Rheological characteristics of soft rock structural surface

There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering the deformation in the starting creep phase,so that the structural surface creep usually displays the strong surface roughness effect,and so does the latter when the asperities in the coarse surface were fractured by shearing.Under the low stress condition,there are only two phases of the decelerating creep and the constant creep for the soft rock structural surface,and as the stress increases and overcomes the rubbing resistance,the accelerating creep failure of the structural surface will happen suddenly.Therefore,a multiple rheological model,which combines the nonlinear NEWTON body(NN) of a certain mass and the empirical plastic body(EM) with the classical SAINT VENANT body,NEWTON body,KELVIN body and HOOKE body,could be used to comprehensively describe the creep characteristics of the soft rock structural surface.Its mechanical parameter values will vary owing to the different surface roughness of the structural surface.The parameters of GH,GK and ηL are positively linearly correlative to the surface roughness.The surface roughness and m are negative exponential function correlation.The long-term strength τS is positively correlative to the surface roughness.

Influence of sand content on the flow characteristics of soft soil under cyclic and high-frequency vibration

The flow characteristics of foundation soils subjected to train loads can present engineering hazards in highspeed railways. In order to verify the feasibility of blending coarse sand in modifying soft subsoil, undrained pulling sphere tests were carried out and the train loads were simulated through localized and cyclic vibration at various frequencies. Laboratory testing results indicate that the fl ow characteristics of soft soil can be signifi cantly enhanced by high-frequency vibration;meanwhile the continuous increase in fl ow characteristics caused by cyclic vibration may be an important reason for the long-term settlement of soft subsoil. The infl uence of sand content on fl ow characteristics is also studied in detail, and it is shown that the addition of coarse sand can weaken the fl ow characteristics of soft soil induced by sudden vibration at lower than 50 Hz. Under the condition of cyclic vibration, the growth of the fl ow characteristics of sand-clay mixtures is mainly caused by the fi rst-time vibration in the cycle, and the increase in sand content can make the fl ow characteristics present a faster convergent tendency.

Compacting Deformation Engineering Characteristics of Weathered Soft Rock Mixture in Subgrade

The engineering characteristics of weathered soft rock are important contents of soft rock mechanics. They also play a significant role in compacting deformation, which has been known to exert a significant amount of influence on the stability of highway filling subgrade engineering. In an effort to investigate this aspect of the problem, compacting tests and unconfined compressive strength tests have been carried out on weathered argillaceous slate and pelitic siltstone rocks, which are broken and graded before the test. The testing results indicate that the relationships of both between stress and strain and between axial strain and tangent modulus are exponential relationships; the size of the grain plays some influence on the deformation modulus, whereas the water content impacts the compressive strength greatly, which shows quadratic function; the unconfined compressive strength is linear with the dry density of loose soft rock mixtures. Therefore, the water content must be controlled in both the design and the construction of subgrade engineering of soft rock filling, and at the same time some effective measures should be taken to reach the requirement of compaction.

Deformation characteristics of surrounding rock of broken and soft rock roadway

A similar material model and a numerical simulation were constructed and are described herein.The deformation and failure of surrounding rock of broken and soft roadway are studied by using these models.The deformation of the roof and floor,the relative deformation of the two sides and the deformation of the deep surrounding rock are predicted using the model.Measurements in a working mine are compared to the results of the models.The results show that the surrounding rock shows clear rheological features under high stress conditions.Deformation is unequally distributed across the whole section.The surrounding rock exhibited three deformation stages:displacement caused by stress concentration,rheological displacement after the digging effects had stabilized and displacement caused by supporting pressure of the roadway.Floor heave was serious,accounting for 65% of the total deformation of the roof and floor.Floor heave is the main reason for failure of the surrounding rock.The reasons for deformation of the surrounding rock are discussed based on the similar material and numerical simulations.

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

Modeling and identification for soft sensor systems based on the separation of multi-dynamic and static characteristics

Data-driven soft sensor is an effective solution to provide rapid and reliable estimations for key quality variables online. The secondary variables affect the primary variable in considerably different speed, and soft sensor systems exhibit multi-dynamic characteristics. Thus, the first contribution is improving the model in the previous study with multi-time-constant. The characteristics-separation-based model will be identified in substep way,and the stochastic Newton recursive(SNR) algorithm is adopted. Considering the dual-rate characteristics of soft sensor systems, the proposed model cannot be identified directly. Thus, two auxiliary models are first proposed to offer the intersample estimations at each update period, based on which the improved algorithm(DAM-SNR) is derived. These two auxiliary models function in switching mechanism which has been illustrated in detail. This algorithm serves for the identification of the proposed model together with the SNR algorithm, and the identification procedure is then presented. Finally, the laboratorial case confirms the effectiveness of the proposed soft sensor model and the algorithms.

