Optimizing support performances of bolt reaming and anchoring in a coal drift

In current practice of bolt reaming and anchoring of roadways in soft coal and rock mass,resin cartridges bend easily under the strong pushing and stirring of bolts,and the resin accumulates in the bolt-reamed area and does not participate in the stirring.As a result,bolts encounter high drilling resistance and cannot reach the bottom of drillholes.The effective anchorage length is far less than the actual anchorage length.Bolts are not centered,and the shear is misaligned at the joint surface in the reaming area,which leads to cracking of the whole anchoring solid and large shear deformation of bolts.This study systematically analyzes the characteristics of roadway bolt reaming and anchoring.The influences of resin stirring force,bolt pull-out force,and reamingeanchoring solid strength on reamingeanchoring performance were analyzed theoretically.The main purpose is to develop a device that enhances reaming and anchoring.The mechanism through which the device strengthens the reamingeanchoring solid was analyzed theoretically.Numerical simulation and experiments were carried out to verify the improved performance of the small-pore reaming and anchoring using the proposed technology.The results showed that the stirring migration rate of the resin cartridge is greatly improved by adding the device to bolts.The reaction rate of the anchoring mixture,stirring pressure,pull-out force of the reaming and anchoring system,bolt concentricity,and shear and compressive strengths of the anchoring solid are also enhanced in the reaming area.This ensures that the resin cartridge in the reaming area is completely stirred,which greatly improves the shear resistance of the reamingeanchoring solid.Meanwhile,the drilling performance,torsional force,and stirring efficiency of bolts are maximized and prevail over those of conventional bolts.

Deep-Hole Inner Diameter Measuring System Based on Non-contact Capacitance Sensor

A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional mic...

Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Numerical simulation and experiment analysis of improving permeability by deep-hole presplitting explosion in high gassy and low permeability coal seam

Created a new damage model for explosive for LS-DYNA3D,taking advantageof the Taylor method aimed at the high gassy and low permeability coal seam,and numericallysimulated and analyzed the deep-hole presplitting explosion.The entire processof explosion was represented,including cracks caused by dynamic pressure,transmissionand vibration superposition of stress waves,as well as cracks growth driven by gas generatedby explosion.The influence of the cracks generated in the process of explosion andthe performance of improving permeability caused by the difference of interval between.explosive holes were analyzed.A reasonable interval between explosive holes of deepholepresplitting explosions in high gassy and low permeability coal seams was proposed,and the resolution of gas drainage in high gassy and low permeability coal seam was putforward.

Experimental research on characteristics of hole reaming and side cutting of one-cone bits

The hole reaming and side cutting characteristics of offset one-cone bit and conventional one- cone bit were investigated on simulated drilling experimental equipment. The borehole diameter was a little larger than the bit diameter due to side force. However, the reaming effect was not very apparent, whether drilling with an offset or conventional one-cone bit. The side cutting displacement increased gradually with increasing depth of drilling and side force. The side cutting displacement of offset onecone bits was larger than that of conventional ones under the same conditions of weight-on-bit （WOB）, rotary speed, side force and borehole depth.

Vigorous Endosteal Reaming across Fracture Site to Aid Union in Atypical Femur Fractures

Background: Bisphosphonate abuse is associated with atypical femur fractures, which despite different fixation methods have increased non-union, delayed union, and re-operation rates. Therefore, there is a need for a surgical technique that may enhance union in such cases. Herein we are introducing a novel technique of sequential multiple vigorous reaming across the fracture site to introduce reaming debris/endosteal bone graft around the fracture site. Materials and Methods: We present a retrospective analysis of five prospectively treated patients with atypical diaphyseal femur fracture who presented to us from January 2015 to August 2019. All the patients were followed up at regular intervals and assessed both clinically and radiologically. Results: All 5 cases operated with our technique showed union at a mean follow-up of 16 weeks (12 - 20 weeks). There were no complications reported in our study at the last mean follow-up of 25 months (12 - 51 months). Conclusion: This technique of multiple vigorous reaming at and around the fracture site provides a new paradigm in the management of AFF. The autograft around the outer cortex promotes the formation of bridging callus and results in the early union.

