透水混凝土作为透水性路面材料，内部连通孔隙结构为雨水提供了渗流通道，也对材料结构受力带来了不利影响，在我国北方季冻区城市应用中，还面临自然冻融循环的侵蚀作用。纤维透水混凝土通过骨料间的嵌锁、水泥浆粘结和纤维的桥架拉结形成独特的孔隙结构特征，对其透水、力学性能及冻融耐久性等的深入研究具有重要理论价值和工程实践意义。

本文以路用玄武岩纤维透水混凝土为研究对象，结合理论分析、室内试验和数值模拟，将透水混凝土CT扫描连续切片灰度图进行三维重构，分析二维和三维细观孔隙结构特征，对真实重构模型进行数值模拟，研究了孔隙结构宏观渗流机制和骨架结构力学性能。根据力学试验参数，理论推导并验证了基于孔隙率的弹性模量、泊松比等变形参数，并建立了试验曲线各阶段的应力-应变响应折线模型。揭示了纤维透水混凝土冻融损伤劣化的微观机理，得出冻融作用下的损伤演化方程，形成透水混凝土细观-宏观-微观的分析模型。最后，采用Weibull分布对室内试验和自然环境冻融下的服役寿命进行预测。主要研究结论如下：

（1）骨料粒径和成型方式相同时，各试样孔隙形状具有一定相似性，球形孔隙比例最高，孔隙球形度为0.33~0.45；试样自身孔隙结构具有局部和整体自相似性，包括孔隙大小、形态、分布、孔隙率等。孔隙直径大小呈高斯正态分布，大小较为均匀，多为小尺寸，直径10mm以上概率极低；随玄武岩纤维的添加和增长，大尺寸孔隙减少、孔隙数目增多、连通性降低，24mm长度玄武岩纤维为孔隙结构特征的阈值。

（2）水温20℃时实测平均透水系数为5.74mm/s，建立考虑有效孔隙率、有效孔隙直径和有效孔隙比表面积的透水混凝土透水系数方程。渗流模型流线分布均匀，长度约为试样边长的1.61~1.73倍，在进出水口压力差为20Pa时，渗流平均速度为19.64mm/s，此时从层流逐渐转变为湍流。在相同渗透压力差下，孔喉位置流速快，渗流流量大小由孔喉和孔隙面积之和最小横断面决定。

（3）强度与总孔隙率和总孔隙直径均呈幂函数负相关，得出考虑总孔隙率和总孔隙直径的纤维透水混凝土强度预测方程。玄武岩纤维的掺入提高了透水混凝土强度等级，对于力学性能的改善，受弯作用最明显，其次是受拉，最后是受压；纤维使裂缝端部张开位移增大，在水泥基开裂之后，阻滞和约束裂缝的开展；纤维在水泥浆中的桥架拉结作用能起到阻裂、增强和增韧效果，以及长纤维对骨料的缠绕增强骨料间嵌锁作用，提高了骨架整体性，同时减小浆体与骨料之间的强度差异；压缩试验中试样从碎裂破坏转变为锥形、截面压剪或劈裂破坏形式，同时提高了抗压破坏后的整体性；纤维的主要破坏形态为滑动和拔出，纤维和骨料极少有断裂现象；纤维对限制裂缝、提高韧性和延性的作用超过强度的增强；骨料胶结体更易形成空间的斜向分布，玄武岩纤维分布在骨料间的最佳桥架长度约为18~36mm。根据骨架结构受力及传递过程，建立了骨料间胶结体梁断裂破坏模型。

（4）基于伺服单轴和三轴试验，得出纤维透水混凝土弹性模量、泊松比、黏聚力和内摩擦角等试验参数，单轴应力-应变可分为初始、弹性和水泥浆胶结体破裂三个阶段，三轴可分为初始、弹性、水泥浆胶结体断裂、水泥浆包裹骨料颗粒挤压、水泥浆胶结体破碎五个阶段。通过基底圆孔隙简化模型，推导出考虑孔隙率的纤维透水混凝土有效弹性模量和泊松比，经基质密实试样的试验验证，理论曲线与试验值较为吻合，并分析了透水混凝土强度准则和能量演化过程。通过“等效基质”处理方法建立纤维透水混凝土应力-应变响应的折线模型，三维重构模型的有限元应力-应变模拟曲线与折线模型和试验曲线一致性较好，揭示了应力-应变响应各阶段的内在机制。

