Prediction models of burst strength degradation for casing with considerations of both wear and corrosion

Casing wear and casing corrosion are serious problems affecting casing integrity failure in deep and ultra-deep wells.This paper aims to predict the casing burst strength with considerations of both wear and corrosion.Firstly,the crescent wear shape is simplified into three categories according to common mathematical models.Then,based on the mechano-electrochemical(M-E)interaction,the prediction model of corrosion depth is built with worn depth as the initial condition,and the prediction models of burst strength of the worn casing and corroded casing are obtained.Secondly,the accuracy of different prediction models is validated by numerical simulation,and the main influence factors on casing strength are obtained.At last,the theoretical models are applied to an ultra-deep well in Northwest China,and the dangerous well sections caused by wear and corrosion are predicted,and the corrosion rate threshold to ensure the safety of casing is obtained.The results show that the existence of wear defects results in a stress concentration and enhanced M-E interaction on corrosion depth growth.The accuracy of different mathematical models is different:the slot ring model is most accurate for predicting corrosion depth,and the eccentric model is most accurate for predicting the burst strength of corroded casing.The burst strength of the casing will be overestimated by more than one-third if the M-E interaction is neglected,so the coupling effect of wear and corrosion should be sufficiently considered in casing integrity evaluation.

Data-driven Methods to Predict the Burst Strength of Corroded Line Pipelines Subjected to Internal Pressure

A corrosion defect is recognized as one of the most severe phenomena for high-pressure pipelines,especially those served for a long time.Finite-element method and empirical formulas are thereby used for the strength prediction of such pipes with corrosion.However,it is time-consuming for finite-element method and there is a limited application range by using empirical formulas.In order to improve the prediction of strength,this paper investigates the burst pressure of line pipelines with a single corrosion defect subjected to internal pressure based on data-driven methods.Three supervised ML(machine learning)algorithms,including the ANN(artificial neural network),the SVM(support vector machine)and the LR(linear regression),are deployed to train models based on experimental data.Data analysis is first conducted to determine proper pipe features for training.Hyperparameter tuning to control the learning process is then performed to fit the best strength models for corroded pipelines.Among all the proposed data-driven models,the ANN model with three neural layers has the highest training accuracy,but also presents the largest variance.The SVM model provides both high training accuracy and high validation accuracy.The LR model has the best performance in terms of generalization ability.These models can be served as surrogate models by transfer learning with new coming data in future research,facilitating a sustainable and intelligent decision-making of corroded pipelines.

Rock burst risk evaluation based on equivalent surrounding rock strength

On-site investigations consistently show that the rock burst inherent to coal seams varies greatly with coal seam thickness.In this study,impact factors related to coal seam thickness and surrounding rock strength were analyzed and a corresponding rock burst risk assessment method was constructed.The model reflects the influence of coal seam thickness on the stress distribution of surrounding rock at the roadway.Based on the roadway excavation range,a stress distribution model of surrounding roadway rock is established and the influence of coal seam thickness on rock burst risk is analyzed accordingly.The proposed rock burst risk assessment method is based on the equivalent surrounding rock strength and coal seam bursting liability.The proposed method was tested in a 3500 mining area to find that it yields rock burst risk assessment results as per coal seam thickness that are in accordance with real-world conditions.The results presented here suggest that coal seam thickness is a crucial factor in effective rock burst risk assessment.

Strength differential effect and influence of strength criterion on burst pressure of thin-walled pipelines

In the framework of the finite deformation theory, the plastic collapse analysis of thin-walled pipes subjected to the internal pressure is conducted on the basis of the unified strength criterion （USC）. An analytical solution of the burst pressure for pipes with capped ends is derived, which includes the strength differential effect and takes the influence of strength criterion on the burst pressure into account. In addition, a USC- based analytical solution of the burst pressure for end-opened pipes under the internal pressure is obtained. By discussion, it is found that for the end-capped pipes, the influence of different yield criteria and the strength differential effect on the burst pressure are significant, while for the end-opened pipes, the burst pressure is independent of the specific form of the strength criterion and strength difference in tension and compression.

