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1.
Hu Yi-li Xu Jun Duan Yong-kong Xu Zhao-yong Yang Run-hai Zhao Jin-ming 《地震科学（英文版）》2004,17(6):725-734
A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve. 相似文献
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Introduction To the impact pattern, the dynamic test with high strain is generally grouped into two kinds.One is stricken by hammer and another is by rocket. The former is widely used and the latter isused widely abroad and seldom used at home. To the analyzing method, it is also divided into twokinds. One is the method of wave equation and another is the method of experimental formula.The methods of Smith, Case and Capwap and other improved methods belong to the former, andthe methods … 相似文献
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叙述一种新的大应变检测单桩竖向承载力的方法. 用重锤或小型火箭筒冲击桩顶，用检波器记录振波图. 引入应变（变形力）的高次项，从理论上证明当为大位移大应变， 即桩相对于土体产生整体滑动时，位移、速度和加速度则不能经过简单积分加速度和微分速度得到，即它们为非线性关系. 由此导出:通过波列振幅计算力（P）和位移（S）,并作（动态）P-S曲线、确定屈服点，进而阐述确定单桩竖向承载力的方法，并利用静载荷试验检验动测结果和确定动静P（Q）S曲线的相关常数. 相似文献
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Xu Zhao-yong Duan Yong-kang Wang Bin Hu Yi-li Yang Run-hai Xu Jun Zhao Jin-ming 《地震学报(英文版)》2004,17(1):138-149
By studying the pile-formula and stress-wave methods (e.g., CASE method), the authors propose a new method for testing piles using the single-impact energy and P-S curves. The vibration and wave figures are recorded, and the dynamic and static displacements are measured by different transducers
near the top of piles when the pile is impacted by a heavy hammer or micro-rocket. By observing the transformation coefficient
of driving energy (total energy), the consumed energy of wave motion and vibration and so on, the vertical bearing capacity
for single pile is measured and calculated. Then, using the vibration wave diagram, the dynamic relation curves between the
force (P) and the displacement (S) is calculated and the yield points are determined. Using the static-loading test, the dynamic results are checked and the
relative constants of dynamic-static P-S curves are determined. Then the subsidence quantity corresponding to the bearing capacity is determined. Moreover, the shaped
quality of the pile body can be judged from the formation of P-S curves.
Foundation item: Key Projects of Tenth Five-year Plan of Yunnan Province (54-02-02). 相似文献
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为了对宝兰客运专线王家沟隧道软弱地基进行加固处理,并了解加固后的桩基受力状态,通过现场试验及数值模拟,研究钢管桩单桩复合地基的荷载沉降特性及钢管桩轴力、桩侧摩阻力以及桩身弯矩的变化规律。研究结果表明:由现场试验所得的P-s(荷载-位移)、s-lgt(位移-时间的对数)以及s-lgp(位移-荷载的对数)曲线没有明显可以确定极限承载力的特征点,根据规范采取控制沉降的方式给出极限承载力特征值为200 kPa,并可以此作为设计依据。根据数值模拟中钢管桩的总沉降量以及荷载沉降"归一化曲线",数值模拟可以作为现场试验的必要补充。数值模拟结果显示:桩身轴力呈"D"状分布,最大值为59.8 kN;在距桩顶2 m桩长范围内有负摩阻力产生,其余部位均为正摩阻力,负摩阻力最大值约为130 kPa,正摩阻力最大值约为50 kPa,且桩身中性点并不唯一;桩身上部有弯矩产生,但数值很小,对钢管桩稳定性的影响可以忽略。 相似文献
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由冲刷引起的深水结构物桩基础周围土体损失致使基础水平承载性能下降的问题越发受到重视。应变楔方法假设桩前土体抵抗为三维楔形体,其尺寸发展与楔形体区域土体发挥的内摩擦角有关,从而得到水平受荷桩的p-y曲线。本文对应变楔方法进行修正和拓展,建立非线性位移假设以考虑桩前楔形体区域土体应变沿深度的非均匀分布,将冲刷坑底以上土体的有效自重作用等效为竖向荷载,对楔形体的深度进行修正,以解决楔形体方法只适用于地表水平的情况,得到砂土中单桩基础冲刷的修正应变楔计算方法;并通过与模型试验及三维有限元分析的对比来验证该方法的合理性。分析结果表明:冲刷深度增加会显著降低桩基水平承载性能,冲刷深度3.2D和6.4D情况下的桩顶位移比平均值分别趋近于1.8和3.0;相比有限元方法,本文修正SW方法计算的p-y曲线结果与实测结果更为接近。 相似文献
