摘要
桩土复合路基是高速公路软基路段常用的处理方法,但现阶段常出现复合路基满足质量检测要求而工后仍有较大沉降的情况,严重影响行车的安全性和舒适性。为预测和早期评价桩土复合路基工后沉降,在分析157段复合路基路段工后沉降情况的基础上,利用理论分析和现场试验,引入弹性垫层和延时持载的手段改进现行静载试验,获得评价参数残余沉降Sr和沉降速率Vt;然后,由实测数据对比利用概率统计分析方法获得的评价指标,建立一种复合路基工后沉降早期检测评价方法。结果表明:在2倍承载力设计值情况下,延时持载试验延时48 h可使90%以上的复合路基完成垫层的桩土应力比调整,达到稳定的承载形式。延时持载试验的最大残余沉降值小于7.0 mm或大于12.0 mm时,采用对数正态分布拟合更好;大于7.0 mm且小于12.0 mm时,采用逆Γ-分布拟合更好。15年工后沉降要求值为100、200和300 mm时,对应的延时持载试验最大残余沉降Sr max分别为4.50、13.30和35.41 mm,对应的Vt=48 h分别为0.021、0.046和0.055 mm/h,满足的概率分别为47.61%、87.49%、96.93%。现场实例验证表明,提出的评价指标值与实际情况比较吻合,有利于工程质量的早期检测评价,及时制定补救措施。该方法不仅可丰富工后沉降预测的方法,且有利于将现有复合路基质量检测指标体系从单一的强度检测拓展为强度、沉降检测。
Pile-soil composite subgrade is a common treatment method for soft foundation section of expressway.However,at present,composite subgrade often meets the requirements of quality inspection but still has a large settlement after construction,which seriously affects the safety and comfort of driving.In order to forecast and evaluate the post-construction settlement of pile-soil composite subgrade early,post-construction settlement under 157 sections of the composite subgrade condition were analyzed.Utilizing the theoretical analysis and field test methods,and introducing elastic cushion and delayed loading to the current static load tests,the evaluation parameters of residual subsidence Sr and sedimentation rate Vt were obtained.Then the evaluation index was obtained from the measured data of composite subgrade after construction by the method of probability statistical analysis.Finally a new method for the early detection and evaluation of post-construction settlement was presented.The results showed that more than 90%of the composite subgrade completed the pile-soil stress ratio adjustment of cushion,and could achieve the stability of the pile soil stress ratio under actual load with a time delay of 48 hours,when conducting the delay load test under the condition of double designed value of bearing capacity.The maximum residual settlement of the delayed load holding tests followed logarithmic normal distribution when it is less than 7.0 mm or greater than 12.0 mm,while it followed the inverseΓ-distribution when it is greater than 7.0 mm and less than 12.0 mm.When the required values of post-construction settlement after 15 years were 100 mm,200 mm and 300 mm,the corresponding maximum residual settlement Sr max of the delayed load holding test were 4.50 mm,13.30 mm and 35.41 mm,respectively.The corresponding Vt=48 h were 0.021 mm/h,0.046 mm/h and 0.055 mm/h,respectively.The probability of satisfaction were 47.61%,87.49%and 96.93%,respectively.The field example showed that the proposed evaluation index was in good agreement with the value of the actual situation.The evaluation method was beneficial to the early evaluation of construction quality and the timely formulation of remedial measures.This method can not only enrich the post-construction settlement prediction method,but also help to expand the existing composite roadbed quality detection index system from single strength detection to strength and settlement detections.
作者
单浩
洪宝宁
刘鑫
徐奋强
SHAN Hao;HONG Baoning;LIU Xin;XU Fenqiang(Key Lab.of Ministry of Education for Geomechanics and Embankment Eng.,Hohai Univ.,Nanjing 210098,China;Jiangsu Research Center for Geotechnical Eng.Technol.,Hohai Univ.,Nanjing 210098,China;Research Inst.of Geotechnical Eng.,Hohai Univ.,Nanjing 210098,China;School of Civil Eng.,Xuzhou Univ.of Technol.,Xuzhou 221018,China;Research Inst.of Tunnel and Underground Eng.,Hohai Univ.,Nanjing 210098,China;School of Architecture Eng.,Nanjing Inst.of Technol.,Nanjing 211167,China)
出处
《工程科学与技术》
EI
CAS
CSCD
北大核心
2020年第4期194-202,共9页
Advanced Engineering Sciences
基金
国家自然科学基金青年基金项目(51609071)
中央高校基本科研业务费项目(B200202087)。
关键词
复合路基
延时持载试验
工后沉降
早期评价方法
概率统计分析
控制标准
composite subgrade
time-delay holding test
post-contruction settlement
early detection and evaluation method
probability statistical analysis
control standards
