Hyperstatic reaction method for calculations of tunnels with horseshoe-shaped cross-section under the impact of earthquakes

Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.

Methodology for Extraction of Tunnel Cross-Sections Using Dense Point Cloud Data

Tunnel deformation monitoring is a crucial task to evaluate tunnel stability during the metro operation period.Terrestrial Laser Scanning(TLS)can collect high density and high accuracy point cloud data in a few minutes as an innovation technique,which provides promising applications in tunnel deformation monitoring.Here,an efficient method for extracting tunnel cross-sections and convergence analysis using dense TLS point cloud data is proposed.First,the tunnel orientation is determined using principal component analysis(PCA)in the Euclidean plane.Two control points are introduced to detect and remove the unsuitable points by using point cloud division and then the ground points are removed by defining an elevation value width of 0.5 m.Next,a z-score method is introduced to detect and remove the outlies.Because the tunnel cross-section’s standard shape is round,the circle fitting is implemented using the least-squares method.Afterward,the convergence analysis is made at the angles of 0°,30°and 150°.The proposed approach’s feasibility is tested on a TLS point cloud of a Nanjing subway tunnel acquired using a FARO X330 laser scanner.The results indicate that the proposed methodology achieves an overall accuracy of 1.34 mm,which is also in agreement with the measurements acquired by a total station instrument.The proposed methodology provides new insights and references for the applications of TLS in tunnel deformation monitoring,which can also be extended to other engineering applications.

Planning Method of Eco-environment Restoration Based on Enlarging Terrace and De-farming in Loess Hilly Region——A Case Study of Yangou Catchment

After expatiating the guiding ideology,contents,standards and principles of eco-environment restoration based on enlarging terrace and de-farming,this paper discussed the planning method and technical flow of enlarging terrace and garden plot in a small catchment of loess hilly region by means of GIS spatial analysis technology,and then the planning method was applied in Yangou catchment.The result showed that it is practicabl,and the areas of newly-built terrace and garden plot in Yangou catchment are at least 295.06 and 4.61 hm2,so that the areas of basic farmland and garden plot reach 359.23 and 622.69 hm2.After the land use structure is regulated,the forest coverage is 48.87%,and the permanent vegetation coverage is about 75% in Yangou catchment,while sediment reduction benefit is above 80% in slope land.In agricultural development,Yangou catchment can yield 1 645.13 tons of food supplies,above 9 340 tons of apples,and can feed 7 500 sheep every year.

RADAR CROSS-SECTION COMPUTATIONS OF ARBITRARILY COMPLICATED TARGETS BY APPLYING THE PANEL METHOD

The present paper deals with the method for the radar cross-section (RCS)computations of arbitrarily complicated targets based on the work by D. Klement et al.(1988).This method is convenient in use, fast in operation and precise in calculating RCS of a complicatedtarget. With this method, the RCS of classic scatterers, for example, a cone and a cylinder, arecomputed with the result of good agreement with experimental data. Furthermore, the RCS’of an aircraft model at various attitudes are calculated with the result of good agreement withexperimental data also.

Three Measurement Methods of Two-photon Absorption Cross-section

Through the experimental design and theoretical analysis, three technologies used for characterizing the two-photon absorption(TPA) properties, such as nonlinear transmission experiment and theory, Z-scan technology and two-photon induced fluorescence method, are introduced. The properties of the three experiments to be utilizable and realizable under desirable limitation are simply analyzed. The advantages of the measurements for TPA characterization are also analyzed.

Cross-section measurement of(n,2n) reactions for Nd isotopes induced by 14 MeV neutrons

Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.

On the Method of Multiplier-enlargement and Approximation of Unbounded Continuous Functions

By combining the classical appropriate functions “1, x, x 2” with the method of multiplier enlargement, this paper establishes a theorem to approximate any unbounded continuous functions with modified positive linear operators. As an example, Hermite Fejér interpolation polynomial operators are analysed and studied, and a general conclusion is obtained.

