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1.
为了探究锚杆不确定性对加固边坡失稳概率的影响, 建立了施加锚杆后的边坡模型, 通过以下两种途径来考虑锚杆的不确定性: 其一是假定锚杆与锚固体之间接触面上的单位表面摩擦力为对数正态分布变量, 其二是引入锚杆与锚固体之间接触面上的单位表面摩擦力衰减系数来考虑运营过程中锚杆的不确定性。采用极限平衡分析法并结合蒙特卡罗抽样法, 计算并对比分析了两种途径下锚固边坡失稳概率变化曲线, 最后以深圳假日酒店基坑边坡支护工程为例, 证明所提方法的有效性。结果表明: 对于途径一, 在相同土体统计参数下, 随着锚杆与锚固体之间接触面上单位表面摩擦力变异系数的增加, 加固边坡的失稳概率缓慢增加, 增幅介于18.03%~41.90%之间。对于途径二, 随着锚杆衰减系数自1.0逐步减小至0, 加固边坡失稳概率迅速增加, 增幅介于55.64%~124.90%之间; 在同一衰减系数下, 加固边坡失稳概率随着锚杆衰减根数的增加而增大。研究结果可以为锚杆施工与运营期间的管理提供决策支持。 相似文献
2.
针对季冻区春融期岩锚失效的问题, 研究了玻璃纤维(GFRP)锚杆在冻融循环作用下的锚固能力。通过设计物理模型对经历25, 50, 75冻融周期的试块进行了加载试验, 根据试验数据和破坏现象分析了GFRP锚杆在冻融后锚杆应力和承载力的变化规律。研究结果表明: 冻融循环会导致环氧树脂砂浆与混凝土的黏结性能下降, 在25, 50, 75周期后承载力损失分别为38.24%, 42.65%, 52.94%。冻融循环加速黏结材料及围岩的材料性能劣化, 荷载向内部传递加速, 使得GFRP锚杆上各点之间的应力差值逐渐减小, 锚杆应力分布比常温状态下更趋于均匀, 但材料性能的劣化导致局部破坏提前, 锚杆整体承载性能降低。研究结果可以为GFRP锚杆的工程应用提供建议。 相似文献
3.
The objective of this research was to assess the characteristics of seismic induced damage and the deformation patterns of pre-stressed cement-grouted cables that are used for rock slope stabilization projects subjected to quasi-static cyclic loading. The experimental configuration includes the installation of 15 pre-stressed cables in a slope model made of concrete blocks (theoretically rigid rock mass) on top of a pre-existing sliding surface. The study showed that: (i) The pre-stressed cables exhibited great seismic performance. Rapid displacement of the model blocks was observed after the complete loss of the initial pre-stress load under continued applied cyclic loads and exceedance of the state of equilibrium, which implies the higher the initial pre-stress load, the better the seismic performance of the rock anchor; (ii) The failure of the pre-stressed cables was due to fracture at the connection of the tendons and cable heads under cyclic loading. The sequence of failure had a distinct pattern. Failure was first observed at the upper row of cables, which experienced the most severe damage, including the ejection of cable heads. No evidence of de-bonding was observed during the cyclic loading; (iii) The stress distribution of the bond length for pre-stressed cables was highly non-uniform. High stress concentrations were observed at both the fixed end and the free end of the bond length both before and immediately after the state of equilibrium is exceeded. The results obtained can be used to evaluate the overall performance of pre-stressed rock anchors subject to seismic loading and their potential as rockfall prevention and stabilization measures. 相似文献
4.
To take advantage of the abundance of both fishery and wave energy resources in offshore sea areas, a novel floating platform with a heaving buoy-based wave energy converter(WEC) assembled with a set of net cages is presented in this work. The floating WEC system provides a power supply, while the net cages are used for aquaculture. It is designed to have an independent and self-operation breeding function. An experimental study is carried out to investigate the hydrodynamic performance of the device in a wave tank considering the factors of net cages, draft depth, and power take-off, and results show that these variables have significant effects on wave energy capture. Incident waves with short periods cause intense interactions that allow the device to undergo large relative motion. The draft depth could be determined according to wave period rather than wave height. This study also explores the response amplitude operator of the device and determines its resonance scope. The experimental results could provide reliable information for future studies on phase differences and the design of two-body WECs. 相似文献
5.
