共查询到20条相似文献，搜索用时 15 毫秒
1.
The dynamic response of an underground powerhouse under seismic waves is studied by time domain BEM for anisotropic media. The responses of displacements and stresses are evaluated. The effects of angle and frequency of incident waves and the degree of media anisotropy on dynamic response of the underground structure are analyzed in detail. Some important findings for engineering are obtained. 相似文献
2.
YANG Zhuan yun 《保鲜与加工》2008,(5):58-62
Pavement structures will be damaged by subgrade soil movement around the pipes introduced by extra shallow underground pipe jacking. Soil layer deformation with shallow deposits on pipes during extra shallow underground pipe jacking is analyzed using 3D FEM. The effects on pavement deformation created by the friction between shield and soil, injection slurry, jacking forces and the vehicle loads are studied with a practical project. The analytical results show that the ground surface deformation is an uplift first followed by settling with the lower part of the cover moving faster than the upper layers. It is demonstrated by comparing computational results of FEM simulation and the observed data from the in situ test that these FEM models can be applied to real world engineering. Subgrade soil settling on extra shallow underground pipe jacking in a cross section will be stable when the shield has passed through a section with a length twice the diameter of the pipe. Horizontal surface subsidence along the lateral distribution is similar to a normal distribution curve, with the primary affected areas on both sides of the axis approximately 1.5 times the diameter of the pipe. 相似文献
3.
A test bed with computer control for hydraulic torque converter test is built up. The structure and principle of the test bed are introduced. The performance characteristic of torque converter for a CVT car is studied, and the mathematic model of the torque converter is established based on test results, which lays a foundation for the exploitation of automatic transmission car with hydraulic torque converter. 相似文献
4.
针对采空区危险性影响因素与其危险性等级之间存在着复杂非线性关系的特点,笔者提出采用支持向量机最优分类理论来识别采空区的危险性等级。研究选取岩体结构、地质构造、岩石抗压强度、弹性模量、采空区形状、矿体倾角、高跨比、空区体积等8个参数作为主要影响因素,根据支持向量机理论,提出了1-V-1的采空区分类算法,并在Matlab中编程,建立了分类预测的SVM模型。以某矿山的实测采空区为例,利用该模型进行了识别,并与BP神经网络预测结果作对比。实例研究表明,采用该方法的分类结果比神经网络更准确,与采空区调查结果一致性好,用支持向量机理论进行采空区危险性评价是可行的。 相似文献
5.
通过开展地下滴灌不同滴灌带不同铺设间距试验,确定本地区采用地下滴灌技术,适宜铺设长度为100m的滴灌带产品有易润、耐特菲姆(厚、薄);壤土条件下,滴灌带铺设间距为120cm以内,可在地下形成一个湿润层,无论地面上采用何种播种方式,播种行无需和滴灌带吻合,也可满足作物需水要求。 相似文献
6.
A numerical simulation test of the internal explosive loading on large space structure was carried out by employing algorithm ANSYS/LS DYNA.An appropriate model was established for calculating the dynamic responses of the large space cylindrical reticulated shell under inner blast loading based on the proof of correctness and reliability of the model and parameters selection.Combining the Ritz vibration mode superposition method with the Proper Orthogonal Decomposition (POD) method, the problems of spatiotemporal asynchrony of shock waveforms and pressure distributions on large space structure surface were solved and the calculation for dynamic response of large space structure was reduced and simplified.Furthermore, the numerical simulation of dynamic responses was carried out.And the influence of the ratio of rise to span and the explosive position on the dynamic responses of the structure was studied.It was found that the calculation model was suitable for the dynamic response analysis of the large space cylindrical reticulated shell under internal explosion and the cylindrical reticulated shells with bigger ratios of rise to span were stronger in the capacity of anti explosion.In general, the damages to the large space structure caused by eccentric blast shock waves were more serious than that caused by central explosion.And it was the most disadvantageous to the edge components of the structure.The more attention should be paid to the anti explosion capacity of the support areas and the edge components while designing the shells. 相似文献
7.