Cuttings transport: Back reaming analysis based on a coupled layering-sliding mesh method via CFD

Inadequate hole cleaning is one of the main reasons for inefficient operations in extended-reach drilling.The mechanism of cuttings transport under the back reaming operation,which is frequently adopted to remove the cuttings,has been investigated in this study.To this end,a coupled layering-sliding mesh method with the Eulerian-Granular approach has been established innovatively.The dynamic layering method has been employed to simulate the axial motion of the pipe,whereas the sliding mesh method has been used to simulate the pipe rotation.The back reaming operation of a connector-furnished pipe has been simulated,and the sensitive parameter analysis has been conducted.The results thus obtained demonstrate that the increase in the initial bed height,inclination,and the diameter and length of the connector causes a significant increase in the cuttings concentration.In addition,the cuttings concentration is observed to decrease significantly with the pipe rotation speed.Furthermore,two main factors contribute towards the cuttings accumulation around the connector,namely,the difference in the cross-sectional area and the pushing effect of the connector—like a“bulldozer”.The“bulldozer”effect of the connector dominates when the tripping velocity is significant compared to the velocity of the cuttings.Conversely,the effect of the difference in the cross-sectional area becomes the leading factor for cuttings accumulation.The“bulldozer”effect of the connector causes a more severe impact on hole cleaning.In both cases,increasing the tripping velocity only mildly affects the cuttings concentration.It is therefore suggested that the tripping velocity should be slower than that of the sand during the back reaming operation.Furthermore,increased fluid velocity might lead to a higher accumulated cuttings concentration around the connector when the cuttings bed has not entirely passed through the connector.A significant flow rate can be safely applied after the cuttings have passed through the connector furnished with a large diameter,such as the bottom hole assembly.This exploration serves as an essential guide to predicting and controlling tight spots while back reaming.

Numerical simulation of deep-hole resistivity anomaly caused by drilling construction in Xinfengjiang geoelectric station

The Xinfengjiang reservoir in Guangdong Province is one of the large reservoirs that have triggered earthquakes of magnitude greater than 6.Numerous earthquakes have occurred since the impoundment of the reservoir,making it one of the most active seismic zones in south China.In 2015,a set of deep-hole resistivity anomalies was observed in the Heping geoelectric station in Dongyuan county,located near the Xinfengjiang reservoir.After a field investigation,we found that a planned well drilling construction of new measuring channels was being carried out during that corresponding period of time.After careful comparison and analysis on the basis of the collected raw data,we had a reason to believe that drilling construction,rather than the inducement of the Xinfengjiang reservoir,was the main culprit for those unusual georesistivity values.So as to verify the above conjecture,we constructed a series of 3D finite element models based on the geological and hydrological infor-mation around Heping station and analyzed the drilling disturbances,respectively.Some significant conclusions were finally drawn according to the precise numerical simulation.This study gives a good example by combining numerical simulation with engineering practice as a way to understand the root cause of georesistivity anomalies in reality.

Determine the Stress Calculating Mode of Sliding Failure of Soil Mass under the Push-Extend Multi-under-Reamed Pile

Through the analysis of the sliding failure form of soil mass under the bearing push-extend reamed of Push-extend Multi-under-reamed Pile, in the paper, the law of coulomb-Mohr is used to establish a stress function and the theory of the sliding line is used to establish Prandtl regional stress field, which determines the stress calculating mode of soil mass and provides a theoretical basis for a further study of this type of pile ultimate bearing capacity of soil mass.

