永临结合装配式地连墙作为一种新型基坑支护体系，具有单墙受力和全预制建造2种相互制约的显著特征。为科学地界定其在受力和产业链运作中的性能，该文首先根据力学试验构建了力学性能理论评估模型；其次，通过对建造过程分析构建了碳排放理论评估模型；然后基于以上模型，进一步建立了适用于永临结合装配式地连墙的“力-碳”双控评估模型，以评估单位力学性能下的建造碳排放量即碳效率；最后，运用该双控评估模型对永临结合装配式地连墙和永临分离结构体系的碳效率进行了对比分析。研究结果表明：相比采用双墙模式的现浇永临分离结构体系，永临结合装配式地连墙因使用高强度预制混凝土，在施工和使用阶段的抗弯承载性能分别提升了74.5 kN·m (增幅4.55%)和426.5 kN·m (增幅26.05%)；同时得益于临时支护的取消，平均每环碳排放(以CO₂当量计算)降低了8.05 t (降幅30.99%)。此外，实心永临结合装配式地连墙虽然抗弯承载性能比带空腔设置方案高出81 kN·m (增幅5.07%)，但每环建造碳排放也增加1.21 t (增幅6.98%)。进一步评估发现，带空腔设置方案每单位抗弯承载性能下的建造碳排放比实心方案降低了0.2 t (降幅1.81%)，表明带空腔设置方案的碳效率更优。该研究结果有助于为复杂地质环境中高强低碳建造技术提供科学评估方法，以促进地下工程的绿色低碳转型。

Objective: As a novel foundation pit support system, a permanently integrated prefabricated diaphragm wall exhibits two mutually constrained characteristics: single-wall bearing and fully prefabricated production. However, these characteristics demonstrate a significant trade-off relationship: the structural volume must be increased to enhance structural mechanics capacity, which adversely impacts the efficiency of the prefabricated production and construction supply chain. Meanwhile, improving supply chain efficiency requires reducing the structural volume or material consumption, which compromises the structural mechanics capacity of the single-wall system. Traditional structural performance evaluations typically rely on a single evaluation metric, failing to synergistically balance mechanical properties and supply chain efficiency for identifying optimal integrated solutions. Given the escalating scale of engineering projects in the complex geological environment, there is an urgent need to develop a novel integrated performance evaluation model to provide actionable guidance for the design decisions of high-strength, low-carbon structural solutions. Methods: This study first establishes a theoretical flexural-load-bearing performance evaluation model based on mechanical experiments. Subsequently, a carbon emission assessment model is developed based on the analysis of the construction process. Using these models, a "mechanical-carbon" dual control evaluation framework is formulated specifically for the permanently integrated prefabricated diaphragm wall system to quantify carbon emission efficiency—defined as construction-related carbon emissions per unit of flexural-load-bearing performance. Finally, a comparative analysis of carbon emission efficiency is conducted between the permanently integrated prefabricated diaphragm wall system and a conventional permanently separated structural system using this dual control model. Results: Research findings indicate that, utilizing single-wall load bearing, the permanent-temporary integrated prefabricated diaphragm wall achieves higher flexural-load-bearing performance than the dual-wall separated system, with performance increasing by 74.5 kN·m (an increase of 4.55%) during the construction stage and 426.5 kN·m (an increase of 26.05%) during the service stage, attributable to the use of high-strength prefabricated concrete. Concurrently, thanks to the removal of a temporary support, average carbon emissions per ring (calculated as the CO₂ equivalent) are reduced by 8.05 t (a decrease of 30.99%). Meanwhile, the solid permanent-temporary integrated prefabricated diaphragm wall exhibits 81 kN·m (an increase of 5.07%) higher flexural-load-bearing capacity than cavity-containing configurations and incurs an additional carbon emission of 1.21 t (an increase of 6.98%). Further dual control evaluation reveals that the cavity-containing configuration exhibits 0.2 t (a reduction of 1.81%) lower carbon emissions per unit flexural-load-bearing performance than the solid configuration, indicating that the carbon emission efficiency of the scheme with the cavity configuration is better. Conclusions: This study demonstrates that the cavity-optimized permanently integrated prefabricated diaphragm wall configurations outperform the solid permanently integrated prefabricated diaphragm wall and conventional permanently separated structural systems in terms of carbon emission efficiency, achieving equivalent flexural-load-bearing performance with reduced carbon emissions and resource consumption. This research further indicates that, in the future, more key indicators can be integrated to establish a more complete and adaptive decision-making performance evaluation framework and method for underground structure construction technology. This research offers a scientific evaluation methodology for high-performance, low-carbon construction technologies in the complex geological environment, advancing the green transformation of underground engineering practices.