咬合桩拱形围护结构在临江拱座深基坑中的应用

为解决二元结构临江拱座深基坑施工过程中渗水量大、水土压力大和征地困难的问题，在满足实际工期需求的前提下，结合临江拱座深基坑特殊的工程地质条件，提出了一种临江拱座深基坑咬合桩拱形支护方案，分析了咬合桩拱形围护结构的特征，校核了咬合桩拱形围护结构强度，并对咬合桩拱形围护结构的变形情况进行了监测。结果表明:1)咬合桩拱形围护结构兼有挡土和止水作用，具有施工工期短、止水效果好、无需内支撑等优点；2)要使拱形结构的冠梁不受弯矩与剪力作用，则冠梁对应的半径应为定值；3)依据冠梁受力特点设计的拱形围护结构能利用冠梁自身强度分担部分土压力荷载，基坑冠梁安全性好，围护结构受力合理，稳定性好，对周边建筑物的影响在允许范围。咬合桩拱形围护结构支护方案实际应用效果良好，可为拱形咬合桩围护结构设计及工程应用提供参考。

Application of arched retaining structure of secant piles in deep foundation pit near the river

In order to solve the problems of large amount of water seepage, high water-soil pressure and difficult land acquisition of binary structure during the arched retaining structure construction in deep foundation pit near the river, under the premise of meeting the requirement of actual construction period, an arched secant pile support method of the arch deep foundation pit near the river was proposed with the special engineering geology taken into account. In this paper, the characteristics of the arched retaining structure of secant piles were analyzed, the arched retaining structure strength was checked and the deformation of the arched retaining structure of secant piles was monitored. The results indicate that: 1) the retaining structure has the functions of retaining soil and stopping water, and it has the advantages of the short construction period, good water stopping effect and unnecessary internal support; 2) to make the top beam of the arch structure free from bending moment and shear, the corresponding radius of the top beam should be a fixed value; 3) the arched retaining structure designed according to the mechanical characteristics of the top beam can share part of the earth pressure load by using the strength of the top beam. The top beam has the advantages of good safety, reasonable stress of retaining structure and good stability, Moreover, the influence of foundation pit excavation on the surrounding buildings is within the allowable range. Overall, the arched retaining structure of secant piles has a good application effect, and the research results can provide a reference for the design and engineering application of the arched retaining structure of secant piles.