加筋膨胀土不同布筋型式三轴试验研究   总被引：1，自引：0，他引：1  

丁万涛  雷胜友 《岩土力学》2010,31(4):1147-1150

基于三轴试验方法,对不同布筋方式的加筋膨胀土试样的强度特性和变形过程进行研究。室内三轴试验表明,非均匀加筋型式较适合低围压、变形小的加筋土体工程;高围压、大变形的加筋土体工程采用均匀布筋型式将会取得较好的效果。试样变形过程表明,加筋试样随着轴压的增加,将会形成多鼓状变形,并且中间土体最终变形将超过端部土体变形;该变形过程可较好地解释加筋挡土墙随着时间和外部荷载的作用出现中间部分突出的现象。试验结果对加筋土体施工将会起到一定的指导意义。  相似文献   

粘结式锚杆在爆炸动载下轴向应力分布研究     

单仁亮  周纪军  夏宇  孔祥松  常力夫  徐成 《岩土力学》2011,32(10):2965-2971

通过物理模型试验,研究在爆炸动载作用下临近工作面支护锚杆的应力状态。根据相似条件和简化假设,采用集中装药进行工程掏槽爆破模拟,利用粘贴在锚杆上的应变片测得近区端锚和全锚锚杆的轴向应变波。测试结果表明,爆破引起锚杆振动时间约为6 ms,经过9 ms的缓降期锚杆变形趋于稳定值;动载期间端锚锚杆在杆体中部锚固段测得峰值应力比杆体尾部自由段的值大,但相差不大,动载过后尾部的残余应力较大;全锚锚杆在杆体尾部测得的峰值应力和残余应力都远大于杆体中部测得值。利用无限体内一点受法向集中力作用的位移势函数,推导锚固体及周围岩体的轴向应力分布,并计算一定预应力在锚固区产生的附加轴向应力,结合动应力的作用分析锚杆的受力状态  相似文献   

干湿循环作用下膨胀土裂隙演化规律试验研究   总被引：27，自引：1，他引：26  

张家俊  龚壁卫  胡波  周小文  王军 《岩土力学》2011,32(9):2729-2734

对南阳膨胀土在反复干湿循环作用下的裂隙演化规律进行了室内试验研究。试验中采用烘干法模拟脱湿过程,采用抽气饱和法模拟饱和过程。在脱湿过程中,定时对土样进行称重、定点拍照,以记录裂隙发育状况。利用矢量图技术对裂隙照片进行矢量化处理,以提取裂隙的各种几何要素,继而进行裂隙度计算。裂隙度变化规律分析结果表明,影响裂隙张开程度的关键因素并非土体含水率,而是含水率梯度,而脱湿速率的空间分布、土块渗透特性以及土块尺寸大小则是决定含水率梯度大小的关键因素;膨胀土裂隙在干湿循环的作用下会逐步发育,主要体现在裂隙总面积与总长度的增加,但此作用有限,裂隙的发育达到一定程度以后便会因为土块尺寸过小而停止;反复干湿循环会使土体产生范性变形,该范性变形与完整土块的胀缩特性并无直接联系,其主要成因是裂隙的发育与土体完整性的破坏,裂隙越发育,土体范性变形量越大  相似文献   

南阳盆地新野县地裂缝现状分析     

李文杰  王邦贤  杨红强  王玉海 《地下水》2009,31(5):117-120

对南阳盆地新野县地裂缝发生的地质环境背景、发育现状、成因及防治对策进行了论证;确定膨胀土为引发地裂缝的主要因素;分析了膨胀土的分布规律、岩性特征、埋藏深度、土体性质及气象条件等因素;对膨胀势进行评价,判定为弱膨胀土,具蒙脱石含量较高,具高塑限、高液限,高收缩性的特点;并提出了地裂缝的防治对策。  相似文献   

A numerical study of the behavior of fully grouted rockbolts under dynamic loading     