股骨近端防旋髓内钉-Ⅱ治疗31-A3型股骨转子间骨折扩髓与否的有限元分析

背景:针对股骨转子间骨折是否需要扩髓的问题尚有争议,一些人认为不扩髓缩短手术时间、减少出血、降低高龄患者术中风险,但此举是否会降低髓内钉支撑效果,尚无依据。另一些人认为扩髓可选择直径更粗的髓内钉,获得更好的力学支撑,但基础研究显示此方法存在脂肪栓塞、破坏骨质(尤其高龄骨质疏松患者)等风险。目的:通过有限元分析股骨近端防旋髓内钉-Ⅱ治疗31-A3型股骨转子间骨折时扩髓与不扩髓的力学分布特点。方法:纳入一名健康志愿者,CT扫描其股骨获取DICOM格式文件,顺序导入Mimics、Geomagic Wrap、SolidWorks、Hypermesh、Ansys软件处理文件,得到A3.1型、A3.2型及A3.3型股骨转子间骨折模型,分别与9,11 mm直径、170 mm长度的股骨近端防旋髓内钉-Ⅱ进行装配,赋予材料属性,设定各接触面相互作用关系及定义载荷及边界条件,之后进行求解。观察不同模型中股骨应力分布、内固定应力分布、股骨位移及内固定位移情况。结果与结论:①各型骨折采用扩髓髓内钉固定时股骨应力均小于非扩髓髓内钉固定,A3.3型骨折股骨最大应力值大于A3.1型和A3.2型;②各型骨折采用扩髓髓内钉固定时内固定应力均大于非扩髓髓内钉固定,A3.3型骨折内固定最大应力值大于A3.1型;③扩髓与非扩髓对股骨及内固定位移影响较小,应力影响较大;④提示采用扩髓髓内钉固定可使股骨应力减小,内固定整体承担应力增大,远端锁钉承担应力减小;与非扩髓髓内钉固定相比,采用扩髓髓内钉固定可能会提供更好的治疗效果。

芯桩承载扩体预制桩的荷载传递计算分析

扩体预制桩由内芯预制桩和外围扩体材料固结体组成,竖向承载时涉及到芯桩、外围扩体和周围土三者的相互作用,荷载传递机制十分复杂。针对芯桩承载全长扩体预制桩的荷载传递特点,采用弹性-破坏模型模拟芯桩-扩体界面相互作用,理想弹塑性模型模拟扩体-土界面非线性相互作用,并综合考虑内、外两界面剪切特性发挥及其耦合作用,构建了芯桩承载扩体预制桩荷载传递计算分析模型,给出了简化计算方法。与工程实例的对比,验证了方法的可靠性,并对芯桩承载扩体预制桩荷载传递规律进行分析。结果表明:外围扩体可有效地将芯桩荷载传递至周围土,扩体厚度和刚度的增加可提升整体承载性能,但较厚的扩体会制约芯桩承载能力的发挥,扩体刚度的提高有利于芯桩与扩体的共同作用。工程设计与实践中,可通过调整扩体厚度和性能来调配芯桩、扩体和周围土的相互作用。

髋臼一次磨锉成形在初次全髋关节置换中的应用

目的回顾性分析应用髋臼一次磨锉成形在初次全髋关节置换中的临床效果。方法2018年1月至2023年1月,江苏省泰州市中医院收治70例单侧髋关节行初次THA的患者。其中,35例采用髋臼一次磨锉成形,为一次磨锉成形组;另35例采用传统方法从最小号髋臼锉开始磨锉,直至软骨下骨出现均匀渗血,为传统磨锉方法组。两组髋臼磨锉结束后再将相应型号的髋臼假体按预定角度打入,股骨侧处理方法一致。记录两组的手术时间、术中出血量,术后髋臼假体前倾角、外展角及Harris髋关节功能评分。结果一次磨锉成形组的手术时间和术中出血量明显少于传统磨锉方法组,差异有统计学意义(P<0.05);两组的平均髋臼前倾角和外展角均在安全范围内,差异无统计学意义(P>0.05);术后2周Harris髋关节功能评分一次磨锉成形组优于传统磨锉方法组,但差异无统计学意义(P>0.05)。两组患者术后3个月门诊复诊均无异常情况。结论髋臼一次磨锉成形可以减少髋臼磨锉失误,缩短手术时间,减少术中出血量,加速患者康复。

