Multistage hydraulic fracturing of a horizontal well for hard roof related coal burst control:Insights from numerical modelling to field application

Multistage hydraulic fracturing of horizontal wells(MFHW)is a promising technology for controlling coal burst caused by thick and hard roofs in China.However,challenges remain regarding the MFHW control mechanism of coal burst and assessment of the associated fracturing effects.In this study,these challenges were investigated through numerical modelling and field applications,based on the actual operating parameters of MFHW for hard roofs in a Chinese coal mine.A damage parameter(D)is proposed to assess the degree of hydraulic fracturing in the roof.The mechanisms and effects of MFHW for controlling coal burst are analyzed using microseismic(MS)data and front-abutment stress distribution.Results show that the degree of fracturing can be categorized into lightly-fractured(D≤0.3),moderately fractured(0.3<D≤0.6),well-fractured(0.6<D≤0.9),and over-fractured(0.9<D≤0.95).A response stage in the fracturing process,characterized by a slowdown in crack development,indicates the transition to a wellfractured condition.After MFHW,the zone range and peak value of the front-abutment stress decrease.Additionally,MS events shift from near the coal seam to the fractured roof layers,with the number of MS events increases while the average MS energy decreases.The MFHW control mechanisms of coal bursts involve mitigating mining-induced stress and reducing seismic activity during longwall retreat,ensuring stresses remain below the ultimate stress level.These findings provide a reference for evaluating MFHW fracturing effects and controlling coal burst disasters in engineering.

Focal mechanism caused by fracture or burst of a coal pillar

As a regional, real-time and dynamic method, microseismic monitoring technology is quite an appropriate technology for forecasting geological hazards, such as rock bursts, mine tremors, coal and gas outbursts and can even be used to prevent or at least reduce these disasters. The study of the focal mechanisms of different seismic sources is the prerequisite and basis for forecasting rock burst by microseismic monitoring technology. Based on the analysis on the mechanism and fracture course of coal pillars where rock bursts occur mostly, the equivalent point source model of the seismicity caused by a coal pillar was created. Given the model, the seismic displacement equation of a coal pillar was analyzed and the seismic mechanism was pointed out by seismic wave theory. The course of the fracture of the coal pillar was simulated closely in the laboratory and the equivalent microseismic signals of the fractures of the coal pillar were acquired using a TDS-6 experimental system. The results show that, by the pressure and friction of a medium near the seismic source, both a compression wave and a shear wave will be emitted and shear fracture will be induced at the moment of breakage. The results can be used to provide an academic basis to forecast and prevent rock bursts or tremors in a coal pillar.

Fracture features of brittle coal under uniaxial and cyclic compression loads

Under the efects of complex geological and stress environments,burst hazards continue to be a major challenge for underground space utilization and deep resources exploration as its occurrence can lead to personnel causalities,equipment damage and structural collapse.Considering the stress path experienced by in-situ coal body,cyclic loading appears in quite various forms for instance shearer cutting,overlying strata breakage,hydro-fracturing and blasting,during tunnel,mining and underground space utilizing process.The stability of the underground coal body subject to periodic loading/unloading stress is extremely important for maintain the function of designed engineering structure for waste storage,safe mining,roadway development,gas recovery,carbon sequestration and so on.The mechanical properties of hard rock subject to cyclic fatigue loads has been intensively investigated by many researchers as the rock burst induced by supercritical loads has long been a safety risk and engineering problems for civil and tunneling engineering under deep overburden.More recently,the mechanical properties of coal samples under cyclic fatigue loads is investigated from the aspect of hysteresis,energy dissipation and irreversible damage as the burst hazards of brittle coal is rising in many countries.However,the crack propagation and fracture pattern of brittle coal need more research to understand the micro mechanism of burst incubation subject to cyclic fatigue loads as brittle coal can store more elastic strain energy and rapidly release the energy when its ultimate strength once reached.This research studied the internal crack status corresponding to diferent cyclic fatigue loading stage of brittle coal samples.The AE monitoring was applied during the uniaxial and cyclic loading process of brittle coal samples to record the crack intensity of samples at diferent loading stages.The damage evolution curve corresponding to loading status was then determined.The fracture pattern of coal samples determined by micro-CT scan was observed and discussed.It has been found by this paper that brittle coal of uniaxial compression tests demonstrated sudden failure caused by major splitting fracture while that of cyclic fatigue tests experienced progressive failure with mixture fracture network.

