黄土具有大孔隙、遇水湿陷、易崩解等特性，使得在黄土地区工程建设过程中，由于水分入渗，易导致黄土强度降低、黄土湿陷，进而引发地基不均匀沉降及黄土边坡失稳等问题。传统土体改良方法已广泛应用于黄土地区土体加固，但仍存在许多不足。已有研究表明，纤维素类固化剂如羧甲基纤维素钠（CMC）、聚丙烯酰胺（PAM）等固化剂在提升土体强度、防治土体侵蚀等方面具有较好的优点，但当前该类固化剂在黄土改良中的应用研究还相对较少。

将不同养护龄期、不同掺量CMC、PAM、CMC混合PAM（简称CMC+PAM）、CMC混合PAM在催化剂作用下（简称CMC+PAM+催化剂）加固洛川Q₃黄土作为试验材料，通过直剪试验，系统研究了养护龄期、固化剂类型及掺量变化等因素组合对于加固黄土抗剪强度的影响规律；借助湿化崩解试验，进一步明确了养护龄期和固化剂种类对加固黄土崩解时间和崩解速率的影响；利用激光粒度分布仪、扫描电镜（SEM）、X射线衍射仪（XRD）对加固黄土粒度分布、矿物成分及微观结构特征进行了分析，从微观角度阐释了宏观力学特性变化的内在机理。主要研究成果如下：

（1）CMC加固黄土、PAM加固黄土与未固化重塑黄土相比，抗剪强度得到明显提升，最优掺量分别为0.075%CMC（CMC与黄土质量比为0.075%）和0.15%PAM（PAM与黄土质量比0.15%）；CMC+PAM加固黄土较单一CMC或PAM加固黄土，抗剪强度得到进一步提升，最优掺量为0.225%CMC+PAM（CMC+PAM与黄土质量比为0.225%）；CMC+PAM+催化剂加固黄土和未加催化剂的CMC+PAM加固黄土相比，抗剪强度得到极大提升，最优掺量为0.225%CMC+PAM+催化剂（CMC+PAM+催化剂与黄土质量比为0.225%）；随养护龄期的增加，未添加固化剂的重塑黄土和添加CMC、PAM、CMC+PAM、CMC+PAM+催化剂的加固黄土的抗剪强度也随之增大。

（2）固化剂种类、固化剂掺量和养护龄期对加固黄土黏聚力有较强的影响，CMC、PAM、CMC+PAM、CMC+PAM+催化剂4种加固黄土方案均使得土体黏聚力增大，其中CMC+PAM+催化剂的效应最为显著，整体增幅约为32% ~ 58%。相同条件下CMC、PAM加固黄土内摩擦角产生变化较小，CMC+PAM、CMC+PAM+催化剂两种加固黄土方案下土体的内摩擦角增幅约为6%~8%；固化剂对黄土粒组含量有影响，对矿物成分无明显影响，各种类固化剂各掺量中粘粒减小最大和粉粒增加最多的为0.225%CMC+PAM+催化剂，各粒组含量排序均为：粉粒＞粘粒＞细砂；固化剂的添加使土体中颗粒边界模糊，颗粒之间的接触方式从分散转变为线接触、面接触，出现大量团聚体、絮凝结构、聚集的土颗粒，团聚体之间也以胶结连结、架桥连结的形式填充孔隙，其中CMC+PAM+催化剂加固黄土的排列结构更为紧密。

（3）CMC、PAM、CMC+PAM、CMC+PAM+催化剂的加入能有效改善黄土试样的崩解性能，减缓黄土试样的崩解速率，延长黄土试样的崩解时间；随养护龄期增加，以上种类固化剂对黄土的崩解速率的减缓作用和对黄土崩解时间的延长作用提高；CMC+PAM+催化剂掺量为0.225%对黄土试样崩解性能的改善最为明显，CMC+PAM次之，CMC、PAM对黄土崩解性能的改善不及前两者。

The loess has the characteristics of large pores, water collapsibility and easy disintegration. In the process of engineering construction in the loess area, due to water infiltration, it is easy to lead to the decrease of loess strength and loess collapsibility, which leads to the uneven settlement of foundation and the instability of loess slope. Traditional soil improvement methods have been widely used in soil reinforcement in loess areas, but there are still many deficiencies. Previous studies have shown that cellulose curing agents such as sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM) and other curing agents have good advantages in improving soil strength and preventing soil erosion. However, there are relatively few studies on the application of such curing agents in loess improvement.