单级套管扩孔一次跟进钻孔技术在滑坡治理中的应用

河南某山地滑坡前后两次治理,效果欠佳,滑坡体未得到有效抑制。工程预应力锚索需穿越残积层与各风化层中成串孤石群及中风化岩层中发育的破碎带,成孔深度长、孔径大。解决成孔中塌孔、卡钻、埋钻等问题,确保成孔质量,成为本滑坡治理工程施工难点与重点。基于此,采用了单级套管扩孔一次跟进钻孔技术。本文详细介绍其基本原理和施工技术要点,并对其治理效果评价分析,结果表明,利用单级套管扩孔一次跟进钻孔技术不仅可较好地对滑坡体进行治理,且可缩短工期、减少施工成本。

煤矿软弱围岩锚固孔底部扩孔区锚固效果保障方法与实验

锚固孔扩孔锚固作为增强锚杆(索)对煤矿软弱围岩巷道支护效果的技术举措,对提升煤矿软弱围岩巷道主动支护质量及安全水平发挥了重要作用,然而,扩孔施工也明显增大了扩孔位置锚固孔的尺寸,导致按照锚杆(索)常规树脂锚固施工方式进行施工时扩孔区锚固剂固化及充填效果不理想等问题,显然这不利于锚固孔扩孔锚固性能的充分发挥。为明晰锚固孔扩孔锚固时扩孔区锚固问题及其影响,并寻找有效的解决途径,以确保锚固孔扩孔条件下锚杆(索)的锚固性能,采用数值模拟及实验室实验相结合的方法开展了系统研究。研究结果表明:施工过程中树脂锚固剂弯折(曲)进入扩孔区使锚索无法对它进行有效搅拌及破碎,以及扩孔位置锚固孔体积的增大使得锚固剂不能有效充满,是导致扩孔区锚固问题的主要原因;锚索拉拔模拟结果显示扩孔区锚固缺陷对锚索的锚固性能及锚固系统的失效形式有较大影响;为改善扩孔区的锚固效果,提出了锚固孔底部扩孔区锚固效果保障方法,并实验验证了该方法的有效性,实验结果表明该方法有效确保了软弱围岩锚固孔底部扩孔区的锚固效果,增强了锚索的锚固性能。本研究有效解决了锚固孔扩孔区的锚固问题,有助于煤矿软弱围岩条件下锚索高强支护能力的充分发挥,为确保锚索对软弱围岩巷道支护效果提供了技术途径。

不同钻进参数下反井钻机扩孔钻进速率与岩渣特征试验研究

通过不同钻进参数下反井钻机扩孔钻进斜井的现场工程测试与室内岩渣筛分试验,分析了不同钻进参数下扩孔钻头破岩钻进速率及其岩渣特征。结果表明:在单轴平均抗压强度41.6 MPa的砂岩地层中,获得了斜井反井钻机扩孔钻压、转速、扭矩等钻进参数与钻进效率之间相关关系;在试验范围内随钻压增加,扩孔钻进速率不断提高;在钻压为14 MPa、转速为9 r/min时,获得的最大扩孔钻进速率为1.41 m/h;在相同转速条件下,随着钻压增加,扭矩也同步升高,而扭矩与钻进速率之间呈线性正相关关系;通过筛分岩渣分析,扩孔钻头破岩形成的岩渣形态分为<0.50 mm的粉末状、0.50~<5.00 mm的颗粒状、5.00~40.00 mm的薄片状和>40.00 mm的大块板状或肋条状4类,岩渣粒度在10.00~20.00 mm范围内占比相对较高。研究成果可为快速判识反井钻机扩孔钻进效果和围岩稳定状态提供理论支撑。

机械扩孔煤体增透应力变化规律研究

机械扩孔作为一种新型煤层卸压增透强化措施,可广泛适用于低透气性瓦斯煤层。为了探究机械扩孔应力演化规律,通过理论分析,揭示机械扩孔应力分布特征,以车集煤矿2616煤层为研究背景,借助ABAQUS数值模拟软件分析扩孔过程中煤层应力演化规律。结果表明:机械扩孔后孔洞周围煤体应力场存在动态演化过程,由内向外呈圆环状分布,依次为破碎区、塑性区、弹性区和原始应力区;机械扩孔过程中造穴阶段应力扰动范围和应力集中情况都显著大于钻进阶段。