IMAGING DIAGNOSIS OF THORACOLUMBAR BURST FRACTURES

Objective To review imaging use in the diagnosis of thoracolumbar burst fractures and to determine the diagnostic va-lue of different imaging methods. Methods One hundred and fourteen patients with 120 thoracolumbar burst fractures were retrospectively reviewed. Pl-ain radiographs were available in all cases; CT scans and MRI were obtained in 96 and 74 cases, respectively. Results A total of 27 burst fractures were misdiagnosed as other types of fractures on radiographs alone, and accounted for 22.5% of all fractures. The results indicated that plain radiographs often fail to delineate the pathological features of thor-acolumbar burst fractures, leading to delay in diagnosis. Conclusion In regard to thoracolumbar injury diagnosis, burst fractures should be differentiated from compression frac-tures. CT should be routinely indicated and MRI examination, when necessary, may be simultaneously considered.

Burst strain disturbance—A new test study on fracture precursor

A multi functional high frequency seismometer, a new instrumental system, is used for recording multi point strain variations of rock samples in the process of fracture development. The results indicate that strain in each point appears burst disturbance synchronously besides a tendency variation before main fracture. The burst disturbance could probably be one of the short impending precursors before great earthquake.

Anterolateral Approach for Unstable Lumbar Burst Fracture with Anterior Compression

Background: Lumbar burst fractures are common spinal injuries that cause severe instability with kyphotic deformities and neurological complications requiring surgical decompression and reconstruction with spinal instrumentation for unstable burst fracture, but there is controversy about the optimal surgical approach anterior, posterior or combined approach. Objectives: To assess the efficacy & safety of anterolateral approach in decompression and reconstruction with spinal instrumentation for lumbar burst fractures. Subjects & Methods: A retrospective study including 16 patients, 10 males and 6 females with lumbar burst fractures and anterior compression treated operatively by anterolateral approach for corpectomy and single level fusion by using expandable cage or mesh cage loaded with bone graft and plat with screws. The clinical and radiological follow up after discharge from the hospital ranged from 12 to 24 months. Results: All patients improved regarding the Frankel score more than one grade after surgery, except 2 cases of grade A didn’t improve. Mean preoperative visual analogue scale was 7.4 improving to 0.9 postoperatively. The mean Local kyphosis improved from 8.8° before surgery to -1° after surgery. Conclusions: Anterolateral approach is feasible, effective, and safe approach for unstable lumbar burst fractures. Angular deformity is successfully corrected when the anterior approach is used.

Influence of different operation methods on vertebral body parameters and GH-IGF axis of patients with thoracolumbar bursts fractures

Objective:To observe the influence situation of different operation methods on the vertebral body parameters and GH-IGF axis of patients with thoracolumbar bursts fractures.Methods:A total of 50 surgical patients with thoracolumbar bursts fractures from February 2014 to January 2016 were selected as the research object, and 50 patients with fractures were divided into two groups by the principle of random allocation, then the group A were treated with surgical treatment by anterior approach, the group B were treated with surgical treatment by posterior approach, then the vertebral body parameters and the serum expression levels of GH-IGF axis indexes of two groups before the surgery and at different time after the surgery were compared.Results: The vertebral body parameters and the serum expression levels of GH-IGF axis indexes of two groups before the surgery were compared (allP>0.05), while the vertebral body parameters and the serum expression levels of GH-IGF axis indexes of two groups at different time after the surgery were all significantly better than those before the surgery, and the results of group B were all better than those of group A (allP<0.05).Conclusions:The influence of surgical treatment by posterior approach for the vertebral body parameters and GH-IGF axis of patients with thoracolumbar bursts fractures are obviously better than those of surgical treatment by anterior approach, so the application value of surgical treatment by posterior approach in the patients with fractures is higher.