Mechanisms of Proton-Proton Inelastic Cross-Section Growth in Multi-Peripheral Model within the Framework of Perturbation Theory. Part 1

We demonstrate a possibility of computation of inelastic scattering cross-section in a multi-peripheral model by application of the Laplace method to multidimensional integral over the domain of physical process. Founded the constrained maximum point of scattering cross-section integral under condition of the energy-momentum conservation. The integrand is substituted for an expression of Gaussian type in the neighborhood of this point. It made possible to compute this integral numerically. The paper has two parts. The hunting procedure of the constrained maximum point is considered and the properties of this maximum point are discussed in the given part of the paper. It is shown that virtuality of all internal lines of the “comb” diagram reduced at the constrained maximum point with energy growth. In the second part of the paper we give some the arguments in favor of consideration of the mechanism of virtuality reduction as the mechanism of the total hadron scattering cross-section growth, which is not taken into account within the framework of Regge theory.

Mechanisms of Proton-Proton Inelastic Cross-Section Growth in Multi-Peripheral Model within the Framework of Perturbation Theory. Part 2

We demonstrate a new technique for calculating proton-proton inelastic cross-section, which allows one by application of the Laplace' method replace the integrand in the integral for the scattering amplitude in the vicinity of the maximum point by expression of Gaussian type. This, in turn, allows us to overcome the computational difficulties for the calculation of the integrals expressing the cross section to sufficiently large numbers of particles. We have managed to overcome these problems in calculating the proton-proton inelastic cross-section for production (n ≤ 8) number of secondary particles in within the framework of φ3 model. As the result the obtained dependence of inelastic cross-section and total scattering cross-section on the energy √s are qualitative agrees with the experimental data. Such description of total cross-section behavior differs considerably from existing now description, where reggeons exchange with the intercept greater than unity is considered.

Mechanisms of Proton-Proton Inelastic Cross-Section Growth in Multi-Peripheral Model within the Framework of Perturbation Theory.Part 3

We develop a new method for taking into account the interference contributions to proton-proton inelastic cross-section within the framework of the simplest multi-peripheral model based on the self-interacting scalar φ3 field theory, using Laplace’s method for calculation of each interference contribution. We do not know any works that adopted the inter- ference contributions for inelastic processes. This is due to the generally adopted assumption that the main contribution to the integrals expressing the cross section makes multi-Regge domains with its characteristic strong ordering of secon- dary particles by rapidity. However, in this work, we find what kind of space domains makes a major contribution to the integral and these space domains are not multi-Regge. We demonstrated that because these interference contributions are significant, so they cannot be limited by a small part of them. With the help of the approximate replacement the sum of a huge number of these contributions by the integral were calculated partial cross sections for such numbers of secondary particles for which direct calculation would be impossible. The offered model qualitative agrees with experimental dependence of total scattering cross-section on energy with a characteristic minimum in the range ≈ 10 GeV. However, quantitative agreement was not achieved;we assume that due to the fact that we have examined the simplest diagrams of theory.

钢筋混凝土拱桥主拱圈加固方式及效果研究

目的 寻求钢筋混凝土拱桥主拱圈最佳加固方式,以改善加固效果,给同类危旧拱桥加固提供参考。方法 基于某实际加固桥例提出3种不同卸载方式的加固改造方案,采用Midas civil软件建立有限元模型,分析不同加固方式的影响规律;对原拱圈初始应力水平、施工阶段内力、成桥状态下应力、内力及挠度进行分析;利用加固层最大应力比、荷载置换率和挠度变化率对加固效果进行评价。结果 方案三的加固层最大应力比分别比方案一、二大45.12%与52.74%,荷载置换效果最显著,最大值达3.82,挠度变化率最大。结论 选择拱上建筑拆除得越多的方式进行加固,加固效果越好;对钢筋混凝土拱桥进行加固时,应基于加固方式制定加固施工方案,同时需考虑施工工期与加固成本。

