High-strain dynamic model of large-diameter pipe piles with soil plug for vertical vibration analysis

A rigorous analytical model is developed for simulating the vibration behaviors of large-diameter openended pipe piles(OEPPs)and surrounding soil undergoing high-strain impact loading.To describe the soil behavior,the soil along pile shaft is divided into slip and nonslip zones and the base soil is modeled as a fictitious-soil pile(FSP)to account for the wave propagation in the soil.True soil properties are adopted and slippage at the pile-soil interface is considered,allowing realistic representation of largediameter OEPP mechanics.The developed model is validated by comparing with conventional models and finite element method(FEM).It is further used to successfully simulate and interpret the behaviors of a steel OEPP during the offshore field test.It is found that the variation in the vertical vibrations of shaft soil along radial direction is significant for large-diameter OEPPs,and the velocity amplitudes of the internal and external soil attenuate following different patterns.The shaft soil motion may not attenuate with depth due to the soil slippage,while the wave attenuation at base soil indicates an influence depth,with a faster attenuation rate than that in the pile.The findings from the current study should aid in simulating the vibration behaviors of large-diameter OEPP-soil system under high-strain dynamic loading.

A theoretical analysis of vertical dynamic response of large-diameter pipe piles in layered soil

Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was derived by Laplace transformation method.The responses in time domain were obtained by inverse Fourier transformation.The results of the analytical solution proposed agree well with the solutions in homogenous soil.The effects of the shear modulus and damping coefficients of the soil at both outer and inner sides of the pipe pile were researched.The results indicate that the shear modulus of the outer soil has more influence on velocity admittance than the inner soil.The smaller the shear modulus,the larger the amplitude of velocity admittance.The velocity admittance weakened by the damping of the outer soil is more obvious than that weakened by the damping of the inner soil.The displacements of the piles with the same damping coefficients of the outer soil have less difference.Moreover,the effects of the distribution of soil layers are analyzed.The results indicate that the effect of the upper soil layer on dynamic response of the pipe pile is more obvious than that of the bottom soil layer.A larger damping coefficient of the upper layer results in a smaller velocity admittance.The dynamic response of the pipe pile in layered soil is close to that of the pipe pile in homogenous soil when the properties of the upper soil layer are the same.

A Theoretical Analysis of the Bearing Performance of Vertically Loaded Large-Diameter Pipe Pile Groups

This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of both a single pile and pile groups.Considering the pile group effect and the skin friction from both outer and inner soils,an analytical solution is developed to calculate the settlement and axial force in large-diameter pipe pile groups.The analytical solution was verified by centrifuge and field testing results.An extensive parametric analysis was performed to study the bearing performance of the pipe pile groups.The results reveal that the axial forces in group piles are not the same.The larger the distance from central pile,the larger the axial force.The axial force in the central pile is the smallest,while that in corner piles is the largest.The axial force on the top of the corner piles decreases while that in the central pile increases with increasing of pile spacing and decreasing of pile length.The axial force in side piles varies little with the variations of pile spacing,pile length,and shear modulus of the soil and is approximately equal to the average load shared by one pile.For a pile group,the larger the pile length is,the larger the influence radius is.As a result,the pile group effect is more apparent for a larger pile length.The settlement of pile groups decreases with increasing of the pile number in the group and the shear modulus of the underlying soil.

High-frequency interference in low strain integrity testing of large-diameter pipe piles

The high-frequency interference exists obviously in low strain integrity testing of large-diameter pipe pile when a transientpoint load is applied. An analytical solution of vertical vibratory response of large-diameter pipe piles in low strain testing isdeduced in this paper. The analytical solution is verified by both numerical simulation and model test results. The time-domainvelocity responses on pile top are analyzed. The calculation results indicate that the time-domain responses at various pointssuffer different high-frequency interferences, thus the peak values and phases of different points are different. The influence ofvibratory modes on high-frequency interference is analyzed. It is found that the high-frequency interference at 90° point main-ly derives from the second flexural mode, but for other points it mainly originates from the first flexural mode. The factors af-fecting the frequency and peak value of interference waves have been investigated in this study. The results indicate that thelarger radius angle between the receiving and 90° points leads to greater peak value of high frequency wave crest. The leasthigh-frequency interference is detected at the angle of 90°. The frequency of interference waves is decreased with the increaseof pile radius, while the peak value is almost constant. The frequency is also related to pile modulus, i.e. the larger pile modu-lus results in greater frequency. The peak value varies with impulse width and soil resistance, i.e., the wider impulse width andlarger soil resistance cause smaller peak value. In conclusion, the frequency of interference waves is dependent on the geomet-rical and mechanics characteristics of the piles such as pile radius and modulus, but independent of the external conditionssuch as impulse width and soil resistance. On the other hand, the peak value of interference waves is mainly dependent on theexternal conditions but independent of the geometrical and mechanics characteristics of the piles. In practice, some externalmeasures should be adopted to weaken high-frequency interference such as using soft hammer, hammer cushion and adoptingsuitable receiving point.