旨在初步探讨丛枝菌根真菌GV对丹参木质结构及合成相关基因PAL、C4H,防御相关基因PR1、WRKY的影响。实验设定对照组和菌根组,测定生长90天后菌根对丹参生长情况及木质部结构的影响,同时采用实时荧光定量的方法测定相关基因PAL、C4H及30、60、75、90、105、130天不同时期PR1、WRKY的表达情况。接种菌根90天丹参根部侵染率为90%,基本达到最大值;地上部分鲜重和叶片数显著高于对照组,约为对照组的2.7倍和1.96倍;根部横切部分的木质部面积,积分光密度显著大于对照组;与对照组相比,地下部分木质素合成基因PAL、C4H表达显著提高,地上部分显著降低;丹参防御基因PR1(地下部分)和WRKY表达量在75天前显著增加,地下部分WRKY表达量在130天显著增加。丛枝菌根真菌能促进丹参生长,增加丹参根部木质部面积以及密度,促进木质素的合成,对提高丹参抗病性有积极作用。 相似文献
8.
This paper introduces the importance of developing the Ground-Source Heat pump and describes the prospects of it.with the method used abroad to acquire the temperature profiles within surrounding soil of the underground heat exchanger with buried tubes, in this paper the line heat source theory and thermal resistance network analysis method were used to set up the heat transfer model.The original temperature of the ground is determined by calculation and is compared with test results. Experiments of running single tube and running three series connection tubes are carried out on the built underground exchangers of vertical buried tube type.And the data which can provide reference for the Ground-Soure Heat pump technique are acquired. 相似文献
9.
旱地小麦窄行条播渗灌栽培技术研究 总被引：15，自引：0，他引：15
1997－1999年对渗灌与播种方式在旱地小麦产量形成中的作用进行了研究。结果表明，在两个栽培因素中，渗灌有极显著的增产作用，两年平均渗灌量为32.0mm，产量达6686．7kg/hm^2，较对照增产19．4％，播种方式间产量存在一定差异，其中，窄行条播与露地穴播增产幅度较大，二者产量分别为6477．9kg/hm^2和6405．4kg/hm^2，分别较诉露地条播增产15．9％与14．6％，窄行条播与渗灌措施间存在明显的协同效应，窄行条播加渗灌产量达7112．0kg/hm^2，较露地条播（不灌）增产33．9％，大于两单项技术与对照相比所表现的增产效应之和。窄行条播、渗灌以及二者的协同作用所表现的增产效应形成了旱地小麦渗灌窄行条播栽培技术体系的基础。 相似文献
10.
Sang Kuk Kim Hong Jib Choi In Jung Lee Hak Yoon Kim 《Journal of Crop Science and Biotechnology》2010,13(1):29-32
The combined effect of indole-3-acetic acid and mepiquat chloride on the endogenous gibberellins of aerial and underground tubers as well as tuber yield was studied on Chinese yam plant. Two plant hormones were combined in the following concentrations: IAA 50, 100, 200, and 300 ppm, plus MC 600 ppm. Combined plant hormones were foliar-sprayed once in early July. Exogenously applied IAA combining mepiquat chloride increased fresh weight of the aerial and underground tubers affecting the increase of endogenous gibberellins. The results suggest that IAA is likely to be one of the active plant hormones responsible for aerial tuber growth and enlargement, stimulating the promotion of endogenous gibberellin when combined with mepiquat chloride. 相似文献
11.
