共查询到18条相似文献，搜索用时 187 毫秒
1.
水平荷载下黄土地基单片地下连续墙现场试验研究 总被引：2，自引：0，他引：2
基于墙顶水平荷载作用下黄土地基中单片地下连续墙的现场试验,分析和研究了地下连续墙的水平受力变形特性,得出了在不同荷载作用下墙身各截面弯矩、水平位移及墙侧土抗力等沿墙深的分布规律。结果表明,在水平荷载下墙体上部的1/3段受荷载的影响最为显著,墙身水平位移及转角沿墙深非线性衰减,并随墙顶荷载的增加而增大;墙身弯矩及墙侧土抗力最大值发生在地表以下一定深度范围内,随荷载的增加其最大值及0值点沿墙身逐渐向下迁移,且土抗力-位移曲线呈现双曲线的特征;墙体剪力在地表处最大,沿墙身向下呈非线性变化。 相似文献
2.
静载荷下黄土地基矩形地下连续墙现场试验研究 总被引：1，自引：0，他引：1
采用自平衡测试技术,在国内外首次进行了竖向静载荷作用下黄土地基中矩形地下连续墙现场试验研究,根据测试结果及黄土的物理力学性质,对黄土地基中矩形地下连续墙的荷载传递性状进行了详细分析。结果表明：黄土地基中矩形地下连续墙的承载特性具有端承摩擦桩的性质;墙的承载力由墙侧摩阻力和端阻力共同承担;墙侧摩阻力和端阻力的发挥与墙土的相对位移量及黄土的物理力学性质等因素有关;墙体达到极限荷载时,墙端阻力荷载分担比为40.3 %;各土层墙侧摩阻力随着墙土相对位移的增加而增大,但其增长幅度不等;加载时墙身轴力在加载处最大,随着各土层墙侧摩阻力作用的发挥,墙身轴力随着离荷载箱距离的增加而减小。 相似文献
3.
基于室内模型试验,就闭合型与单片地下连续墙基础在竖向承载性能上的差异进行了对比分析,并采用FLAC-3D软件进行数值分析来丰富室内模型试验,探讨了土体变形模量、密度、内聚力以及内摩擦角对闭合型地下连续墙竖向承载力的影响。结果表明：闭合型地下连续墙基础外侧摩阻力的发挥过程与单片地下连续墙基础大致相同,但由于土芯的存在,其内侧摩擦阻力发挥机理更复杂;闭合型与单片地下连续墙基础均可视为端承摩擦型基础;随着墙周土变形模量的增加,闭合型地下连续墙基础竖向位移显著减少,墙体轴力也减少;密度对闭合型地下连续墙基础沉降的影响不显著;内聚力对侧摩擦阻力的影响程度受地下连续墙和土体之间相对位移量的控制;只有闭合型地下连续墙基础的沉降量超过20 mm时,土体内摩擦角才对基础的竖向承载力有较大影响。 相似文献
4.
近海取水工程板桩墙安全性离心模型试验研究 总被引：1，自引：0，他引：1
板桩墙明沟结构是海岸电厂取水工程的一种结构型式。根据电厂取水工程初步设计方案,对电厂取水工程结构进行离心模型试验研究,分析板桩墙结构在波浪荷载作用下的安全性。试验表明,悬臂式斜拉桩板桩墙结构在设计最大波浪荷载作用下会产生较大的水平位移,墙身弯矩较大;引起板桩墙位移、弯矩的主要荷载是海床面以上的波浪荷载,板桩墙承载力主要由桩墙被动侧土体抗力提供。工程中板桩墙入土深度的增加不能有效改善墙体水平位移和墙身弯矩,不会提高板桩墙结构的承载能力。 相似文献
5.
