant azimuths in which severe bore wall breakouts tookplace. The result shows that the maximum horizontal principal compressive stress axis in the northern part ofthe seg lies in the direction of N(79±6°)W, while in the southern part it is in N (79°±18°)E, retaining a didference of about 22°between the former and the later. A two dimensional finite element simulation using alinear elastic plane stress model indicates that the clock-wise rotation of the principal stress direction in thenorthern Dongpu seg relative to that in its surroundings may be attributed to the softness of the seg rocks andits geometry of narrow northern and wide southern part. The magnitude range of the maximum and minimumhorizontal principal stresses is estimated from the most shallow depth at which the radially unsymmetric elongation of a wellbore initiates. Finally, evidences showing local variation of stress state with sites and depths are presented.

An investigation of machine learning techniques to estimate minimum horizontal stress magnitude from borehole breakout

Borehole breakout is a widely utilised phenomenon in horizontal stress orientation determination,and breakout geometrical parameters,such as width and depth,have been used to estimate both horizontal stress magnitudes.However,the accuracy of minimum horizontal stress estimation from borehole breakout remains relatively low in comparison to maximum horizontal stress estimation.This paper aims to compare and improve the minimum horizontal stress estimation via a number of machine learning(ML)regression techniques,including parametric and non-parametric models,which have rarely been explored.ML models were trained based on 79 laboratory data from published literature and validated against 23 field data.A systematic bias was observed in the prediction for the validation dataset whenever the horizontal stress value exceeded the maximum value in the training data.Nevertheless,the pattern was captured,and the removal of systematic bias showed that the artificial neural network is capable of predicting the minimum horizontal stress with an average error rate of 10.16%and a root mean square error of 3.87 MPa when compared to actual values obtained through conventional in-situ measurement techniques.This is a meaningful improvement considering the importance of in-situ stress knowledge for underground operations and the availability of borehole breakout data.

Numerical Simulation and Prediction for Sticking Type Breakout Behavior in Slab Contiuous Casting

A two-dimensional heat transfer model was developed to calculate the mould wall temperature field under normal operations condition and to determine its changing behavior when breakout occured. On the numerical simulation of sticking type breakout process and the breakout related wall temperature evolution, parameters of prediction were suggested.

“创新突围赛”:基层政府社会治理创新的组织逻辑

进入新时代,社会治理创新纷纷涌现,基层政府愈发热衷于“擦亮”治理品牌。本文以一个街道为深度案例,追踪基层社会治理创新的实践过程,探究基层政府将创新实践转化为政绩生产的运作机制,并揭示“创新突围赛”的组织逻辑。研究发现,基层政府打造创新品牌,是对组织环境变革的回应,围绕目标设置—资源汇集—经验创制形成了一种新型创新运行机制,并呈现出与“晋升锦标赛”不同的注意力竞争、资源最优化以及政绩可视化等多重组织逻辑。本文延展了“印象政绩”的建构机理,提出“创新突围赛”的整合性概念和描述性框架,在经验层面丰富了新的制度环境下基层政府创新行为的微观探讨,在理论层面拓宽了权变组织的适应性逻辑和府际创新竞争的研究范畴。

小零食大市场 量贩零食店的崛起与突围

近年来,随着国家整体经济实力的提升和消费者需求的变化,我国休闲零食市场不断发展,在向前推进的浪潮中,量贩零食店更是凭借丰富的商品和低廉的价格迅速崛起,并席卷下沉市场。尤其是2022-2023年,各种品牌量贩零食店在我国低线城市遍地开花。文章探讨了我国量贩零食店的特点、崛起原因,并针对当前激烈竞争如何成功突围提出建议对策。

ChatGPT赋能CSCL:未来图景与突围路径

CSCL作为培养高阶思维发展的一种新型学习方式,已经历了30年的颠簸历程,但因跨学科的特征致使其发展与探索呈现复杂性。随着以ChatGPT为代表的生成式AI迅速渗透各行各业,为CSCL的创新发展带来了曙光。为此,文章首先进行了ChatGPT的基本概述,并从内容生成、语境理解、语言转译及场景复刻刻画了其应用优势。然后,文章基于对CSCL手册的分析与思考,融合ChatGPT的特征与能力,从影响CSCL发展的外延与核心两个层面,依据复刻境脉、助力变革、面向多元、支持学习、辅助教学、解密黑箱六个维度,构建了ChatGPT赋能CSCL发展的未来图景。最后,文章提出了基于ChatGPT的CSCL生态创新发展的突围路径,以期为CSCL的创新发展与教育领域内ChatGPT的理论探索与实践应用提供参考。

Molten Steel Breakout Prediction Based on Thermal Friction Measurement

By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitored by thermocouples fixed to the mould.Breakouts,whether caused by shell cracking,shell sticking or entrained impurities,can therefore be predicted and effectively avoided through monitoring the change characteristics of friction and thermocouples temperature during the process.