为了明确现有耕作制度下,河北省农田地下害虫发生种类及其在不同作物田分布特点,笔者采用挖土法,于2011~2014年调查了河北省不同区域内主要作物地下害虫发生情况。总体来看,河北省作物田地下害虫年度间发生差异较大。发生种类上,蛴螬和金针虫占全部地下害虫种类的80～90%,但不同种类蛴螬年度间发生也存在较大差异。不同区域地下害虫发生量存在较大差异,坝上地区和沿海地区发生虫量相对较低,分别为0.96±0.11头/m2和2.31±0.75头/m2,山前平原发生虫量较大,达到了8.09±3.28头/m2。不同作物田地下害虫发生情况来看,马铃薯和莜麦田以金针虫为主,占全部地下害虫的60～70%,小麦和玉米田内以蛴螬为主,占75～80%,花生田内以蛴螬为优势种,占90%以上。笔者根据地下害虫发生危害受分布地域、土壤结构和作物种类等多因素影响,提出了不同区域地下害虫分区分类防治策略。 相似文献
12.
Two monolayer concrete frames with the same reinforcement, KJ1 and KJ2, were designed. KJ1 was designed to simulate low cyclic reversed loading test under weak earthquake. Besides, the fire response test, including temperature rising and lowing, was made by fixing the axial compression ratio of the column. For KJ2, the fire response test at the fixed axial compression ratio was made. The deformation response of the concrete frames in fire was studied. Comparative analysis of the apparent phenomenon, temperature curves, bearing capacity change of the frames were made based on the test results of KJ1 and KJ2. According to the simplified temperature distribution, the ultimate bearing capacity of the column under the high temperature was preliminarily determined. It is illustrated that the calculation results and finally test phenomenon are consistent according to the simplified section. 相似文献
13.
Zhu Jingmin Zhu Keshan Wang Liwei Gu Jincai Wang Jianting Chongqing Institute of Architecure Engineering The Chinese PLA No. Chongqing Deigning Institute of Building Surveying 《保鲜与加工》1989,(1)
A modelling design approach for the preliminary dimensioningof underground opening supports is presented in this paper. The method is basedon the model test results under the condition of plane deformation, It is tobe used for the analysis and design of the primary support measures and theproper thickness of secondar linings as welt as appropriate construelion tech-niques adapted to the condition of the Caiyuan Tunnel in Chongqing. 相似文献
14.
For the safety of salt rock underground deposit, uncertainties and their influences are considered, and failure probability during operation period is analyzed. Based on finite element model, equation of limit state surface is transformed into explicit equation by response surface method. Combined with Monte Carlo method, computation efficiency is improved. The deposit could be simulated as a series-parallel system. The element with highest failure probability is determined first, then failure mode and system reliability are computed. Taking Jintan underground gas deposit as an example, the analysis indicates that as storage pressure increases, failure probability of middle part of deposit decreases firstly, then increases gradually when storage pressure accumulates to a certain extent. The failure probabilities of upper part and underside of deposit increase as storage pressure increases. During operation period, controlled failure mode is shear failure of upper part and underside of deposit under high storage pressure. In conclusion, the storage pressure during operation period should be controlled strictly. 相似文献
15.
Sand is a typical particle structure. The effective stress and corresponding deformation are both determined by the particle characteristics of the medium skeleton, and the changeable condition of the particles will further affect the mechanical response of the earth pressure cell in the test process. To correctly measure the earth pressure value, micromechanical method was applied to analyse the force chain formed by the particles contact under loading unloading condition, and the transferring process, the force strain curve and relationship between the cell mechanical response and the ideal response curve were analyzed in detail, which verified the above mechanical response model based on Particle Flow Code (PFC) method. According to the structural characteristics of the sand and above numerical model, the loading condition, porosity, friction coefficient between the particles and stiffness of the earth pressure cell affecting mechanical response of the earth pressure cell were deeply investigated, the numerical results indicated that there were obvious hysteresis and strain irreversibility for the response curve, and the measured value was sensitive to the above factors. Therefore, research on the force chain structure and corresponding evolution law brings forward a scientific base and new research means for understanding its micromechanical characteristics, and different factors influencing the earth pressure cell are also important for cell calibration and practical monitoring to get more correct earth pressure value. 相似文献
16.