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基于云南省内及邻区2009—2020年GNSS观测数据解算结果,在各个测点时间序列和速度场的基础上,采用克里金插值方法估计区域应变率场;以连续基准站时间序列为约束,获取漾濞MS6.4地震近场区域的块体应变时间序列。分析发现:漾濞地震发生在前期最大剪应变高值区以及面应变高梯度带的张压转换区,发震的时间处于区域应变积累速率逐渐降低的过程之后。震中近场区域均以NW向断层的右旋走滑应变积累为主,且大多呈现持续增强趋势,与漾濞地震的发震断层走向及其破裂特征一致。震前震区东部块体出现了短期应变趋势转折及反向加速的异常现象,反映了应力-应变积累在接近临界破裂状态时的非线性调整。 相似文献
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A Review of the Calculation Formula for the Four-component Borehole Strainmeter and Application to Earthquake Cases 总被引：1，自引：0，他引：1
Based on the principle formula for the four-component strainmeters, we can directly obtain the specific plane strain, shear strain and azimuthal angle of the principal strain, and the maximum and minimum principal strains calculated afterwards are the indirect result. The problems of practicality of the sensitivity coefficients A and B of plane strain and shear strain are then discussed. Based on this idea, we analyzed the observation data of several four-component borehole strainmeters near the epicenter of the Yiliang MS5.7 earthquake in 2012 and the Ludian MS6.5 earthquake in 2014 in the Zhaotong area, Yunnan Province. The results show that the analysis based on the perspective of plane strain and shear strain has an obviously better effect than that based on the component readings, and can directly peel off the respective abnormality of the plane strain and shear strain. In addition, the correlation coefficient curves between measured data of two plane strains show significant anomalies which often occur several days before and during the earthquake. 相似文献
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2021年5月22日,青海省果洛州玛多县发生7.4级地震,中国强震动观测网络在主震中捕获16组强震动数据。对48条三分向加速度记录进行基线校正、滤波等常规处理,计算相应的地震动参数,发现位于断层破裂前向位置的63DAW台NS向记录的地震动速度波形具有长周期分量丰富的特征。分析6个典型台站的单自由度加速度反应谱,并与我国建筑抗震设计谱比较,分析此次地震的频谱特性。将实际观测到的PGA、PGV和S_a(T=0.1 s、T=1.0 s、T=2.0 s、T=5.0 s)与国内广泛使用的几种地震动预测模型对比,研究此次地震的影响场。通过分析S_a-S_d曲线,探讨此次地震靠近断层区域地面运动大位移与桥梁落梁震害间可能存在的关系。 相似文献
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Xu Zhao-yong Duan Yong-kang Wang Bin Hu Yi-li Yang Run-hai Xu Jun Zhao Jin-ming 《地震科学（英文版）》2004,17(1):138-149
By studying the pile-formula and stress-wave methods (e.g., CASE method), the authors propose a new method for testing piles using the single-impact energy and P-S curves. The vibration and wave figures are recorded, and the dynamic and static displacements are measured by different transducers near the top of piles when the pile is impacted by a heavy hammer or micro-rocket. By observing the transformation coefficient of driving energy (total energy), the consumed energy of wave motion and vibration and so on, the vertical bearing capacity for single pile is measured and calculated. Then, using the vibration wave diagram, the dynamic relation curves between the force (P) and the displacement (S) is calculated and the yield points are determined. Using the static-loading test, the dynamic results are checked and the relative constants of dynamic-static P-S curves are determined. Then the subsidence quantity corresponding to the bearing capacity is determined. Moreover, the shaped quality of the pile body can be judged from the formation of P-S curves. 相似文献
12.
