Analysis on the Deformation and Stress Control Measures of Metro Tunnel Near a Foundation Pit

It has become a very common phenomenon that the influence of pit excavation to the adjacent environment, what corresponding measures should be taken in design and construction to ensure the safety of construction in process and existing has become a key part. This Paper analyses the influence of pit construction to adjacent tunnel by using the finite element software plaxis. The analysis results show that strengthening the palisade structure stiffness and partitioning symmetric excavation can significantly control the deformation of the existing tunnel. The design and construction of the engineering can ensure the safety of the existing tunnel compared with the conventional construction methods, and it also shows that preliminary analysis of influence to the adjacent underground building before pit excavation is very necessary.     

Safe Monitor and Analysis of Deep Excavation with Total Station

During the process of deep excavation digging,it is an important task to monitor the excavation and affected building to make sure the spot's safety and go on wheels with the schedule.In this article some causation of slip and the calculation methods of freely setting station are first discussed,and then combined with the theory of polar coordinates a forecast method through distortion course curve analysis is put forward.The method with its low cost and speediness,can satisfy the precision requirement and provide the base data for safe evaluating and designing.     

Study of Optimization Design of the Excavation and Support of the Zhuziba Material-Yard Slope

Taking Zhuziba material-yard slope as an example,it use FLAC 3D to dynamically simulate the excavation process. Numerical calculation is carried out and strength reduction method is used to identify the plastic zone and the potential sliding surface. Sensitivity analysis is carried out to determine the influence on the the values of c and φ of the monitoring points on displacement. And combined with the measured displacements of the point, back analysis is carried out to determine the mechanical parameter of the potential slip surface. Based on analyzing the effect of anchorage on the anchoring method, 2 excavation - supporting schemes are designed. The results show that it can be accepted to identify the potential sliding surface by using strength reduction method, because the result is similar to what is drawn by using stereographic projection. The displacement of monitor point is linear to φ. The influence of φ(c) is similar on displacement at same c(φ).It also can be accepted to determine the best interval of anchor and length of anchoring section of double anchor by using numerical calculation to make the most considerable use of building materials.     

A NEW IDEA FOR PROTECTING ROCK AROUND UNDERGROUND EXCAVATION-STUDIES OF SOFTENING SURROUNDING ROCK METHOD

This paper advances a new idea for protecting rock around underground excavation, based on the analyese of movements of surrounding rock,then studies the sloting in surrounding rock-a kind of softening technique for surrounding rock by means of BEM and modle tests. It is proved that this method is useful and effective.     

Calculation of Influence on Longitudinal Deformation of Adjacent Tunnels Due to Excavation

Unloading of excavation of foundation pit has influence on adjacent tunnels, therefore it is important to predict the deformation of metro tunnels to ensure the operation of tunnel. The displacement effect due to the surrounding wall soil unloading of adjacent excavation was not considered by the theoretical analysis method, and the analysis procedure of FEM was usually too complicated to get a satisfied result, so the horizontal and vertical additional stress were calculated by the Mindlin solutions. Furthermore, the tunnel structure was considered as the beam with infinite length. The additional stress was imposed on the Winkler model and the governing equation was built up on the adjacent tunnel structure. Finally, displacements and internal forces of existing tunnels were obtained. Compared with the numerical simulation and an engineering case, the results of the presented formula are in good agreement. It can provide certain theoretical and calculation basis for metro tunnels influenced by adjacent excavation.     

水稻种质资源的分子鉴定和育种利用

水稻种质资源包括栽培稻、野生稻及育种材料等各种类型,是水稻新品种选育、生物技术研究以及农业生产的物质基础。中国具有丰富的水稻种质资源,但其利用率却不高,原因之一就在于传统方法不能够对其进行准确的研究评价。理想的分子标记具有稳定性高、重复性好、检测简单快速和共显性遗传等优点。本文综述了分子标记技术在水稻种质资源遗传多样性分析、重要功能基因的挖掘、品种DNA指纹库的构建及分子育种材料遗传基础的拓展等方面的作用,旨在为更充分的将分子标记技术应用于水稻种质资源的鉴定和分子育种提供参考。     

The analysis on pre splitting blasting to improve permeability draining rate in heading excavation

Aiming at the problem of low excavation speed and high risk of coal and gas outburst because of low gas draining rate in heading excavation,and taking an excavation heading of a mine for example,the test of deep hole pre splitting blasting is processed.The amount of gas draining after pre splitting is compared with the amount of direct draining,and the effective radius of draining is surveyed.The test result shows that the draining rate of K1 coal seam reaches 37.13 %,which reduces the draining time by 60%,10 days after pre splitting,and the gas desorption index exceeds the standards until the fifth blasting.The draining rate of K4 needs 12 days to reach 34.28 %,which reduces the draining time by 60%,and the gas desorption index exceeds the standards when the third blasting processes.Obviously,the effect of gas draining is improved by pre splitting blasting.The effective draining radius of K1 and K4 are 4.5 and 5.2 m respectively after pre splitting blasting.The research can provide reference for the fieldwork of pre splitting blasting.     

