Measures for controlling large deformations of underground caverns under high in-situ stress condition--A case study of JinpingⅠhydropower station

The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.

Research advances in enhanced coal seam gas extraction by controllable shock wave fracturing

With the continuous increase of mining in depth,the gas extraction faces the challenges of low permeability,great ground stress,high temperature and large gas pressure in coal seam.The controllable shock wave(CSW),as a new method for enhancing permeability of coal seam to improve gas extraction,features in the advantages of high efficiency,eco-friendly,and low cost.In order to better utilize the CSW into gas extraction in coal mine,the mechanism and feasibility of CSW enhanced extraction need to be studied.In this paper,the basic principles,the experimental tests,the mathematical models,and the on-site tests of CSW fracturing coal seams are reviewed,thereby its future research directions are provided.Based on the different media between electrodes,the CSW can be divided into three categories:hydraulic effect,wire explosion and excitation of energetic materials by detonating wire.During the process of propagation and attenuation of the high-energy shock wave in coal,the shock wave and bubble pulsation work together to produce an enhanced permeability effect on the coal seam.The stronger the strength of the CSW is,the more cracks created in the coal is,and the greater the length,width and area of the cracks being.The repeated shock on the coal seam is conducive to the formation of complex network fracture system as well as the reduction of coal seam strength,but excessive shock frequency will also damage the coal structure,resulting in the limited effect of the enhanced gas extraction.Under the influence of ground stress,the crack propagation in coal seam will be restrained.The difference of horizontal principal stress has a significant impact on the shape,propagation direction and connectivity of the CSW induced cracks.The permeability enhancement effect of CSW is affected by the breakage degree of coal seam.The shock wave is absorbed by the broken coal,which may hinder the propagation of CSW,resulting in a poor effect of permeability enhancement.When arranging two adjacent boreholes for CSW permeability enhancement test,the spacing of boreholes should not be too close,which may lead to negative pressure mutual pulling in the early stage of drainage.At present,the accurate method for effectively predicting the CSW permeability enhanced range should be further investigated.

Magnetically controlled self-sealing pressure-preserved coring technology

Pressure-preserved coring is an effective means to develop deep resources. However, due to the complexity of existing pressure-preserved technology, the average success rate of pressure-preserved coring is low. In response, a novel in situ magnetically controlled self-sealing pressure-preserved coring technology for deep reserves has been proposed and validated. This innovative technology distinguishes itself from conventional methods by employing noncontact forces to replace traditional pretensioning mechanisms, thereby enhancing the mechanical design of pressure-preserved coring equipment and significantly boosting the fault tolerance of the technology. Here, we report on the design,theoretical calculations, experimental validation, and industrial testing of this technology. Through theoretical and simulation calculations, the self-sealing composite magnetic field of the pressure controller was optimized. The initial pre-tensioning force of the optimal magnetic field was 13.05 N. The reliability of the magnetically controlled self-sealing pressure-preserved coring technology was verified using a self-developed self-sealing pressure performance testing platform, confirming the accuracy of the composite magnetic field calculation theory. Subsequently, a magnetically controlled self-triggering pressure-preserved coring device was designed. Field pressure-preserved coring was then conducted,preliminarily verifying the technology's effective self-sealing performance in industrial applications.Furthermore, the technology was analyzed and verified to be adaptable to complex reservoir environments with pressures up to 30 MPa, temperatures up to 80℃, and p H values ranging from 1 to 14. These research results provide technical support for multidirectional pressure-preserved coring, thus paving a new technical route for deep energy exploration through coring.

In situ polymerization coating and characteristics of coated NPK compound fertilizer

Controlled release NPK compound fertilizers were prepared by means of in situ polymerization of monomers on the surface of fertilizer granules at room temperature. Methacrylate, α-methyl acrylic acid, and ethylene dimethylacrylate were used as monomers, Dibenzoyl peroxide as initiator, and cobalt naphthenate, and triethyl amine as promoters. The structures of coating materials were characterized by IR spectra. The thermogravimetric analysis result indicated that the coating materials were of good thermal stability. The mean thickness of single coating measured with screw gauge was ca. 140 μm. The morphologies of uncoated and coated fertilizer granules analyzed by using scanning electron microscopy were changed from porosities and gullies to hills and plain. The release rate of coated compound fertilizers in water could be controlled by the hydrophicity and thickness of coating. The increase in coating hydrophicity caused the increase in release rate of fertilizer. The increase in thickness of coating slowed the release rate.