以岩质边坡中常见的平面滑动为研究对象,研究其最优锚固方向角的计算方法。将锚索自由段单位长度能提供的最大抗滑增量作为目标控制变量,将坡面和滑动面特征参数与锚索设计参数作为优化控制自变量,通过坐标系转换得到的线性方程组对锚索的预拉力进行分解,并根据锚索支护时的三维模型建立了锚索自由段长度的优化公式,进而推导了用于锚固方向角三维优化的新计算方程。在该方程的基础上借助MATLAB软件中的fmincon函数对锚索加固方向不受限制时的锚固方向角进行了优化。最后通过锚固方向角敏感性分析与工程实例分析相结合,证明了推荐的最优锚固方向角计算方法的有效性与先进性。新方法有效地解决了边坡坡面与滑动面走向存在夹角时最优锚固方向角的求解问题,可进一步提高锚索的锚固效益,降低边坡的支护费用。 相似文献
6.
滑坡治理中格构式锚杆框架结构设计 总被引：2，自引：0，他引：2
结合略阳县城狮子山滑坡的治理，讨论了格构式锚杆框架结构治理松散堆积体滑坡设计的全过程。根据防治区的工程地质情况和相应的规范要求，确定了防治工程的安全等级。利用格构式锚杆框架结构所采用的小间距、小吨位锚杆及连续格构梁柱．从而使格构梁柱受力较均匀，适合松散堆积体滑坡治理的需要，即同时满足深层抗滑和浅层护坡。给出了坡面推力的计算模型和计算公式．对于格构式锚杆框架结构中的格构梁柱、锚杆和框架间面板也分别给出了相应的结构设计方法和公式．再就施工中应注意的事项给出了明确的建议和要求。 相似文献
7.
The observed deflections and internal forces of pile-anchor retaining excavation were studied in spring area in Jinan city of China. Based on field measured data, the ground surface settlement, deflection of retaining piles and wall, internal force analysis of concrete piles, axial anchoring forces, groundwater table, and the deformation of surround building and pipelines were investigated. The results indicates that the combining application of concrete piles, jet grouting columns and anchors support system can effectively control excavation-induced surface ground settlements. The field maximum lateral wall deflections are between 0.02% and 0.19% of the excavation depth due to the competitive site conditions. The bending moment-depth relationship curve is S-type. Groundwater leakage results in the sharp drop in groundwater level, which is part of the reasons for the adjacent building settlement. The axial anchoring forces of the upper layer of anchors increase gradually during the excavation, but those of the lower layer of anchors slightly reduced firstly and then tend to be stable during the excavation procedure. In comparison with the histories of excavation cases, the small lateral wall deflection in this study results from the favorable site condition and the relative rigidity of the retaining structure system. 相似文献
8.
针对抗滑桩常因地质条件、地形地貌等原因导致受荷段底面与嵌固段顶面不在同一水平面的情况,将此段划为次受荷段,并推导了次受荷段桩后设计荷载大小计算公式和荷载分布公式,以及在弹性地基梁和悬臂梁模型下的适用于悬臂桩和锚索桩内力与挠度计算通用公式。以巴东县焦家湾移民安置点库岸防护工程预应力锚索桩为例,研究次受荷段对抗滑桩内力和挠度影响。结果表明:忽略次受荷段后土压力作用的传统计算方法会使桩身弯矩计算结果偏小,导致桩身配筋量不足,存在设计安全隐患。再以锚索排数、位置为控制变量,研究其对预应力锚索桩内力和挠度的影响,提出预应力锚索可有效地降低抗滑桩工程造价;增加预应力锚索的排数有利于调节抗滑桩内力分布,设计时应优先考虑将锚索设置为多排锚索。 相似文献
9.
In analyzing seismic stability of a slope with upper bound limit analysis method, the slip surface is often assumed as a log-spiral or plane slip surface. However, due to the presence of a weak layer and unfavorable geological structural surface or a bedrock interface with overlying soft strata, the preexisting slip surface of the slope may be irregular and composed of a series of planes rather than strictly log-spiral or plane shape. A computational model is developed for analyzing the seismic stability of slopes with pre-existing slip surfaces. This model is based on the upper bound limit analysis method and can consider the effect of anchor bolts. The soil or rock is deemed to follow the Mohr-Coulomb yield criterion. The slope is divided into multiple block elements along the slip surface. According to the displacement compatibility and the associated flow rule, a kinematic velocity field of the slope can be obtained computationally. The proposed model allows not only calculation of the rate of external work owing to the combined effect of self-weight and seismic loading, but also that of the energy dissipation rate caused by the slip surface, interfaces of block elements and anchorage effect of the anchors. Considering a direct relationship between the rate of external work and the energy dissipation rate, the expressions of yield acceleration and permanent displacement of anchored slopes can be derived. Finally, the validity of this proposed model is illustrated by analysis on three typical slopes. The results showed that the proposed model is more easily formulated and does not need to solve complex equations or time consuming iterations compared with previous methods based on the conditions of force equilibrium. 相似文献
10.