BRIEF REVIEW OF THE STRENGTH AND DEFORMATION CHARACTERISTICS OF SEDIMENTARY SOFT ROCK

The strength and deformation characteristics of sedimentary soft rock evaluated in relation to several large-scale researc and construction projects in Japan are reviewed.The elastic stiffiness at small non-linearity due to strain and pressure level,and viscous properties are described.The elastic stiffness from triaxial tests using high-quality core samples while measuring stresses and strains accurately is basically the same as the corresponding value from field shear wave velocity.It is necessary to take into account the dependency or stiffness on shear and pressure level,which could be evaluated by relevant laboratory stress-strain tests while referring to results trom relevant field loading tests.Loading rate effects due to the material viscous properties could be simulated by a non-linear three-component model.

Experimental analysis of pore structure and fractal characteristics of soft and hard coals with same coalifcation

Accurate and quantitative investigation of the physical structure and fractal geometry of coal has important theoretical and practical signifcance for coal bed methane(CBM)development and the prevention of dynamic disasters such as coal and gas outbursts.This study investigates the pore structure and fractal characteristics of soft and hard coals using nitrogen and carbon dioxide(N_(2)/CO_(2))adsorption.Coal samples from Pingdingshan Mine in Henan province of China were collected and pulverized to the required size(0.20–0.25 mm).N_(2)/CO_(2)adsorption tests were performed to evaluate the specifc surface area(SSA),pore size distribution(PSD),and pore volume(PV)using Braunuer-Emmett-Teller(BET),Barrett-Joyner-Halenda(BJH),and Density Functional Theory(DFT).The pore structure was characterized based on the theory of fractal dimensions.The results unveiled that the strength of coal has a signifcant infuence on pore structure and fractal dimensions.There are signifcant diferences in SSA and PV between both coals.The BJH-PV and BET-SSA obtained by N_(2)-adsorption for soft coal are 0.029–0.032 cm^(3)/g and 3.523–4.783 m^(2)/g.While the values of PV and SSA obtained by CO_(2)-adsorption are 0.037–0.039 cm^(3)/g and 106.016–111.870 m^(2)/g.Soft coal shows greater SSA and PV than hard coal,which is consistent with the adsorption capacity(VL).The fractal dimensions of soft and hard coal are respectively diferent.The Ding coal exhibits larger D1 and smaller D_(2),and the reverse for the Wu coal seam is observed.The greater the value of D1(complexity of pore surface)of soft coal is,the larger the pore surface roughness and gas adsorption capacity is.The results enable us to conclude that the characterization of pores and fractal dimensions of soft and hard coals is diferent,tending to diferent adsorption/desorption characteristics.In this regard,the results provide a reference for formulating corresponding coal and gas outburst prevention and control measures.

Research progress of cholesteric liquid crystals with broadband reflection characteristics in application of intelligent optical modulation materials

Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.

Rolling element bearing instantaneous rotational frequency estimation based on EMD soft-thresholding denoising and instantaneous fault characteristic frequency

The accurate estimation of the rolling element bearing instantaneous rotational frequency(IRF) is the key capability of the order tracking method based on time-frequency analysis. The rolling element bearing IRF can be accurately estimated according to the instantaneous fault characteristic frequency(IFCF). However, in an environment with a low signal-to-noise ratio(SNR), e.g., an incipient fault or function at a low speed, the signal contains strong background noise that seriously affects the effectiveness of the aforementioned method. An algorithm of signal preprocessing based on empirical mode decomposition(EMD) and wavelet shrinkage was proposed in this work. Compared with EMD denoising by the cross-correlation coefficient and kurtosis(CCK) criterion, the method of EMD soft-thresholding(ST) denoising can ensure the integrity of the signal, improve the SNR, and highlight fault features. The effectiveness of the algorithm for rolling element bearing IRF estimation by EMD ST denoising and the IFCF was validated by both simulated and experimental bearing vibration signals at a low SNR.

HPLC Study on HPLC Characteristic Spectrum of Huoxiang(Herba Agastachis)Eliminating Summer-heat Soft Capsule

To establish HPLC characteristic spectrum of Huoxiang(Herba Agastachis)Eliminating Summer-heat Soft Capsule.Chromatographic separation was performed on Tech Mate C18-ST(5 um,4.6×250 nm)column by Agilent 1260 high performance liquid chromatograph,eluted with acetonitrile and 0.05%phosphoric acid in a gradient elution at a flow rate of 1.0 mL∙min-1.The detection wavelength was set at 270 nm.Hesperidin was selected as the reference peak to calculate the RSD of the relative retention time.Precision,stability and reproducibility were investigated as well.80 different samples from 5 manufacturers were included in this study.The HPLC characteristic spectrum of Huoxiang Eliminating Summer-heat Soft Capsule was constructed with 11 specific chromatographic peaks in 80 samples.The method is accurate,reliable and with good reproducibility,and could overall control the quality of Huoxiang Eliminating Summerheat Soft Capsule.