带扩大桩靴桩基施工挤土效应解析研究

提出新型带扩大桩靴预应力管桩基础.不同于均匀截面管桩的施工挤土效应,由于桩靴尺寸大于预制管桩桩身,桩端扩张不宜视作理想球体而更接近于扁球体(旋转椭球体).基于扁球体扩张源对新型带扩大桩靴桩基施工挤土位移场进行解析求解,基于圆孔扩张理论考虑桩周土塑性区域的体积变形,对扁球体扩张应变路径法计算结果进行修正.通过提出的解析解,研究带扩大桩靴桩基施工挤土效应.结果表明,桩周场地可以根据位移场分布规律,大致分为近地表、近桩端以及桩身附近3个区域.扩张源形态越“扁”,桩身附近区域水平“排开”效应略有增强,近地表区域地面“隆起”位移及近桩端区域竖向位移显著减小,这对于挤土桩施工而言是非常有益的.

双拉钩胸骨抬高法在胸腔镜剑突下胸腺扩大切除术中的临床应用

目的分析胸腔镜剑突下胸腺扩大切除术中采取双拉钩胸骨抬高法的临床应用效果。方法选取广东省农垦中心医院于2021年2月—2022年2月收治的42例胸腺瘤伴重症肌无力患者为研究对象,由随机数表法分为两组,即参考组(常规入路方式实施胸腔镜剑突下胸腺扩大切除手术)21例、研究组(参考组的基础上实施双拉钩胸骨抬高方案)21例,对比两组效果、手术操作时间、术后发生并发症情况。结果研究组治疗有效率为95.24%,高于参考组的90.48%,但差异无统计学意义(χ^(2)=0.000,P>0.05);研究组手术相关指标优于参考组,差异有统计学意义(P均<0.05)。研究组并发症发生率为4.76%,低于参考组,差异有统计学意义(P<0.05)。结论以双拉钩胸骨抬高方案辅助胸腕镜剑突下胸腺扩大切除手术治疗胸腺瘤伴重症肌无力患者时,手术视野扩大,手术操作的空间拓展,手术时间缩减,不会给机体带来较大创伤,手术成功率、安全性良好。

Low-energy inelastic electron scattering from carbon monoxide:Excitation and de-excitation of the X^(1)Σ^(+),a^(3)Π,a'^(3)∑^(+),A^(1)Π,d^(3)Δ,e^(3)∑^(-),I^(1)∑^(-)and D^(1)Δelectronic states

Cross-sections for electronic excitation and de-excitation among the ground state and lowest-lying seven electronic excited states of carbon monoxide(CO)by low-energy electron impact are computed using the R-matrix method.The excitation cross-sections from the ground state to the electronic states a^(3)Π,a'^(3)Σ^(+)+and A^(1)Πagree with previous experimental and theoretical results.In addition,the cross-sections for the I^(1)Σ^(+)-and D^(1)Δstates of CO,which will cascade to CO a'^(3)Σ^(+)+and A^(1)Πstates,are calculated.Furthermore,in contrast to the typical increase in electronic excitation cross-sections with collision energy,the de-excitation cross-sections show a negative trend with increasing energy.

Toward Establishing a Low-cost UAV Coordinated Carbon Observation Network(LUCCN):First Integrated Campaign in China

In this study,we introduce our newly developed measurement-fed-perception self-adaption Low-cost UAV Coordinated Carbon Observation Network(LUCCN)prototype.The LUCCN primarily consists of two categories of instruments,including ground-based and UAV-based in-situ measurement.We use the GMP343,a low-cost non-dispersive infrared sensor,in both ground-based and UAV-based instruments.The first integrated measurement campaign took place in Shenzhen,China,4 May 2023.During the campaign,we found that LUCCN’s UAV component presented significant data-collecting advantages over its ground-based counterpart owing to the relatively high altitudes of the point emission sources,which was especially obvious at a gas power plant in Shenzhen.The emission flux was calculated by a crosssectional flux(CSF)method,the results of which differed from the Open-Data Inventory for Anthropogenic Carbon dioxide(ODIAC).The CSF result was slightly larger than others because of the low sampling rate of the whole emission cross section.The LUCCN system will be applied in future carbon monitoring campaigns to increase the spatiotemporal coverage of carbon emission information,especially in scenarios involving the detection of smaller-scale,rapidly varying sources and sinks.