Clinical Research of Pre-Hospital Emergency Care, Nursing, Infection Prevention and Control for Senile Osteoporotic Vertebral Compression Fracture during Epidemic Period

Background: Novel coronavirus pneumonia (NCP) and osteoporotic vertebral compression fractures (OVCF) are the high incidences of diseases in the elderly. During the epidemic period, if not treated in time, the complications are high and the mortality is high. If we do not pay attention to infection prevention and control in pre-hospital emergency care, it will lead to the first time infection of medical staff and in-hospital cross infection in emergency outpatient receiving area. The correct consideration of both and the establishment of perfect pre-hospital emergency treatment and infection prevention and control synchronous strategy is an important premise to ensure the stable, orderly and safe medical treatment. Objective: To explore the effect of synchronous implementation of pre-hospital emergency care, nursing and infection pre-vention and control for senile OVCF during the epidemic. In order to improve the efficiency of pre-hospital emergency care and prevent the spread of infection. Method: A total of 92 elderly patients with OVCF who received pre-hospital treatment in 18 hospitals in Zhangjiakou City during the epidemic prevention and control period from January 2020 to November 2022 and met the inclusion criteria were selected as research objects, including 24 males and 68 females, aged 65 - 82 (74.2 ± 2.2) years. All patients were associated with concomitant injuries and underlying diseases. All patients in this group underwent predictive pre-hospital rescue and infection prevention and control procedures. Results: All the 92 elderly patients with OVCF received timely pre-hospital treatment during the epidemic period, and no aggravation occurred of the 92 patients, 35 were in the high risk area, 10 were in the medium risk area, and 47 were in the low risk area. Exclude OVCF for NCP Patients were treated according to the conventional diagnosis and treatment principles. Suspected and confirmed cases are transferred to designated surgical hospitals for treatment. All patients were followed up 3 months, 6 months and 12 months after treatment. There was no death rate, high satisfaction of pre-hospital first aid, high diagnostic accuracy, and good curative effect. None of the rescue personnel had any infection rate, and no hospital infection transmission and nosocomial cross infection occurred. Conclusion: It is the first step to safely treat patients and prevent cross infection to establish a perfect synchronous strategy of pre-hospital first aid and infection prevention and control.

Controlled-release Properties of Microencapsulated Disperse Dyes

Some disperse dyes were microencapsulated by means of in- situ polymerization. These microencapsulated disperse dyes was extracted respectively by ethanol under certain conditions. The controlled-release properties of disperse dyes through the shell of microcapsules were measured by spectrophotometer. According to the results, it was drawn that the type of disperse dyes, the auxiliaries contained in disperse dyes, the quantity of system controlling medium used and the core/shell ratio of microcapsules play important roles in controlling the release properties of microcapsules. The different controlled- release properties of microcapsules, which were prepared under given conditions, however, would in turn influence the performance of microcapsules in multiple-transfer printing.

An in situ monitoring method for PECVD process equipment condition

A key to successful consistent plasma processing is maintaining a consistent process chamber condition over a certain production period.To alleviate the concern,in situ process monitoring sensors are employed to investigate the plasma chamber conditions of both the deposition step with direct plasma and the cleaning step with a remote plasma system.In situ sensors are optical emission spectroscopy (OES),optical plasma monitoring sensors (OPMS),voltage current probes (Ⅵ-probes),and self-plasma OES (SP-OES).During the deposition,we perform the monitoring of a plasma condition associated with the applied RF power via OES,OPMS,and a Ⅵ-probe.In the chamber cleaning step using a remote plasma system does not allow plasma monitoring through the sidewall because the plasma is not formed in the process chamber,thus we employed SP-OES to monitor the by-product gas chemistry during the chamber cleaning process step.Successful monitoring results with some useful applications,such as arc detection,part failure detection,and cleaning process chemistry analysis,are presented in this paper.The use of in situ sensors with proper combination can help to understand the plasma process better,to achieve more precise control of plasma processing.

Effects of Controlled-Release Fertilizers and Their Application Methods on Germination and Seedling Growth of Dent and Sweet Corns