The Luochuan Q₃ loess reinforced by different curing ages, different dosages of CMC, PAM, CMC mixed PAM (CMC+PAM) and CMC mixed PAM under the action of catalyst (CMC+PAM+catalyst) was used as the test material. Through direct shear test, the influence of curing age, curing agent type and dosage change on the shear strength of reinforced loess was systematically studied. The effects of curing age and curing agent type on the disintegration time and disintegration rate of reinforced loess were further clarified by means of wetting disintegration test. The particle size distribution, mineral composition and microstructure characteristics of the reinforced loess were analyzed by laser particle size distribution instrument, scanning electron microscope (SEM) and X-ray diffractometer (XRD), and the internal mechanism of the change of macroscopic mechanical properties was explained from the microscopic point of view. The main research results are as follows :

(1) Compared with uncured and reshaped loess, the shear strength of CMC reinforced loess and PAM reinforced loess has been significantly improved, with the optimal dosage of 0.075% CMC (CMC to loess mass ratio of 0.075%) and 0.15% PAM (PAM to loess mass ratio of 0.15%), respectively; CMC+PAM reinforced loess has further improved its shear strength compared to single CMC or PAM reinforced loess, with an optimal dosage of 0.225% CMC+PAM (CMC+PAM to loess mass ratio of 0.225%); Compared with CMC+PAM+catalyst reinforced loess without catalyst, the shear strength of loess reinforced with CMC+PAM+catalyst has been greatly improved, with an optimal dosage of 0.225% CMC+PAM+catalyst (CMC+PAM+catalyst to loess mass ratio of 0.225%); As the curing age increases, the shear strength of remolded loess without curing agent and reinforced loess with CMC, PAM, CMC+PAM, CMC+PAM+catalyst also increases.

(2) The type, dosage, and curing period of curing agent have a strong impact on the cohesion of reinforced loess. CMC, PAM, CMC+PAM, and CMC+PAM+catalyst all increase the cohesion of soil. Among them, CMC+PAM+catalyst has the most significant effect, with an overall increase of about 32% to 58%. Under the same conditions, there is little change in the internal friction angle of the loess reinforced with CMC and PAM. The increase in the internal friction angle of the soil under the two reinforcement schemes of CMC+PAM and CMC+PAM+catalyst is about 6%~8%; Curing agents have an impact on the content of loess particle groups, but have no significant effect on mineral composition. Among various types of curing agents, the largest decrease in clay particles and the largest increase in powder particles are 0.225% CMC+PAM+catalysts. The order of content of each particle group is: powder particles>clay particles>fine sand; The addition of curing agents blurs the boundaries of particles in the soil, and the contact mode between particles changes from dispersion to line contact and surface contact, resulting in a large number of aggregates, flocculent structures, and aggregated soil particles. The pores between aggregates are also filled in the form of cementation and bridging connections, and the arrangement structure of CMC+PAM+catalyst reinforced loess is more compact.

(3) The addition of CMC, PAM, CMC+PAM, CMC+PAM+catalysts can effectively improve the disintegration performance of loess samples, slow down the disintegration rate of loess samples, and extend the disintegration time of loess samples; As the curing age increases, the slowing down effect of the above types of curing agents on the disintegration rate of loess and the prolonging effect on the disintegration time of loess increase; The CMC+PAM+catalyst dosage of 0.225% has the most significant improvement on the disintegration performance of loess samples, followed by CMC+PAM, and the improvement of loess disintegration performance by CMC and PAM is not as good as the first two.

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