| 加筋泡沫轻质土三轴剪切力学特性 |
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| 引用本文： | 许江波, 王元直, 骆永震, 晏长根, 张留俊, 尹利华, 杨晓华, 裘友强, 兰恒星. 加筋泡沫轻质土三轴剪切力学特性[J]. 交通运输工程学报, 2020, 20(4): 120-133. doi: 10.19818/j.cnki.1671-1637.2020.04.009 |
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| 作者姓名： | 许江波 王元直 骆永震 晏长根 张留俊 尹利华 杨晓华 裘友强 兰恒星 |
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| 作者单位： | 1.长安大学 公路学院，陕西 西安 710064;;2.中交第一公路勘察设计研究院有限公司，陕西 西安 710075;;3.中国科学院 地理科学与资源研究所，北京 100101 |
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| 基金项目： | 陕西省重点研发计划项目;青海省科技计划;中央高校基本科研业务费专项;国家自然科学基金;国家重点研发计划;陕西省自然科学基金 |
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| 摘 要： | 通过三轴剪切试验, 对比在不同加筋率和围压下, 聚丙烯纤维加筋泡沫轻质土的剪切力学特性; 研究了泡沫轻质土各强度参数与加筋率、围压之间的关系, 获取了加筋泡沫轻质土裂纹扩展规律, 建立了应力-应变全曲线方程, 提出了加筋泡沫轻质土各强度参数关于加筋率和围压的本构方程; 将不同加筋率的试验数据归一化处理后进行分析, 得到了加筋泡沫轻质土的应力-应变全曲线方程, 获取了曲线方程中各参数关于加筋率、围压2个变量之间的函数关系。分析结果表明: 加筋泡沫轻质土三轴剪切强度和黏聚力均随加筋率增加呈现先增加后减小的趋势, 在加筋率达到0.75%时达到峰值; 加筋泡沫轻质土的内摩擦角受加筋率影响较小, 说明纤维作用主要是通过改变材料黏聚力来影响加筋泡沫轻质土的强度; 而强度降低率随着加筋率增加呈现明显的下降趋势, 最大从40%左右降低至10%左右时达到稳定; 加筋率一定时, 加筋泡沫轻质土的极限强度和残余强度均随着围压的升高呈增加趋势; 经过分析体积裂纹曲线发现加筋泡沫轻质土破坏时主要经历受压、产生裂缝、纤维承受拉力限制裂缝、裂缝扩展张力过大纤维拔出4个阶段, 而加筋泡沫轻质土达到屈服阶段时往往包括裂纹的稳定扩展阶段和裂纹的不稳定扩展阶段2个裂纹发育过程, 由于缺乏筋材, 泡沫轻质土属于脆性破坏, 因此, 没有裂纹不稳定增长阶段。
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| 关 键 词： | 软土路基 加筋泡沫轻质土 三轴剪切试验 应力-应变关系 裂纹闭合模型 残余强度 |
| 收稿时间： | 2020-02-19 |
Triaxial shear mechanical properties of reinforced foam lightweight soil |
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| XU Jiang-bo, WANG Yuan-zhi, LUO Yong-zhen, YAN Zhang-gen, ZHANG Liu-jun, YIN Li-hua, YANG Xiao-hua, QIU You-qiang, LAN Heng-xing. Triaxial shear mechanical properties of reinforced foam lightweight soil[J]. Journal of Traffic and Transportation Engineering, 2020, 20(4): 120-133. doi: 10.19818/j.cnki.1671-1637.2020.04.009 |
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| Authors: | XU Jiang-bo WANG Yuan-zhi LUO Yong-zhen YAN Zhang-gen ZHANG Liu-jun YIN Li-hua YANG Xiao-hua QIU You-qiang LAN Heng-xing |
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| Affiliation: | 1. Highway School, Chang'an University, Xi'an 710064, Shaanxi, China;;2. CCCC First Highway Consultants Co., Ltd., Xi'an 710075, Shaanxi, China;;3. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China |
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| Abstract: | Through the triaxial shear test, the shear mechanical properties of polypropylene fiber reinforced foam lightweight soil under different reinforcement ratios and confining pressures were compared. The relationships between the strength parameters of the reinforced lightweight foamed soil and the reinforcement rate and confining pressure were investigated. The crack propagation law of reinforced lightweight foamed soil was obtained, and the stress-strain full curve equation was established. The constitutive equations for the strength parameters of foam lightweight soil in terms of reinforcement ratio and confining pressure were proposed. The experimental results with different reinforcement ratios were analyzed through the data normalization. The stress-strain full curve equation of reinforced foam lightweight soil was obtained. The functional relationships between the parameters of the curve equation and the two variables(reinforcement rate and confining pressure) were obtained. Analysis result shows that the triaxial shear strength and cohesion of reinforced foamed lightweight soil emerge a trend that increases first and then decreases with the increase of the reinforcement rate, and reach the peak values when the reinforcement rate reaches 0.75%. While the reinforcement ratio has limited influence on the internal friction angle of reinforced foam lightweight soil, which indicates that the function of fiber affects the strength of reinforced foam lightweight soil by changing the cohesive force of the material. The strength reduction rate presents an obvious descend trend with the increase of the reinforcement rate, at most, it decreases from about 40% to about 10%, and then keeps stable. When the reinforcement rate is kept constant, the ultimate strength and residual strength of reinforced foamed lightweight soil present an increase trend with the confining pressure. Through analyzing the volume crack curve, it is found that the reinforced lightweight foamed soil is mainly subjected to four stages when it is damaged: compression, cracking, crack restriction because of the fiber tension, and pulling out of fiber due to the large crack extension. When the reinforced foam lightweight soil reaches the yield stage by two crack development processes: the stable and unstable growth of crack. Due to the lack of reinforcement, the failure type of foam lightweight soil belongs to brittle failure, hence, there is no instability growth stage of crack. |
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| Keywords: | soft soil subgrade reinforced foam lightweight soil triaxial shear test stress-strain relation crack closure model residual strength |
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