Effects of controlled-release fertilizers (CRFs) (C-AS, polyolefin coated ammonium sulfate, 50-day-type; Dd-LP, polyolefincoated urea with dicyandiamide, 40-day-type; C-ANP, polyolefin coated ammonium nitrate phosphate, 40-day-type; andC-DAP, polyolefin coated diammonium acid phosphate, 40-day-type), ammonium sulphate and no fertilizer control, andtheir application methods (spot, band, surface and mixed) on germination and seedling development of sweet corn (Zeamays L.var. saccharata Sturt.) and dent corn (Zea mays L.var. indentata Sturt.) were investigated in a greenhouse. Underco-situs application (band and spot) of CRFs, there were no obvious differences in the germination speed and rate for bothdent corn and sweet corn relative to control. Mortality rates of sweet corn seedlings under co-situs application were highin experiment 1, but were very low in experiment 2, because the environmental conditions were different in the twoexperiments. That is, under lower temperature and weaker sunlight, young seedlings easily die due to high soil nutrientconcentration and slow growth speed of corn. Shoot weight of both dent and sweet corn did not greatly decrease inexperiment 1. In experiment 2, there were no significant differences in shoot and root weight of both corns between co-situs and surface or mixed application methods. However, with spot and band application of ammonium sulfate, shoot androot weight were significantly reduced. Soil EC and pH were considerably affected by co-situs application, especially atthe fertilizer application site. For both dent and sweet corn, EC in the 0-3 cm soil was significantly higher under co-situsapplication and surface application than that under mixed application, whereas in the 3-6 cm soil depth the situation wasreversed. Compared with control, mixed application of CRFs decreased soil pH slightly (0-3 cm depth) or greatly (3-6 cmdepth).

Azobenzene mesogens mediated preparation of Sn S nanocrystals encapsulated with in-situ N-doped carbon and their enhanced electrochemical performance for lithium ion batteries application

In this work,azobenzene mesogen-containing tin thiolates have been synthesized,which possess ordered lamellar structures persistent to higher temperature and serve as liquid crystalline precursors.Based on the preorganized tin thiolate precursors,Sn S nanocrystals encapsulated with in-situ N-doped carbon layer have been achieved through a simple solventless pyrolysis process with the azobenzene mesogenic thiolate precursor served as Sn,S,N,and C sources simultaneously.Thus prepared nanocomposite materials as anode of lithium ion batteries present a large specific capacity of 604.6 m Ah·g^（-1）at a current density of 100 m A·g^（-1）,keeping a high capacity retention up to 96% after 80 cycles,and display high rate capability due to the synergistic effect of well-dispersed Sn S nanocrystals and N-doped carbon layer.Such encouraging results shed a light on the controlled preparation of advanced nanocomposites based on liquid crystalline metallomesogen precursors and may boost their novel intriguing applications.

畜牧养殖智能饮水控温系统设计与试验

为提升草原放牧牛羊福利化养殖装置性能,开发一种基于多传感器原位数据检测与模糊PID控制相结合的畜牧养殖智能饮水控温系统。该系统主要由数据采集模块、注水加热模块、温度控制模块以及远程数据监测模块组成。数据采集模块是采用多种传感器对饮水装置中水温、水质、水量等信息实时采集;注水加热模块采用底部注水加热的形式,便于水温自下而上发生层流流动,使水温分布更均匀;温度控制模块采用基于闭环负反馈模糊PID控制算法,自整定PID系数,实现水温精准控制;远程数据监测模块是针对用户设计,便于用户实时观察饮水装置的工作情况。对系统开展模糊PID控温测试以及水温温场均匀性试验验证与仿真分析,试验结果表明:模糊PID控温效果与常规PID控温相比,模糊PID控温曲线更光滑,加热响应速度更快,当预设水温目标温度为23℃,入水水温分别为7℃、9℃、11℃、13℃、15℃时,实际加热温度与目标温度的波动幅度最大仅为0.3℃;对不同测温点加热,得同一水平面不同测温点最大温差为0.3℃,水槽不同截面水温温差小于0.2℃,装置测温点水温能精准控制在23℃±0.5℃。畜牧养殖智能饮水控温系统的水温温度场均匀性良好,能够为福利化养殖提供装备支持。

分缝护栏致空心板梁桥L型裂缝预应力控制方法研究

为提高护栏分缝桥梁的耐久性和承载力,以台金高速公路杨司高架桥预制空心板梁桥为背景,研究通过施加预应力控制因护栏分缝引起L型裂缝的有效性,并针对既有桥梁加固和新建桥梁设计提出通用的有效方法。采用Abaqus软件建立既有桥梁和新建桥梁的有限元模型,研究车道荷载作用产生的应力放大效应;分析预应力筋布置高度和长度对边梁梁底应力的影响及对既有桥梁护栏分缝导致的预应力损失;在此基础上,提出L型裂缝的预应力控制方法。结果表明:边梁应力放大系数随桥梁跨径和护栏高度的增加而增大,其取值范围为[1.42,2.14];预应力筋布置高度越低,边梁跨中梁底应力越大;预应力筋布置长度越短,既有桥梁梁底应力越大,对新建桥梁应力没有影响;分缝护栏对既有桥梁施加预应力产生损失,对新建桥梁不会产生预应力损失;在边梁跨中施加相应的预应力,可有效抵消跨中的应力集中效应,防止主梁跨中产生L型裂缝。

