平面应变仪是一种开发较早但至今尚不完善的一种土工试验仪器，随着国家基础设施建设的发展，平面应变试验及试验方法在许多领域得以应用，显示出了平面应变试验在工程设计和研究中的重要性。通过回顾国内外平面应变仪的发展，提出了开发一种新型的土工平面应变三轴仪的思路，以实现更科学、更精确地进行复杂应力加载条件下土平面应变试验的研究。以此为目的，从压力室结构、加载系统及控制量测系统等方面提出了相应的改善措施，开发了一种新型的土工平面三轴仪。并通过重塑黄土的平面应变试验及改进的真三轴仪平面应变试验对比、以及平面应变试验强度参数与常规三轴试验强度参数对比分析，验证了所研制的新型卧式土工平面应变仪的合理性和研制思路的正确性。最后，通过对该平面应变仪应变试验的黄土破坏特性与改进真三轴平面应变试验的黄土破坏特征的对比分析，验证了本文所开发的平面应变仪在描述土体应变局部化问题的合理性。

Plane strain apparatus is an early-developed, relatively widely used, and yet immature experiment apparatus for soil testing. With the development of infrastructures, the plane strain tests and the related testing methods are applied to many project fields, showing their importance in engineering design and research. This paper reviews the historical development of plane strain apparatus at home and abroad, pointing out that it is necessary to explore a new kind of plane strain triaxial test apparatus for soil to achieve more reasonable and accurate plane strain data under complex stress loading conditions. For this purpose, by improving the structure of pressure chamber, loading system and control system, a new horizontal plane strain triaxial apparatus for soil has been developed. The results of the plane strain test are compared to those of the modified true triaxial test on remolded loess; and the strength parameters are determined using the new apparatus and compared with those of the conventional triaxial tests, showing the accuracy and reliability of the new horizontal plane strain triaxial apparatus. Finally, the failure characteristics determined by the new plane strain apparatus are compared to those obtained by the modified true triaxial apparatus, showing the applicability of the new plane strain apparatus in capturing the main features of soil localization.