止水帷幕对土钉墙的增强作用研究

发布时间：2018-05-04 18:10

本文选题：止水帷幕 + 土钉墙　；参考：《河北工程大学》2017年硕士论文

【摘要】：在现行规范与工程设计中,止水帷幕一般当作安全储备而不考虑其挡土作用,往往使基坑支护设计偏于保守,容易造成工程浪费,不利于土钉墙支护技术的推广。因此研究止水帷幕对土钉墙工作性能的影响很有必要。本文针对水泥土桩止水帷幕+土钉支护这种复合土钉墙支护形式,利用显示有限差分软件FLAC 3D以摩尔-库伦本构模型、强度折减法、传统极限平衡法等理论为基础,结合某基坑工程案例按照具体施工工况建立了考虑止水帷幕与不考虑止水帷幕的两种计算模型。通过对计算结果的对比,定量分析了止水帷幕对土钉墙的增强程度。为了验证数值模拟的可靠性,还和现场实际监测数据进行了比对。文中从土钉墙的整体稳定性、变形与土钉轴力三个方面,总结了止水帷幕对土钉墙增强幅度的量化指标。(1)止水帷幕增加了塑性区的范围,被动土区域塑性区范围的增加最为明显,说明了被动土作用范围在扩大;止水帷幕还有效阻隔了边坡塑性区的贯通,塑性贯通区绕过了止水帷幕的底部向外扩展,相应的滑裂面范围向外扩展较明显;考虑止水帷幕土钉墙支护的安全系数最大可提高近30%。(2)止水帷幕减小了土钉墙坡顶44%的沉降,沉降较大区域整体向远离基坑的方向移动,最大沉降点远离到了1.42倍基坑深度外,优化幅度较大;止水帷幕减小了土钉墙坡面49.6%的水平位移,水平位移较大区域的范围也有所缩小,被动土压力区产生作用的区域有所扩大;施工过程中土钉墙的垂直位移与水平位移均逐渐增加且整体变化幅度相对比较均匀,位移趋势基本一致,说明了止水帷幕在一定程度上有效抑制了土钉墙的变形。(3)在考虑止水帷幕作用时土钉轴力最大减小幅度为71.9%,在土钉墙的中下部减小幅度最为明显。研究表明,止水帷幕对土钉墙的增强作用相当明显,考虑其作用可以进一步优化基坑设计,降低工程成本,提高土钉墙支护的性价比。从而使基坑设计更加贴合工程实际,有利于推广土钉墙支护技术。
[Abstract]:In the current code and engineering design, the waterproof curtain is generally regarded as a safe reserve without considering its retaining effect, which often causes the foundation pit support design to be conservative, which is easy to cause engineering waste, and is not conducive to the popularization of soil nailing wall supporting technology. Therefore, it is necessary to study the influence of waterproof curtain on the working performance of soil nailing wall. In this paper, in view of the composite soil nailing wall support form of cement soil pile waterproof curtain and soil nailing, the display finite difference software FLAC 3D is based on the theory of Moore Coulomb constitutive model, strength reduction method, traditional limit equilibrium method, and so on. Combined with a foundation pit engineering case, two calculation models are established according to the concrete construction conditions, which consider the waterproof curtain and do not consider the waterproof curtain. Through the comparison of the calculation results, the reinforcement degree of the waterproof curtain to the soil nailing wall is quantitatively analyzed. In order to verify the reliability of the numerical simulation, the field monitoring data are compared. In this paper, from the aspects of overall stability, deformation and axial force of soil nailing wall, the paper summarizes the quantitative index. The increase of the plastic zone in the passive soil area is the most obvious, which indicates that the action range of the passive soil is expanding, and the water-stop curtain also effectively obstructs the penetration of the plastic zone of the slope, and the plastic penetrating zone bypasses the bottom of the waterproof curtain and extends outwards. The corresponding range of sliding crack surface extends outward obviously, considering that the maximum safety factor of water-stop curtain soil nailing wall support can be increased by nearly 30%.) the waterproof curtain reduces the settlement of the slope top of soil nailing wall by 44%, and the settlement of the larger area moves away from the foundation pit as a whole. The maximum settlement point is far from the depth of 1.42 times of foundation pit, and the optimization range is larger, the horizontal displacement of soil nailing wall slope is reduced by 49.6%, and the range of horizontal displacement area is also reduced. In the process of construction, the vertical displacement and horizontal displacement of the soil nailing wall increase gradually, the whole variation range is relatively uniform, and the displacement trend is basically the same. The results show that the deformation of soil nailing wall can be effectively restrained by the waterproof curtain to a certain extent) the maximum reduction range of axial force of soil nailing is 71.9 when considering the action of water-proof curtain, and the most obvious decrease is in the middle and lower part of soil nailing wall. The research shows that the reinforcement effect of the waterproof curtain on the soil nailing wall is quite obvious. Considering its effect, the foundation pit design can be further optimized, the engineering cost can be reduced, and the performance and price ratio of the soil nailing wall support can be improved. Therefore, the foundation pit design is more suitable for engineering practice and is conducive to popularizing soil nailing wall support technology.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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