水绵在水环境中生长控制与利用研究进展

系统梳理了水绵的危害,水绵在春末夏初开始大量生长,易于形成藻垫漂浮在水面上产生腥臭味,破坏生态系统平衡,危害水源水质安全,影响水域生态景观。分析表明水绵的生长受水动力条件、光照强度、营养物质和水温等条件的影响。重点研究了水绵的原位控制方法,水绵防控是一个系统工程可结合物理法、化学法应急清除水绵,长期控制水绵则需要选择生物法。同时,水绵在恶劣环境条件下具有较好的繁殖,可利用水绵其固碳和吸附等能力进行生物修复,应用于水生态环境中。对水绵在水环境中的水体营养、生态环境和生物监测的评价等方面的前景进行了展望。

鄂尔多斯高原台地边缘地带地应力随钻测量与分布特征

传统水压致裂法和新的热胀致裂法等测量地应力均属于先成孔后测量,容易发生钻孔后变形、自然开裂和应力释放,很难从根本上保证裂纹是试验时发生还是钻孔后已自然发生,难以保证测量结果的准确性.为了克服常规水压致裂法地应力测量过程中钻孔完整性和致裂过程真实性难以确定的问题,采用地应力光声随钻测试系统对鄂尔多斯高原西南边缘地带典型区域地应力进行了水压致裂法测试,揭示了高原台地边缘地区的应力特点,获得了地应力随深度的变化规律,并与华北平原典型区域地应力测试统计结果进行了比较.研究表明,鄂尔多斯高原西南边缘台地地带的地应力处于中国大陆浅层地壳地应力统计结果的低段区间,高原边缘地带的地应力随深度呈线性增长,最小水平主应力随深度的增长速度高于最大水平主应力的增长速度;最大最小水平主应力低于华北平原区;受区域构造及高原台地地形等影响,鄂尔多斯台地边缘的地应力方向相较于华北平原区,向东发生了偏转;最大最小水平主应力与垂直应力之比所反映的侧压系数低于华北平原区,但两个水平最大最小主应力的差异性高于华北平原区.这说明,尽管高原边缘地带地应力总体水平低于华北平原区,但较大的水平应力差异性容易使地下空间发生剪切破坏,将不利于地下工程的稳定性.由此可见,在台地边缘区域进行地下工程设计和建设时,应重点关注井巷工程的方向布置和低水平应力高应力差值带来的负面影响.

层内自生低界面张力泡沫调驱技术研究与应用——以渤海KL油田A20井组为例

针对渤海KL油田A20井组平面注水突进、纵向吸水不均及常规调剖体系难以注入等问题,开展了层内自生低界面张力泡沫调驱性能评价实验。采用界面流变仪、泡沫扫描仪和泡沫调驱动静态评价装置等设备,筛选优化了层内自生低界面张力泡沫体系的组成药剂及最佳复配浓度比,并采用多功能物理模拟驱替装置考察了该体系的动态调驱性能。结果表明:优选组成药剂及配比为10%生气药剂A+10%生气药剂B+2%释气药剂C+0.5%起泡剂PA-5+0.3%稳泡剂PJ(质量浓度),该复配体系可在可视化填砂管中稳定生泡;一维填砂管驱油效率可在水驱的基础上提高19.1%;非均质填砂管并联驱油时,注入复配体系可进一步驱洗高渗填砂管残余油并有效封堵高渗通道,扩大低渗填砂管的波及系数,分液率从0增至34%。从矿场实践来看,A20井组实施层内自生低界面张力泡沫调驱作业后,生产曲线呈含水下降、产油上升的形态,3个月内累计增油2007.29 m3,初步说明层内自生低界面张力泡沫调驱技术在海上油田具有广阔的推广应用前景。

水利水电工程施工场地地下水污染的控制与修复研究

针对水利水电工程施工场地在岩溶地区、高原地区等复杂地质环境下的地下水污染问题,提出了一种新的控制与修复方法,旨在应对因地质条件导致的污染物迁移加速和扩散范围扩大的挑战。构建地下水中污染物的迁移方程,明确污染物的迁移规律与水流流向的关联性;提出地下水污染的控制策略,设计原位修复技术和异位修复技术。实验结果表明:应用所提方法经过28天的修复治理后,某大型水利水电施工场地地下水污染物中苯的浓度出现大幅度降低,最大程度的苯浓度变化236 mg/L^(-1)下降到了5.36 mg/L^(-1),由此可知研究方法下受污染的地下水得到了有效修复。

