基于室内实验研究了人工冻土(重塑粉质黏土)在三点式和四点式两种加载方式下加载速率对抗折强度的影响规律。结果表明:两种加载方式下,破坏类型均呈明显的脆性破坏特征,加载速率对破坏特征几乎无影响。三点式加载方式下,抗折强度与跨中最大相对挠度均随加载速率的增大而呈线性增大趋势, 试验范围内(加载速率30～75 N/s),加载速率提高1 N/s,强度增大0.023 MPa,跨中最大相对挠度增大0.038; 而四点式加载方式下加载速率对抗折强度及试件破坏时跨中最大相对挠度均无影响。仅从研究人工冻土抗折强度基本特性出发,采用四点式加载方式确定其抗折强度更为合理。
Abstract
The impact of loading rate for the flexural strength of artificial permafrost(remodeling silty clay)in three-point and four-point loading was investigated based on laboratory experiments. The results showed that the both loading showed significant damage type of brittle failure characteristics, but the loading rate had almost no effect on the failure characteristics. The flexural strength and the maximum relative deflection at midspan were increased with loading rate linearly increasing trend when three-point loading method was adopted. When the loading rate was in the range of 30-75 N/s, the intensity increases 0.023 MPa and the maximum relative deflection at midspan increases 0.038 as the loading rate increased 1 N/s. However, the four-point loading rate did not affect its flexural strength and the maximum relative deflection at midspan damaged. From the point of studying the basic characteristics of the flexural strength of artificial permafrost, it is more reasonable to use four-point loading method for determining its flexural strength.
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 煤炭行业煤矿专用设备标准化技术委员会.MT/T 593-2011.人工冻土物理力学性能试验[S].北京:中国标准出版社,2011.
[2] 齐吉琳,马巍.冻土的力学性质及研究现状[J].岩土力学, 2010,31(1):133-143.Qi J L,Ma W. State-of-art of research on mechanical properties of frozen soils[J]. Rock and Soil Mechanics,2010,31(1):133-143.
[3] 吴成义,徐兵壮,李嘉玲.人工冻土抗弯试验研究[C]//全国矿山建设学术会议论文选集:上册,2004:61-64. Wu C Y,Xu B Z,Li J L. Bending test of artificial permafrost[C]// National Conference Papers Mine Construction Anthology:First Volume,2004:61-64.
[4] 牛富俊,夏慧民.人工冻结梁构件中不同加筋作用的对比试验研究[J].西安工程学院学报,2002,24(2):1-3.Niu F J,Xia H M. Comparative experimental study on the embedded freezine pipes reinforcement over the artificial frozen component[J]. Journal of Xi’an Engineering University,2002,24(2):1-3.
[5] 郑周练,刘长江,龚文川,等.“三点弯曲法”在线检测缆索张力力学模型[J].土木建筑与环境工程,2009,31(2):29-32.Zheng Z L,Liu C J,Gong W C,et al. Mechanical model with on-line measuring the cable tension with “three point bending” method[J]. Journal of Civil,Architectural & Environmental Engineering,2009,31(2):29-32.
[6] 刘家泳,汪尧,戈晓,等.四点弯曲试验研究[J].物理测试,2010,28(2):44-47.Liu J Y,Wang Y,Ge X,et al. Research of four-point bending test[J]. Physics Examination and Testing,2010,28(2):44-47.
[7] 陈有亮,王明,徐珊,等.上海人工冻结软黏土抗压抗拉强度试验研究[J].岩土工程学报,2009,31(7):1046.Chen Y L,Wang M,Xu S,et al. Tensile and compressive strength tests on artifical frozen soft clay in Shanghai[J]. Chinese Journal of Geotechnical Engineering,2009,31(7):1046.
[8] 赵晓东,周国庆,陈国舟.温度梯度冻结黏土破坏形态及抗压强度分析[J].岩土工程学报,2010,32(12):1854-1860.Zhao X D,Zhou G Q,Chen G Z. Failure modes and compression strength of frozen clay under thermal gradient[J]. Chinese Journal of Geotechnical Engineering,2010,32(12):1854-1860.
[9] 高丹盈,付超云,赵利梅.加载速度对塑性混凝土强度的影响[J].人民黄河, 2009, 31(6):115-116.Gao D Y,Fu C Y,Zhao L M. Impact of loading speed on the plastic concrete strength[J]. Yellow River,2009,31(6):115-116.
[10] 苏捷,方志,杨钻.混凝土抗折强度尺寸效应的试验研究[J].工业建筑, 2012,42(12):62-66.Su J,Fang Z,Yang Z. Experimental study on the size effect of concrete bending strength[J]. Industrial Construction,2012,42(12):62-66.
[11] Watanabe K,Wake T. Measurement of unfrozen water content and relative permittivity of frozen unsaturated soil using NMR and TDR[J]. Cold Regions Science and Technology,2009,59(1):34-41.
[12] 马芹永,袁璞,陈文峰,等.人工冻土单轴与围压状态冻土动力学性能对比分析[J].地下空间与工程学报,2014,10(1): 26-29.Ma Q Y,Yuan P,Chen W F,et al. Comparative analysis on dynamic mechanical properties of artificial frozen soil under uniaxial load and confining pressure[J]. Chinese Journal of Underground Space and Engineering,2014,10(1):26-29.
[13] 孙星亮.冻结粉质粘土细观变形机理及其各向异性损伤模型研究[D].武汉:中国科学院武汉岩土力学研究所,2004.Sun X L. Analysis of submacroscopic deformation mechanism of frozen silty clay and a study on its anisotropic damage models[D].Wuhan:Institute of Rock and Soil Mechanics,Chinese Academy of Sciences, 2004.
[14] Christ M,Park J B. Ultrasonic technique as tool for determining physical and mechanical properties of frozen soils[J]. Cold Regions Science and Technology,2009,58(3):136-142.
基金
收稿日期:2014-08-29 修回日期:2014-11-27
基金项目:国家自然科学基金项目(51478226); 宁波轨道交通有限公司科研资助项目
第一作者:张春进,高级工程师。*通信作者:杨平,教授。E-mail: yangping@njfu.edu.cn。
引文格式:张春进,朱峰,杨平,等. 加载速率及方式对人工冻土抗折强度的影响[J]. 南京林业大学学报:自然科学版,2015,39(3):179-182.
PDF(1388878 KB)
