GFRP抗浮锚杆锚固机理试验研究与理论分析

发布时间：2018-03-11 18:41

本文选题：GFRP抗浮锚杆　切入点：裸光纤光栅　出处：《青岛理工大学》2015年博士论文　论文类型：学位论文

【摘要】：玻璃纤维增强聚合物(GFRP)锚杆是一种由树脂和玻璃纤维复合而成的新型锚杆,与传统的钢筋锚杆相比,它具有比强度高、耐腐蚀性强、介电性好等优点,将GFRP材料引入抗浮锚杆体系,能够克服传统金属锚杆存在的地下水腐蚀和电化学腐蚀等问题,特别适用于地铁车站抗浮。本文借助于植入式裸光纤光栅传感技术进行一系列现场及室内试验,揭示了荷载作用下GFRP抗浮锚杆的应力应变分布规律及黏结破坏机理,获得了GFRP抗浮锚杆与地基锚固(内锚固)、与底板混凝土锚固(外锚固)的锚固性能及长期荷载作用下的蠕变特征,提出“全变形”的概念,完善了设计理论和方法。主要工作及研究成果如下:1、通过GFRP抗浮锚杆现场拉拔破坏性试验,成功地将植入式裸光纤光栅传感技术应用于抗浮锚杆拉拔试验中,并与钢筋抗浮锚杆进行对比,研究风化岩地基中GFRP抗浮锚杆内锚固承载特征、荷载传递机制和界面黏结特性。研究表明:(1)GFRP抗浮锚杆的破坏形式有2种:短锚杆主要发生砂浆和围岩界面(第二界面)剪切破坏,长锚杆主要在锚杆杆体和砂浆界面(第一界面)出现剪切破坏,其破坏实质是杆体最大剪应力处基体材料发生剪切破坏。(2)锚杆轴力沿深度方向逐渐递减,并且超过一定深度后杆体不再受力;GFRP锚杆的应力传递深度比钢锚杆大,钢锚杆的轴力沿深度衰减的速率比GFRP锚杆快。剪应力的峰值随荷载增加逐渐增大并向深部移动,但GFRP锚杆的剪应力峰值比钢筋锚杆大,钢筋锚杆的剪应力比GFRP锚杆发挥早。(3)锚固体介质为M32.5水泥砂浆,锚固长度为2.0 m,直径为28 mm的GFRP抗浮锚杆的极限抗拔承载力约为225 k N。对于直径为28 mm和32 mm的GFRP抗浮锚杆,第一界面的平均黏结强度为1.50~1.54 MPa,第二界面的平均黏结强度为0.32~0.37 MPa,且第二界面平均黏结强度随锚杆直径的增加而增大。(4)GFRP抗浮锚杆的极限抗拔承载力随锚杆直径和锚固长度的增加而增大,一般均高于钢筋抗浮锚杆。中风化花岗岩地层中,GFRP抗浮锚杆的合理锚固长度建议取值为3.5~5.0 m。2、将螺母托盘锚具用于抗浮锚杆的外锚固,通过自行设计的室内大型构件对拉试验,研究了不同锚固形式和不同锚固长度的GFRP抗浮锚杆的外锚固性能,对极限荷载作用下外锚固变形量(滑移量)及极限承载力进行了测试。结果表明:(1)GFRP抗浮锚杆外锚固的破坏形式有2种:锚杆材料强度不足产生劈裂破坏;GFRP锚杆和混凝土界面相对滑移较大,产生拔出破坏。(2)对于直锚筋锚固和螺母托盘锚固的GFRP抗浮锚杆,外锚固长度为30d的极限承载力分别为356 k N、384 k N,比外锚固长度为15d的极限承载力分别提高65.6%、43.8%。对于不同锚固形式、相同锚固长度的GFRP锚杆,螺母托盘锚固的GFRP抗浮锚杆界面黏结强度比直锚筋锚固形式提高约7.9~24.4%。(3)GFRP抗浮锚杆与混凝土之间的平均黏结强度随着外锚固长度的增加而降低,随滑移量的增大而提高。(4)当荷载水平低于200 k N时,直径为28 mm、混凝土标号为C25、外锚固长度为15d、30d的全螺纹GFRP抗浮锚杆,其外锚固变形量均不超过2.5 mm,能够满足工程需要。3、通过4根全长黏结螺纹GFRP抗浮锚杆在长期荷载作用下的拉拔蠕变试验,研究了GFRP抗浮锚杆抗拔的蠕变力学模型,计算出模型中的蠕变参数并对模型的正确性进行验证。引入时间损伤效应的概念,结合蠕变力学模型推导出GFRP抗浮锚杆的长期抗拔力。研究表明:(1)GFRP抗浮锚杆在40%的极限荷载下才会发生蠕变,且蠕变变形较小。在实际工程中,40%左右的极限荷载能满足在长期荷载下的抗浮要求。(2)Burgers力学模型能够很好地描述GFRP抗浮锚杆的蠕变规律,模型预测结果与试验结果吻合较好。(3)基于损伤力学理论,结合Burgers模型推导了GFRP抗浮锚杆的损伤变量随时间变化规律,并由此得到了GFRP锚杆抗拔承载力随时间的变化规律,给出的GFRP抗浮锚杆的长期抗拔承载力与实际长期拉拔力相差不大,说明建立的蠕变损伤模型用于预测GFRP抗浮锚杆的长期抗拔承载力具有较好的适用性。4、在内锚固、外锚固及蠕变试验的基础上,分析论证了GFRP抗浮锚杆第一界面、第二界面及杆体材料的剪切破坏机制,并提出了“全变形”的概念,有助于深化对GFRP抗浮锚杆工作机制的认识。
[Abstract]:Glass fiber reinforced polymer (GFRP) is a kind of new type of anchor bolt is composed of resin and glass fiber composites, compared with the traditional steel bolt, it has high strength, strong corrosion resistance, the advantages of good dielectric properties, the GFRP material is introduced into the anti floating anchor system can overcome the groundwater corrosion and electrochemistry the corrosion problems of traditional metal bolt, especially suitable for the subway station. A series of anti floating field and indoor tests on bare fiber grating sensing technology implanted with the help of revealing the anti floating anchor load under GFRP stress and strain distribution and bond failure mechanism, obtained the GFRP anti floating anchor and Anchor Foundation (within the anchorage, and concrete anchor) (Anchorage) creep characteristics of anchorage performance and long-term load, puts forward the concept of "whole deformation", improve the design theory and method. The main work and research The results are as follows: 1, through the GFRP anti floating anchor site drawing destructive test, successfully implanted bare fiber grating sensing technology used in anti floating anchor pullout test, and reinforcement of anti floating anchor comparison study on weathering characteristics of bearing GFRP anti floating anchor anchorage rock foundation, the load transfer mechanism and interfacial bond characteristics. The research showed that: (1) failure form of GFRP anti float anchor has 2 kinds: short bolt mainly interface mortar and surrounding rock (second interface) shear failure, long anchor bolt and mortar in the main interface (the first interface) to shear failure, the failure is the essence of the rod the maximum shear stress of matrix the material shear failure. (2) the bolt axial force decreases gradually along the depth direction and depth of rod body no longer force; GFRP anchor stress transfer depth ratio of steel bolt, steel bolt axial force along the depth attenuation rate than GFRP Bolt shear quickly. The peak stress increases with the increase of load and move to the deep, but the peak value of