共查询到20条相似文献，搜索用时 500 毫秒
1.
According to the complex conditions of deep excavation in Nantong mine, FLAC program are carried out for strata movement, ground pressure and surface displacement due to coal extraction. Based on the analysis of Nantong mine, the basic features of strata movement, the fundamental behavior of ground pressure and the related parameters of surface displacement are obtained. The results are of referential value for mining, supporting and preventing of surface displacement. 相似文献
2.
WANG Ke zhong 《保鲜与加工》2008,(5):42-46
Based on the large scale conceptual model theory of similar material, a physical model of metro station tunnel excavation was simulated. The excavation process of metro station tunnel between existing double tubes also was simulated. Ground settling, soil deformation and displacement of specific points around tunnels were studied. The influence of a cast in place pile on reducing soil displacement was simulated. The dynamic mechanical behavior and deformation laws of the soil were obtained along with some useful conclusions. The conclusions are beneficial for guiding the construction and expanded excavation of metro station spaces between existing double tubes. 相似文献
3.
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. 相似文献
4.
When shield crossed the sandy cobble stratum in Chengdu metro line 1, ground subsidence reached as high as dozens of times. The losing stability of excavation face caused excessive ground loss. Conditions of engineering geology and hydrogeology about sandy cobble stratum in Chengdu were analyzed. Mechanical characteristics of sandy cobble were obtained via large-scale triaxial test. According to the low cohesion and heavily discrete characteristics of sandy cobble, numerical computation was conducted by discrete element method. Based on numerical simulation of the large scale triaxial test, the micro parameters of the sandy cobble were calibrated. The influence of support pressure on shield excavation face deformation, surface settlement, max horizontal displacement and stress of soil was analyzed. The results show that: 1) Collapse pattern of excavation face by numerical simulation coincides with result of centrifuge model test in sand. 2) When supporting pressure is small, contact forces of particle in front of excavation face is low. The tendency of particle flow is apparent. Since over-excavation is easily brought out, cavity in the ground is caused after shield tunneling. 3)Soil arching effect in shield construction is obvious. Shield excavation forms cavity in deep ground and obvious earth surface collapse is not observed. This is main reason for lagged settlement phenomena of shield tunneling in Chengdu. 相似文献
5.
In the Wenchuan earthquake, steep dip bedding slope is a kind of slope that seismic mountain disaster very development and the slope earthquake disaster is often exacerbated by the excavation. In order to reproduce the process and analysis regularity of slope deformation and failure under the action of seismic load. The author chooses San Shuping landslide located Pingwu County as the typical examples of steep dip excavation damage bedding slope, and the indoor physical model test of slope deformation and failure under the action of seismic load are carried out. The results show that slope deformation and failure is intensified by the excavation. Collapse and sliding is the main form of failure and the results consistent with the field investigation. From the whole process of deformation and failure of view, it can be divided into the four stages. First, the initial phase of the earthquake. A wedge rock by excavation small slides along the rock layers and the slope toe stress increase sharply under the action of seismic load in this stage. Second, rock layers by excavation break-bend at slope toe. Third, the rock layers by excavation overall decline stage. Last, the rock slide blocked and dumping. 相似文献
6.
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。 相似文献
7.
Large particle size gravel strata layer is very difficult for TBM construction which brings about a series of problems for EPB TBM advancing in Beijing Metro. Cutting wheel is an important component of EPB TBM and cutting wheel with reasonable structure is essential for EPB TBM to advance steadily and effectively in large particle size gravel strata. In-situ EPB TBM advancing tests are carried out in large two adjacent shield interval where the strata conditions make it possible to find out the most efficient cutting wheel structure by monitoring key parameters through Real-time Information Management System. Based on the analysis and comparison of advancing efficiency, strata adaptability of key parameters and tools wearing, the following conclusions can be obtained: 1) Spoke cutting wheel has better strata adaptability and higher efficiency than panel cutting wheel as well as more advantages in controlling tools wearing. 2) open ratio ranging from 55% to 65% is the reasonable for cutting wheel. 3) Advancing speed and earth pressure are very important for EPB TBM construction. Compared with panel cutting wheel, spoke cutting wheel can obtained higher advancing speed and more stable earth pressure in tests. However the change of earth pressure should also be paid attention when EPB TBM advancing in fast speed. The advancing speed should be controlled in the range of 20 to 60 mm/min. 相似文献
8.
The Application of Controlling Excavation Immersed Tube Technology in Active Pipeline Moving Process
Taking an example from Zhong-Wu Lang Ping Valley Gas Pipeline Project, we combined the engineering geological of the site area, and learn from experience in similar projects. Then, on this basis, we carried out the design of the immersed work, introduced the applications of the immersed controlled excavation work. The results show that the immersed controlled excavation work achieved the expected results. Practice shows that the controlled excavation construction not only prevent gravity retaining wall concrete construction disturbance and construction personnel devastation, but also improved the depth of pipeline settlement (original design maximum settlement increased to -1.5m from -1.0m.). The program for Zhong-Wu Lang Ping Valley Gas Pipeline engineering success, and can providing guidance for other similar pipeline project. 相似文献
9.
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. 相似文献
10.
Based on the elastic theory, an analysis can be made on stress and plastic deformation under tunnel excavation and shotcrete support.FLAC 3D can be used to simulate the mechanical behavior of excavation and support, getting the deformation of surrounding rock stress and plastic without support and shotcrete. The results show that, the prestress applied on the anchor equals to the supporting force when the tunnel plastic zone disappears. This support improves the self bearing capacity of surrounding rock, effectively suppresses the expansion of the plastic zone after the tunnel excavation, and prevents further damage to the tunnel surrounding rock. 相似文献
11.
