为了研究桩撑支护的深基坑在开挖过程中混凝土支撑的轴力特性,本文以珠海地区深基坑为典型案例,分析了基坑开挖过程中支撑轴力监测值的时序特征,研究了计算值与监测值之间的关系。针对轴力现场监测值超过警戒值、基坑未开挖时轴力持续...为了研究桩撑支护的深基坑在开挖过程中混凝土支撑的轴力特性,本文以珠海地区深基坑为典型案例,分析了基坑开挖过程中支撑轴力监测值的时序特征,研究了计算值与监测值之间的关系。针对轴力现场监测值超过警戒值、基坑未开挖时轴力持续增加等情况,从荷载、温度、徐变和收缩4个方面进行了分析,揭示了基坑在开挖过程中支撑轴力的演化机制。研究表明:(1)随着基坑开挖深度的增加,支撑轴力均表现出增大的趋势;基坑开挖到底后,第1、2层支撑轴力现场监测值是理论计算值的1.67~3.52倍。(2)温度对轴力有明显的影响,达68 k N/℃;收缩及徐变的影响更大,约为轴力现场监测值的1/3。(3)根据拆撑前后的实测数据,切断支撑消除外荷载后,应力计仍能测到轴力,约为未切断前轴力的60%。本文研究结果可为深基坑支撑设计、施工和监测提供参考。展开更多
To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column sp...To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1.展开更多
文摘为了研究桩撑支护的深基坑在开挖过程中混凝土支撑的轴力特性,本文以珠海地区深基坑为典型案例,分析了基坑开挖过程中支撑轴力监测值的时序特征,研究了计算值与监测值之间的关系。针对轴力现场监测值超过警戒值、基坑未开挖时轴力持续增加等情况,从荷载、温度、徐变和收缩4个方面进行了分析,揭示了基坑在开挖过程中支撑轴力的演化机制。研究表明:(1)随着基坑开挖深度的增加,支撑轴力均表现出增大的趋势;基坑开挖到底后,第1、2层支撑轴力现场监测值是理论计算值的1.67~3.52倍。(2)温度对轴力有明显的影响,达68 k N/℃;收缩及徐变的影响更大,约为轴力现场监测值的1/3。(3)根据拆撑前后的实测数据,切断支撑消除外荷载后,应力计仍能测到轴力,约为未切断前轴力的60%。本文研究结果可为深基坑支撑设计、施工和监测提供参考。
基金the National Natural Science Foundation of China under Grants Nos.51261120377 and 51008173
文摘To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1.