Rock Deformation, Stability Monitor Active Control About Excavation of Super-span Tunnel

According to the measurement during excavation of Jinzhou tunnel with four lanes in one cave which lies on the rebuilt highway from Shenyang to Dalian, this paper analyzes the rock deformation rule, discusses the reason of instability after a highway tunnel was excavated, emphasizes the necessity of the construction stability monitor and active control. The importance of support is Fresented with bolts and shotcrete to improve and enhance the carrying capability of the rock. It is necessary to insist on the rule of measurement and active control to ensure the safety and quality of tunnel construction.     

Smooth blasting design and optimization of large spanurban highway tunnels

Vibration resistance can be incorporated into blasting designs to avoid damages caused by the excavation of large span tunnels in busy urban areas, but only by basing excavation design schemes on actual situations. In view of the actual situation in the Jahua tunnel in Chongqing, P. R. China, research was conducted to identify a relevant explosion scheme. The research was based on theoretical analysis and in situ testing. Face step excavation was considered in the broadening band A, and upper drift excavation was adopted in broadening bands B, C, D and E. We simultaneously proposed selection criteria for smooth blasting parameters and the construction layout of broadening band B. Based on a regression analysis of the blasting vibration monitoring results, a spread orderliness of blasting vibration was drawn. Explosion parameters optimization measures were put forward, selected from the maximum charge quantity, millisecond blasting, reasonable blasting time difference, and the excavation plan. Field testing achieved satisfactory results. These findings will play an important role in guiding excavation blasting construction of tunnel projects and assuring the safety of ground buildings.     

深层开挖条件下自平衡试桩法上段桩承载力损失简化计算方法

针对在深层开挖条件下进行自平衡法试桩时,通过采取有效措施消除开挖段的侧摩阻力影响后,由于深层覆土开挖卸荷导致工程桩桩周土体围压减小,从而导致荷载箱上段桩抗拔承载力降低这一问题,通过借鉴目前在抗拔桩方面已有的相关分析方法、负摩阻力、基底附加应力以及相关土力学基础理论,提出了基于Mindlin解的简化分析方法以及负摩阻力-附加应力法两种简化分析方法,并以北京某地铁车站中间柱下桩为例,分别估算深层开挖土体卸荷引起的上段桩承载力的损失值。两种方法所得出的估算值存在较大差异,对其原因进行了初步分析。两种简化分析方法的合理性及准确性还有待于进一步完善和实践验证。     

Stability Analysis for the Excavation Engineering Under Coupling Effect of Seepage from Heavy Rain and River Fluctuation

The seepage accident is very easily occurred, when the excavation engineering has been constructed in rainy season and it is very easily influenced by the coupling effect of seepage duo to heavy rain and water level fluctuation of neighboring river. So a coupling seepage equation that based on the theory of Dupuit has been established for the ground water in the layered foundation. And then, the water table surrounding the excavation engineering has been determined on the consideration of the coupling effect of seepage duo to heavy rain and water level fluctuation of river. In the meantime, by means of the theory of coupling analysis of stress and seepage and the software of Midas, a model of coupling analysis of stress and seepage has been built for the specific excavation engineering and the seepage destroy characteristics of this project has been researched.     

Nonlinear Rheological Analysis on Tunnel Displacement Induced by Adjacent Excavation in Soft Clay

Deep excavation in soft clay often brings soil stress disturbance and soil deformation, which would bring differential settlement and structural cracks. It probably brings safety problems to adjacent underground tunnels. Therefore, it is necessary to predict tunnel displacement induced by excavation for tunnel’s security. A new method was proposed to estimate the heave of underlying tunnel induced by adjacent excavation verified by field measurements. The soil deformation by excavated soil gravity was analyzed by application of Boussinesq solution. The soil deformation by tunnel surface pressure was analyzed by Mindlin solution. The tunnel was assumed to be an elastic beam on foundation to simulate the tunnel, in which interaction analysis of tunnel and soil was employed. In consideration of rheologic soil, Viscoelastic model was employed to analyze soil nonlinear displacement with time in soft clay. Tunnel displacements were discussed by different excavation cases. A case study showed a good agreement between the results from the prediction and the measurement.     

