Stress Sharing Behavior and Its Mechanism during Consolidation Process in Composite Ground Improved by Sand Compaction Piles with Low Replacement Area Ratio     

S.-K. You  K. Oda 《Marine Georesources & Geotechnology》2013,31(4):287-304

In order to accurately design a sand compaction pile (SCP) with low replacement area ratio, it is important to understand the mechanical interaction between the sand pile and clay ground and its mechanism during consolidation process in composite ground. In this article, therefore, a series of numerical analyses on composite ground improved by SCP with low replacement area ratio were carried out. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, were confirmed by comparing the results obtained from a series of laboratory model tests with the composite ground improved by SCP. Through the results of the numerical analyses, mechanical behavior of the sand pile and clay in composite ground during consolidation is elucidated, together with a stress sharing mechanism between sand pile and clay.  相似文献   

强夯置换墩法处理公路软基的机制研究   总被引：3，自引：0，他引：3  

王宏祥  闫澍旺  冯守中 《岩土力学》2009,30(12):3753-3758

近年来,强夯置换墩法以其工期短、施工简单等特点在软基工程中得到了越来越广泛的应用。但由于对其加固机制的研究还不是很深入,理论研究远远滞后于工程实践,难以建立起符合强夯碎（块）石墩特点的设计理论和方法。为此针对海满高速公路实际工程,结合有限元分析,对该方法处理湿地软基的加固机制进行了深入研究,其结果可供施工设计人员参考。  相似文献   

海相淤泥软土地基强夯置换砂桩试验分析     

徐东升  汪稔  孟庆山  胡明鉴 《岩土力学》2009,30(12):3831-3836

针对某海相淤泥软土的处理工程,选取了一强夯砂桩置换试验区,监测了强夯置换过程中夯坑及其周围土体的变形,超孔隙水压力的增长和消散情况以及深层土体水平位移。分析结果表明,单个置换砂桩夯击8次较为合理;强夯置换后静置一段时间,可以有效减小强夯过程中的超静孔隙水压力,且一遍强夯后静置7 d后超孔隙水压力基本消散完;深层土体的水平位移主要发生在地表以下3～6.5 m深度范围内。  相似文献   

置换碎石桩联合强夯在北部湾填海复杂型软弱地基处理中的应用          下载免费PDF全文

胡纯龙 《探矿工程》2009,36(2):29-31,34

从广西北部湾大量填海（塘）造陆工业基地所遇到的复杂型软弱与夹层地基处理工程实例中,结合建（构）筑物具体特点,扩展应用置换（挤密加固,纵横排水）碎石桩联合强夯的地基处理方法,在解决大面积地基不均匀沉降,软弱夹层纵横排水与挤密固结、综合夯实提高总体地基持力层承载力方面取得了“安全、经济、高效”的良好效果,并具有推广前景和意义。  相似文献   

振冲碎石桩在龙头石水电站坝基加固中的应用          下载免费PDF全文

彭第  王伟  孟玉红  李静 《地质找矿论丛》2009,24(1):83-86

针对龙头石水电站坝基的深厚砂砾石地层.采用振冲碎石桩处理,通过检测,处理后的地基达到工程要求.并消除了液化,效果较好.  相似文献   

置换减载与加筋复合处理方法对路基不均匀沉降控制效果研究     

卢谅  石通辉  杨东 《岩土力学》2019,(9):3474-3482

为了解决高速公路常见的不均匀沉降问题,提出了一种置换减载与加筋相结合的复合路堤处理技术。该技术利用具有一定刚度的PVC管置换路堤填土,减轻路堤自重荷载的同时发挥圆管的加筋作用,使得地基中附加应力减小,从而达到控制路基不均匀沉降的目的。为了验证该技术对地基不均匀沉降的控制效果,开展了置换减载与加筋复合处理路堤与未经处理普通路堤的大型模型试验,通过观测其在多级荷载作用下不均匀沉降的发展规律及沉降随时间的变化规律,并结合沉降理论进行分析验证,揭示了置换减载与加筋复合处理方法控制不均匀沉降的机制。该成果为加筋路堤或轻质置换路堤的设计及计算提供了理论依据。  相似文献   

Gas accumulation mechanism in Denglouku Formation of Changling fault depression,southern Songliao Basin,China     

YANG Guang  FAN Yeyu  LIU Changli 《世界地质(英文版)》2017,20(3)