Theory and application of rock burst prevention using deep hole high pressure hydraulic fracturing

In order to analyze the mechanism of deep hole high pressure hydraulic fracturing, nonlinear dynamic theory, damage mechanics, elastic-plastic mechanics are used, and the law of crack propagation and stress transfer under two deep hole hydraulic fracturing in tectonic stress areas is studied using seepage-stress coupling models with RFPA simulation software. In addition, the effects of rock burst control are tested using multiple methods, either in the stress field or in the energy field. The research findings show that with two deep holes hydraulic fracturing in tectonic stress areas, the direction of the main crack propagation under shear-tensile stress is parallel to the greatest principal stress direction. High-pressure hydraulic fracturing water seepage can result in the destruction of the coal structure, while also weakening the physical and mechanical properties of coal and rock. Therefore the impact of high stress concentration in hazardous areas will level off, which has an effect on rock burst prevention and control in the region.

微震定位精度影响下采场裂隙表征与冲击地压预警

我国深部煤矿高强度开采和复杂地质环境造成冲击地压灾害频发,对矿井安全高效生产造成严重威胁。目前,我国冲击地压矿井配备的微震监测系统在震源定位精度上仍存在不足,冲击地压灾害依然存在“灾源找不准、灾害控不住”的难题。为准确描述采场微震活动空间演化特征,降低震源定位误差对微震预警造成的不利影响,基于冲击地压矿井现有微震监测条件,采用仿真正演试验法探究了煤矿微震台网定位误差矢量分布特征,提出了一种考虑微震定位精度影响的微震裂隙贯通表征方法,并在某矿井回采工作面进行了冲击地压预警实践。研究结果表明:采场不同区域震源定位精度的矢量性差异是造成冲击地压微震预警偏差的重要原因;提出的微震破裂贯通可能性指数F_(sum)采用与震源能级相关的近场区域半径表征震源破裂尺度,并考虑定位误差对不同距离震源间破裂贯通的影响,最大程度还原了采场煤岩体裂隙扩展贯通可能性的分布规律,与冲击地压危险具有F_(sum)良好对应关系;在冲击地压危险相关性上显著优于微震频次,同时危险区域识别效率又强于微震能量,可兼顾预警精准率和召回率,是理想的冲击地压周期性预警评价指标。研究成果将为评价微震台网监测能力、提高冲击地压微震预警能力与防治效率提供参考。

鲜水河构造带隧道高地应力区岩爆特性分析

研究目的:青藏高原持续隆升,导致鲜水河构造带及邻区高地应力特征突出,地应力场极其复杂,研究高地应力的孕灾特征有助于隧道岩爆的风险防控,特别是时滞型岩爆的孕灾和致灾机理的研究。本文阐述鲜水河构造带地貌、地层岩性、构造及地应力场特征的孕灾总体认识,通过对该区域隧道近10 km约1300次岩爆统计,从发生概率、等级、埋深、位置、时间、距离等多角度研究岩爆特征,对发生的5次时滞型岩爆和隧道时效性变化特征进行分析,展望后续岩爆研究的重点。研究结论:(1)鲜水河构造带及邻区受高地应力影响,隐伏小微构造发育且无规律,为岩爆创造了特殊的孕灾环境,岩爆发生的随机性大;(2)该区域隧洞岩爆等级以轻微岩爆为主,具有“分区破裂”和脆性变形特征,时滞型岩爆一定程度上具有“继承性”;(3)建议加强沟谷应力场低埋型岩爆和滞后型岩爆或硬岩潜在时效破坏的监测研究;(4)本文研究成果可为类似高地应力环境下岩爆预测和防控提供借鉴。

