Stability Analysis of Large Section Rocky Tunnel Support Structure

In order to study the stress characteristics of the initial support and secondary lining of the large section tunnel and to solve the problem of secondary lining cracking during operation. Taking the large section tunnel in Zihong village, Qi County as the research object, a numerical simulation method was used to establish a finite element model of the large section tunnel. So as to simulate and analyze the stress characteristics of the support structure of this tunnel. Through the simulation of the initial support and second lining of this large section tunnel in terms of displacement, stress, plastic zone damage and anchor shaft force, the results show that as the excavation progresses, the stress and displacement on the surface of the newly excavated tunnel profile is faster, especially at the side walls and arch footings, the stress and displacement values are slightly larger than other characteristic points, but the final values are stable and converge, and are basically consistent with the field monitoring results, which indicates that this support system is basically in stable state. Therefore, during the tunnel excavation and support process, special attention should be paid to the stability of the sidewalls and footings, and the results of this study will be of great practical significance for tunnel construction and maintenance.

A Cross-Sectional Study on Appetite, Nutritional Status and Nutritional Support of Hospitalized Patients

Objective: To understand the appetite and nutritional status of hospitalized patients in a tertiary A general hospital in Guangzhou, Guangdong Province. Methods: A cross-sectional survey of appetite and nutritional status assessment on inpatients in 44 wards of the hospital was conducted. Taking all “conscious patients hospitalized for more than 48 hours” in the hospital on November 25, 2020 as the survey subjects, the patients’ appetite, dietary intake, nutrition and nutritional support in the past week were investigated. Results: A total of 890 cases were investigated, among which 25 cases (2.81%) with missing data were excluded, and thus 865 investigated cases were considered effective. The incidence of nutritional risk was 28.67%, malnutrition 13.29%, external tube feeding nutrition 3.24%, parenteral nutrition 7.05%, and oral nutritional supplement 10.40%. The average score of appetite assessment was (6.99 ± 2.43) points. Among them, cases with appetite assessment scores < 5 points accounted for 15.84%, and 52 patient cases utilized appetite-improving drugs. Among the 137 patients with appetite scores < 5, only 7 patients utilized appetite-improving drugs. The patients’ dietary self-evaluation scores were averagely (4.08 ± 1.16) points, and the daily intake compliance rate of patients was 85.78%. Appetite assessment score was correlated with dietary intake score (r = 0.548) and daily intake compliance rate (r = 0.263) (p < 0.01). The differences in body weight, BMI, grip strength, albumin, and hemoglobin concentration of patients with different appetite states were statistically different (p < 0.01). Appetite was an influencing factor of weight change (β = −0.079, p = 0.023). The difference between the appetite assessment scores and the daily intake compliance rates of patients with different nutritional support methods was statistically significant (p < 0.05);the individualized diet group had the highest appetite assessment score (8.57 ± 1.70), while the parenteral nutrition group had the lowest appetite assessment score (4.90 ± 2.99);the individualized diet group had the highest daily intake rate of 100%, followed by the parenteral nutrition group with 96.72%, and the regular diet group had the lowest rate of 84.02%. Conclusion: The appetite of hospitalized patients is closely related to nutritional status, and therefore, attention should be paid to the appetite status and nutritional status of hospitalized patients. Inpatients with different nutritional support methods should be given individualized appetite and nutritional interventions.

Construction and stability of an extra-large section chamber in solid backfill mining

In solid backfill mining without gangue removal, the gangue is separated directly underground and backfilled into goaf. This necessitates the underground construction of an extra-large section chamber for separation equipments. For the construction of an extra-large section chamber in the Tangshan mine, we proposed an active support through a combination of bolting, anchor cables, lining, and a reinforced chamber floor by inverted arch pouring. ABAQUS software was used to analyze the surrounding rock deformation and the plastic zone development of the chamber under different excavation schemes.The best excavation scheme was determined, and the effectiveness of the combined supports was verified. In practice, the engineering installation showed good overall control of the movement of the surrounding rock, with roof-to-floor and side-to-side convergences of 154.6 and 77.5 mm, respectively,which meets the requirements for underground coal gangue separation.

