爆夯动力固结法加固软基试验研究   总被引：1，自引：0，他引：1  

连峰  龚晓南  徐杰  吴瑞潜  李阳 《岩土力学》2009,30(3):859-864

爆夯动力固结法是一种爆炸作用和上覆荷载相结合的新型地基处理方法。其作用原理是利用条形炸药在设置有排水通道的软土地基中爆炸产生高能量瞬变荷载使土体结构发生变化,软土中超静孔隙水压力急剧上升、消散,并在上覆荷载的作用下使土体快速排水固结。在广东佛山合顺－北滘公路干线拟建路段进行的现场试验和室内试验均表明了其加固软土地基的有效性,并结合沉降数据推算了爆夯设计参数,确定本次试验爆夯效果相当于3.2 m高的堆载。  相似文献   

波浪作用下黄河口粉土液化与“铁板砂”形成机制的模拟试验研究   总被引：2，自引：0，他引：2  

张民生  刘红军  李晓东  贾永刚  王秀海 《岩土力学》2009,30(11):3347-3351

通过室内水槽试验,观测波浪作用下土体产生的振荡现象,分析土体内孔隙水压力的变化及波浪作用后土体强度变化特征,研究了波浪荷载作用下黄河口粉土粒径粗化和“铁板砂”的形成过程。试验及讨论结果表明：在波浪作用下上层粉土体大部分时间处于液化状态;由液化土形成的振荡土层与下部土层之间形成“W”型的滑动面,振荡土层的厚度随着波浪作用时间的增加而变小;细粒物质从振荡土层中的骨架中脱离进入水体中,并在土体表层形成一层以黏粒为主的絮凝状沉积物,其厚度随波浪作用时间的增加而增加,在土体停止振荡前达到最大值;土体液化是“铁板砂”形成的必要条件,而波浪引起的液化土体振荡则使“铁板砂”的形成成为可能。  相似文献   

重庆主城区粉质黏土动力特性研究     

蔡辉腾  危福泉  蔡宗文 《岩土力学》2009,30(Z2):224-228

采用自振（共振）柱和动三轴试验方法,得到重庆主城区粉质黏土动剪切模量和阻尼比随剪应变变化试验结果,比较分析试验值、文献[1]给出的推荐值和文献[2]给出的规范值的差异,并通过土层反应计算初步给出了这种差异对地表反应谱的影响,结果表明：(1) G/Gmax-γ关系中,规范值在中等应变时给出的G/Gmax比试验值和推荐值低;大应变时,相比较于试验值和推荐值,规范值衰减更快;(2) 相比较于λ-γ关系,G-γ关系经过Gmax归一化后,更具有一致性,粉质黏土阻尼离散性较大;(3) 试验值和推荐值计算的地表反应谱相差较小,但试验值和规范值计算的地表反应谱相差较大,特别是在随着输入地震动强度增大,这种差异性更显著。分析表明,重庆主城区进行土动力计算过程中,当无土动力特性试验资料时,选用规范值具有一定的局限性和风险,相比较于规范值,推荐值在一定程度上更具适用性。  相似文献   

Consolidation of inelastic clays under rectangular cyclic loading     

Mohammad M. Toufigh  Ahad Ouria 《Soil Dynamics and Earthquake Engineering》2009

This paper presents a semi-analytical solution for one dimensional consolidation problem of inelastic clays under cyclic loading considering the effect of the change of the consolidation coefficient of the soil layer. Due to change of the consolidation coefficient, and time-dependant loading, Terzaghi's theory would not be applicable in cyclic conditions. In this research, a method based on the time variable exchange along with the superimposing rule is employed to overcome these shortcomings. Changes in the consolidation coefficient are applied in the solution by modifying the loading and unloading durations introducing a Virtual Time. Based on the superimposing rule a set of continuous static loads in specified times are used instead of the cyclic load in the transformed time space. Each full cycle of loading is replaced by a pair of static loads with different signs. Based on the Terzaghi's theory the pore-water pressure distribution and the degree of consolidation are calculated for each static load and the results are superimposed. A set of laboratory consolidation tests under cyclic load and numerical analysis are performed in order to verify the presented method. The numerical solution and laboratory tests results showed the accuracy of the presented method.  相似文献   

Design and commissioning of a laminar soil container for use on small shaking tables   总被引：2，自引：0，他引：2  

Alper Turan  Sean D. Hinchberger  Hesham El Naggar 《Soil Dynamics and Earthquake Engineering》2009

This paper describes the design, fabrication and commissioning of a single axis laminar shear box for use in seismic soil–structure interaction studies. A laminar shear box is a flexible container that can be placed on a shaking table to simulate vertical shear-wave propagation during earthquakes through a soil layer of finite thickness. The laminar shear box described in this paper was designed to overcome the base shear limitations of a small shaking table at The University of Western Ontario. The design details of the box are provided in addition to results of dynamic tests performed to commission the box. A synthetic clay comprising sodium bentonite mixed with diluted glycerin was used as the model soil and 1-G similitude theory was employed to maintain model to prototype similarity. The model soil was compacted into the container in lifts to achieve soil stiffness that increased with depth. A series of shaking table tests and numerical analyses that were performed to study the performance of the laminar box and non-linear seismic behavior of the model clay are described. The results of this study show that the laminar box does not impose significant boundary effects and is able to maintain 1-D soil column behavior. In addition, the dynamic behavior of the model clay during scaled model tests was found to be consistent with the behavior measured during cyclic laboratory tests.  相似文献   