椎弓根内固定术联合椎体成形术对胸腰椎爆裂性骨折患者的影响

目的:分析椎弓根内固定术联合椎体成形术对胸腰椎爆裂性骨折患者的影响。方法:选取2020年8月-2022年8月北京丰台医院收治的82例胸腰椎爆裂性骨折患者。根据随机数表法将其分为单一组和联合组,各41例。单一组给予椎弓根内固定术,联合组给予椎弓根内固定术联合椎体成形术。比较两组围手术期指标,术前、术后1周、术后1个月、术后6个月疼痛程度,术前、术后1个月、术后6个月功能障碍,影像学结果,并发症。结果:联合组手术时间长于单一组,住院天数短于单一组,差异有统计学意义(P<0.05)。术后1周,1个月、6个月,两组视觉模拟评分法(VAS)评分均低于术前,联合组VAS评分均低于单一组,差异有统计学意义(P<0.05)。术后1个月、6个月,两组Oswestry功能障碍指数评分(ODI)评分均低于术前,联合组ODI评分低于单一组,差异有统计学意义(P<0.05)。术后6个月,两组椎体前缘高度升高,Cobb's角明显降低,差异有统计学意义(P<0.05);术后6个月,两组椎体前缘高度、Cobb's角、椎体前缘矫正丢失度、Cobb's角矫正丢失度比较,差异无统计学意义(P>0.05)。两组并发症发生率比较,差异无统计学意义(P>0.05)。结论:椎弓根内固定术联合椎体成形术治疗胸腰椎爆裂性骨折,有助于患者快速出院,改善脊柱功能障碍,缓解疼痛,同时能改善患者影像学指标,具有一定安全性。

稳定型胸腰椎爆裂骨折非手术治疗失败率和预测因素

目的探讨稳定型胸腰椎爆裂骨折(thoracolumbar burst fractures,TBF)非手术治疗的失败率和预测因素。方法选择2015年1月~2020年12月在该院接受非手术治疗的稳定型TBF患者资料进行回顾性分析,记录患者非手术治疗失败率。观察非手术治疗失败和非手术治疗成功患者的性别、年龄、体质量指数(body mass index,BMI)、个人史、伴随疾病、损伤原因、损伤椎体、疼痛视觉模拟评分(visual analogue scale,VAS)、椎体压缩率(vertebral body compression rate,VBCR)、椎体前缘高度压缩百分比(percentage anterior high compression,PAHC)、Cobb角、椎弓根间距(interpedicular distance,IPD)和椎管压缩程度,采用Logistic回归分析确定影响非手术治疗效果的独立因素。结果71例患者有21例非手术治疗失败,发生率29.58%。非手术治疗失败患者年龄、BMI、糖尿病、VBCR、PAHC、Cobb角、IPD、椎管压缩和VAS均高于非手术治疗成功患者(P<0.05)。多因素Logistic回归分析结果显示,年龄和IPD是影响非手术治疗效果的独立风险因素(P<0.05)。年龄预测非手术治疗失败的灵敏度、特异性、截断值和AUC分别为71.40%、86.00%、47岁、0.811,IPD预测非手术治疗失败的灵敏度、特异性、截断值和AUC分别为71.43%、88.00%、16.7%和0.771。结论年龄和IPD是影响稳定型TBF患者非手术治疗失败的风险因素,对预测手术失败具有一定临床价值。

经Wiltse肌间入路长节段内固定联合椎板间有限减压治疗胸腰段爆裂骨折的临床疗效

目的对比经Wiltse肌间入路长节段内固定联合椎板间有限减压与传统入路固定减压治疗胸腰段爆裂骨折的临床疗效。方法选择42例单节段胸腰段爆裂骨折手术患者,依据入路的不同将患者分为经Wiltse肌间入路组(n=20)及传统组(n=22),记录并比较两组患者手术时间、术中出血量等围术期指标;手术前后伤椎椎体前缘高度比和矢状位Cobb角的变化;术前及术后3个月神经功能恢复情况。结果经Wiltse肌间入路组患者的手术时间、术中出血量、术后引流量、术后住院时间、术后VAS评分均优于对照组(P均<0.05)。两组患者术后矢状位Cobb角及伤椎椎体前缘高度均较术前改善(P均<0.05)。两组患者术后3个月Frankel分级比较,差异无统计学意义(P>0.05)。结论在采取长节段椎弓根钉内固定减压治疗胸腰段爆裂骨折的患者中,与传统入路相比,经Wiltse肌间入路置钉联合有限减压具有手术时间短、出血少、保护椎旁肌、最大限度保留后方稳定结构的优势。

