软弱土层复合土钉支护试验研究

复合土钉支护是从土钉支护基础上发展起来的、应用范围更广的一项基坑支护新技术。笔者通过模型试验，研究了复合土钉支护的作用原理，为其设计和施工提供了参考依据，促进了这项技术快速发展。基坑模型采用“相似模型的长度与变形的时间成反比”的相似法则设计，相似比为1:10。试验模拟现场分步开挖与支护的过程，测试内容包括土体位移、地表沉降、基底隆起、地面裂缝及超挖引起的破坏形态。试验结果表明：复合土钉支护能够充分调动周围土体共同作用，有效地控制基坑变形；复合土钉支护中止水帷幕的插入深度和强度对控制边坡变形与失稳有较大作用；复合土钉支护效果明显优于一般的土钉支护。

Study on composite soil nailing in soft subsoil by model test

Composite soil nailing, which has been developed on the basis of soil nailing and gotten wide application, is a new retaining technique for excavation. The working principles of composite soil nailing were studied by model tests so as to provide reference to design and construction of the retaining system. The excavation models were designed by a similitude law, that is, the model length is inverse proportion to deformation duration, and the adopted model similitude ratio is one over ten. The tests simulated the actual procedure in situ with staged excavation and retaining construction. The measurements included soil displacements, land subsidence, bottom rebound deformations, surface cracks and failure configurations. The results show that surrounding soil will be acted on together with the composite system to a high degree to control the deformations during excavation effectively; the inserted depth and the strength of the cement-soil waterproof wall will play a great role in controlling the deformation and failure of the composite system; and the behaviors of composite soil nailing will be superior to that of soil nailing.