Plastic zone analysis and support optimization of shallow roadway with weakly cemented soft strata

Based on a shallow roadway with weakly cemented soft strata in western China, this paper studies the range and degree of plastic zones in soft strata roadways with weak cementation. Geological radars were used to monitor the loose range and level of surrounding rocks. A mechanical model of weakly cemented roadway was established, including granular material based on the measured results. The model was then used to determine the plastic zone radium. The predicted results agree well with measured results which provide valuable theoretical references for the analysis of surrounding rock stability and support reinforcing design of weakly cemented roadways. Finally, a combined supporting scheme of whole section bolting and grouting was proposed based on the original supporting scheme. It is proved that this support plan can effectively control the deformation and plastic zone expansion of the roadway surrounding rock and thus ensure the long-term stable and safe mining.

Support vector regression model for complex target RCS predicting

The electromagnetic scattering computation has developed rapidly for many years; some computing problems for complex and coated targets cannot be solved by using the existing theory and computing models. A computing model based on data is established for making up the insufficiency of theoretic models. Based on the ＂support vector regression method＂, which is formulated on the principle of minimizing a structural risk, a data model to predicate the unknown radar cross section of some appointed targets is given. Comparison between the actual data and the results of this predicting model based on support vector regression method proved that the support vector regression method is workable and with a comparative precision.

矿井采煤过程中大断面巷道支护技术研究

煤炭资源是中国重要的能源资源之一,然而在矿井采煤过程中,巨大煤矿的开采和应力变化等因素导致支护不足和大断面巷道变形严重。为了解决这一问题,需要开展更深入、更系统的研究。首先介绍了大断面巷道的特点以及在采煤过程中存在的支护难题,包括巷道变形、支架开裂等问题。然后分析了传统支护方式存在的不足之处,并提出了一种新型支护技术——填充式支护技术。该技术采用填充材料将巷道周围空隙填满,从而增强了支护效果,提高了大断面巷道开采的安全性和可靠性。

A Multi-Disciplinary Approach of a Patient with Extensive Arterio-Venous Malformations Undergoing a C-Section

The presence of both uterine and arteriovenous malformation in a patient is rare. For these patients a cesarean section can be life threatening due to uncontrolled massive hemorrhage. Prevention and control of massive blood loss utilizing a multidisciplinary approach can be lifesaving. We present a case report of a 33 years old pregnant woman at 35 weeks of gestation diagnosed with an extensive uterine arteriovenous malformation and innumerable tortuous vessels who was scheduled for a cesarean section. Her previous vaginal delivery was complicated by significant bleeding requiring uterine artery embolization. Pre-operative prophylactic aortic and right iliac artery balloon occlusion catheters were placed under monitored anesthesia care. The extracorporeal life support team was available to initiate veno-venous or arteriovenous bypass. Cesarean section was performed with careful identification of the uterine vessels under ultrasound guidance and ultimately the bleeding was well controlled. Postoperatively, the patient underwent uterine artery embolization. It is our strong belief that although we did not face a major disaster during this cesarean section, our comprehensive plan and multi-disciplinary approach were essential to ensuring the safety of the parturient and newborn.

美观满意度和家庭支持对剖宫产腹部瘢痕患者治疗意愿的影响分析

目的:探讨美观满意度和家庭支持对剖宫产腹部瘢痕患者治疗意愿的影响。方法:纳入2021年3月-2022年1月笔者医院134例剖宫产腹部瘢痕患者为研究对象,所有患者均接受美观满意度、家庭支持度及治疗意愿调查评估。分析美观满意度和家庭支持对剖宫产腹部瘢痕患者治疗意愿的影响,并根据患者治疗意愿分为意愿组和非意愿组,采用Logistic回归方程分析患者剖宫产腹部瘢痕患者治疗意愿的影响因素。结果:Pearson相关系数分析显示美观满意度与剖宫产腹部瘢痕治疗意愿呈负相关(P<0.05),家庭支持度均与剖宫产腹部瘢痕治疗意愿呈正相关(P<0.05);Logistic回归分析显示年龄高(OR=1.885)、美观满意度高(OR=1.299)是剖宫产腹部瘢痕患者治疗意愿的危险因素(P<0.05),家庭月收入高(OR=0.221)、家庭支持度高(OR=0.462)是剖宫产腹部瘢痕患者治疗意愿的保护因素(P<0.05)。结论:美观满意度和家庭支持均显著影响患者剖宫产腹部瘢痕患者治疗意愿,同时患者年龄及家庭月收入也影响患者剖宫产腹部瘢痕患者治疗意愿。