苏北平原周庄镇浅钻沉积物粘土矿物分布特征及其环境意义     

舒强  陈晔  张茂恒  赵志军 《地理科学》2012,(2):238-243

利用X衍射法分析了苏北平原浅钻剖面(YZ1)的粘土矿物类型和含量,并对其环境意义进行了探讨。结果表明,YZ1浅钻沉积物粘土成分主要由4种粘土矿物(伊利石、高岭石、绿泥石、蒙脱石)和少量长石、石英碎屑组成;研究区的古气候环境演变主要经历3个阶段,13 770~11 600 cal a B.P.期间的低温冷干阶段;11 600~9 610cal a B.P.期间的逐步升温阶段;9 610~1 520 cal a B.P.期间的全新世暖湿阶段,在这3个大的阶段背景条件下也存在一些次级波动。  相似文献   

地铁列车循环荷载试验论证研究          下载免费PDF全文

丁智  张涛  魏新江  张孟雅 《地震工程学报》2015,37(3):789-793,802

地铁循环荷载作用下饱和软黏土的动力特性研究对于揭示软黏土在地铁荷载下的孔压、强度以及变形模式具有重要意义,可以为控制地铁长期沉降、降低运营风险提供理论依据。试验加载形式的不同会带来不同的动力特性表征,需选取最能反映地铁列车真实性质的荷载形式。本文在列车荷载作用下研究土动力特性,采用室内动三轴试验的方法,对比分析不同形式下动力荷载作用效果。试验研究表明:偏压正弦波可以作为简化波形研究列车荷载,它不仅可以确保加载过程中地基土只有压应力,而且能较好地模拟列车循环荷载。  相似文献   

致密砂岩气藏可动流体赋存特征的微观地质因素: 以苏里格气田东部盒8段储层为例     

任大忠  孙卫  卢涛  李跃刚  张茜  周楷 《现代地质》2015,29(6):1409-1417

以苏里格气田东部盒8段典型的致密砂岩气藏为例,运用核磁共振、恒速压汞、铸体薄片、物性、X-衍射等实验资料,探讨了影响可动流体赋存差异的微观地质 因素。结果表明,盒8段储层可动流体饱和度低,T₂谱分布均为左高峰右低峰的双峰态;黏土矿物的充填与孔隙类型是孔隙结构复杂的重要因素,孔隙结构是影响可动流体赋存特征的关键;面孔率、喉道 半径、孔喉半径比是影响可动流体饱和度的主要因素,有效孔隙体积、分选系数对可动流体饱和度影响明显,储层物性、黏土矿物、有效喉道体积、孔隙半径对可动流体饱和度影响较弱。  相似文献   

Fracture grouting and geonails for soft soil tunnelling     

Y. M. Cheng  S. K. Au  H. Wong 《Geomechanics and Geoengineering》2019,14(2):99-117

To stabilise the tunnel faces and slopes in soft clay for the Airport Link construction in Australia, fracture grouting and glass fibre-reinforced plastic (GFRP) soil nails are proposed for the soil improvement as well as ease of handling. The compensation caused by the fracture grouting and the gain in strength due to consolidation as well as the geonail have stabilised the soft clay during construction. Only a small amount of ground settlement during soft clay box-jacking operation is generated so that the railway traffic above the embankment can be maintained without interference. The design method of the fracture grouting ground improvement study for this difficult project is discussed in this paper. Extensive laboratory and field tests were employed to verify the design assumptions and to fine-tune the ground improvement studies. The success of this project in poor ground conditions results from combined efforts of extensive field tests, an improved ground improvement design method and a realistic numerical analysis to assess the unstable/highly stressed zones for the placement of soil reinforcement.  相似文献   

粉质黏土填料在K30试验加载进程中的变形时间效应状态分析     

熊勇  罗强  张良  蒋良潍  朱江江 《岩土力学》2018,39(3):863-871

变形稳定标准和分级加载制度是影响K30试验效率和准确性的关键因素,与加载进程中填土的变形时间效应状态密切相关。开展了3组最优含水率下压实系数K分别为0.90、0.95和1.00填土模型的小型平板载荷试验,获得了不同荷载作用下填土变形时程曲线和弹塑性变形数据,讨论了在K30试验加载进程中填土变形状态的变化及其对加载稳定时间的影响。试验表明：良好压实的粉质黏土填料,在K30试验进程中的变形以弹性为主,处于缓慢收敛状态,随着加载级数增加,塑性变形比例逐渐增大,变形时间效应呈现出由微弱进入明显状态的演化趋势,变形1.25 mm对应于缓慢收敛中的微弱时间效应亚状态;“变形速率不超过0.01 mm/min”变形稳定标准分级加载时间随时间效应指数呈加速增长规律,能在保证试验精度的基础上提高试验效率;以最大荷载下填土变形时间效应不应超过显著状态、变形量不小于1.25 mm为约束条件,针对5级加载、0.04 MPa荷载增量的加载制度,可得K30试验的适宜范围为60～160 MPa/m。  相似文献