Predicting Bursting Strength Behavior of Weft Knitted Fabrics Using Various Percentages of Cotton, Polyester, and Spandex Fibers

The bursting strength is an essential quality parameter of knit fabric. The fabric structure, weight, types of fibers, and fiber blend proportion influence the bursting strength parameter. The tenacity of polyester fiber is better than cotton and spandex. The study focused on predicting knit fabric bursting strength test value using different fibers (cotton, polyester, and spandex) with varying percentages of the blend ratio. This study used fifteen categories of blended fabrics. The Pearson Correlation and the hypothetical ANOVA regression analysis were conducted to do the statistical significance test. The experimental result reveals that the bursting strength test result increased with the increased percentage of polyester and suggested a suitable regression equation. The dominance of the polyester fiber was observed throughout the experiment, i.e., the higher the polyester blend proportion, the higher the bursting strength value. The inclusion of polyester in blends can reduce the cost of fabric. The developed prediction model or equation can help the fabric manufacturer make appropriate decisions regarding getting the expected bursting strength. The researcher hopes that the findings from this study will motivate new researchers, advanced researchers, and the textile manufacturing industry.

改性国产OCC废纸纤维抄造箱纸板的工艺优化

以超声处理的国产OCC长纤维和接枝淀粉处理的OCC短纤维为原料配抄箱纸板,基于纸板的物理强度性能,优化原料配比和助剂添加工艺。结果表明:优化的配抄工艺为长纤维与短纤维配比为1∶1、干强剂用量1.2%、助留助滤剂用量0.02%、施胶剂用量1.0%,此工艺条件下获得的纸板性能达到了箱纸板的质量要求。与助剂添加工艺获得的纸板性能相比,在助剂用量降低的情况下,纸板的耐破指数、撕裂指数、抗张指数和疏水性得到明显改善。

高性能内燃机用滤纸的制备及其对性能的影响

采用高强高模聚乙烯(UHMWPE)纤维与针叶木浆混抄,制备具有力学性能高、疏水性好和透气性适当的内燃机用滤纸。通过探讨原纸制备工艺、树脂浸渍和热压工艺对滤纸性能的影响,确定试验条件下的最佳参数,并采用相关手段表征了滤纸的力学性能、热稳定性能、孔径大小以及疏水性能。结果表明:在试验条件下,当UHMWPE纤维与针叶木浆的质量比为8∶2、针叶木浆打浆度为22°SR、分散剂PEO和增强剂CPAM相对于绝干浆的质量分数分别为0.5%和0.1%、热压时间为15 min、热压压力为10 MPa、热压温度为140℃时,制备的内燃机用UHMWPE滤纸性能最佳,其中,滤纸抗张指数为50.28 N·m/g,耐破度为503.55 kPa,接触角为123.52°且1 min内不渗透,熔点提高至155℃。

GB/T 22848《针织成品布》标准修订研究与解读

GB/T 22848《针织成品布》是针织行业普遍使用的标准之一,为针织服装及服饰产品的生产提出了基本的质量要求。随着行业快速发展,各类针织面料层出不穷,原有标准已不能满足生产使用需求,新标准修订对标准适用范围、内在质量要求、外观质量要求等内容进行了多方面修改和调整,以适应各类针织里、面料的质量要求,并提供科学的符合生产实际的检测依据。文章从标准适用范围、规格、内在质量要求、外观质量要求、试验方法等方面,详细解读GB/T 22848—2022标准的修订情况及内容变化,对满足生产企业和检测部门需求以及正确理解标准、使用标准起到帮助作用。

基于正交实验优化304不锈钢丝网吸液芯制备工艺

为制备混合型多孔丝网吸液芯,为金属热管的设计与加工提供基础数据,本文以100目、200目、300目304不锈钢丝网为原材料,试样采用电阻焊进行焊接,研究了搭接目数、搭接角度、焊点间距以及焊接能量对组合型丝网吸液芯的拉伸和顶破性能.研究结果表明:搭接目数对试样的拉伸与顶破性能影响最大,焊接能量对试样的拉伸与顶破性能的影响最小.

洗涤用品纸箱外包装设计及实例

纸箱在洗涤用品重要防护、承压、仓存、搬运、物流等方面起重要作用。纸箱设计涉及外观、印刷、尺寸、耐破强度、抗压强度等,其中抗压强度尤为重要,需充分考虑码放高度和安全系数,安全系数需对存储湿度条件、存储期、码放方式、搬运次数等充分评估。对设计纸箱进行抗压试验和码垛试验,验证是否达到设计要求。