致密碳酸盐岩气藏裂缝预测与主控因素分析——以四川盆地高石梯地区灯影组储层为例

天然裂缝是致密碳酸盐岩气藏重要的储集空间和渗流通道,定量预测其发育程度与分布规律、揭示主控地质因素,对气藏开发具有重要实践意义。本文以四川盆地中部乐山—龙女寺古隆起的高石梯地区灯影组致密碳酸盐岩储层为研究对象,在裂缝参数表征基础上建立应力场-能量-裂缝参数的计算模型,结合多期裂缝叠加算法定量预测裂缝发育分布规律,并重点分析了岩性、断层和构造形态对裂缝发育的影响。结果表明:①高石梯地区灯影组储层裂缝表现为张剪缝为主、高角度缝、半充填特征,裂缝优势走向为NW-SE与近N-S方向,裂缝密度在0~2条/m,高值区主要分布在断层带及中部地区;②高石梯地区的天然裂缝长度与裂缝密度呈负指数幂关系,裂缝发育具层间差异性,灰岩储层的缝发育程度高,泥岩对裂缝延伸具阻挡作用;③裂缝发育规模及产状发育受断层、褶皱影响显著,断层周围裂缝密度大、开度大、长度小,剪切缝与走滑断层近于平行或呈低角度,张性缝与主走滑断层呈高角度;褶皱主要通过构造曲率影响裂缝开度,弯曲变形程度高的构造部位裂缝开度大,翼部变形小,裂缝开度小。研究成果可为研究区及其他类似地质条件地区气藏高效勘探开发提供参考与借鉴。

钦州港首座大型高桩梁板码头建设关键技术与对策

钦州港目前已有大型码头主要为重力式结构,依托金鼓江作业区19号泊位工程,探讨本地区首座大型高桩梁板码头实施的关键技术问题与对策,并统计分析其实施功效,为当地的港口发展提供一种新的结构选型,有效丰富了技术储备。本文论证了高桩结构的适应性,突出建设中克服的主要难点,包括采用引孔植桩的新工艺,解决了深水裸岩环境下的临时辅助钢管桩与灌注桩钢护筒的施打难题;首次研究了炸礁与灌注桩浇筑的交叉施工机制,填补了行业实践空白;提出了新结构形式下的相应安全管理要求,补充了当地的安全文化建设。

基于数差控制模型的液压设备原位控制与检测

为准确检测原位故障行为并有针对性地实施故障控制,提出一种基于数差控制模型的液压设备原位控制与检测方法。计算设备元件剩余运行价值,并构建动态故障树模型,以便于实现对液压设备运行能力评估。分析液压设备原位受力情况,联合PID控制技术,实现对液压设备原位故障的控制。调节检测传感器部件,并联合耦合性检测条件,实现对液压设备原位故障行为的检测。实验结果表明,在数差模型的作用下压力表示数差不超过0.1×10^(-3)N,能够实现对原位故障行为的准确检测,为提出针对性故障控制策略提供保障。

软土地区刚性桩复合地基沉降控制综述

软土在沿海地区广泛分布,而软土地基的沉降控制较难,因而复合地基逐渐成为软土地基处理的主要形式。刚性桩复合地基作为复合地基的典型代表之一,其桩和土均发挥了部分承载作用,该类地基沉降控制首要考虑软土因素及地基处理措施。为此从“软土”及“地基处理措施”两方面,分析地基沉降的主要影响因素,并综述了软土地区刚性桩复合地基沉降的控制要点。

结合药剂缓释体的原位化学氧化技术持续修复有机污染地下水的研究及应用进展

有机污染物的反扩散、拖尾和反弹等问题严重影响传统原位化学氧化(In-Situ Chemical Oxidation,ISCO)技术对污染地下水的修复效果。药剂缓释技术可以实现对污染地下水的长时间持续修复,是保证原位化学氧化修复效果的有效方式。经过大量文献调研,介绍药剂缓释体-原位化学氧化(Controlled Release Materials-In-Situ Chemical Oxidation,CRM-ISCO)技术原理及缓释体材料组成,系统分析国内外CRM-ISCO技术修复地下水的研究现状及工程应用进展,总结技术应用存在的问题并对前景进行展望,以期为CRM-ISCO技术在我国有机污染地下水修复中的推广和应用提供参考。