矩形闭合地下连续墙基础（简称闭合墙基础）是一种新型的桥梁基础。通过室内模型试验,对闭合墙基础的群墙效率、沉降比等进行了研究,同时探讨了闭合墙墙间距（即内侧边长）对群墙效应的影响。试验中采用了2组不同截面尺寸的模型墙,其中A组模型墙边长小于B组模型墙,墙厚和墙高均相同。试验研究表明,闭合墙与单片墙在相同沉降下的荷载比一般都大于1,B组闭合墙荷载比和群墙效率均大于A组闭合墙;闭合墙与单片墙在相同墙顶应力下的位移比和沉降比基本都大于1,A组闭合墙位移比大于B组闭合墙。在保持墙厚和墙高不变的情况下,适当增大闭合墙基础的内侧边长可以有效地提高群墙效率和承载性能,从而获得更好的经济效益。 相似文献
6.
为正确评估分舱对于海上风电筒型基础承载特性的影响,对有、无分舱板的相同钢筒进行室内模型对比试验,分别得出在水平荷载及弯矩共同作用下和竖直荷载作用下的荷载-位移曲线,及筒内外侧壁土压力及顶盖土压力的分布规律,同时进行有限元分析模拟。试验和计算结果表明：在竖向荷载作用下,分舱板使基础的极限承载力略有提高,分舱板分担了筒顶盖和筒壁的竖向承载,降低了顶盖的承载比例;在水平荷载和弯矩共同作用下,分舱板为筒型基础提供了较大的抗拔承载力,使筒型基础在水平和弯矩荷载作用下的极限承载力提高了20.2%,降低了极限状态下的水平位移和倾角。总之,分舱板不但可以提高海上风电基础施工浮运过程的稳定性,还可以提高基础运行时的极限承载力。 相似文献
7.
风积沙地基装配式偏心基础抗拔试验研究 总被引：1，自引：0，他引：1
在毛乌素沙漠中开展装配式偏心基础在上拔、上拔+水平力组合荷载作用下的现场试验研究。根据试验加载过程中监测的基础顶部位移、地表竖向位移及基础底板土压力数据,分析基础顶部的荷载-位移特性,研究装配式偏心基础的抗拔承载机制。结果表明,（1）在上拔、上拔和水平力组合作用下,基础顶部上拔和水平位移曲线均呈二阶段的承载特性;（2）当仅受上拔荷载作用时,基础偏心引起的附加弯矩,使得基础底板产生偏转,基础及底板上覆部分沙土自重抵抗上拔荷载,而在上拔和水平力组合荷载工况下,基础偏心引起的附加弯矩小,与上拔荷载工况相比,基础极限抗拔承载力提高8.7％,即在组合荷载工况下装配式偏心基础能够发挥更多的沙土来抵抗上拔荷载;（3）根据装配式偏心基础的抗拔承载机制,引入外荷载合力作用线与支架作用线之间的夹角δ来反映水平荷载对装配式基础抗拔破坏因子的影响,其影响规律为装配式基础的抗拔破坏因子随δ增加而降低。 相似文献
8.
基于典型冲刷坑形态,通过改变冲刷深度来模拟不同局部冲刷作用,对典型的9桩群桩进行了冲刷前、后水平承载试验,对相同参数的单桩进行了平行对比试验,详细分析了荷载-位移特性、桩身弯矩分布、群桩效率系数以及荷载分担比的变化规律。结果表明,随着冲刷深度增加,单桩和9桩基础水平承载力均呈现减弱趋势,水平群桩效率系数逐渐增大,承台约束作用效应更加明显,桩身弯矩增大,最大弯矩点位置向桩端移动,前排桩荷载分担比增大,中、后排桩荷载分担比减小;前排角桩受冲刷深度和水平荷载影响最大,设计时需采取有效的加强措施。 相似文献
9.
以琼州海峡跨海大桥工程为背景,通过4组不同型式深水桥梁基础模型试验,对新型带桩沉箱复合基础的水平向承载性能进行了初步研究。试验得到了4组模型在砂性土层中的Q-s曲线及水平向极限承载力,并对复合基础在各级水平荷载下的桩身弯矩和剪力进行了详细分析,同时对沉箱-桩荷载分担比展开了讨论。试验结果表明：当增加裙边、钢管桩、或同时增加钢管桩和裙边后能够使单体沉箱基础的水平向极限承载力分别提高1.2倍、1.6倍和2.0倍;桩身最大弯矩点均出现在桩身中部即泥面下约0.5 m处。水平荷载主要由上部沉箱基础及桩身中上部土体承担,钢管桩桩顶与沉箱连接部位出现最大剪力,在实际工程中应在此处采取加固措施。研究成果可为这一新型深水桥梁基础的推广应用提供诸多有益参考。 相似文献
10.
