Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata

In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality.

Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.

Seepage field distribution and water inflow laws of tunnels in water-rich regions

Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.

Numerical research on stability control of roofs of water-rich roadway

In order to study the strength-weakening law of roofs of water-rich roadway, this study used FLAC software, and simulated and analyzed the failure characteristics of the surrounding rock of water-rich roadway under the condition of different cross sections and support parameters, finally obtained the stress distribution of the principle stress of the roadway as well as the displacement variation of its surrounding rock. Results indicate that the roof stability of roadway with semicircular cross section is better than the roadway with inclined rectangular cross section under water-rich condition. Besides, the surrounding rock deformation of roadway under the action of water shows a pronounced increase compared to the roadway without the action of water due to the fact that water will obviously weaken the surrounding rock of roadway, especially its roof. It is very beneficial to control roof stability of water-rich roadway and guarantee the roadway stability during its service life by improving the pretension of bolt and cable as well as decreasing inter-row spacing of the bolt.

Water shutoff model test in water-rich sandy stratum by phosphoric acid-water glass grout

The rheological behavior of phosphoric acid-water glass grout in different mixing ratios was studied. Grout made of water glass with Baume degree of 20° and 13.4% phosphoric acid by 1:1 volume ratio is found to be more effective in stopping water. Laboratory model test of water shutoff by grouting was conducted. Test results show that the diffusion length and water cutoff effect of the grout are significantly improved as the grout head is raised, due to the dilution of underground water, and it takes the grout longer than its gel time to cut off water.

Application of 3-D Parallel Electrical Technology Detecting the Water-Rich Areas

Coal working face is damaged more and more seriously by water below the coal face floor. Therefore, floor water detection is a must in the process of extraction. This article aims to introducing application and principle of the two-gateways parallel 3-D electrical technology and the arrangement of the observation system. The authors use this method to detect the water under the floor of a mine in north of Anhui. The results show that the two-gateways parallel 3-D electrical technology can accurately locate the water-rich areas, providing the basis for drilling drainage and grouting construction.

社区慢性病共病患者自我同情现状及影响因素分析

目的了解社区慢性病共病患者自我同情现状及其影响因素,为护理人员采取针对性措施促进社区慢性病共病患者的身心健康发展提供科学依据。方法采用一般资料调查问卷、自我同情量表、Herth希望量表和领悟社会支持量表对社区402例慢性病共病患者进行调查。结果社区慢性病共病患者的自我同情得分(79.04±7.82)分。多元线性逐步回归分析显示,希望水平和领悟社会支持水平是社区慢性病共病患者自我同情的影响因素(均P<0.05)。结论社区慢性病共病患者自我同情处于中等水平,护理人员应加强患者自我同情的识别与干预,制订针对性护理方案,充分调动患者及其家庭对慢性病共病相关身心健康管理的积极性,以提升社区慢性病共病患者的自我同情水平。

广州市老年人慢性病共病与中医体质兼夹的关联性分析

【目的】分析广州市老年人慢性病共病与中医体质兼夹的关联模式。【方法】基于广州市3个社区的体检数据,选取3078名老年人为调查对象,通过关联分析探讨不同人口学特征的老年人慢性病共病与中医体质兼夹的关联规则。【结果】老年人慢性病共病率为76.54%(2356/3078);老年人群中,倾向血瘀质+痰湿质的兼夹体质组合与慢性病共病的关联规则置信度最高,为95.87%;不同性别的老年人兼夹体质组合与慢性病共病的关联规则基本相同,男性中痰湿质+倾向阴虚质的兼夹体质组合与慢性病共病的关联规则置信度为94.38%,女性中痰湿质+倾向血瘀质的兼夹体质组合与慢性病共病的关联规则置信度为97.46%;随着年龄的增高,慢性病共病老年人的兼夹体质逐渐发展为痰瘀互结,气虚质、阳虚质相关兼夹体质逐渐明显。【结论】老年人慢性病共病率较高,不同年龄组的人群慢性病共病与兼夹体质组合的关联模式不同,医疗机构可根据老年人的兼夹体质状态,通过中医药手段调理体质,改善老年人的慢性病共病情况。

有机酸对污染土壤中铜和镉的浸提效果

以采自湖北省大冶矿区长乐山的4种土壤为供试材料,研究了柠檬酸、酒石酸和EDTA在不同浓度、浸提时间和加入电解质等因素影响下对土壤中铜和镉的浸提效果。结果表明,有机酸对土壤中铜和镉的浸提量随有机酸浓度的增加而增加,但增幅与有机酸的种类有关。土壤中铜浸提30min,镉浸提1h可接近平衡。在柠檬酸处理中,加入电解质对铜和镉的浸提起抑制作用。