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. 相似文献
12.
基坑复合土钉墙转角处有明显的空间效应,受力变形较小,对支护结构有利,但不清楚转角定量的有利影响范围,目前设计中仍按照与基坑中部一样保守设计,为在此范围内降低土钉用量,避免保守设计,对水泥土搅拌桩复合土钉支护结构建立了全尺寸整体三维有限元模型,这种模型包含基坑的转角,能考虑基坑的空间效应,通过建立接触面单元,能考虑土体和搅拌桩、土体和土钉的相互作用,量化分析了基坑转角对支护结构受力和变形的有利影响范围,计算结果表明,基坑转角对开挖面水平位移、地表沉降、坑底隆起、土钉轴力的有利影响范围分别约为1.3、1、1、1.2倍的开挖深度。经与实际工程现场实测值对比,验证了该模型分析结果的可靠性,同时分析结果优于平面二维和局部三维有限元模型,结论为复合土钉支护结构的优化设计和安全施工提供了理论依据和研究方法。 相似文献
13.
To know well the impact on the deformation of underground diaphragm wall caused by soil excavation, centrifugal model tests reflecting Shanghai soft soil creep effects were designed, and finite element was used to calculate the deformation of underground diaphragm wall caused by different excavation timeline, sequence and width based on the top down construction method in the deep and large foundation pit of Shanghai Expo axis underground complex project. Centrifuge model tests and monitoring data indicate that the results of numerical calculation are approximately close to the horizontal displacement of the underground diaphragm wall measured in site, which reflects the deformation behavior of excavation. The results show that remained berm and middle plate have good control over the deformation of underground diaphragm wall. Most part of underground diaphragm wall deformation caused by soil creep occurs after the remained berm is excavated. So in order to decrease the deformation of underground diaphragm wall, it would be useful to conduct plate structures as soon as the remained berm is excavated. The excavation width of remained berm in the north part is less than that in the south part. It will be advisable to finally excavate the remained berm where there are protected objects nearby. 相似文献
14.
考虑降水、支护结构变形以及基坑隆起3个因素引起的基坑周围土体的沉降,根据降水引起土体沉降的机理,运用修正的分层总和法单独计算出由降水引起的周围土体沉降。通过研究基坑开挖引起坑外土体沉降的规律,推导出由基坑开挖引起的坑外土体沉降理论公式。把降水引起的沉降及基坑开挖引起的沉降进行叠加,加入修正系数,最终以简化的理论公式合理地计算出基坑周围土体沉降。具体工程验证表明,推导的理论解析解与实测数据十分接近,能有效预估基坑周围土体沉降,为施工方案编制提供可靠的理论依据,最大限度减少基坑施工对周围环境的影响。 相似文献
15.
Combined with the design practice in foundation excavation engineering,the problems for combined supporting from inner supports and composite soil nailing wall under binary geological conditions,including soil layers and rock stratum with weak intercalation in range of excavation depth,are analyzed.These problems mainly include the following: calculation model of earthen pressure,the local bearing capacity of foundations below steel pipe piles,stiffness coordination at the junction of rigid and flexible supports,internal bracing stability influencd by restrained condition of upright post,etc.Problems of concern for design of similar foundation pit supports are pointed out,and measures for solving these problems are proposed.All these can provide references for similar projects. 相似文献
16.
The influence of blasting vibration on the adjacent buildings is inevitable if blasting is employed for excavation. Daping station tunnel of Chongqing light railway project, on which there is dense with population and buildings, has a minimum buried depth of only four meters and maximum span length of 26.3 meters. The stepped excavation mode with short hole, multi round and V shaped cut are adopted. The maximum charge weight of one delayed interval is determined by the permitted vibration velocity. The smooth blasting technology with adding vibration reduction holes is used. Meanwhile, the charge weight per hole is strictly controlled. With the simulation and on site test, it is found that the proposed technology for tunnel construction is feasible. 相似文献
17.
Recently, the construction of neighboring highway tunnels with small interval gets more and more in China. The construction of such tunnels proceeds usually by excavating one after another. The second tunnel is constructed with the surrounding rock disturbed by the first one. And the construction of second tunnel also has effect on the first excavated one. For revealing the interaction laws of such tunnel construction in combination with the engineering practice of Lanfeng tunnel at Jinshan Road in Chongqing, The FE numerical simulation analysis was used to study the characters of surrounding rock deformation, stress field, and plastic zone of the tunnel. From this analysis, it clearly shows that the excavation of second tunnel has significant influence on the first one. This study provides a scientific basis for design and excavation of neighboring highway tunnels. 相似文献
18.
Huag Yunfei Yang Weihuai 《保鲜与加工》1988,(3)
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. 相似文献
19.
Calculation of Influence on Longitudinal Deformation of Adjacent Tunnels Due to Excavation 总被引：1，自引：0，他引：1
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. 相似文献
20.
When tunnels are through water bearing section of fractured rock mass, a complex interaction process between rock mass deformation and fluid transportation is one of the most important reasons for water gushing, water bursting and mud bursting.To study the rock mass deformation and fluid transportation in tunnel excavation under complex geological conditions, a hydraulic model of complex crack rock mass was established from the relationship between the crack growth degree of surrounding rock in deep buried tunnel and the engineering scale, with which fracture network of different levels in rock mass could be considered simultaneously.Furthermore,a computer Fortran program was put forward to simulate the solid fluid coupling of excavation process of a deep buried tunnel.And it was found that the principal fractures had strong flowing action and network fractures had storage function and lag effect in seepage area.And the yield area of surrounding rock was increased under the coupling of seepage field and stress field. 相似文献