寒门子弟向上流动的驱动力——一个农村“80后”阶层突围者的自我民族志

寒门子弟能否向上流动是衡量社会平等开放程度的重要标志。寒门子弟向上流动的驱动力是什么?作者以局内局外双重视角和夹叙夹议的方式凸显个人反思,呈现个人成长叙事和学理思考两条主线,旨在回答底层苦难经历与教育奋斗、阶层突围的密切关系。物质条件的窘迫、农业劳动的艰辛、家人的耳提面命等能促使寒门子弟早早洞悉自己的命运,不仅使其养成自律克制、勤俭节约、孝顺懂事的品格,也驱使其加强时间管理、锤炼心志和移情父母并与之结成命运共同体,还激发出强烈的向上流动意愿和内驱力;重要他人的助力、环境文化的熏陶、社会结构机会、特定机缘与情势是助推寒门子弟阶层突围的外驱力,与底层家庭原因引发的内驱力共同驱动寒门子弟实现阶层突围。因此,底层也有自己独特的文化资本,成为寒门子弟取得高学业成就的密钥,进而脱离“子承父业”的泥沼,解除阶层代际传递的“魔咒”;底层家庭要注重子女抗逆力的培养,促使其养成正确的认知和积极的心态,形成良好的个性品质,从而积极地、理性地应对逆境;寒门子弟要相信“读书改变命运”,积极发挥主观能动性,努力创造条件,将有限的家庭资本转化为学业成就;社会应重视教育在促进弱势群体子女向上流动中的中介作用,进一步加大欠发达地区基础教育投入,进一步完善弱势家庭子女就学政策,对教育机会竞争中的弱势群体予以帮扶,进而帮助更多寒门子弟找到突破阶层代际传递的“黑匣子”,实现阶层突围。

Measures for Reducing the Rate of Breakout of Slab Casters

In order to reduce the rate of breakout of slab caster, improve the operating rate and ensure the stability of the caster, measures including the tundish casting auto-start, the mold level automatic control system optimization, the SEN one-button automatic quick-change technology, the mold breakout forecast system optimization, the mold oscillation parameters optimization, the mold taper measurement optimization and the mold powder management have been adopted by a steel plant of WISCO. As a result, the breakout rate of slab caster was significantly reduced to be zero level in the first 3 years, which is a new record for all steelmaking plant in China.

2012—2022年常州市某区副溶血性弧菌引起的食源性疾病暴发事件归因分析

目的 分析2012—2022年江苏省常州市新北区副溶血性弧菌引起的食源性疾病暴发事件,为该类事件处理提供参考依据。方法 收集新北区2012年1月1日—2022年12月31日由副溶血性弧菌引起的食源性疾病暴发事件的相关资料,并进行回顾和分析。描述食源性疾病暴发事件的一般情况,以及副溶血性弧菌引发食源性疾病暴发事件的时间分布、地域分布以及患者人群分布;比较食源性疾病暴发事件的患者临床症状、发生场所分布以及发生原因分布。结果 2012年1月1日—2022年12月31日新北区共上报食源性疾病暴发事件19次,涉及患者数287例;其中由副溶血性弧菌引起的食源性疾病暴发事件发生9次(占47.37%),涉及患者数103例(占35.89%)。由副溶血性弧菌引发的食源性疾病暴发事件均发生在6~10月,其中在9月发生次数最多(5次,占55.56%);副溶血性弧菌引发食源性疾病暴发事件在城区发生3次(占33.33%),在农村地区发生6次(占66.67%);由副溶血性弧菌引起的食源性疾病暴发事件涉及的103例患者中,男性53例(占51.46%),女性50例(占48.54%);在年龄分布中,以45~64岁年龄段患者占比最高(54例,占52.43%);患者职业分布中,居家及待业人员的比例最高(35例,占33.98%);可疑食物分布中,海产品及其制品的比例最高(30例,占29.13%)。副溶血性弧菌引发食源性疾病患者人群中,有腹痛症状91例(88.35%),腹泻95例(92.23%),恶心60例(58.25%),呕吐55例(53.40%);副溶血性弧菌引发食源性疾病患者人群出现腹痛、腹泻、恶心、呕吐的比例显著高于其他病原体引发的食源性疾病患者。副溶血性弧菌引起食源性疾病暴发事件的发生场所中,其他的比例最高(3次,占33.33%);副溶血性弧菌和其他病原体引起食源性疾病暴发事件的场所分布比较差异无统计学意义;副溶血性弧菌引起食源性疾病暴发事件的原因分布中,交叉污染的比例最高(5次,占55.56%);副溶血性弧菌与其他病原体引起食源性疾病暴发事件的发生原因分布比较差异无统计学意义。结论 该区发生的食源性疾病暴发事件中由副溶血性弧菌引发的占比较大,患者以中老年为主,事件发生时间集中在夏季和秋季,肉类和水产品是主要的可疑食物,患者以急性胃肠炎为主要临床表现,引发该类事件的主要原因为交叉感染。