基于组态思想的旋转机械状态监测系统

为适应旋转机械状态监测系统多样化需求，提出一种新颖的基于组态思想的旋转机械状态监测系统。该系统以配置研究设计的组态化状态监测系统管理分析软件平台的通用计算机为核心，加上研制的电涡流信号采集前置分机、压电信号采集前置分机、工艺量信号采集前置分机和系统组合控制分机组成。系统可以依据工业现场状态监测的实际需要，由用户方便地组建成具有多种信号采集和数据分析功能的离线的便携式振动数据采集分析系统、准在线状态监测系统、或在线状态监测系统。所有信号采集前置分机和系统组合控制分机都是以ＤＳ８０Ｃ３２０高速处理单片机为核心设计的高速、小型化、低功耗系统。论述系统总体方案、系统分机设计和管理分析软件设计，并给出系统在工业现场的应用结果。

坡面细沟流侵蚀临界条件研究

从适用于陡坡的水动力学模型出发,研究坡面水流细沟侵蚀临界状态的判断方法。讨论了坡长、坡度、坡面投影长对细沟侵蚀的影响,采用临界摩阻流速随坡度变化、临界摩阻流速不随坡度改变两种假定分别进行模拟计算,以摩阻流速作为判别坡面细沟流侵蚀临界状态的水动力学指标,在给定的坡面尺寸、净雨强和初始微地形条件下,计算得出了细沟流摩阻流速达到临界值时所对应的坡度。

培养条件对Streptococcus equisimilis合成透明质酸相对分子质量的影响

作者比较了不同培养条件对Streptococcus equisimilis合成透明质酸相对分子质量的影响。结果表明：高质量浓度葡萄糖有利于长链透明质酸的合成,当发酵体系葡萄糖初始质量浓度从20g/L上升至80g/L,相对分子质量从1.24×10^6增大到2.02×10^6,提高了62.9%。葡萄糖补料培养不利于高相对分子质量透明质酸的合成,利用葡萄糖间歇和连续补料培养的方式得到透明质酸相对分子质量分别为1.53×10^6和1.42×10^6,比分批培养下降了19.9%和25.7%。在33-39℃范围内,较低温度有利于高相对分子质量透明质酸的合成,在33℃培养条件下透明质酸相对分子质量最高可达2.54×10^6。发酵液p H显著影响透明质酸的相对分子质量,在p H8时,达到了最高的2.38×10^6。较高溶氧水平有利于高相对分子质量透明质酸的合成,在0-45%溶氧浓度范围内,相对分子质量随溶氧水平的增加从1.16×10^6提升至2.43×10^6,增长了109.4%。本研究结果为后续高相对分子质量透明质酸的生产提供有用的实验依据。

中间轴承对船舶轴系力学状态影响的数字模拟

本文以主机为WNSD7RTA62U的某油轮的轴系为对象,通过对比分析四种不同的中间轴承的布置方案,评价了中间轴承对船舶轴系力学状态的影响。本文轴系合理校中与轴系回旋振动的数字计算结果表明,中间轴承对船舶轴系的状态存在着比较复杂的作用,首先在常规设计中,必须对中间轴承的位置进行三维优化;其次取消中间轴承的非常规设计,对船舶轴系的状态的改善是可行的。这对解决大型船舶轴系校中受船体变形影响和革新大型船舶轴系的传统设计与计算是有用的。

爆破拆除冷却塔倾倒条件的研究

从理论上研究了定向爆破拆除冷却塔的倾倒条件,建立了结构极限弯矩和倾倒力矩的表达式。计算结果表明，当爆破切口圆心角为0.626×2π时，假设结构受压区和受拉区的钢筋和混凝土同时达到塑性状态，倾倒力矩仅为结构极限弯矩的1.09倍;若按照材料力学理论以受拉区的最大拉应力大于混凝土的抗拉强度为极限条件，则倾倒力矩为结构极限弯矩的2.91倍；若按照弹塑性理论分析，则倾倒力矩为结构极限弯矩的1.62倍。最后，文章分析了支撑部位的破坏过程。

