为提高膨胀土的无侧限抗压强度，降低工程危害。在木质素改良膨胀土的研究基础上，通过单因素试验研究纤维长度、纤维掺量及木质素掺量对膨胀土抗压强度的影响规律，基于单因素试验结果，通过BBD（BOX-Behnken design）响应面设计法进行响应面试验，建立二次回归模型，研究了双因素交互作用对膨胀土无侧限抗压强度的影响。结果表明：单因素作用时，膨胀土无侧限抗压强度在各因素作用下均呈现先增大后减小的趋势；双因素交互作用时，木质素掺量和聚丙烯掺量二者交互作用显著性最好。由BBD响应面法得到的最优组合为：聚丙烯纤维长度为9 mm、纤维掺量为0.3%、木质素掺量为3%，该变量下平行试验组的平均抗压强度为552.48 kPa，相比于素膨胀的抗压强度提升了76.97%，可见此方案下对素膨胀土的无侧限抗压强度提升效果最好。研究成果为新乡地区弱膨胀土的改良提供了借鉴，为复合改良土的试验设计提供了新思路。

In order to improve the unconfined compressive strength of expansive soil and reduce engineering hazards. Based on the research of lignin modified expansive soil, the influence of fiber length, fiber content and lignin content on the compressive strength of expansive soil was studied by single factor test. Based on the results of single factor test, the response surface test was carried out by BBD (BOX-Behnken design) response surface design method, and a quadratic regression model was established to study the effect of two-factor interaction on the unconfined compressive strength of expansive soil. The results show that under the action of single factor, the unconfined compressive strength of expansive soil increases first and then decreases under the action of each factor. When the two factors interact, the interaction between lignin content and polypropylene content is the best. The optimal combination obtained by the BBD response surface method is: the length of polypropylene fiber is 9 mm, the fiber content is 0.3%, and the lignin content is 3%. The average compressive strength of the parallel test group under this variable is 552.48 kPa, which is 76.97% higher than the compressive strength of the plain expansion. It can be seen that this scheme has the best effect on the unconfined compressive strength of the plain expansive soil. The research results provide a reference for the improvement of weak expansive soil in Xinxiang area, and provide a new idea for the experimental design of composite improved soil.