MJS水泥土的试桩成桩效果分析  

Study on pile-forming effect of MJS cement soil test pile

作　　者：刘欣 杨平[1] 郑盛 王岩梓 陈潋 杨宁 LIU Xin;YANG Ping;ZHENG Sheng;WANG Yanzi;CHEN Lian;YANG Ning(College of Civil Engineering,Nanjing Forestry University,Nanjing 210037,China;East China Construction Co.Ltd.of China Railway No.3 Group Co.Ltd.,Nanjing 211106,China)

机构地区：[1]南京林业大学土木工程学院,南京210037 [2]中铁三局集团华东建设有限公司,南京211106

出　　处：《林业工程学报》2022年第1期169-176,共8页Journal of Forestry Engineering

基　　金：国家自然科学基金(51478226);中铁三局集团科研项目。

摘　　要：以南京地铁7号线中胜站全断面承压含水砂层MJS加固下穿既有运营10号线车站工程为背景,基于试桩芯样对MJS水泥土试桩成桩效果进行研究,研究不同桩型、不同水泥掺入比、不同地层下各部位MJS水泥土试桩的成桩效果(加固范围、成桩质量、抗压强度、弹性模量、水泥含量),并与室内MJS水泥土强度数据比较。结果表明:全圆桩整体成桩效果优于半圆桩,断面上部芯样强度最大,中部次之,下部最小;半圆桩50%掺入比成桩效果最佳,60%次之,45%最差,断面中部芯样强度最大,上部次之,下部最小;芯样强度与弹性模量随掺入比增加而增大,且表现为脆性破坏;粉砂层芯样强度较大,且脆性更明显;全圆桩芯样强度较大,脆性较半圆桩弱;因现场施工与养护条件不均匀、钻孔取芯损伤等因素,室内水泥土强度远大于试桩芯样,为其3~4倍;实测水泥含量较设计值低8.8%~9.8%,尚未达到设计掺入比要求,需要进一步优化施工参数,半圆桩50%及全圆桩45%掺入比区域水泥含量与强度变化规律相对应。In this study,based on the project of crossing the existing line 10 station with MJS reinforcement at Zhongsheng station of Nanjing Metro Line 7,the pile-forming effect of MJS cement soil test pile was studied based on the test pile core sample,and the pile-forming effects(reinforcement range,pile quality,compressive strength,elastic modulus)of MJS cement soil test pile under different pile types,different cement mixing ratios and different strata were studied.The results were compared with the strength data of MJS cement soil.The results indicate that the overall pile-forming effect of full round pile is better than that of semi-circular pile,and the strength of core sample in the upper part of section is the largest,followed by the middle part,and the lower part is the smallest one.The pile-forming effect of 50%mixing ratio of semi-circular pile is the best one,followed by those of 60%and 45%.The strength of core sample in the middle part of section is the largest one,followed by the upper part,and the lower part is the smallest one.The strength and elastic modulus of core sample is increased with the increase in mixing ratio,and show brittle failure.The strength and elastic modulus of core sample in silty sand layer is increased.The results show that the strength of the sample is larger and the brittleness is more obvious.The strength of the full circle pile core sample is larger and the brittleness is weaker than that of the half circle pile.Due to the non-uniform construction and maintenance conditions,the drilling core damage and other factors,the indoor cement soil strength is much larger than that of the test pile core sample,which is about 3-4 times.The measured cement content is 8.8%-9.8%lower than the designed value,which has not yet reached the designed mixing ratio requirements,and the 50%of half circle pile and the 45%of full circle pile are mixed with water.The change law of mud content is corresponding to mud strength.

关 键 词：MJS水泥土 水泥掺入比 钻芯取样 抗压强度 成桩效果 

分 类 号：TU472[建筑科学—结构工程]