关系型主动数据库的事件模型与监测

ECA(事件一条件一动作)规则是主动数据库系统中广泛采用的主动服务机制,其荃本语义是:当事件发生时,即时地或在规定时刻检查条件是否满足。

响应面法优化球孢白僵菌CXJ-1的发酵工艺条件

为了提高球孢白僵菌CXJ-1(Beauveria bassiana CXJ-1)在液体发酵过程中分生孢子的产孢量,采用响应面法对球孢白僵菌CXJ-1产孢的发酵工艺条件进行优化。采用单因素实验确定了产孢发酵条件最适初始pH、发酵转速和发酵温度。通过Plackett-Burman实验设计和Box-Behnken实验设计响应面分析优化,确定了球孢白僵菌CXJ-1产孢最佳发酵工艺参数为:温度28.07℃,转速198.95r/min,初始pH 6.10,预测孢子浓度可达9.5×108个/mL,在优化发酵条件下进行验证实验,孢子浓度达到9.7×108个/mL,表明验证值和预测值有较高的吻合度。

秦皇岛主要入海河流污染及其对近岸海域影响研究

利用饮马河、洋河、汤河和戴河的水文和水质监测资料,分析了各河流的污染状况、营养状态、污染物入海通量及其对海域水质的影响。结果表明:秦皇岛市入海河流中饮马河和洋河污染较重;通过污染分担率分析,秦皇岛入海河流的首要污染物为DIN、COD,其次为PO43--P;采用综合营养状态指数法评价,汤河处于轻度富营养状态,戴河处于中度富营养状态,而洋河和饮马河都已达到重度富营养化状态,可见秦皇岛入海河流的富营养化现象非常严重;秦皇岛主要河流污染物入海通量近年来基本呈减小趋势,饮马河和洋河年均入海污染物量占到秦皇岛市陆源入海污染物总量的94.91%;通过相关分析表明,秦皇岛近岸海域的水质主要受入海河流影响,尤其是CODMn、DIN、PO43--P在河、海间存在线性关系,具有强相关性。因此应加强对入河污染物的管理,重点应放在生活污水、农业面源污染的治理上,从而改善近岸海域的水质状况。

乳腺癌前不同病变中多种生物标志的变化规律及意义

目的探讨多种生物标志在乳腺癌前不同病变中的变化规律及意义。方法免疫组化法检测ER、PR、pS2、p53和c-erbB-2在正常乳腺组织、单纯性增生、不典型增生和早期癌中的表达。结果ER、PR表达与乳腺增生病情程度密切相关(r=0.446,P<0.0001;r=0.363,P<0.0001),阳性表达率在不典型增生组分别为64.4%和73.3%,显著高于正常组(分别为11.5%和15.4%)和单纯增生组(分别为22%和28%)。pS2、p53、c-erbB-2在癌前不同病变中的表达率较低。发现>2个指标的共表达在不典型增生组为68.9%,显著高于正常组(3.8%,P<0.01)和单纯增生组(14%,P<0.01)。结论ER、PR是促进乳腺增生发展和癌变的重要影响因子,临近癌变存在显著增高的多生物指标共表达。

重组大肠杆菌产β-胡萝卜素的发酵条件

对重组大肠杆菌产-胡萝卜素发酵条件进行了研究.在M9培养基中添加Span-200.7g/L有利于细胞生长和β-胡萝卜素表达,初始pH值6.0、接种体积分数5%、发酵温度28℃、抗生素氨苄青霉素质量浓度80μg/mL和氯霉素质量浓度40μg/mL为最佳发酵条件,在7L发酵罐进行发酵动力学试验表明,重组菌最适发酵周期为22h,细胞干重最高可达1.55μg/L,β-胡萝卜素表达量可达0.75μg/mL.

蜡样芽孢杆菌培养条件的优化及其溶藻方式的研究

通过优化培养温度、转速、装瓶量、接种量、发酵时间等培养条件提高蜡样芽孢杆菌的溶藻活性,为水华的防治提供新的选择。结果显示,蜡样芽孢杆菌(Bacillus cereus)通过分泌一种耐高温的代谢产物或细胞外物质起到对铜绿微囊藻905的溶藻作用,属于间接溶藻。通过单因素实验和响应面实验并结合实际条件的可控制性考虑,得到蜡样芽孢杆菌的最佳培养条件:温度39℃、转速170r/min、装瓶量75mL、接种量6%(体积分数)、发酵时间9h。在最佳培养条件下,蜡样芽孢杆菌对铜绿微囊藻905的叶绿素a清除率为86.72%。