（5）建立不同冻融循环次数下纤维透水混凝土质量、强度、CT值和能量的损失演化方程，可依据冻融循环80次时，损失率分别超过5%、25%、5%、36%，来判定试样失效。以有效孔隙率和总孔隙率冻融损伤劣化规律，分别得到纤维透水混凝土透水系数和强度演化方程。物理方面，基质的失水收缩以及与骨料的热膨胀系数的差异是导致界面过渡区微观内应力不均匀而产生裂缝成为冻融薄弱区的根本原因；纤维与水泥浆体的粘结性，能抵抗部分冻胀力和温度疲劳应力，缓和了冻融产生的应力集中。化学方面，二氧化硅能够提高水泥浆及界面过渡区水泥水化程度；反应消耗掉Ca(OH)₂有害晶体；与反应产物硅酸钙C-S-H凝胶填充该区域有害孔隙，使微孔结构更加密实。宏观方面，纤维的网状结构阻碍冻融作用下微裂纹的产生和发展。微观方面，掺入适量玄武岩纤维相当于引气剂作用，缓冲膨胀压力。硅灰的添加比水泥标号的提高对冻融耐久性影响更大，宏观上表现为性能衰减速率缓慢，二氧化硅对纤维透水混凝土微观结构的改善机理解释了宏观性能的演化规律。

以双参数Weibull分布模型建立了玄武岩纤维透水混凝土冻融循环寿命预测方程，根据自然环境与室内冻融试验的关系，预测出在兰州市一个受冻龄期的服役寿命。

As a pervious pavement material, the connected pores of pervious concrete provides seepage channel for rain water, and also brings adverse effects on the mechanical properties. The pervious pavement also suffers the erosion of natural freeze-thaw cycles in application of north seasonal freezing urban of China. Fiber pervious concrete have unique pore structure characteristics through interlocking between aggregates, cement paste bonding and fiber bridge tensioning. Further researches on the permeability, mechanical properties and freeze-thaw durability have an important theoretical value and engineering practical significance.

Taking road basalt fiber pervious concrete as the research object, this dissertation reconstructed the three-dimensional model of pervious concrete using CT scan continuous section gray map combining theoretical analysis, laboratory test and numerical simulation, and analyzed 2D and 3D mesoscopic pore structure characteristics. The macroscopic seepage mechanism of pore structure and mechanical properties of skeleton structure were studied by numerical simulation of real reconstruction model. According to the mechanical test parameters, the elastic modulus, Poisson's ratio and other deformation parameters were theoretically deduced and verified based on porosity, and the stress-strain response broken-line model of the test curve at each stage was established. The microscopic mechanism of freeze-thaw damage and deterioration of fiber pervious concrete was revealed, damage evolution equations were obtained, and the Meso-Macro-Micro analysis model was formed. Finally, Weibull distribution was used to predict the service life under freeze-thaw cycles in laboratory tests and natural environments. The main research conclusions are as follows:

(1) When the aggregate size and molding method are the same, the pore shape of all samples is similar to a certain extent, and the proportion of spherical pores is the highest, ranging from 0.33 to 0.45. The partial and the whole pore structures in the sample are similar, including pore size, morphology, distribution, porosity, etc. The pore diameter shows a Gaussian normal distribution, the size is relatively uniform with mostly small size, and the probability above 10mm is very low. With the addition and growth of basalt fibers, the large size pores decrease, the number of pores increases, and the connectivity decreases. The basalt fibers with 24mm length are the threshold of pore structure characteristics.