桩承式路基在我国高铁路基中广泛应用,因此,论文建立地震荷载作用下轨道-路基-地基三维数值计算模型,研究地震荷载作用下桩承式路基的地震反应特性,分析桩径、桩长、桩间距、桩身弹性模量等计算参数对路基地震反应的影响,并与自由式路基的地震反应对比。自由式路基地震反应特性表明,地震荷载作用下水平x方向钢轨振动位移幅值最大,是z方向的5倍,路基坡脚处振动位移幅值是基床表层的25.2倍,轨道、路基频谱曲线主频单一,且主频范围为2.5～7.5 Hz;与自由式路基相比,桩承式路基对轨道水平方向位移幅值、加速度幅值有增大作用,但减小了轨道竖向位移幅值、加速度幅值;对路基各结构层位移幅值、加速度幅值都有明显减小作用。综合考虑,桩承式路基抗震性能最佳桩径为0.8 m,最佳桩长为8～10 m,最佳桩间距为2 m,最佳桩弹性模量为20 GPa。 相似文献
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2022年1月8日,青海省门源县发生MS6.9地震,造成震中附近的兰新高铁大梁隧道受损,导致高铁长时停运。文章通过建立二维平面应变模型,加载双向门源波进行动力时程分析,得到了大梁隧道的地震动响应结果,并对模型在震后的受力变形及震害特征进行详细分析。结果表明：在门源波双向加载下,大梁隧道的地震动响应受水平地震荷载影响很大;沿着y轴正向,隧道的截面形状对纵向位移和加速度的地震动响应有加强作用;拱顶处地震动响应最大,其竖向及横向地震动响应加速度分别为5.206 4 m/s2、4.534 8 m/s2,竖向及横向位移分别为7.070 9 cm、0.641 5 cm;拱底处地震动响应最小,其竖向及横向地震动响应加速度分别为3.287 6 m/s2、4.511 2 m/s2,竖向及横向位移分别为4.851 6 cm、0.625 2 cm;拱肩、拱脚处存在明显的应力集中现象,拱顶、拱底、拱肩及拱脚处内力的受力形式发生变化,但是衬砌应力和内力的极值均发生在拱腰及拱脚处,说明拱腰及拱脚处为震害严... 相似文献
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为了研究近断层地震动速度脉冲及强竖向地震动对风机塔地震响应的影响,以某陆上风电场1.5 MW风机塔为研究对象开展了结构在水平向脉冲型地震动、水平向非脉冲型地震动、水平与竖向地震动组合3种地震输入工况的时程分析。通过3种工况下塔顶位移时程、加速度时程、塔底剪力、弯矩及轴力的对比分析发现:近断层速度脉冲对结构塔顶水平位移、塔顶水平加速度、塔底剪力与弯矩均影响显著;竖向地震动会加大结构的塔顶竖向加速度响应及塔底轴力响应;随着竖向与水平加速度峰值比增大,塔顶竖向加速度响应增大,最大轴力随着峰值比增大而增大,最小轴力随着峰值比增大而减小。此外,增量动力分析表明,采用自接触的有限元模型可以更真实地预测风机塔的失稳破坏机制。 相似文献
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Performance-based methodology for assessing seismic vulnerability and capacity of buildings 总被引：1，自引：0，他引：1
This paper presents a performance-based methodology for the assessment of seismic vulnerability and capacity of buildings. The vulnerability assessment methodology is based on the HAZUS methodology and the improved capacity- demand-diagram method. The spectral displacement (Sd) of performance points on a capacity curve is used to estimate the damage level of a building. The relationship between Sd and peak ground acceleration (PGA) is established, and then a new vulnerability function is expressed in terms of PGA. Furthermore, the expected value of the seismic capacity index (SCev) is provided to estimate the seismic capacity of buildings based on the probability distribution of damage levels and the corresponding seismic capacity index. The results indicate that the proposed vulnerability methodology is able to assess seismic