杭州电竞中心结构设计重难点概述

杭州电竞中心内圈主体结构采用钢框架-支撑结构,外圈采用“大倾角梭形斜柱+多段钢折梁框架”,是集承重与抗侧力于一体的结构体系,屋盖采用车辐式索承网格自平衡结构形式。详细介绍了地下结构、中央场馆结构的设计要点,门厅处利用建筑造型空间设计为多段钢折梁与跨层桁架相结合的结构形式;室内二层至三层楼面设计一浮空弧形人行桥,截面形式为薄壁钢箱梁,桥宽2.2m,跨度57m,采用“上挂下支”的稳定结构形式。对整体结构进行了静力弹性、动力弹塑性、振动台试验、典型节点有限元、整体稳定以及局部稳定等系列分析与试验。结果表明:结构在静力荷载和地震作用下强度和刚度均满足规范要求;典型节点极限承载力为荷载设计值的4.17倍;结构整体稳定性安全系数为3.79;斜柱局部稳定安全系数为2.52。合理的设计保证了结构的安全、经济和实用性。

北京某三级甲等医院营养支持现状横断面调研分析

目的:对中日友好医院(以下简称“该院”)营养支持现状进行调研,评价营养支持的合理性,探讨营养支持对住院费用及住院时间的影响。方法:开展横断面研究,纳入2023年3月1—15日入住该院并接受营养支持的成人患者,收集患者基础信息,对患者进行营养风险筛查与评估,评价营养支持指征的合理性;观察能量及蛋白摄入情况对患者血清白蛋白、住院时间及住院费用的影响。结果:共纳入602例患者,经筛查存在营养风险的患者所占比例为58.0%(349/602);与无营养风险的患者比较,有营养风险的患者住院时间长(P=0.008)、费用高(P=0.001),差异均有统计学意义;肠外营养应用比例为68.6%(413/602)。能量及蛋白摄入达60%目标需求的有290例(占48.2%),与能量及蛋白摄入不足60%目标需求的患者比较,达标患者营养支持后血清前白蛋白水平升高,差异有统计学意义(P=0.000)。存在营养风险的围手术期患者,充足的营养支持显著缩短其住院时间(P=0.041)。无营养风险的围手术期患者,营养支持显著增加其住院费用(P=0.006)。无营养风险的消化系统疾病患者,营养支持显著延长其住院时间(P=0.000),增加其住院费用(P=0.005)。结论:规范的营养支持与患者血清前白蛋白水平改善相关,可在不增加住院费用的前提下缩短围手术期患者住院时间。该院现阶段临床营养支持存在营养不良诊断不完善及方案不合理等问题,需要进一步完善营养支持路径,促进临床营养支持规范化。

倾斜煤层回采巷道断面形状优选及支护研究

为解决香山矿倾斜煤层回采巷道变形复杂、稳定性差、支护难的问题,以香山矿二水平己一采区己_(16-17)倾斜煤层为工程研究背景,通过数值模拟比较分析巷道不同断面形状围岩变形情况,选择合适巷道断面并提出相应的支护方式,结合现场观测以验证选取巷道断面以及支护方式的有效性。结果表明:采用斜顶梯形巷道断面及锚网索支护后巷道顶板最大下沉量与支护前相比降低了19%,两帮最大位移量降低了12.7%,梯形巷道断面支护可以将巷道围岩的变形和破坏控制在较小的范围内,回采巷道变形得到有效控制。研究香山矿倾斜煤层回采巷道稳定性,可为矿井安全生产提供依据。

南阳煤业大断面巷道支护方案设计及应用

针对南阳煤业3#煤层厚度大、回采巷道断面大、支护困难等问题,采用理论分析、数值模拟的方法,确定了合理的巷道支护方案,并在3302轨道巷进行现场试验。对3302轨道巷巷道围岩变形量、顶板离层量及锚杆受力进行实时监测。现场监测数据显示,巷道围岩变形量不大,顶板无离层、失稳风险,锚杆受力状态良好,可有效约束巷道围岩变形。