经皮单侧椎体后凸成形术治疗骨质疏松型胸腰椎爆裂性骨折的临床效果分析

目的:探讨经皮椎体后凸成形术(PKP)治疗骨质疏松型胸腰椎爆裂性骨折的临床效果及影响因素.方法:选取我院2021年4月—2023年4月收治的92例骨质疏松型胸腰椎爆裂性骨折患者为研究对象,均行PKP治疗,根据疗效分为有效组(n=78),无效组(n=14).对PKP治疗效果进行单因素和多因素分析.结果:治疗结束后,92例患者中治疗有效者78例(84.78%),无效者14例(15.22%).有效组与无效组骨水泥用量、手术穿刺方法、术前骨密度值、椎体骨折数比较,差异均有统计学意义(P<0.05).骨水泥用量过多、单侧穿刺手法、术前低骨密度值、多椎体骨折数均是PKP治疗骨质疏松型胸腰椎爆裂性骨折的影响因素(P<0.05).结论:PKP治疗骨质疏松型胸腰椎爆裂性骨折效果良好,骨水泥用量、手术穿刺方法、术前骨密度值、椎体骨折数均会影响PKP术后疗效,临床可针对上述情况给予防治措施,提高手术效果.

覆岩高位整层爆破卸压“人造预裂层”源头防治冲击地压技术体系及应用

主动卸压防冲是落实强化煤矿冲击地压源头治理的重要措施。现行的主动卸压防控方式,或采用回采工作面平巷布孔卸压,或采用井下原位水力压裂技术,具有卸压保护范围有限、卸压施工进度制约等不足;或采用地面水力压裂防冲系统,具有卸压范围广时效长等优点,也需要解决前期投入等。因此,秉持源头防治、防患未然、经济高效的一体化的防冲卸压创新战略思想,研究一种实践易行、效果显著、可全面推广的新型区域卸压源头防冲技术体系势在必行。提出了覆岩高位超前整层爆破卸压技术体系,针对可产生动载荷的较高位关键层,创新高位岩巷、高位钻场、爆破钻孔布置,将高位坚硬岩层超前、整体、均匀爆破预裂,从而形成“人造预裂层”。该方法突破了一般的长钻孔距离限制,使得岩层爆破的卸压高度、卸压范围、卸压效果均大幅提高,可形成覆盖整个工作面区域甚至多个工作面的超前工作面开采的高位“人造预裂层”。高位爆破“人造预裂层”首先使得该高位坚硬岩层的来压步距和来压强度大幅减弱,其次也缓冲减弱了其上硬岩层向下传递的矿山压力,最后还可降低其下方硬岩层的来压步距。在陕西长武亭南煤业3409工作面首次进行了覆岩高位整层爆破卸压“人造预裂层”技术试验后,现场实测效果表明采用该方法较之常规爆破卸压区域,支架的平均来压强度、来压步距、来压持续距离和压力报警频次均大幅减少;巷道深孔和浅孔应力也均减少;微震事件总能量、大能量微震事件大幅度减少,且密集程度显著降低,工作面中段的微震事件尤为稀疏;地音高能事件、震源CT获得的冲击风险区域也有减少,各种实测手段均验证了高位爆破人造预裂层卸压防冲技术的优越性。