锚索抗滑桩系统内力变形研究 总被引：1，自引：0，他引：1
在对锚索抗滑桩系统内锚索与抗滑桩受力状态综合分析的基础上,认为锚索的拉伸变形对锚索抗滑桩系统的内力及变形存在一定影响,基于锚索与抗滑桩的变形协调原理,提出了锚索拉力及其变形的计算方法,推导了抗滑桩桩身位移和内力的计算公式,并将该方法用于工程实例分析。通过与其他方法比较,说明使用该方法计算锚索抗滑桩的合理性和经济价值,并分析了锚索变形以及拉力大小对锚索抗滑桩系统内力变形的影响,所得结果已得到后期模型试验的数据支持。 相似文献
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12.
The Muzhailing extra-long highway tunnel and corresponding inclined shafts in Lanzhou,Gansu Province,China passes through structurally complex carbonaceous slate that is under high ground stress.Rationally-designed and effective support is of high importance for achieving safe and efficient tunnel construction.The No.2 inclined shaft of Muzhailing Tunnel was taken as the engineering background prototype,for which,a similar model test was conducted to evaluate the effect of highly pretightened constant resistance(NPR,Negative Poisson’s Ratio)anchor cable support provision to the geologically complex carbonaceous slate at different depths.Two schemes were proposed during testing:one scheme was without support and the second was with asymmetric support from highly pre-tightened constant resistance anchor cable.Digital speckle displacement analysis system and micro-groundstress sensors were employed to measure the deformation and shear stress distribution of the tunnel.The results demonstrated that through the second support scheme,the deformation of the surrounding rock could be effectively ameliorated,while this support scheme was applied on the project site of the No.2 inclined shaft,to explore the rationality of the scheme through field engineering tests.On-site monitoring indicated that the deformation of the surrounding rock was within the reasonable design range and the problem of severe tunnel deformation was effectively controlled.The research methods and related conclusions can be used as a reference for the treatment of large deformation problems in deep-buried soft rock tunnels. 相似文献
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14.
锚索抗滑桩是滑坡的主要支护结构之一。目前, 软硬相间地层条件下锚索抗滑桩的受力与变形特征尚缺乏系统研究。以软硬相间地层为地质背景, 基于自主研发的柔性测斜仪和自动加载系统, 构建了锚索抗滑桩加固滑坡物理模型试验系统, 开展了锚索抗滑桩加固滑坡的物理模型试验, 揭示了推力不断增加过程中抗滑桩、锚索和滑体的变形与受力特征, 对比研究了布锚方式对桩-锚受力与变形的影响规律, 通过数值模拟的方法分析了软硬相间地层对锚索抗滑桩的影响机理, 并以双锚点抗滑桩为例进行了理论分析。研究结果表明: ①在滑坡-锚索抗滑桩体系中, 桩身各点位移和滑体深部位移均随桩身深度的增加而减小, 滑体后部位移速率大于中部, 且滑体位移速率大于桩身位移速率; ②单锚点抗滑桩的桩-锚推力分担比经历了4个阶段的变化, 趋于稳定时桩-锚推力分担比约为9∶1, 锚索拉力作用下桩身弯矩呈"S"型分布, 正负弯矩非对称; ③锚固角度越大, 锚索拉力的增速越大, 不同锚固角度对桩身内力值的影响主要体现在受荷段; ④多锚点抗滑桩结构的锚索分担更多的推力, 与单锚点抗滑桩相比, 双锚点与三锚点抗滑桩的最大桩身弯矩分别减小了22.41%和40.55%;⑤与均质地层相比, 软硬相间地层中软、硬岩交界面处基岩应力发生突变, 不同软岩厚度比和桩底是否嵌入硬岩, 均对锚索拉力和桩-岩之间的相互作用有不同程度的影响; 其次, 双锚点抗滑桩内力的理论值与试验结果较为接近。本研究成果可为软硬相间地层中锚索抗滑桩加固滑坡工程的优化设计提供依据。 相似文献
15.
As a combined supporting structure,the anchor cable and lattice beam have a complex interaction with the slope body.In order to investigate the seismic behaviors of the slope reinforced by anchor cable and lattice beam,a largescale shaking table test was carried out on a slope model(geometric scale of 1:20)by applying recorded and artificial seismic waves with different amplitudes.The acceleration and displacement of the slope,the displacement of lattice beam and the axial force of anchor cable were obtained to study the interaction between the slope and the supporting structure.The test results show that:(1)the acceleration responses of the slope at different relative elevations display obvious nonlinear characteristics with increasing of the peak ground acceleration(PGA)of the inputted seismic waves,and the weak intercalated layer has a stronger effect on acceleration amplification at the upper part of the slope than that at the lower part of the slope;(2)the frequency component near the second dominant frequency is significantly magnified by the interaction between the slope and the supporting structure;(3)the anchor cables at the upper part of the slope have larger peak and residual axial forces than that at the lower part of the slope,and the prestress loss of the anchor cable first occurs at the top of the slope and then passes down;(4)the peak and residual displacements inside the slope and on the lattice beam increase with the increase of relative elevation.When the inputted PGA is not greater than 0.5 g,the combined effect of anchor cable and lattice beam is remarkable for stabilizing the middle and lower parts of the potential sliding body.The research results can provide a reference for the seismic design of such slope and the optimization of supporting structure. 相似文献
16.
