土工合成材料加筋土桥台变形特性的离心模型试验

Centrifugal Model Tests on Deformation Characteristics of Geosynthetics Reinforced Soil Abutment

摘要:

针对工作状态下加筋土桥台变形特征，以桥梁基础偏移距（即梁座基础到面板内侧的距离）和梁座基础宽度2个影响因素为变量，开展了5组离心模型试验，通过在离心场内分级施加荷载以揭示加筋土桥台的变形规律。试验结果表明：加筋土桥台变形与基础偏移距大小和基础宽度尺寸密切相关，变形值随基础偏移距增加而减小，但存在最优基础偏移距，超过该值对控制桥台变形作用不大；变形值随基础宽度增加而增大。试验结果还揭示，筋材应变极值随基础偏移距增加而减小，随基础宽度增加而增大；每层筋材应变极值出现在桥台基础下方并逐渐向筋材与面板连接处过渡，且呈上大下小的特点；加筋土桥台体积应变均小于0.15%，在设计计算时仍可采用“零体积应变”假设；现行规范给出的面板最大水平位移计算值与实测值存在较大偏差，不能很好地反应基础偏移距和基础宽度的影响，需要进一步优化。研究成果可为加筋土桥台设计及相关技术标准的制定提供参考和依据。

Abstract:

Five centrifugal model tests were conducted to investigate the deformation characteristics of geosynthetics reinforced soil （GRS） abutment under service conditions. The setback distance （i.e.， the distance from the beam seat to the inner of the facing） and beam seat width were considered as two influencing factors. The GRS abutment was loaded through multi-stage loading in centrifugal field. Test results indicate that the deformation of the GRS abutment is closely related to the setback distance and the beam seat width. The deformation decrease as the setback distance increases， there exists an optimal setback distance， beyond which the effect on controlling the abutment deformation becomes minimal. The deformation increase as the beam seat width increases under the same load. In addition， the maximum reinforcement strain decreases as the setback distance increases， and increases as the beam seat width increases. At each reinforcement layer， the maximum strain occurs below the beam seat and gradually transitions toward the setback area along the facing. Additionally， the peak strain at each reinforcement layer also decreases from top to bottom. The volumetric strain of GRS abutments in all tests is less than 0.15%， and the assumption of “zero volumetric strain” can still be used for GRS abutments. There is a significant deviation between the calculated values of the maximum horizontal displacement given by the existing specification and the measured values， which cannot well reflect the influence of setback distance and beam seat width， indicating the need for further optimization. The results can provide references and basis for the design of GRS abutments and the formulation of relevant specifications.