单侧椎板开窗自制夯实器椎体后壁复位减压治疗椎管占位胸腰椎爆裂性骨折的临床研究

目的探讨单侧椎板开窗自制夯实器椎体后壁复位减压治疗椎管占位胸腰椎爆裂性骨折(TLBF)的安全性和有效性。方法前瞻性研究2016年12月—2018年12月重庆市中医骨科医院和自贡市第四人民医院收治TLBF患者67例,男性48例,女性19例;年龄19~63岁,平均41.1岁。根据椎管减压方式不同分为实验组(33例)和对照组(34例)。实验组采用后正中入路单侧椎板有限开窗、自制夯实器对椎体后壁骨折进行夯实复位减压内固定融合术,对照组采用后正中入路全椎板切除减压复位内固定融合术。实验组男性23例,女性10例;年龄22~63岁,平均40.9岁;道路交通伤13例,高处坠落伤18例,其他2例;脊髓损伤Frankel分级:C级13例、D级12例、E级8例。对照组男性25例,女性9例;年龄19~59岁,平均41.2岁;道路交通伤12例,高处坠落伤19例,其他3例;脊髓损伤Frankel分级:C级12例、D级13例、E级9例。比较两组患者手术时间、术中出血量,术前、术后1周及末次随访伤椎前缘压缩比、伤椎Cobb角、椎管矢状径比值,术前和末次随访脊髓神经功能Frankel分级,并随访观察内固定相关并发症。结果实验组术中出血量少于对照组[(163.3±44.6)mL vs.(229.4±53.0)mL,P<0.001]。实验组术前较术后1周、末次随访伤椎前缘压缩比小[(51.8±10.1)%vs.(90.0±3.4)%vs.(88.8±3.5)%]、伤椎Cobb角大[(20.7±2.8)°vs.(3.4±1.5)°vs.(3.8±1.8)°]、椎管矢状径比值小[(43.4±9.5)%vs.(91.8±2.9)%vs.(93.3±4.7)%],术前较末次随访脊髓神经功能Frankel分级差[(C级13、D级12、E级8)vs.(C级3、D级5、E级25)],差异均有统计学意义(P<0.05);对照组术前较术后1周、末次随访伤椎前缘压缩比小[(51.4±9.3)%vs.(88.8±3.0)%、(51.4±9.3)%vs.(87.4±3.4)%]、伤椎Cobb角大[(21.7±3.6)°vs.(3.9±1.8)°vs.(4.0±2.0)°]、椎管矢状径比值小[(43.2±8.6)%vs.(91.5±2.7)%vs.(92.6±4.2)%],术前较末次随访脊髓神经功能Frankel分级差[(C级12、D级13、E级9)vs.(C级4、D级5、E级25)],差异均有统计学意义(P<0.05);两组患者组间手术时间,术前、术后1周、末次随访伤椎前缘压缩比、伤椎Cobb角、椎管矢状径比值,术前、末次随访脊髓神经功能Frankel分级比较差异均无统计学意义(P>0.05)。结论单侧椎板开窗自制夯实器减压和传统全椎板切除减压治疗TLBF,伤椎前缘压缩比、伤椎Cobb角、椎管矢状径比值和脊髓神经功能Frankel分级均明显改善,而椎板单侧开窗减压术中出血量更少。

复合关键层厚硬顶板诱冲机制与防治技术模式

【目的】厚硬顶板是诱发煤矿冲击地压、矿震等灾害的关键因素,其中煤层顶板发育有复合关键层厚硬顶板条件下灾害更为严重,揭示复合关键层厚硬顶板诱冲机制,构建防治技术模式迫在眉睫。【方法】运用物理相似模拟和力学分析等方法,建立复合关键层硬顶板和其非协同破断判识方法,揭示复合关键层厚硬顶板诱冲机制,优选防冲技术模式。【结果和结论】结果表明:(1)复合关键层厚硬顶板呈现“大-小”周期来压规律,来压期间声发射频次和微震能量分别为非来压的5.3倍与7.3倍;上、下位关键层厚硬顶板同步破断扰动叠加,叠合“周期”和“见方”来压效应诱发大型冲击地压灾害。(2)建立了以中性轴线为基础的复合关键层判识模型,两层及以上关键层厚硬顶板形成复合关键层前提是梁模型横截面上剪切应力不超过对应的抗剪强度。(3)形成了“悬臂梁”和“砌体梁”两种模式下合理破断线距离定量判识方法,提出了复合关键层厚硬顶板上、下单层和双层协同3种水力压裂卸压技术模式。(4)分析显示下位关键层压裂主要改变了厚硬顶板关键层完整性和强度,缩短了来压步距,无法控制上位关键层“拱壳”结构大能量冲击地压;上位关键层压裂控制“大周期”破断扰动载荷,减弱了复合关键层耦合效应,大幅降低冲击地压危险性,是冲击地压主控层位,“上-下位”关键层协同压裂为最优卸压防冲模式。该研究成果将为复合厚硬顶板冲击地压地压、矿震灾害区域的精准防治提供重要依据。