自张式膨胀管技术的研究与应用

孔内膨胀管钻探技术是保障复杂地层孔壁稳定的有效技术之一。本文针对易出现缩径、坍塌、掉块的强水敏性地层,提出了一种自张式膨胀管护壁方法,并根据该方法的护壁原理研制了相适配的新型扩孔钻具、膨胀管及膨胀管投送装置,在不改变钻孔结构的情况下,对复杂孔段进行局部扩孔,投送膨胀管借助自身张力自然弹开而固定在相应的扩孔段,实现钻进时护壁。通过室内及现场试验对机具进行了优化,最终取得了良好的应用效果。试验证明:该方法操作简单可靠、易于定位,相较于水泥浆护壁具有处理速度快、停待时间短、减少重复处理等优势,适用于岩心钻探领域多孔段复杂地层的固壁与护壁,有利于降低孔内事故处理的成本、提高钻进效率,具有较好的推广应用价值。

导向槽定向水力压裂煤层增透强化瓦斯抽采技术及应用

针对低透气性高瓦斯煤层预抽瓦斯困难问题,提出导向槽定向水力压裂煤层增透技术,通过理论推导计算煤层段扩孔后塑性区分布,分析穿层钻孔煤层段水压裂缝的起裂与扩展,揭示导向槽定向水力压裂煤层增透的力学机制,研发导向槽定向水力压裂煤层增透装备。在山西中兴煤矿进行现场应用,结果表明:利用水射流方法对穿层钻孔煤层段进行扩孔,使得煤中产生形似圆柱孔洞,穿层钻孔围岩塑性区半径与钻孔半径成正比,钻孔扩孔是增大塑性区范围的一种有效方法,裂隙扩展明显,瓦斯采出率提高。同时研发了一种导向槽定向水力压裂防突成套装备,主要部件有移动高压水力泵站、喷头、喷嘴、螺旋辅助排渣水射流高压钻杆、孔口防喷装置以及高压旋转接头,结合井下水力化作业远程监测和控制,现场监测结果表明,通过增透作业钻孔的方法,平均瓦斯浓度和瓦斯抽采混合量提高到常规孔的2.75倍和1.81倍,说明采取导向槽定向水力压裂措施的增透效果显著。

静钻根植桩挤土扰动圆孔扩张理论研究

绿色环保的静钻根植桩技术在地铁或敏感性建筑附近能否应用,目前还缺乏理论分析手段。对此,结合静钻根植桩的施工特点,首先给出扰动分析物理模型与基本假设;然后,基于圆孔扩张理论推导植桩施工引起的桩周土体应力与应变,结合连续条件建立桩侧极限扩孔压力与塑性区范围的关系式;在理论与实测比较检验该法可靠性的基础上,开展多工况算例分析。结果发现:相较于传统预制桩施工方法,植桩施工极限扩孔压力下降48%,桩周土体塑性区影响范围下降57%;增加桩侧水泥土内摩擦角和黏聚力,植桩施工极限扩孔压力增大,扰动塑性区范围减小。研究成果为精细化评估静钻根植桩施工扰动效应提供了理论基础。

特厚煤层孤岛煤柱水力扩孔防冲卸压技术研究

砚北煤矿2502采区大巷保护煤柱两侧采空,为孤岛煤柱,应力集中程度高,由于煤层较厚,传统大直径钻孔卸压无法取得较好的防冲效果,针对该问题,提出了煤层水力扩孔卸压的技术。通过理论分析研究了水射流破煤和扩孔的卸压机理,水力扩孔通过增加钻孔孔径扩大了单孔的卸压范围;确定了砚北煤矿特厚煤层水力扩孔的主要技术参数,采用数值模拟分析了钻孔内分段扩孔的卸压模式;开发了相应的配套设备,采用双层高压钻杆实现煤体的“钻-割”一体化卸压,提高了卸压效率。通过砚北煤矿现场试验表明,煤层水力扩孔在水压40 MPa和高压喷嘴作用下,扩孔半径能够达到0.35~0.5 m,钻屑量在扩孔区域明显降低,表明水力扩孔能够显著降低煤体内应力集中,达到冲击地压防治的目的。