Experimental Analysis of Construction Time Space Effect for Large Span and Flat Multi Arch Tunnel

For the large span and flat, together with the interaction effect of construction and disturbance of surrounding rock, the mechanical of large span and flat multi arch tunnel is very complicated, and the time space effect is different from that of two lane multi arch tunnel or separated tunnel. Adopting the “CTSSSRH”, the 3 D dynamic process of the tunnel construction was simulated. Analyzing the rule of surrounding rock displacement and stress with excavation, the time space effect of large span and flat multi arch tunnel was proposed.     

Safety Assessment of Circular Arches Tunnel Evacuation on Surrounding Geotechnical Environment

Based on the stochastic medium theory, influence on the surrounding rock and soil by tunnel excavation was studied. formula for predicting movement and deformation of rock and soil mass caused by tunnelling were deduced. And especially for the tunnel with circular arch section, half analytic solution for this problem was put forward. Furthermore, a program was developed to compute the movement and deformation of the rock and soil mass resulted from excavation. The deformation failure criterion of stochastic medium for estimating the surroundings safety was provided and was applied in an engineering example, which proved that the results of the research were reasonable and significant for the tunnel safety construction.     

冷冻干燥速溶蛋花汤的加工技术

介绍了运用冷冻干燥技术进行速溶蛋花汤的加工,研究了生产工艺、特点以及影响产品质量的主要因素。试验表明,采用冷冻干燥技术加工的速溶蛋花汤,具有营养丰富、风味独特、方便快捷等特点。     

Measuring of Quantity of Matter-mass and the Measuring of Inertia of Matter-momentclm

A new definition of inertia,i.e. the momentum is the measuring of inertia of matter, is proposed. The article through and etc., subjects, the correctness of the new notion of inertia:The monentum is the measuring of inertia has been demonstrated, and the unsolved contradictions of the traditional definition of inetia. And the mass is the measuring of inertia has been revealed.     

香蕉遗传转化方法研究进展

香蕉是热带亚热带发展中国家重要的粮食作物和碳水化合物来源。但近年来,香蕉生产受到严重的病虫危害。大多数香蕉栽培品种是三倍体,生长周期长,而且不孕。由于没有种子,给繁殖和育种带来一定的困难。遗传转化技术的发展为香蕉品种的改良提供了一种有效的手段。香蕉的遗传转化方法有电激法、基因枪法、农杆菌介导法等。农杆菌介导法的应用是香蕉品种改良的一个重大突破。香蕉遗传转化的外植体也发展到多种,有原生质体,胚性细胞悬浮系,分生组织,以及横切薄片等。近几年,随着分子生物学的发展,出现了转化效率更高,重复性更好的香蕉遗传转化技术。如农杆菌和基因枪结合法,离心辅助农杆菌介导法、真空渗透技术等。这些新技术新方法的出现,必将推动香蕉产业高速发展。     

壳聚糖对石榴果汁澄清效果的影响

利用壳聚糖的絮凝作用对壳聚糖在甜石榴汁澄清中的应用效果进行了研究,试验结果表明,壳聚糖用量为0.3g/L、澄清时间为60min、温度为35℃时,甜石榴汁透光率可达85%以上,且通过对壳聚糖处理前后可溶性固形物、总酸、VC等营养成分含量的比较,确定以上工艺参数为甜石榴汁澄清的最佳选择。     

新疆布尔津县土地利用格局特征研究

基于RS与GIS技术,利用景观生态学理论及景观格局指数对布尔津县土地利用现状进行定量分析。结果显示为：（1）布尔津县以草地、林地为主要景观类型,镶嵌着耕地、水域等景观类型。（2）四个分区（即高山区、丘陵区、平原区、荒漠区）的林地资源组成差异明显,耕地、居民、交通及工矿用地集中分布在丘陵区和平原区（3）从各项指数来看,高山区的多样性指数较低;平原区是受人文因素最多的区域,景观优势度低,各种土地利用类型比例差异不大,有利于生态可持续发展,但要合理的开发利用;荒漠区生态环境相对脆弱,要加强生态环境的保护与改善。通过该研究对布尔津县的土地利用现状作一个了解,为该县乃至整个地区的景观规划和可持续发展战略提供科学依据。     

酸枣幼根原生质体的制备

以生长6～9 d的酸枣种子幼根为试验材料,0.7 mol·L-1甘露醇作为渗透压稳定剂、pH值5.5～6.0、28℃恒温水浴条件下,以光学显微镜观察的水解总时间、初始产生原生质体的时间、原生质体产量及细胞碎片量为指标,研究通过酶水解来制备酸枣幼根原生质体的方法.结果表明,在含1％果胶酶+4％纤维素酶R-10+3％纤维素...