干骺端爆裂征在膝关节软骨下不全骨折和骨性关节炎上的鉴别价值研究

目的:探讨干骺端爆裂征在膝关节软骨下不全骨折(SIFK)和骨性关节炎(OA)影像鉴别诊断中的价值。方法:回顾分析我院2020年1月—2023年7月经手术证实为SIFK、OA患者的影像资料并分析各自MRI图像特点,观察两者是否存在干骺端爆裂征,即病变关节髁的干骺端存在骨旁软组织水肿。结果:26例SIFK患者中24例存在干骺端爆裂征,29例OA患者中5例存在干骺端爆裂征,此征象出现率在2组间有统计学差异(χ^(2)=30.99,P=0.00)。干骺端爆裂征鉴别SIFK和OA的受试者工作特征曲线下面积为0.875(95%CI 0.77~0.98),灵敏度为82.8%,特异度为92.3%。结论:干骺端爆裂征是诊断SIFK新的间接征象,有助于与OA鉴别。

微雕关节突关节经椎间孔复位椎管内骨块减压术治疗胸腰椎爆裂骨折的疗效分析

目的探讨微雕关节突关节经椎间孔复位椎管内骨块减压术治疗胸腰椎爆裂骨折的临床效果。方法回顾性分析2016年2月至2023年2月四川省宣汉县人民医院骨科收治的伴有骨块压迫并导致神经症状的胸腰椎爆裂骨折患者64例。接受经肌间隙入路微雕关节突关节行椎体后缘直接减压复位治疗的32例患者为观察组,接受经椎板入路行患侧椎板切除间接减压治疗的32例患者为对照组。比较两组术中出血量、手术时间、截骨量;比较两组术前、术后治疗12个月伤椎Cobb角、伤椎体前缘高度比、功能障碍ODI指数、疼痛程度评分以及末次随访脊髓神经功能分级。结果观察组术中出血量、手术时间、截骨量明显小于对照组(P<0.05);术后12个月观察组伤椎Cobb角明显小于对照组,伤椎体前缘高度比值显著大于对照组,ODI指数、VAS评分明显低于对照组,脊髓神经功能分级显著优于对照组(P<0.05)。结论微雕关节突关节建立减压通道,较常规经椎板切开减压能显著减少出血和创伤,提高椎体稳定性,恢复椎体高度,缓解功能障碍,改善脊髓神经功能。

深井高应力大巷煤柱释能改性防冲机理及应用

针对当前我国深井高应力大巷煤柱频繁发生冲击地压的现状,采用现场调查、理论分析、数值模拟和工程试验等方法,研究了我国大巷煤柱冲击地压发生类型与机理,提出了一种高应力大巷煤柱释能改性防治冲击地压的新方法,基于该方法开展了防冲原理研究、技术体系设计、井下工业试验等一系列研究工作,得到:基于大巷煤柱冲击地压的主导力源类型,结合多起冲击地压典型案例,将我国大巷煤柱冲击地压划分为基础应力叠加型、附加应力诱发型和自身蠕变失稳型3类,分别建立并推导了3类大巷煤柱冲击地压发生机理的力学模型与工程判据,揭示了3类大巷煤柱冲击地压的发生机制。提出一种深井高应力大巷煤柱压裂−注浆协同防治冲击地压的方法,其防冲原理体现在“释能”和“改性”2个方面,井下工业试验发现弹核煤体起裂压力约40 MPa,整体最大压裂宽度达19.5 m,现场监测验证该方法能够降低大巷煤柱能量积聚水平,提高大巷煤柱整体冲击阈值。设计了深井高应力大巷煤柱释能改性防冲成套技术体系,包括孤立煤体冲击危险“评估−检验−校核”方法、弹性核水力压裂增缝释能技术和整体注浆加固改性技术。研发了大巷煤柱弹性核压裂“震动−应力−位移”三场监测设备和PS-Z-A/B型无机双组份速凝整体注浆改性材料。