连续油管落鱼套铣冲砂工艺初探

连续油管砂卡后一般经强力活动、诱喷、震荡等进行解卡,解卡过程中环空固相颗粒进一步沉积并形成致密砂塞,致使连续油管作业机解卡失败,需要采用修井机进行套铣冲砂的解卡作业。由于连续油管在井筒内挠曲、贴井壁和易破碎的特点,因此需要确定套铣工艺参数,保护好落鱼,避免井下情况复杂化。针对51/2"套管内的2"连续油管落鱼,提出了特殊套铣工具的设计思路,探讨了套铣冲砂时的入鱼、套铣过程中的相关参数,供实际施工中借鉴。

回注管洗井工艺的理论验证及应用效果分析

为了验证现场回注管洗井工艺下入井的长度是否达到洗井目的,对循环洗井液液滴进行受力分析,发现当液滴所受重力等于气体对其浮力加拖曳力之和时,液滴沉降至井底的速度为最小速度;将其代入伯努利方程,可计算出回注管最小长度;通过将计算结果与实际下入回注管长度进行对比,得出目前应回注管洗井工艺的11口井循环洗井液液滴均可沉降至井底,都可达到洗井的目的。该公式能够为回注管洗井工艺提供理论支撑,正确指导后期现场应用。

液压和稀油润滑系统中间配管快速冲洗

在冶金设备施工期间,对液压及稀油润滑系统的冲洗至关重要。结合实际施工案例,通过理论计算对影响冲洗效果的温度、流量和压降等3个要素进行了分析研究。结果表明:冲洗工作要想做到既有速度又有质量,则必须在设计阶段对以上3个要素有一个清晰的分析并做好准备工作。

防火封堵材料GB 23864-2023与GB 23864-2009对比分析与解读探讨

防火封堵材料标准的变化对生产制造、应用、检验都有重要影响,依据历次标准的实施过程来看,在新标准的初始实施阶段,特别是变化比较大的情况下,总会产生一些对标准理解不够充分、理解混乱甚至错误使用标准的现象发生,给相关从业者带来损失。为使相关从业者更好的理解、正确使用新标准,本文对新标中影响较大的增加部分:电缆填充率、管道贯穿率、使用场所、多组分封堵材料、产烟毒性、气密性、冲水试验性能;标准变化部分:火灾环境条件、试验升温条件、炉内压力条件、试件制作、综合判定准则,结合工程应用、现代建筑要求、防烟灭火救援需要、检验的变化、与其他标准的关联等作了进一步的分析论述与解读,并对新标指导下产品的生产、使用、检验作出了探讨。

管式湿式电除尘器冲洗清灰结构改进与优化

为了提高管式湿式电除尘器冲洗清灰效果,解决设备积灰问题,针对管式湿式电除尘器阴极系统和冲洗系统,提出无冲洗遮挡的阴极结构和移动冲洗系统的结构改进与优化措施,并开展项目应用与验证。结果显示,相关措施可有效改善设备的冲洗清灰效果,降低设备因积灰发生短路运行故障的概率,为非电领域颗粒物超低排放要求下的管式湿式电除尘器长期高效稳定运行提供保障。

柳州地区页岩气地质调查井钻探技术研究与应用

页岩气地层裂隙发育,胶结性差,表现为岩石破碎、水敏性强、孔壁强度低。在钻进过程中容易出现坍塌、掉块、缩径等复杂情况,从而引发孔壁失稳、卡钻、埋钻等孔内事故。对广西柳州地区页岩气地质调查井工程进行钻探技术研究,应用PVA1788成膜体系无固相冲洗液和成膜防塌体系无固相冲洗液、绳索取心液动锤钻进技术、膨胀波纹管护壁新技术、螺杆钻具定向钻进纠斜技术,在现场勘探施工中取得了良好的效果,保证了项目的顺利施工。

从油松苗木的水力结构探讨管道模型

为探讨管道模型的合理性 ,该文应用水力结构的基本理论 ,在温室条件下 ,用改良的冲洗法测定 4年生油松苗木各部位的水力结构参数 .实验和模拟的结果表明 ,苗木各部分木质部的导水率、比导率和叶比导率差异很大 ,限速区的导水率明显低于非限速区 ,供给单位叶量生长的功能木质部组织投入量也不是定值 ,即胡伯尔值是变化的 .因此 ,尽管管道模型已在一些领域被认可 ,但从苗木水分生理的角度 ,管道模型的前提假设是有局限的 。

水平井裸眼防砂失效因素分析及解决措施

针对水平井裸眼防砂完井一体化工艺技术失效的情况,对工艺进行了反复研究与分析,认为水平井裸眼防砂失效的主要因素为基管强度低、筛网强度差及洗井阀密封机构可靠性差。解决措施为:(1)选用专为稠油热采井设计的钢级为TP110的套管作为滤砂管的中心管;(2)对筛管的网眼布局和孔眼参数进行优化,优化后的网眼布局为177.9 mm×9.19 mm筛管、相位角30°、孔密240孔/m、孔半径12.6 mm;(3)研制了密封洗井阀球座的水平井洗井阀堵塞装置。