(2) When the water is 20℃, the average permeability is 5.74mm/s. The permeability equation of pervious concrete considering effective porosity, pore diameter and specific surface area was established. The flow lines of the seepage model are evenly distributed, and the length is about 1.61~1.73 times of the sample side length. When the pressure difference between inlet and outlet was 20Pa, the average seepage velocity was 19.64mm/s, which gradually changed from laminar flow to turbulent flow. Under the same seepage pressure difference, the velocity of pore throat is fast, and the seepage flow is determined by the minimum cross section area of pore throat and pore.

(3) The strength was negatively correlated with total porosity and pore diameter by power function, and a strength prediction equation was obtained. The addition of basalt fiber improves the strength grade of pervious concrete, and the improvement of mechanical properties is flexural, tensile and compressive in order. The opening displacement of fracture end increases by adding basalt fiber, which blocks and restricts the development of fracture after cement paste cracking. Fiber bridge hitch in cement paste has the function of cracking resistance, strengthening and toughening, and reduce the strength difference between cement paste and aggregate. The winding of long fiber to aggregate enhances the interlocking effect between aggregates and improves the skeleton integrity. In the compression test, the sample changed from cataclastic to conical failure, sectional compression-shear or split failure, and the integrity was improved. The main failure modes of fiber are sliding and pulling out, and fiber and aggregate rarely break. The effect of fiber on limiting crack, improving toughness and ductility is more than that of strengthening. The aggregate cement body is more likely to form a diagonal distribution in space, and the best bridge length of fiber between aggregates is about 18~36mm. According to the stress and transfer process of skeleton structure, the fracture failure model of cement body beam between aggregates was established.

(4) Based on the servo uniaxial and triaxial tests, the elastic modulus, Poisson's ratio, cohesion and internal friction Angle of fiber pervious concrete were obtained. Uniaxial stress-strain curve can be divided into three phases of initial, elastic and cement rupture, and triaxial can be divided into five stages of initial, elastic, cement fracture, aggregate particles extrusion, cement broken. The effective elastic modulus and Poisson's ratio of fiber pervious concrete considering porosity were derived by the simplified model of the circular pore. The theoretical curves are in good agreement with the experimental values by the test of dense matrix samples, and the strength criterion and energy evolution process of the pervious concrete were analyzed. A broken-line model of stress-strain response of fiber pervious concrete was established by "equivalent matrix ". The finite element stress-strain simulation curve of the 3D reconstruction model is in good agreement with the broken-line model and test curve, and the internal mechanism of stress-strain response at each stage was revealed.

(5) The loss evolution equation of mass, strength, CT value and energy of fiber pervious concrete under different freeze-thaw cycles was established, and the sample failure could be determined according to the loss rate exceeding 5%, 25%, 5% and 36% when freeze-thaw cycles were 80 times. Based on the freeze-thaw damage laws of effective porosity and total porosity, the permeability and strength evolution equation of fiber pervious concrete were obtained respectively. In terms of physics, the water-loss shrinkage of the matrix and the difference of thermal expansion coefficient between the matrix and the aggregate are the fundamental reasons of the uneven internal stress in the interfacial transition zone, which generates crack resulting in the freeze-thaw weak zone. The bonding between fiber and cement paste can resist part of frost heave force and temperature fatigue stress, and alleviate the stress concentration caused by freeze-thaw. In terms of chemistry, silica can improve the hydration degree of cement paste and interfacial transition zone, and consumes the harmful crystals of Ca(OH)₂. The secondary reaction product and Calcium silicate C-S-H gel fill the harmful pores in the region, making the micropore structure more dense. Macroscopically, the network structure of fibers hinders the generation and development of microcracks under freeze-thaw cycles. Microcosmic, the right amount of basalt fiber added is equivalent to the effect of entraining agent, and buffers expansion pressure. The addition of silica ash has a greater improvement on the freeze-thaw durability than cement label, and the performance decay rate is slow macroscopically. The improvement mechanism of silica on the microstructure of fiber pervious concrete explains the evolution law of the macro properties.

The prediction equation of freeze-thaw cycles life of fiber pervious concrete was established using the two-parameter Weibull distribution model. According to the relationship between freeze-thaw cycles in natural environment and laboratory, the service life in Lanzhou was predicted.