The Changling gas field is occurs in tight sandstone reservoirs of the Lower Cretaceous Denglouku Formation in the Changling fault depression , southern Songliao Basin , China, which constitutes a new gas-pro-ducing area in the depression .Using information on the source-reservoir-cap rock assemblage of the Denglouku Formation, fault activity, and single well burial history of well CS 1, together with data on reservoir fluid inclu-sion and laser Raman spectroscopy , we described the formation of the Changling gas field and determine that this fault depression did not possess suitable conditions for hydrocarbon generation .Coal-derived methane gen-erated from underlying hydrocarbon source rock accumulated in the Lower Cretaceous Yingcheng Formation .At the end of the Late Cretaceous Qingshankou Stage , underwater volcanic eruptions occurred in the northern part of the Changling gas field near Qian'an, resulting in the reactivation of deep faults .Mantle-sourced inorganic CO2 migrated along faults to hydrocarbon gas reservoirs in volcanic rocks of the Yingcheng Formation ;Mean-while, displaced methane ( hydrocarbon gas ) migrated upward to sand reservoirs of the Denglouku Formation . The methane accumulated and formed secondary gas reservoirs ,Therefore fault activity was the main factor con-trolling the generation of gas reservoirs in the Denglouku Formation .The main accumulation period of the Yingcheng hydrocarbon gas reservoirs was 82 Ma.Whereas gas reservoir formation in the overlying Denglongku Formation was 79 Ma, slightly later than the time of formation of the Yingcheng gas reservoir in CS 1 well area. At 79 Ma, the burial depth of the Denglouku Formation was 1800-2000 m, the diagenesis is relatively weak and the physical properties of the reservoir are relatively favorable for accumulation .This period is not only at gas generation peak time of three sets of source rock but also at the reactivation of deep faults during the forma -tion of fault-bound depressions , thereby providing favorable conditions for the migration and accumulation of methane .  相似文献   

复合地基等效弹性参数研究   总被引：3，自引：0，他引：3  

张仪萍  王洋  李涛 《岩土力学》2011,32(7):2106-2110

考虑复合地基边界约束条件的影响,采用复合地基单元体模型,基于变形一致的原则,推导了复合地基在弹性变形阶段的等效变形模量和等效泊松比的解析解。研究表明,复合地基的等效弹性常数与复合单元体侧向约束条件有关,侧向约束越强,等效变形模量越大,泊松比越小。侧限条件和无侧限条件的等效弹性常数是复合地基各种约束情况下的2个极值,在较强的侧限约束条件下,等效泊松比随置换率的变化相对明显。研究还表明,按面积加权法计算的复合变形模量偏小,而计算的复合压缩模量偏大,等效压缩模量与加权法计算的差值随置换率不同而异,并随着桩土压缩模量比的增大而增加,其差异一般可达20%～30%  相似文献   

疲劳动剪应变门槛与武广高铁无碴轨道路堑基床长期动力稳定     

刘晓红  杨果林  方薇 《岩土力学》2010,31(Z2):119-124

针对武广高铁无碴轨道红黏土路堑基床长期动力稳定性问题,利用改造后的应力控制式动三轴仪代替国内尚无的剪应变控制式共振柱仪,测试土体疲劳动剪应变门槛值,提出了一套完整的试验方案和数据处理方法,为疲劳动剪应变门槛的确定开辟了新的试验途径。通过疲劳动三轴试验,获得了9种试验条件下红黏土疲劳动剪应变门槛值。按曲线走势特征,红黏土 - 曲线可分为稳定型、临界型、破坏型3类,且不同试验条件下同类型的曲线具有相似的走势特征;探讨了含水比、围压对红黏土疲劳动剪应变门槛的影响,给出了简单实用的疲劳动剪应变门槛经验估算公式;基于室内试验及现场动响应测试成果,采用动剪应变法初步评价了武广高铁无碴轨道红黏土路堑基床的动力稳定性,给出了不同物理状态下红黏土基床最小换填厚度建议值。研究成果为我国高速铁路无碴轨道土质路基动力稳定性评价及路堑基床换填厚度的确定提出了新的思路,也为红黏土疲劳特性的深入研究提供了宝贵的第一手资料。  相似文献   

The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions   总被引：3，自引：1，他引：2  

Dominik R. D. Niedermeier  Andrew Putnis  Thorsten Geisler  Ute Golla-Schindler  Christine V. Putnis 《Contributions to Mineralogy and Petrology》2009,157(1):65-76

The mechanism of re-equilibration of albite in a hydrothermal fluid has been investigated experimentally using natural albite crystals in an aqueous KCl solution enriched in ¹⁸O at 600°C and 2 kbars pressure. The reaction is pseudomorphic and produces a rim of K-feldspar with a sharp interface on a nanoscale which moves into the parent albite with increasing reaction time. Transmission electron microscopy (TEM) diffraction contrast and X-ray powder diffraction (XRD) show that the K-feldspar has a very high defect concentration and a disordered Al, Si distribution, compared to the parent albite. Raman spectroscopy shows a frequency shift of the Si-O-Si bending vibration from ~476 cm⁻¹ in K-feldspar formed in normal ¹⁶O aqueous solution to ~457 cm⁻¹ in the K-feldspar formed in ¹⁸O-enriched solution, reflecting a mass-related frequency shift due to a high enrichment of ¹⁸O in the K-feldspar silicate framework. Raman mapping of the spatial distribution of the frequency shift, and hence ¹⁸O content, compared with major element distribution maps, show a 1:1 correspondence between the reaction rim formed by the replacement of albite by K-feldspar, and the oxygen isotope re-equilibration. The textural and chemical characteristics as well as the kinetics of the replacement of albite by K-feldspar are consistent with an interface-coupled dissolution-reprecipitation mechanism.  相似文献