以琼州海峡跨海大桥工程为背景,通过4组不同型式深水桥梁基础模型试验,对新型带桩沉箱复合基础的水平向承载性能进行了初步研究。试验得到了4组模型在砂性土层中的Q-s曲线及水平向极限承载力,并对复合基础在各级水平荷载下的桩身弯矩和剪力进行了详细分析,同时对沉箱-桩荷载分担比展开了讨论。试验结果表明:当增加裙边、钢管桩、或同时增加钢管桩和裙边后能够使单体沉箱基础的水平向极限承载力分别提高1.2倍、1.6倍和2.0倍;桩身最大弯矩点均出现在桩身中部即泥面下约0.5 m处。水平荷载主要由上部沉箱基础及桩身中上部土体承担,钢管桩桩顶与沉箱连接部位出现最大剪力,在实际工程中应在此处采取加固措施。研究成果可为这一新型深水桥梁基础的推广应用提供诸多有益参考。 相似文献
12.
黄土地区水平荷载作用下闭合型地下连续墙基础承载 性状分析 总被引：1，自引：0，他引：1
地下连续墙基础相对于一般桩基础的一个显著特点就是整体刚度大,水平荷载作用下基础一般有两种工作状态和破坏机理:其一是刚性短桩,表现为转动或平移破坏;其二是弹性长桩,表现为挠曲破坏。数值模拟表明:在一定范围内随着墙体埋深的增加,在大小相等的水平荷载作用下,基础埋深越大,其水平位移则越小。但埋深超过30m后,墙体埋深对基础的水平变形影响变得不显著。即当闭合墙体的埋深超过一定深度后,过分的加大闭合墙体的埋深无助于提高基础的水平承载性能。 相似文献
13.
土钉墙墙底地基土的承载力验算是土钉墙支护设计的一项重要内容。国内的工程实践中,通常将土钉墙地基承载力与坑底土抗隆起验算合并考虑。针对具体案例,通过Plaxis3D有限元数值模拟,分析研究了土钉墙底部土体发生地基承载力失稳的破坏模式、破坏荷载以及土钉墙墙底应力分布特点等,探讨了依据我国相关规程进行土钉墙坑底隆起或地基承载力计算可能存在的问题。借鉴国外加筋土挡墙地基承载力计算的一般方法,将土钉墙作为荷载倾斜、偏心的刚性基础对待,利用荷载倾斜、偏心条件下传统刚性浅基础的地基承载力的Meyerhof解和Vesic解,对土钉墙地基承载力进行了计算和对比,通过对比发现,Meyerhof解更接近实际,据此,提出了土钉墙地基承载力计算的合理模式。 相似文献
14.
Installation of buttress walls against diaphragm walls has been used as an alternative measure for the protection of adjacent buildings during excavation, but their mechanism in reducing movements has not yet been fully understood. This study performs three-dimensional finite element analyses of two excavation case histories, one in clay with T-shape buttress walls and another in dominant sand with rectangular buttress walls, to establish analysis model. Then, a series of parametric study were performed by varying soil types, types and length of buttress walls based on the above-mentioned excavations. Results show that the mechanism of buttress walls in reducing wall deflections mainly came from the frictional resistance between the side surface of buttress wall and adjacent soil rather than from the combined bending stiffness from diaphragm and buttress walls. The buttress wall with a length <2.0 m had a poor effect in reducing the wall deflection because the soil adjacent to the buttress wall had almost the same amount of movement as the buttress wall, causing the frictional resistance little mobilized. Since the frictional resistance of buttress walls in a deep excavation has fully been mobilized prior to the final excavation depth, the efficiency of buttress walls in reducing the wall deflection in a deep excavation was much less than that in a shallow excavation. Rectangular shape of buttress walls was of a better effect than T-shape in the shallow excavation because frictional resistance between buttress walls and adjacent soil played a major role in reducing the wall deflection rather than bearing resistance of the flange. When the excavation went deeper, the difference in reducing the wall deflection between the R-shape and T-shape became small. 相似文献
15.