内眦开大术联合改良Park法重睑成形术在双侧单睑伴内眦赘皮患者中的应用效果观察

目的观察内眦开大术联合改良Park法重睑成形术在双侧单睑伴内眦赘皮患者中的应用效果。方法选取82例于2020年9月至2023年9月在贵州医科大学附属乌当医院就诊的有求美需求的双侧单睑伴内眦赘皮患者,均为女性,按照治疗方式不同分为研究组和对照组,各41例(82只眼)。对照组采取内眦开大术联合传统Park重睑成形术,研究组采取内眦开大术联合改良Park法重睑成形术。比较两组患者术中出血量、瘢痕消失时间、术后满意度和临床疗效。结果研究组术中出血量少于对照组,手术时间短于对照组,瘢痕消失时间早于对照组,术后总满意度高于对照组患者,术后7天眼睑宽度小于对照组,眼裂高度大于对照组,术后半年上睑提肌肌力大于对照组,临床疗效总有效率高于对照组,并发症总发生率小于对照组,差异有统计学意义(P均<0.05)。结论内眦开大术联合改良Park法重睑成形术用于治疗双侧单睑伴内眦赘皮临床疗效较好,术中出血量少,术后并发症少,瘢痕消失时间早,恢复速度快,重睑形态对称自然,患者满意度高,值得临床应用。

建筑工程中增大截面法加固模板与支撑系统对比研究

随着加固工程占比的提升,影响加固工程效率与成本的模板工程重要性凸显。基于当前工程领域使用的模板和支撑系统的种类,分析了它们的优缺点及适用范围。论述了加固工程增大截面法所用模板、脚手架对成本和效率的不利影响,提出了标准分块模板与伞式折叠支撑杆系统的做法,给出了后者的有限元分析结果,为加固工程品质提升、效益提高提供了参考。

墩身偏位原因及纠偏加固方案数值模拟研究

为探究某大桥墩身偏位的原因,在原位勘察结果的基础上,分析研究了导致墩身发生偏位的影响因素,这些因素包括桩底下卧软弱破碎带、桩侧及桩底岩层软化、桩侧钻孔、桩侧及桩底岩层在振动耦合作用下的加剧软化等。通过数值模拟发现,岩层软化对于墩身偏位的影响程度最大,桩底下卧软弱破碎带次之,桩侧钻孔对于墩身偏位的影响最小。在探明墩身发生较大偏位的主要原因后,针对补桩过程中墩身发生第二次较大偏位的现象,提出预注浆加固的方法进行纠偏加固。数值模拟结果表明,预注浆加固可使补桩引起的6#墩身偏位量减小80%。优化后的6#墩纠偏加固顺序为:原5#~8#桩底预注浆加固、补桩、增大墩身截面纠偏墩身。

既有铁路桥梁桩基检测与病害加固处治

某既有铁路桥梁因水害导致墩身位移,为快速无损进行桩基完整性检测,采用基于桩侧切割小平台作为激发点的瞬态激振的双速度法,共检测5根角桩,判定3根桩无缺陷反射,2根桩局部有缺陷异常反射。对其中2根无缺陷桩和1根有缺陷桩进行钻孔验证,3根桩芯样结果与检测结果一致。针对墩身位移病害,分两阶段进行加固处治,第一阶段主要采取山体侧清方卸载、设置环形截水沟、临空侧设置钢板桩及填土反压等应急抢险措施,阻止病害程度进一步加剧;第二阶段综合采取增设仰斜孔排水、锚杆框架梁、锚固桩、扩大承台及加桩等永久整治措施。经两阶段加固处治后线路恢复运营,桩身应变、墩身及轨道位移监测数据均正常。

一种梁增大截面加固法施工技术

建筑由于改变使用功能的原因,导致结构部分构件不符合受力要求,需要采取结构加固技术,确保结构稳定。以某科研楼改造工程为例,对其进行布局改造,采用增大截面加固法对于改造部位框架梁进行加固,并围绕加固要求和施工工艺,提出了多种技术优化措施。