海相软土力学特性及其对城市地下轨道交通工程的影响分析

中国东部沿海地区广泛分布的海相软土,因其独特的力学特性和地质成因,对城市轨道交通建设产生了重大影响。针对中国五个典型区域的11个城市中的海相软土进行详细分析,旨在深入理解其地质成因、颗粒组成、矿物成分和微观结构特点,并总结其物理力学性质、蠕变性和触变性等关键工程特性。通过典型工程案例分析,揭示了城市轨道交通建设在海相软土地层中遭遇的工程风险,并基于实例分析,提出一系列海相软土地区轨道交通工程设计和施工的指导建议。特别强调有效控制和管理相关风险的策略,包括土体加固、改良技术和智能化监测手段的应用。该研究为理解海相软土的复杂工程行为提供了新的视角,对推进沿海地区城市轨道交通建设的安全与稳定具有重要意义。

开挖顺序及内支撑早期刚度对软土基坑稳定性影响规律

深基坑开挖变形控制是软土基坑工程的难题,工程中常采用密集的混凝土内支撑来提高支撑刚度,然而实际工程中未能合理考虑软土深基坑的开挖顺序和混凝土内支撑早期刚度影响,往往导致基坑实际变形远大于设计值。结合珠三角水资源配置工程的软土深基坑,利用验证后的数值模拟方法研究了不同开挖顺序及混凝土内支撑早期刚度对基坑受力和变形特性的影响规律,得出了分层分区非对称开挖和对称开挖对地连墙水平位移和地表沉降的影响规律。结果表明:尽管非对称开挖会造成基坑两侧的地连墙位移和地表沉降差异,但是密集内支撑条件下非对称开挖比对称开挖对于基坑周围地表沉降和地连墙水平位移影响更小并能够大量节约工期;受混凝土内支撑早期刚度影响,施作内支撑后越早进入下一步开挖,地连墙水平位移和周围地表沉降越大;考虑内支撑早期刚度影响时基坑上部的内支撑轴力会增大,而下部的内支撑轴力会减小,早期刚度越小,这种趋势越明显;现场施工时难以实时动态监测混凝土的弹性模量,极易造成内支撑轴力的早期监测数据失真,甚至给工程带来错误决策。

方位侧向电阻率成像随钻测井仪软聚焦仿真分析

随钻方位侧向仪器工作时,由于钻铤长度较长,使表面电位衰减严重,钻铤流出的电流会产生轴向分量,不能严格垂直于钻铤表面流出,导致测量结果不准确。针对该问题,根据方位侧向电阻率成像随钻测井仪(RIT)的电极结构,设计5种软聚焦工作模式,并给出不同工作模式下的方位侧向电极电流和视电阻率的计算表达式;软聚焦工作模式可模拟不同源距的对称天线同时工作,以保持钻铤表面等电位,并通过线性叠加差值近似的方法获得更精确的轴向电流。通过三维有限元方法计算不同软聚焦工作模式在渐变薄互层的响应,并与原始测井响应进行对比,结果表明软聚焦方法能平滑单个发射天线界面处存在的尖峰现象及台阶现象,对薄层的识别及视电阻率计算更加准确,对仪器实际测井数据资料解释有一定的指导意义。

软土地层双洞口顶管接收井下沉力学特性研究

相较于常规沉井,顶管接收井几何形式的差异对结构受力、变形的影响规律尚不明确,亟待对此展开深入研究。以武汉市某排水顶管工程矩形接收井为依托,对沉井结构受力及下沉姿态开展现场监测,并利用数值模拟进行了对比验证和拓展研究。结果表明:预设顶管接收洞口引起的结构局部刚度降低,会导致结构在初沉阶段受弯效应增强,从而使接收洞口附近的内层钢筋压应力减小并使钢筋转向受拉状态,并且在下沉后期加剧该处钢筋应力变化幅度;因沉井外壁摩阻力增大而产生的附加应力叠加弯矩作用,使结构内、外层纵向钢筋沿井壁厚度方向的内力分布不均。对软土地层进行土体加固,有利于提高顶管接收井结构稳定性和顶管机头接收精度。