In order to better understand the seismic performance of the hybrid structure, numerical analysis and shaking table model testing were conducted on a real tall building constructed in Beijing. The nonlinear analytic model of the structure was established with the aid of PERFORM-3D program, and the elastoplastic time-history analysis was performed. From displacement responses and energy dissipation of the entire structure, and deformations and plastic hinge forming condition of components, the response features under different earthquake levels were obtained. Based on the predetermined allowable limits of performance indices, the seismic performance of the structure was evaluated. In the mean time, the numerical analysis results were compared with test results. Both of test results and numerical analysis results indicate that the hybrid structure has good seismic performance. 相似文献
17.
Xiao Qinxue 《保鲜与加工》1997,(2):94-99
In this paper,a series of bolts and shotcrete experiments are made with the model materials which have different soft structure surfaces,and their acting mechanism is discussed.The experimental results have some practical values of the bolts and shotcrete design in underground engineering. 相似文献
18.
G. Economou O. Tzakou A. Gani A. Yannitsaros D. Bilalis 《Journal of Agronomy and Crop Science》2002,188(4):248-253
The allelopathic influence of four plant tissues of Conyza albida (stems, leaves and inflorescences) on oat growth were investigated using in vivo tests. Oat growth (fresh and dry weights of above and underground parts) was inhibited from phytotoxic activity of upper leaves and inflorescence tissues of C. albida in pot studies. The inhibition was significantly higher than in the other tissues studied. The inhibiting action of crude extracts and volatile compounds from young plants (rosette) and mature plants were examined using two bioassay methods: (a) seed germination and radicle growth of oat and (b) fresh weight of duckweed plants. Both bioassayed species exhibited greater phytotoxic response from the young plants, collected in winter, than from the mature ones. 相似文献
19.
环境中水分含量变化对于生长期油菜的产量和品质影响极大。国内外研究表明,异源表达Sub1A基因具有提高水涝条件下植物的抗逆性和恢复生长的潜能。本研究以组成型表达Sub1A基因的甘蓝型油菜作为实验材料,测试了其在水浸胁迫30 d内的生长速度和抗氧化水平。结果表明,超表达株系在地上部分和地下部分的生物量积累速率均显著高于野生型油菜,在胁迫早期尤为明显,表现出响应水浸胁迫的优良表型。同时,抗氧化酶(SOD,POD,CAT和GPX)活性和胁迫响应基因的表达变化也基本一致,呈现出胁迫早期强,随着处理时间增加呈逐渐降低的趋势。以上结果说明超表达Sub1A基因可能通过提高细胞的抗氧化酶活性、提高胁迫响应基因的表达水平提升抗水浸胁迫能力。本研究将为深入研究外源表达Sub1A基因提高油菜抗水浸胁迫提供依据,并为抗涝油菜新品种的开发提供前期基础。 相似文献
20.
饥饿对微小花蝽成虫捕食作用的影响 总被引：1，自引：0，他引：1
摸清不同饥饿处理对微小花蝽成虫捕食朱砂叶螨的功能反应和捕食速度的影响。采用叶碟法测定了微小花蝽Orius minutus（Linnaeus）成虫的耐饥饿能力,并研究了不同饥饿程度对其捕食朱砂叶螨Tetranychus cinnabarinus（Boisduval）成螨的功能反应和捕食速度的影响。微小花蝽成虫可忍受80h的饥饿处理;不同饥饿程度的微小花蝽成虫捕食朱砂叶螨成螨的功能反应均可拟合为HollingⅡ型;饥饿72h的微小花蝽成虫24h内对朱砂叶螨的捕食作用主要集中在开始捕食的12h,尤其是前4h内,而未经饥饿处理的微小花蝽成虫的捕食作用则平均分布于整个测试时段。一定程度的饥饿处理不能改变微小花蝽成虫捕食功能反应的类型,但对其特定时段内的捕食速度有明显影响。 相似文献