《山地科学学报》2020,17(10):2548-2561
The long-term stability of a prestressed anchored slope might be influenced by the durability of the anchorage structure. To understand long-term stability of anchored rock slopes, the research presented herein evaluated the performance evolution of a prestressed anchored bedding slope system in a corrosive environment by model test. The corrosion process in a prestressed anchor bar was monitored in terms of its open-circuit potential(OCP), corrosion current density(CCD), and electrochemical impedance spectroscopy(EIS). The stability of the prestressed anchored slope was evaluated by monitoring changes in anchorage force and displacements. The experimental results show that prestress and oxygen could reduce the corrosion resistance of the anchor bar, and anchor bars in a chloride-rich environment are very susceptible to corrosion. Prestressed tendons in a corrosive environment suffer a loss of anchorage force, the prestress decreases rapidly after locking, and the rate thereof decreases until stabilising; in the later stage, corrosion leads to the reduction of the cross-sectional area of the steel bar which may cause the reduction in anchorage force again. Anchorage force controls the deformation and stability of the anchored slope, the prestress loss caused by later corrosion may lead to an increased rate of displacement and stability degradation of the prestressed anchored rock slope. 相似文献
17.
Centrifugal model tests are playing an increasingly important role in investigating slope characteristics under rainfall conditions. However, conventional electronic transducers usually fail during centrifugal model tests because of the impacts of limited test space, high centrifugal force, and presence of water, with the result that limited valid data is obtained. In this study, Fiber Bragg Grating (FBG) sensing technology is employed in the design and development of displacement gauge, an anchor force gauge and an anti-slide pile moment gauge for use on centrifugal model slopes with and without a retaining structure. The two model slopes were installed and monitored at a centrifugal acceleration of 100 g. The test results show that the sensors developed succeed in capturing the deformation and retaining structure mechanical response of the model slopes during and after rainfall. The deformation curve for the slope without retaining structure shows a steep response that turns gradual for the slope with retaining structure. Importantly, for the slope with the retaining structure, results suggest that more attention be paid to increase of anchor force and anti-slide pile moment during rainfall. This study verifies the effectiveness of FBG sensing technology in centrifuge research and presents a new and innovative method for slope model testing under rainfall conditions. 相似文献
18.
At present, most underwater positioning algorithms improve the positioning accuracy by increasing the number of anchor nodes which resulting in the increasing energy consumption. To solve this problem, the paper proposes a localization algorithm assisted by mobile anchor node and based on region determination(LMRD), which not only improves the positioning accuracy of nodes positioning but also reduces the energy consumption. This algorithm is divided into two stages: region determination stage and location positioning stage. In the region determination stage, the target region is divided into several sub-regions by the region division strategy with the smallest overlap rate which can reduce the number of virtual anchor nodes and lock the target node to a sub-region, and then through the planning of mobile nodes to optimize the travel path, reduce the moving distance, and reduce system energy consumption. In the location positioning stage, the target node location can be calculated using the HILBERT path planning and trilateration. The simulation results show that the proposed algorithm can improve the positioning accuracy when the energy consumption is reduced. 相似文献
19.
Large-scale shaking table tests were conducted to study the dynamic response of a slope reinforced by double-row anti-sliding piles and prestressed anchor cables. The test results show that the reinforcement suppressed the acceleration amplification effectively. The axial force time histories are decomposed into a baseline part and a vibration part in this study. The baseline part of axial force well revealed the seismic slope stability, the peak vibration values of axial force of the anchor cables changed significantly in different area of the slope under seismic excitations. The peak lateral earth pressure acting on the back of the anti-sliding pile located at the slope toe was much larger than that acting on the back of the anti-sliding pile located at the slope waist. The test results indicate an obvious load sharing ratio difference between these two anti-slide piles, the load sharing ratio between the two anti-sliding piles located at the slope toe and the slope waist varied mainly in a range of 2-5. The anti-slide pile at the slope waist suppressed the horizontal displacement of the slope surface. 相似文献
20.
By using numerical analysis methods to simulate the deep excavation, a lot of analyses are established on the basis of two-dimensional plane strain, ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation, people always take linear and nonlinear model, without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics, the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement. 相似文献