灰岩矿溜井开挖支护与降段爆破参数优化

“贮矿降段法”是溜井口在露天矿中随露天开采向下进行而延伸的一种溜井降段方法,常用多孔爆破方式进行溜井降段。目的降段过程中,维持溜井井壁的稳定性是生产过程中的重要环节,但溜井内部状态具有不可视性,因此,研究溜井爆破降段前井口的合理支护方式和爆破降段时更优的爆破参数对溜井井壁稳定性尤为重要。方法基于某灰岩矿溜井,对溜井井壁稳定性影响进行理论分析,研究溜井降段前与爆破降段时井壁稳定性,通过数值模拟手段研究溜井掘进后不同支护条件下及多次爆破降段时井壁稳定性。结果研究结果揭示了爆破产生的扰动对井口和井壁影响程度与井筒距爆破中心距离呈负相关关系,明确了掘进后和爆破降段时溜井的应力分布和井壁破坏规律,确定了更为合理的井口支护方式。结论在此灰岩矿溜井井口进行C40级混凝土支护,可有效削弱日常爆破开采产生的震动对井口围岩的破坏,确定爆破辅助孔底盘抵抗距3.5 m,孔距3.5 m,排距3.5 m时更加合理,为爆破降段过程的安全性提供理论依据和参考价值。

Midwives’ Adherence to Preoperative Care Guidelines Prior to Emergency Caesarean Section at Bwaila Maternity Hospital in Malawi

A study was conducted to describe midwives’ adherence to preoperative care during emergency caesarian section at Bwaila Maternity Wing in 2012 in Malawi. The study utilized a descriptive prospective and retrospective design. A structured questionnaire was administered to all 28 midwives who were directly involved in the preparation of clients for emergency caesarean section. Clients charts were also reviewed using a standard checklist to determine adherence to preoperative care. Data were analyzed using SPSS version 16.0 and descriptive statistics in the form of frequencies and percentages were computed for the dataset. A midwife was supposed to score at least 80% on each component of preoperative care guidelines to be compliant to the stipulated pre-operation standards. The midwives scored above 80% on only four of the 14 preoperative care guidelines which were;bladder catheterization (100%, n = 14), obtaining informed consent (92.9%, n = 12), administration of IV (96.4%, n = 13) and administration of preoperative antibiotics (82.1%, n = 11). Midwives however scored less than 80% on preoperative procedures that dealt with vital signs (28.6%, n = 4): BP check (28.6%, n = 4);Pulse rate check (25%, n = 3.5);respiration check (25%, n = 3.5) and temperature check (25%, n = 3.5). The midwives scored further below standard on blood specimen collection (78.6%, n = 11). Psychological support to clients was also below standard at 60.7%, n = 8. Other components of psychological support such as surgery information (57.1%, n = 8), allowing clients ask questions (28.6%, n = 4) and answering clients’ questions (25%, n = 3.5) were also scored below standard. Overall the standard of preoperative care was below standard at the facility. Most of the midwives were new graduates, who had never received any in-service training on preoperative care. Therefore in service training it is recommended for the midwives to provide good quality of care.

深井软岩巷道顶帮强力适时锚注支护技术研究

为解决软岩巷道支护锚杆受强剪破坏及锈蚀问题,提出以全长锚固为基础的顶帮强力适时锚注支护技术,在原有支护结构上设计了顶帮补强锚索支护技术。结合适时注浆理论和现场测量数据通过Maple计算出最佳注浆时间,采用数值模拟方法研究对比了端头锚固支护与全长锚固支护情况下的巷道围岩位移、应力及塑性区分布。结果表明,以全长锚固为基础的全断面支护技术能够有效控制顶板下沉,采用全长锚固的锚杆能够在有效防止腐蚀的情况下抵抗强剪破坏,最佳注浆时间为巷道开挖后的10~20 d。结合现场监测结果表明,在顶帮强力适时锚注支护下,整体矿压及顶板下沉量基本稳定,锚杆主动支护效果好。

多匝道变截面支架法现浇连续箱梁线形控制方法研究

文章以某桥梁工程为例,对影响现浇连续箱梁线形的因素进行了分析,在此基础上研究了现浇连续箱梁施工过程中的线形控制方法,包括竖桥向线形和横桥向线形控制两大方面,经过结构预拱度计算、梁体线形计算、支架预压及监测等工程活动后,采取针对性的梁体线形控制措施,有效解决了变截面支架法现浇连续箱梁施工中线形差的问题,顺利完成了现浇箱梁施工活动并保证了箱梁线形的合理性,取得了良好的施工效果。

沿空大断面巷道预应力锚注支护技术应用

针对沿空大断面巷道掘进期间围岩变形控制难题,以王家岭矿东翼胶带大巷为工程实例,应用预应力锚注裂隙岩体加固原理,采用预应力注浆锚杆与自应力注浆联合支护方式,选用快硬早强高流态微纳米硅质复合注浆料,改善煤岩体的整体性和约束应力状态,浆液的黏结作用使锚杆变为全长锚固状态,使锚杆、浆液结石体、围岩三者形成完整的整体,提高围岩抗剪强度、破碎煤岩体应力状态和煤岩体自有强度,支护7 d后围岩变形速度明显降低,顶底板、两帮最大移近量分别为179 mm、294 mm,比支护设计优化前分别少移近198mm、386mm。