《Soil Dynamics and Earthquake Engineering》2013

The widespread preference for rockbolts in providing adequate rock stability in underground mines and man-made cavities make it necessary to obtain a better understanding of the response of these support systems. It is widely accepted that the fully grouted rockbolts provide better roof stability in areas of very poor roof condition which may be caused by high ground stress conditions. There is little information about the in situ behavior of these systems especially under dynamic loading. Hence, to study the behavior of fully grouted rockbolts under dynamic loading, a numerical modeling study was conducted using the FLAC^3D code. In this study the behavior of three types of fully grouted rockbolts were compared with each other including rockbolts with and without head plate and a yielding type one. The results of analyses indicated that under dynamic loading the fully grouted rockbolts without the head plate are incapable of controlling the rock mass movement. Although fully grouted rockbolts with head plate damp a considerable amount of the dynamic energy through friction as these bolts slide within the grout, but the elongation of the rockbolt is not possible due to the rapid breakage of the rockbolt–grout interface. Yielding rockbolts are the best choice for the absorption of the dynamic stress wave and controlling of the rock mass movement. The obtained results show that the optimal design of yielding rockbolt should be in such a way that after dynamic loading, anchoring part of bolt has a limited movement to prevent stress concentration in the shaft of rockbolt and its breakage.  相似文献   

混凝土膨胀剂使用中存在的问题及解决措施     

莫庆瑗 《中国勘察设计》2012,(7):80-82

混凝土膨胀剂具有补偿混凝土干燥收缩的效果,但在地下室防水混凝土工程中,使用效果不理想,存在掺加膨胀剂后地下室底板和外墙出现混凝土开裂渗漏的现象。本文从设计源头,力求全面地、准确有效地提出解决措施。  相似文献   

深部取心钻探拧卸工具机械化的思考和实践          下载免费PDF全文

黄洪波  张文举  臧臣坤  张雅石 《探矿工程》2011,38(7):1-4

通过分析钻杆拧卸对地质钻探起下钻效率的制约以及目前拧卸工具存在的问题,提出了适合深部取心钻探的拧卸工具机械化研制思路及技术要点,介绍了SQ114/8型绳索取心钻杆专用液压钳的技术、性能特点和应用效果。  相似文献   

Enriched finite element procedures for analyzing decoupled bolts installed in rock mass   总被引：1，自引：0，他引：1  

Debasis Deb  Kamal C. Das 《国际地质力学数值与分析法杂志》2011,35(15):1636-1655

Numerical procedures are developed to analyze interaction between fully grouted bolts and rock mass using ‘enriched finite element method (EFEM)’. A solid element intersected by a rock bolt along any arbitrary direction is termed as ‘enriched’ element. The nodes of an enriched element have additional degrees of freedom for determining displacements, stresses developed in the bolt rod. The stiffness of the enriched element is formulated based on properties of rock mass, bolt rod and grout, orientation of the bolt and borehole diameter. Decoupling at grout–bolt interface and elasto‐plastic behavior of rock mass have also been incorporated into the EFEM procedures. The results of this method are compared with analytical pull‐out test results presented by Li and Stillborg (Int. J. Rock Mech. Min. Sci. 1999; 36 :1013–1029). In addition, a numerical example of a bolted tunnel is provided to demonstrate the efficacy of the proposed method for practical applications. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

纤维对石灰改良膨胀土性质的影响分析     

李治朋  张宇亭  马希磊 《岩土工程技术》2011,25(4):214-216,F0003

首先对膨胀土基本性质做了试验分析,通过天然膨胀土和掺人纤维前后的石灰土的击实试验,得出了掺人少量纤维对石灰土的最优含水率和最大干密度影响很小.通过有荷膨胀率试验,得出了纤维能够抑制石灰土的膨胀性,纤维掺人量在0.05%～0.1%之间时,线膨胀率随纤维掺人量的增多而降低显著,在0.1%～0.2%之间时降低幅度减小.由无侧...  相似文献   

基于集对分析的膨胀土胀缩性Vague集评价模型     

魏东方  汪明武  李健  徐鹏 《上海国土资源》2013,(3)

膨胀土胀缩性等级评价是膨胀土地区工程治理中的首要问题。本文探讨了基于集对分析的膨胀土胀缩性等级评价模型,以克服膨胀土胀缩性评价指标的不确定性和复杂性。模型以Vague集描述膨胀土胀缩性等级的确定性和不确定性,并应用集对分析构造Vague集的隶属函数。通过实例应用及与其他方法评价结果的对比分析,表明该模型应用于膨胀土胀缩性等级评价是有效可行的,且具有判断结果准确、易于操作等优点。  相似文献