Piles and diaphragm wall-supported berthing structure on marine soils are loaded laterally from horizontal soil movements
generated by dredging. The literature on the adequacy of the finite element method modeling of berthing structure to analyze
their behavior during dredging is limited. This paper describes a finite element approach for analyzing the lateral response
of pile and diaphragm wall during dredging. Piles are represented by equivalent sheet-pile walls and a plane strain analysis
using the finite element method is performed. Results from the finite element method are compared with full-scale field test
data. Full-scale field test was conducted on a bearing structure to measure the lateral deflection on pile and diaphragm wall
for their full length using inclinometer during dredging in sequence. The finite element method results are in good agreement
with full-scale field results. Conclusions are drawn regarding application of the analytical method to study the effect of
dredging on piles and diaphragm wall-supported berthing structures. 相似文献
16.
A series of three-dimensional finite element analyses of deep excavations with the integrated system between buttress walls and diaphragm walls was conducted to investigate the effect of the buttress wall intervals, treatments, locations, height, and thickness on limiting deformations induced by deep excavation. The integrated retaining system was formed by maintaining buttress walls when soil was excavated. The wall deflection control mechanism of the integrated retaining system mainly came from the combined stiffness between the buttress wall and the diaphragm wall. In addition, the ground settlement control mechanism came from the combined stiffness between the buttress wall and the diaphragm wall, and the frictional resistance between the buttress wall and the surrounding soil. For achieving 50% reduction in the wall deflection and the ground surface settlement, the length and intervals of buttress walls that were applied to the integrated retaining system were at least 4 and 8 m, respectively. When the deflection at the diaphragm wall head was well restrained, for example, by the floor slab, the position of the buttress wall head could be located at a depth the diaphragm wall starts to bulge out. In such a case, the performance between the full height and limited height of buttress walls was quite close. Furthermore, a new well-documented excavation project was analyzed to verify the performance of the integrated retaining system. Results showed that the integrated retaining system worked excellently if the joints between buttress walls and diaphragm walls were constructed properly. 相似文献
17.
Previous plane strain analysis of a case history has shown that cross walls in an excavation can effectively reduce movements induced by deep excavation. This study performed three-dimensional numerical analyses for 4 deep excavation cases with different installations of cross walls, including different excavation depths, cross wall intervals and cross wall depths. Both the observed and computed wall deflections for the 4 cases were compared with those of the same excavations that were assumed with no cross walls installed to demonstrate the effectiveness of cross walls in reducing lateral wall deflections. The results show that the cross wall also had a corner effect similar to that of the diaphragm wall. The deflection of the diaphragm wall was smallest at the location of the cross wall installed and then increased with the increasing distance from the cross wall, up to the midpoint between two cross walls. Many factors such as in situ soil properties, diaphragm wall properties, construction procedure, cross wall depth and so on may affect the amount of reduction in lateral wall deflections due to the installation of cross walls. Under the same condition, the amount of reduction was highly dependent on the depth of cross walls, distance to the cross walls and the cross wall interval. 相似文献
18.
Finite-element modeling of a complex deep excavation in Shanghai 总被引：2，自引：0，他引：2
The excavation of the north square underground shopping center of Shanghai South Railway Station is a complex deep excavation
using the top-down construction method. The excavation has a considerable size and is close to the operating Metro Lines.
In order to predict the performance of the excavation more accurately, 3D finite-element analyses are conducted to simulate
the construction of this complex excavation. The effects of the anisotropic soil stiffness, the adjacent excavation, and zone
excavation on the wall deformation are investigated. It is shown that the numerical simulation with anisotropic soil stiffness
yields a more reasonable prediction of the wall deflection than the case with isotropic soil stiffness. The deformation of
the shared diaphragm wall between two excavations is influenced by the construction sequence of the two excavations. The zoned
excavation can greatly reduce the diaphragm wall deformation. However, only the zoned excavation at the first excavation stage
affects the deformation of the walls significantly. When the depth of the excavation increases, the zoned excavation has minor
effect on the deformation of diaphragm walls. 相似文献