超浅埋暗挖车站隧道下穿城市主干道沉降控制技术

超浅埋暗挖技术现已经广泛应用到地铁施工建设中,以济南地铁4号线邢村站附属结构A号出入口地下通道为例,利用ABAQUS软件建立超浅埋暗挖地铁隧道下穿管线三维有限元模型,对地下通道部分开挖过程进行了模拟。研究地下通道在有无管棚注浆预支护条件下横穿城市主干道管线变形和周围地表沉降变形规律,分析了隧道衬砌的变形和受力。结果表明,在管棚预支护条件下进行隧道开挖,能有效地减小地表沉降和管线沉降,其地表最大沉降值与未采用管棚预支护相比,分别下降60.24%和66.8%;矩形断面的横通道在开挖过程地表和管线的沉降影响大于标准拱型断面。

剖宫产术后产妇分娩心理创伤调查及影响因素分析

目的:探讨剖宫产术后产妇分娩心理创伤现状并分析其影响因素。方法:采用便利抽样法选取2021年10月-2023年10月本院产科行剖宫产术分娩的产妇112例为研究对象,采用一般资料调查问卷、城市分娩创伤量表(City BiTS)、社会支持评定量表(SSRS)、视觉模拟评分法(VAS)、心理弹性量表(CD-RISC)对产妇进行调查。利用单因素分析与利用多因素logistic回归模型分析探究剖宫产术后分娩心理创伤的影响因素。结果:本次调查共发放112份问卷,有效回收108份,有效回收率96.4%。108例产妇中33例符合分娩心理创伤阳性症状标准,阳性率30.6%,分娩相关总体症状评分为(49.0±4.6)分(43~55分)。阳性症状组与阴性症状组对不确定事件产生恐惧、创伤性分娩史、孩子性别与期盼是否符合、医护人员不恰当的护理、分娩环境陌生、产后母婴关系缺失、社会支持评分(32.6±4.2分比37.4±4.2分)、剖宫产术后疼痛评分(6.1±1.5分比4.7±1.6)、心理弹性评分(54.0±5.3分比59.8±4.7分)等存在差异(P<0.05)。多因素logistic回归分析,对不确定事件产生恐惧、创伤性分娩史、孩子性别与期盼不符合、医护人员不恰当的护理、分娩环境陌生、产后母婴关系缺失、低社会支持评分、高剖宫产术后疼痛评分、低心理弹性评分是产妇剖宫术后分娩心理创伤的影响因素(均P<0.05)。结论:剖宫产术后产妇分娩心理创伤较为普遍,影响因素多样,应加强防控干预,减少分娩心理创伤发生。

深部煤系软岩大巷全断面锚注修复技术研究

为解决深部煤系软岩大巷变形剧烈、持续时间长且支护困难的问题,以王洼煤矿8煤层南深部集中运输大巷为工程背景,采用现场勘查、矿物组分分析、围岩应力测试、数值模拟分析等方式,揭示了造成深部煤系软岩大巷产生强烈变形的主要原因,得出加强深部煤系软岩大巷支护的控制思路,并在此基础上根据煤系软岩的劣化程度和支护失效特征,提出了基于全断面高强锚索支护+喷浆+全断面注浆锚索锚注支护+钢棚支护的主被动联合补强修复支护方案,并建立了修复支护的“三个阶段、四个步骤”工艺体系。研究结果表明:8煤层南深部集中运输大巷围岩成分复杂、质地软弱、遇水易膨胀崩解,且处于高地应力环境,应力集中系数达到1.46,总体表现出变形速率快、持续时间长、变形量大的特点;原支护设计存在支护强度不足、未针对软岩特性采取有效措施的缺陷,导致顶板、巷帮部分锚杆锚索破断失效;进行全断面锚注修复支护后,形成高强度、范围大、连续性强的预应力场,预应力场有效影响深度增大至原支护的1.5倍。现场试验监测显示:补强修复支护后,大巷巷帮及顶底板变形趋于稳定,表明全断面锚注修复支护工艺对深部煤系软岩大巷的稳定性控制效果显著。