深部磷矿围岩动力灾害分析与高强预应力锚杆控制技术研究

深井磷矿房柱式开采易发生岩爆灾害,为研究其对顶板支护的影响,本文采用实验室试验、理论分析、数值模拟及现场实践的方法研究了苏家坡磷矿开采的垂直应力与水平应力演化规律。通过室内试验结合强度脆性系数法对岩爆发生进行判别,明确了矿体内矿柱应力集中程度,给出了双应力指标下对应判别岩爆主体发生原因与次生灾害冒顶的适应性,指出水平应力主导作用下的磷矿巷道顶板联动失稳区域、垂直应力主导作用下的矿柱高应力集中隐患区,并提出采用高强预应力锚杆强力控顶,模拟验证了高强预应力锚杆的控顶压应力峰值达0.8 MPa,实现低耗材、高强度控顶的效果。现场工程实践表明:对矿房内巷道围岩进行30 d持续性观测,巷道顶板变形量最大达59.9 mm,两帮变形量最大达43.6 mm,验证了高强预应力锚杆控顶的合理性,实现了千米深井高地压条件下的硬岩顶板控制,防止主-次生灾害循环交替导致的岩爆灾害发生。

纺织品顶破强力和胀破强力探讨

纺织品顶破强力和胀破强力主要针对的是针织物,涉及的标准有GB/T 19976-2005《纺织品顶破强力的测定钢球法》、GB/T 7742.1-2005《纺织品织物胀破性能第1部分:胀破强力和胀破扩张度的测定液压法》、GB/T 7742.2-2015《纺织品织物胀破性能第2部分:胀破强力和胀破扩张度的测定气压法》。通过对常用纺织品顶破强力和液压法胀破强力标准及数值分析,得出常见纺织品的顶破强力和胀破强力通常能符合国家标准要求。以高校蚊帐为试验材料,对经编网眼针织物的顶破强力与胀破强力进行试验分析,研究得出,在含量、经纬密度及结构一致的条件下,一定范围内克质量与织物的胀破强力成正比。采用相同织物测试自动胀破强力时,在一定条件下,随着试验面积的增大,试样的胀破强度明显减小。

天然彩棉纤维的表征及织物性能研究

为了降低染色织物对环境的污染,介绍天然彩棉纤维的长度、线密度、强力等指标,分析其纺高档纱线难度大的原因,并给出改进可纺性的方法;以棕色彩棉纤维为例,测试对比彩棉织物、染色棉织物及白棉织物的顶破性、耐磨性、透气性等。指出:彩棉纤维细短、强力低、短绒含量大,是其可纺性差、纺纱难度大的主因;彩棉织物的顶破强力、耐磨性均高于染色棉织物、差于白棉织物;生物培育技术的发展及先进智能纺织设备的应用,使彩棉织物取代染色棉织物成为可能。

不同加载速率下煤单轴抗压强度测试与冲击倾向性影响分析

针对冲击倾向性测试中煤样单轴抗压强度数据随加载速率变化和离散性问题,以内蒙古鄂托克前旗长城六号煤矿3号煤为研究背景,通过设置0.50、0.75、1.00 MPa/s三种不同加载速率进行煤样标准件的分组测试。测试结果表明,3种不同加载速率测试得到煤的单轴抗压强度测试值均存在离散性;加载速率与单轴抗压强度测试值无明显线性关系;在舍去每组离散性较大的最大值和最小值后,再次计算在不同加载速率条件下煤单轴抗压强度的平均值和标准差,可以得到离散性相对较小的测试值;煤样单轴抗压强度测试值与加载速率无明显比例关系,加载速率的变化可导致同煤层冲击倾向性等级的变化。

煤矿巷道断层滑移型冲击地压试验系统研制与试验验证

断层滑移型冲击地压是煤矿冲击地压的主要类型,目前对其发生全过程缺乏系统研究,其机理与防控仍是根本难题。为实现断层滑移型冲击地压的试验模拟,研制了煤矿巷道断层滑移型冲击地压试验系统,开发了低强高脆相似模拟材料,制备了包含断层与巷道的大尺寸相似模型,开展了一系列验证试验,实现了巷道冲击破坏模拟与断层剪切滑移模拟。煤矿巷道断层滑移型冲击地压试验系统具备三向六面加载功能,竖向加载能力为20 MPa,模型尺寸为1.50 m×0.75 m×0.75 m;主体框架创新采用键板连接,确保了主体框架的高刚度;发明了蜂窝加载壳结构,实现了密集油缸群加载,能够满足断层滑移型冲击地压试验模拟的要求。开发了适用于断层滑移型冲击地压模拟的相似材料,材料以水玻璃为胶结物、以氟硅酸钠为固化剂、以滑石粉为骨料,单轴抗压强度介于3.44~7.81 MPa,冲击能指数为9.2,弹性能指数为8.83,兼具低强高脆特性。基于试验系统和低强高脆材料实现了静载巷道冲击破坏模拟,验证了低强高脆相似材料模拟巷道冲击破坏的可行性,获得了巷道极限平衡状态的加载条件,巷道帮部连续片落为巷道冲击破坏的显著前兆特征。实现了粗糙锯齿断层的剪切滑移模拟,证实粗糙断层剪切滑移会对巷道形成动载扰动,获得了断层剪切滑移的合理加载方式,采用动区顶部先加载、底部后卸载的方式能够实现断层的瞬间滑移,并能消除对静区应力状态的影响。