自制引流冲洗管用于白血病患者化疗后肛周脓肿的效果观察

目的探讨白血病患者化疗后肛周脓肿的有效治疗方法。方法将42例白血病化疗后合并肛周脓肿患者随机分为观察组(22例)和对照组(20例)。观察组采用浓盐水坐浴30min后用自制引流冲洗管行药物冲洗,每日2次;对照组用浓盐水坐浴30min,每日2次。结果观察组疗效显著优于对照组(P<0.01)。结论自制引流冲洗管行药物冲洗能有效治疗白血病化疗后肛周脓肿,值得临床上推广使用。

城区雨水管网径流污染特征研究

以新乡市城区屋面作为汇水区域,开展试验对雨水管网中场次降雨径流水文水质过程进行研究,可为有效利用城市雨水、控制非点源污染等提供依据。水质指标包括SS、COD和TN。结果表明:水质指标中SS、COD变化趋势基本一致,随着降雨过程的持续浓度逐渐降低并趋于一个稳定值;TN随着雨量的累积浓度逐渐降低,但在降雨结束前有反弹趋势;指标标准差率呈SS】COD】TN的趋势;径流初期屋面冲刷效应明显,初期径流量可定义为前1~3mm的降雨量;径流中SS与COD、TN之间的相关性较好,在控制径流污染时可采取措施同时去除;径流污染物直接通过城区排水管网汇入受纳水体后对其水质影响较大,尤以SS、COD的变化最为明显。

大型天然黄土洞穴系统现场冲刷试验

通过现场冲刷试验,结合勘探、调查及室内含泥率测定等手段对大型天然黄土洞穴系统的三维空间展布特征、水文特性及侵蚀特征进行了研究。结果表明:黄土洞穴系统侵蚀过程具有明显的期次性;洞穴过水流量过程曲线可分为增加阶段、相对稳定阶段和减小阶段3个特征流量段,其中在第一阶段普遍存在"滞流效应",第二阶段具有小幅波动的特性,并发现洞穴内的总渗流损失量随设计注水流量的增大而有所增加;根据含泥率随时间变化曲线,分析了不同流量过程段含泥率的变化特点,通过不同工况的累积侵蚀量对比发现洞穴的侵蚀速率与流量显著正相关。从机理上对产生上述过程、现象及结果的原因进行了合理解释,为黄土潜蚀机理及潜蚀速率的研究提供了可靠的现场试验数据。

电厂冲管对汽水管道系统的安全性影响

分析了冲管参数和冲管系统接入位置对汽水管道系统的安全性影响。以某新建电厂亚临界600MW机组冲管为例,分析了冲管时影响汽水管道系统安全性的主要因素,提出了解决以及降低影响汽水管道安全性的方法。通过以上实例,归纳出机组冲管整个过程需注意的问题,从而提高电厂汽水管道系统的安全性。

双壁钻杆注氮气冲砂工艺技术研究

塔里木油田哈拉哈塘、哈得等区块裸眼完成的油气井,因井壁垮塌、出砂,严重影响正常生产。常规液力冲捞砂工艺在这类低压、易漏井中无法建立循环,难以完成冲砂需求。通过分析研究提出一种用双壁钻杆加井口注氮气的冲砂工艺,并用瞬态多相流软件OLGA进行模拟。分析了钻杆内外两种不同注入方式下,井筒内注入气及冲砂液复杂的流动现象。得出钻杆外注氮气无冲砂效果、钻杆内注气能搅动冲砂液在井筒内形成闭式循环的结论。最后通过参数的敏感性分析,针对钻杆内注气的双壁冲砂工艺,得出结论:最佳注气量为13308~26617 m 3/d;注气阀的合理位置为静液面处;管柱的理想组合为内管长度1000 m、外管尺寸127 mm;冲砂过程始终为负压。该工艺在塔里木油田的成功应用,为深层低压井的冲砂提供了技术借鉴。

UPVC井管在云南抗旱供水井中的应用

在水井工程中,国外现在应用较多的是UPVC全塑料井管,而在我国却不然。分析了UPVC全塑料井管在水井应用中的优缺点,并通过其在云贵高原的应用实例,介绍了UPVC全塑井管在下井管、止水、洗井工艺中的关键技术。实际应用表明,UPVC井管可以保证成井质量,提高施工技术,UPVC全塑井管在农村及干旱地区的应用前景巨大,有很好的推广价值。

冷连轧机组液压管路的安装、酸洗与循环冲洗

该文以攀华1450五机架冷连轧机组为例对液压系统中管路的安装、酸洗与循环冲洗进行了比较详细的介绍,通过分析给出了一些计算公式及经验参数。

连铸机液压系统新管路清洗方法的应用

针对伊朗某钢厂连铸机液压系统安装工期紧张及冲洗时间短的要求,提出了一种新的管路清洗方法,该方法省却了管路酸洗过程,直接进行管路油洗。并详细论述了该液压系统的管路安装、短接和打压、一次冲洗、二次冲洗、管路恢复等过程。实践证明,该清洗方法周期短,且液压系统的运行稳定。