异型坯连铸机黏结漏钢的原因分析及控制措施

对异型坯连铸机黏结漏钢的原因进行了分析,导致异型坯黏结的主要原因与保护渣的理化性能、钢种、异常操作、浸入式水口偏斜、钢水温度、结晶器液面波动、结晶器铜板使用寿命等方面有关。在这些方面制定了相关控制措施,有效降低了连铸机黏结漏钢概率。

A discrete element exploration of V-shaped breakout failure mechanisms in underground opening

V-shaped breakouts,which may appear in underground opening during excavation,are the results of two different failure mechanisms:tensile spalling and shear fracturing.This study uses discrete elements in exploring the conditions that would lead to different breakout mechanisms under plane strain conditions.The test tunnel of the Mine-by Experiment in Lac du Bonnet granite batholith is adopted as the base problem.In order to carry out the study,some fundamental issues need to be addressed.First,an exponential softening bond that enables the incorporation of fracture energy is adopted.In order to obtain a reasonable ratio between the uniaxial compressive strength,rc,and the uniaxial tensile strength,rt,discrete disc particles are tied together to form an irregular shape clump as the basic discrete element.This effort is supported by a successful reproducing of test results from Lac du Bonnet granite in DEM modeling.The issue of sensitivity of discrete particle size on results is examined.The reduction of strength with increase in specimen size is also modeled.After the calibration work is completed,the Mine-by tunnel behavior is studied.Finally,this study shows that a reduction in rc/rt ratio,under the same setup,would cause the failure mechanism to transit from tensile spalling to shear fracturing in V-shaped breakouts.

Relationship between rock macro-and micro-properties and wellbore breakout type

This study numerically investigates the effect of material micro-and macro-parameters on the failure mechanisms and geometry of a wellbore breakout.The analysis of the borehole breakout is essential in addressing wellbore stability,well completion,and sand production problems.The three-dimensional discrete element method(DEM)was used in the simulations.The numerical tool was used in numerical model simulations of drilling through sandstone in cubic samples at the laboratory scale subjected to pre-existing far-field stresses.Besides,a series of triaxial testing simulations were performed to relate the micromechanical parameters to the macromechanical material properties.The results showed that the geometry of the breakout is affected,among the material micro-parameters,by the particle contact modulus,bond normal and shear strengths,particle crushing strength,and particle size distribution.Further,it was found that the macro-parameters including Young’s modulus,friction and dilation angles,and uniaxial compression strength(UCS)also affect the type of breakout.

回归泮塘 从荔湾湖公园西北区景观提升议景观的微地理再造

荔湾湖公园是位于广州荔湾传统城区的著名老公园,一方面,在当下城市文旅活化的潮流趋势中,它呈现了固有之魅力风采,另一方面则表现为各类历史和现实问题层叠累积而“遭遇”的现实窘境。为其寻找突围策略,是景观提升规划设计的诉求与挑战。文章通过解读历史文献与图像中的荔湾人文地理风貌,分析了传统地理景观作为城市基底与社会记忆的重要属性,并以其作为城市历史保护研究与活化的一种方法,通过地景重塑,再造泮塘的地理肌理和褶皱,并从空间规划、地形改造、风景构筑改建、植被提升等专项,提出具备岭南想象力与文化复魅可能的概念方案。