damage of a large number of building stock directly and quickly following an earthquake. The SCev provides an effective index to measure the seismic capacity of buildings and illustrate the relationship between the seismic capacity of buildings and seismic action. The estimated result is compared with damage surveys of the cities of Dujiangyan and Jiangyou in the M8.0 Wenchuan earthquake, revealing that the methodology is acceptable for seismic risk assessment and decision making. The primary reasons for discrepancies between the estimated results and the damage surveys are discussed. 相似文献
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为了研究强震区桥梁跨活动断层时,桩基在地震中的动力响应,以海文大桥为工程背景,利用Midas GTS有限元软件建立其强震区桩-海床岩土体-断层耦合作用的数值模型,研究不同强度(0.20g～0.60g)的50年超越概率为10%的地震波(后文简称5010地震波)作用下,桥梁桩基加速度、位移、弯矩及剪力的动力时程响应特性。结果表明：上部大厚度松散土体对桩身加速度有放大及滤波作用,而基岩对桩身加速度几乎不产生作用;断层上、下盘桩基础的桩顶水平位移随输入地震动强度的增大而增大,但达到振幅的时刻一致;上、下盘桩基础桩顶竖向位移时程响应都在50 s以后产生永久沉降;桩身最大弯矩截面处时程响应均在40 s以后产生永久弯矩;应重点考虑上部覆盖层软硬土体界面和基岩界面的抗弯承载力设计,及桩顶和基岩面附近的抗剪承载力设计;上盘桩基础按桩身加速度、弯矩、桩顶水平位移等动参数控制设计,下盘桩基础按动剪应力控制设计。 相似文献
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水合物分解对桩基础应力和变形影响的研究 总被引：1，自引：0，他引：1
赋存于海底沉积物中的天然气水合物与固体颗粒相互胶结,增加了沉积物的强度,一旦水合物分解,会引起沉积物剪切强度降低,如果在含有水合物层上面或附近存在桩基础,必然影响其稳定性。本文采用应力释放法,通过数值计算,分别讨论了桩基础底部位于含水合物地层不同深度时,水合物分解对桩基础应力和变形的影响规律。计算结果表明,随着水合物分解过程中的模量软化和强度衰减,桩基础的水平和竖向位移增大,由于地基水平,土体没有驱动剪应力,水平位移增加不大,地基和桩基础主要表现为竖向沉降;桩底部位于水合物层中间的桩基础的沉降变形,比桩底穿过水合物层的桩基础大,在桩基础及其附近的土体产生较大的应力。 相似文献
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2021年5月21日云南漾濞发生6.4级地震,中国数字化强震动观测网络在主震中捕获28组加速度数据。对84条三分向加速度记录进行常规处理,计算出对应的地震动参数,并绘制震中附近水平向PGA和PGV等值线图,结果显示其走向和形态与震后烈度调查结果相近。将实际观测的相对持时进行曲线回归,求得相关系数,并据此计算出T_d(5%～95%)持时对应的震源持续时间在10.22～13.06 s间,与震源破裂过程反演结果基本一致。再通过分析近场6个台站记录的加速度反应谱,并与抗震设计谱比较,总结此次地震的频谱特性,为该区域抗震设防提供参考依据。 相似文献
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结合构建的饱和土结构性动力本构模型以及通用有限元程序,以城市高架桥梁建设中常采用的单柱墩基础为原型,建立了摩擦桩-土-结构体系、端承桩-土-结构体系的有限元-无限元计算模型。分完全粘结、滑移无开裂、开裂无滑移、开裂滑移四种情况考察了桩土界面力学行为对两种系统动力反应特性的影响,得出如下结论:无论是端承桩还是摩擦桩,界面力学行为对桩截面的剪应力和桩身水平位移分布形态影响均不大。四种情况中,完全粘结时,摩擦桩在近地表处桩截面剪应力值最大,开裂滑移时最小,而端承桩则刚好相反。水平位移分布均可分为线性增大和加速非线性增大两个阶段,以近地表处为分界点,且均以开裂滑移时最大,完全粘结时最小。界面力学行为极大地改变了端承桩桩身加速度时程的分布形态,但对摩擦桩则几乎没有改变;对于不同界面力学行为,两种桩型在近地表处均出现加速度峰值,完全粘结时值最大,开裂滑移时最小。相比摩擦桩而言,界面力学行为对端承桩的影响要大的多,研究分析时应引起足够的重视。 相似文献