复合土钉支护工程施工过程中的土压力分析

水泥土桩复合土钉支护体系是目前我国基坑工程中常用的基坑支护形式，其特点是水泥土桩改善了基坑边壁的直立临空高度，基本做到土钉的随挖随支和随支随挖，大大加快了施工速度，缩短了施工工期，但其施工过程中需要进行土钉锚固体施工，由此而导致基坑边壁侧移较大、基坑施工影响范围内地面下沉，基坑影响范围内的建筑物发生不均匀沉降变形和局部构件裂缝甚至倒塌破坏。本文探讨了饱和粉土和粉细砂土层为主的地质条件下，水泥土桩复合土钉支护基坑施工过程中常可能出现的环境问题和主要技术原因，分析研究了降水、渗流对土体侧压力的直接影响，对提高此类支护结构的施工安全性及稳定性，降低和避免此类基坑工程的施工环境事故具有一定的理论指导意义。

Earth pressure analysis of composite soil nailing in construction course

Composite retaining of cement-soil pile and soil nailing (CRCSPSN) is often used in retaining and protection of foundation excavations now, whose characteristic is that the unretaining height of pit side is heightened, which ensures the consecutive construction of soil nailing. So construction speed is highly increased. What is unpleasant is that the displacements of pit side are big and the ground within the influence range of foundation excavations settles due to anchor construction of soil nails, which may lead to asymmetrical settlements and local cracks even collapse of buildings. In this paper, it has been analyzed and discussed that surrounding and technical problems and effects on earth pressure caused by dewatering and seepage during construction of CRCSPSN in geological conditions mainly of saturated silt and silty fine sand, which may provide some guidance to improving the security and stability of such retaining structure's construction and to reducing and avoiding such foundation pit's surrounding accidents.