肌骨超声检查对创伤性浅表软组织损伤的临床诊断价值分析

目的探讨肌骨超声检查对创伤性浅表软组织损伤的临床诊断价值。方法选取本院收治的疑似创伤性浅表软组织损伤206例患者,均行超声检查及磁共振成像(Magnetic Resonance Imaging,MRI)检查,以手术病理检查结果为“金标准”,观察超声检查诊断结果及其安全性与准确性、超声检查声像图特点。结果以手术病理检查结果为“金标准”,超声检查与MRI检查两种方式对诊断效能、损伤类型及阳性预测值与阴性预测值比较,差异无统计学意义(P>0.05),但MRI检查对半月板撕裂检出率高于超声检查,差异有统计学意义(P<0.05)。12例神经损伤患者超声检查可见受压部位横断面减小,回声逐渐降低,彩色多普勒检查可探及少量血流信号;19例实性肿块患者声像图可见形态不规则回声区,边缘模糊,多普勒探查无血流信号;28例囊性肿块患者声像图可见部分液性暗区或无回声区,部分可探及血流信号,边缘清晰;24例韧带撕裂患者声像图可见患侧韧带弥漫性增厚且回声减低、结构紊乱,并可见血流信号;15例肌腱损伤患者声像图可见呈条带状低回声,且有连续性中断伴裂隙样低回声,断端可见血流信号;61例半月板撕裂患者声像图显示半月板连续性中断伴内部不均匀回声,彩色多普勒检查可探及血流信号。结论肌骨超声检查在创伤性浅表软组织损伤的检查中,可有效鉴别损伤类型及其范围,准确率较高,可作为患者初步筛查手段,且具有无创、安全及可重复性等优点,应用价值高。

基于灰度图谱分析的IP软核硬件木马检测方法

随着芯片设计、制造、封装等流程的分工细化,利用第三方知识产权(IP)软核进行二次开发可以明显提升设计效率,减少重复工作。但是大量非自主可控IP软核被用于加速设计时,可能导致芯片在设计阶段被植入硬件木马,使得芯片安全性难以保证。当前IP软核安全检测方法主要依赖功能测试、代码覆盖率和翻转率分析,或在语义层面进行关键字匹配,且无法对加密IP软核进行检测。在分析硬件木马结构及其在IP软核中实现特征的基础上,利用非可控IP软核与“Golden”IP软核中寄存器传输级(RTL)代码灰度图谱的特征差异,基于Trust-Hub构建“Golden”软核集,提出基于灰度图谱特征的IP软核硬件木马检测模型和算法。以功能篡改型IP软核B19-T100为实验对象,通过调整合适的成像矩阵参数,利用分块匹配对比方式实现硬件木马检测,结果表明,该算法的检测精度达97.18%。在对B19、B15、S38417等5类共18个样本进行测试时,所提算法的平均检测精度达92%以上,表明其可实现对硬件木马的有效识别,检测精度和适用性较强。

六盘水地区魔芋软腐病病原菌鉴定及侵染特性研究

软腐病是魔芋栽培中危害最为严重的病害之一。为了明确引起六盘水地区魔芋软腐病的病原菌种类及其侵染特性,从7个魔芋产区采集病害材料,对分离到的16株病株病原菌进行形态学观察、16S rDNA分子生物学、生理生化、生物学特性和侵染特性分析。结果表明,16株病株的病原菌为海芋果胶杆菌(Pectobacteriumaroidearum)和方中达迪克氏菌(Dickeya fangzhongdai),其中P.aroidearum分离率高达81.25%,是六盘水地区魔芋软腐病主要病原菌;2种病原菌对魔芋叶柄和叶片的侵染速度快于球茎,同时还能引起番茄、甘薯、胡萝卜、西葫芦、马铃薯和萝卜等植物组织腐烂;D.fangzhongdai在28~35℃范围内能快速增殖和侵染魔芋,最适生长和侵染温度为30℃,P.aroidearum在20~30℃时增殖和侵染最快,最适生长和侵染温度为28℃。

套筒强夯长短桩复合地基承载特性研究

【目的】随着大型海洋工程项目不断发展,对水下软土地基处理提出了新的挑战,水下挤密砂桩和水下水泥搅拌桩复合地基等传统方法具有定位难、制桩难、桩体质量差等问题,始终制约着其在海洋工程中的应用和发展。【方法】借鉴陆上孔内深层强夯施工方法,因地制宜地提出水下套筒强夯复合地基成桩技术,该技术使用套筒阻隔海水进入桩孔,具有定位准、加固深和强度高等优点,通过模型试验的方法对该技术进行研究。【结果】结果表明,在强夯碎石桩与传统碎石桩相结合的工况下,地基极限承载力提高50%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升18%;在全部采用强夯碎石桩的工况下,地基极限承载力提高170%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升3.7%。【结论】全部采用强夯碎石桩的复合地基比强夯碎石桩与传统碎石桩组合而成的复合地基承载力提高更多,在提高承载力方面,采用套筒强夯长短桩复合地基更加经济有效。