基于ISABO-SVM的冲击地压危险等级预测

为有效提高冲击地压危险等级预测的准确率,建立了基于改进的减法平均算法(ISABO)优化支持向量机(SVM)的冲击地压危险等级预测模型。通过提取声发射信号的上升时间和绝对能量等5个时域特征参数,结合煤岩体抗压强度,构建了冲击地压预测的特征参数数据库;根据特征参数数据库计算每个样本的综合危险指数,将冲击地压危险性划分为四个等级。以特征参数数据库和危险等级为模型输入和输出,通过ISABO优化SVM预测冲击地压危险等级过程中的核参数和惩罚因子。结果表明,与传统SVM模型以及减法平均算法(SABO)优化后的SVM模型相比,建立的ISABO-SVM模型预测准确率提高至98%。

基于多重判据的六苴矿区深部岩爆倾向性研究

以大姚六苴礅区矿山6个中段的3种岩性为研究对象,通过地应力测量、室内单轴抗压强度、巴西圆盘劈裂强度、弹性变形测量,结合E.Hoek判据、Russenes判据、徐林生判据、脆性判据对不同中段的岩爆倾向性进行分析。四种判据通过复合判据结合进行研判。研究结果表明:670中段会发生轻微岩爆~中等岩爆,710、740、770均无岩爆,800的紫红色细粒砂岩及860的矿石会发生轻微岩爆。基于多重判据的六苴矿区岩爆倾向性分析为地下矿山的岩爆灾害预防提供了一定的参考价值。

管道凹陷研究现状

在对管道凹陷进行分类的基础上,综述了不同类型凹陷静压爆破强度和疲劳强度的研究现状。介绍了凹陷的回弹机理、回弹量的计算方法以及外载与凹陷深度的关系等方面的研究成果。对开展管道凹陷的力学行为、形成机理、评估方法等方面的研究提出了建议。

云南不同烤烟品种叶片物理特性的差异分析

选择云南4个烤烟品种3个部位叶片作为研究对象,测定其12个物理指标,统计分析不同烤烟品种间的差异。结果发现,4个烤烟品种3个部位的烟叶在多数物理指标上存在显著差异。上部叶以云烟85拉力最大,为3.236 7N,中、下部叶以K326拉力最大,分别为3.303 3N、2.616 7N;上、中部叶K326耐破度最大,分别为82.666 7kPa、116.666 7kPa,云烟85次之;下部叶以云烟87耐破度最大,为110.666 7kPa,云烟85次之,说明K326、云烟85烟叶的弹性较好。上、中部烟叶以云烟87填充值最大,分别为3.463 4cm3/g、3.564 0cm3/g,下部烟叶以云烟85填充值最大,为3.430 9cm3/g,K326次之,说明云烟87填充性较强。综合来看,上部烟叶以红大、云烟85的物理特性较好,中、下部烟叶以云烟85、K326的物理特性较好。

单层厚壁内压圆筒设计公式改进效果的可靠性研究

改进设计公式是提高设计公式精度的重要方法。均值与变异系数是分析设计公式精度的基础。分析比较相同设计公式在不同应用范围时的精度,或者分析比较不同设计公式在相同或不同应用范围时的精度,是评价设计公式改进效果的重要内容。建立设计公式改进效果的评价指标与方法,是选择和确定设计公式的重要依据。采用强度-载荷干涉模型,建立了比较单层厚壁圆筒爆破强度设计公式改进效果的可靠性评价指标和方法。在相同或不同应用范围时,分析比较了单层厚壁圆筒爆破强度四个计算公式的改进效果,可供工程设计人员在选择和确定设计公式时参考。