the shear stress of GFRP anchor bolt reinforced ratio, shear stress ratio GFRP steel anchor bolt played early. (3) the anchor solid medium for M32.5 cement mortar, the anchorage length is 2 m, diameter limit 28 mm GFRP anti floating anchor pullout capacity is about 225 K N. with diameter of 28 mm and 32 mm GFRP anti float anchor, average bond strength of the interface in the first 1.50~1.54 MPa, the average bond strength of second 0.32~0.37 interface for MPa, and the average bond strength of the second interface increased with the increase of bolt diameter increases. (4) increased with the increase of bolt diameter and anchorage length of the ultimate uplift capacity of anti floating anchor GFRP, are generally higher than the reinforced anti floating anchor. In weathered granite formation, anchoring length values of anti floating anchor GFRP 3.5~5.0 for m.2, the nut holder Anchorage anchorage disc for anti floating anchor, through indoor large components designed for tensile test, outer anchorage performance of different anchorage forms and different anchorage length GFRP anti floating anchor, anchor on the ultimate load under external deformation (displacement) and ultimate bearing capacity were tested. The results showed that (1): GFRP damage in the form of anti floating anchor anchorage has 2 kinds: the strength of bolt material problems of splitting failure; GFRP anchor and concrete interface slip greatly, produce pullout failure. (2) for the GFRP anchor bar and anchor nut tray anchoring anti floating anchor anchorage length is 30d the ultimate bearing capacity was 356 K N, 384 K N, the ratio of anchorage length 15d ultimate bearing capacity were increased by 65.6%, 43.8%. for different anchorage forms, GFRP the same bolt anchorage length, the bonding strength of GFRP anchor nut tray anti floating anchor interface Anchor bar anchorage forms increased by about 7.9~24.4%. (3) average bond strength between GFRP anti floating anchor and concrete decreased with the increase of anchorage length, increased with the amount of slip. (4) when the load level is lower than 200 K N, 28 mm in diameter, the concrete grade is C25, the outer anchorage length 15d, full thread GFRP 30d anti floating anchor, the outer anchorage deformation is less than 2.5 mm, can meet the needs of Engineering.3, floating anchor pullout creep test under long-term loading by 4 full length bonding thread GFRP anti creep mechanical model of anti floating anchor pullout resistance of the GFRP study, the calculated creep the parameters of the model and the correctness of the model is verified. By introducing the concept of time damage effect, combined with the creep mechanical model derived long-term pullout force of anti floating anchor GFRP. Research shows that: (1) GFRP in 40% of the anti floating anchor limit load under creep will occur Change, and the creep deformation is small. In practical engineering, the ultimate load of about 40% to meet the requirements of anti floating in the long-term load. (2) Burgers model can well describe the creep behavior of GFRP anti float anchor, the prediction results agree well with the experimental results. (3) based on the theory of damage mechanics the Burgers model is derived, combined with the law of damage variable GFRP anti float anchor changes with time, and the resultant GFRP anchor pullout capacity changes with time, the anti float anchor GFRP are long-term uplift bearing capacity and the actual long-term drawing force of little difference, that creep damage model for prediction of resistance floating anchor GFRP long-term uplift bearing capacity with.4, good applicability, anchoring, anchoring and creep tests based on analysis of anti floating anchor GFRP first machine interface, second interface and shear failure of rod material The concept of "full deformation" is put forward, which helps to deepen the understanding of the working mechanism of GFRP anti floating anchor.

【学位授予单位】：青岛理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU476

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