相邻基坑土条土压力计算方法探讨

基坑工程实践中，经常遇到相邻基坑土条土压力如何计算的问题，现行基坑规范尚没有计算方法。通过理论探索和工程实践，对前、后期的基坑支护型式进行了归类和组合，提出了相临基坑宽度的确定原则；提出了建立在库仑土压力理论基础之上的简化计算方法--叠加法，推导并给出了非黏性土和黏性土在不同坡率和地面分布有荷载条件下主动土压力系数和土压力的计算公式，并提出了临界宽度的概念和土条土压力折减系数的计算公式。利用所提出的叠加法、临界宽度的概念和土条土压力折减系数的计算公式，可以简捷地计算不同土层、不同坡率和地面荷载条件下的土条土压力合力及土压力强度。工程实践表明，该方法概念清晰、理论依据充分、计算公式简便，以此设计的基坑支护结构安全合理，可供类似基坑支护工程设计参考。

Discussion on calculation method of earth pressure of earth-strip between neighbouring excavations

The Problem of how to calculate the earth pressure for the earth-strip neighbouring excavations is run against frequently in excavation engineering practice; but there is no calculation method in the existing criterion of excavation for the moment. First, the retaining and protection forms between neighbouring excavations are classified and put together, the affirming principle of the width between two excavations is put forward; then, the superposition method on Coulomb’s earth pressure theory is presented; and the calculation formulas of the active earth pressure coefficient and earth pressure are derived and presented for clay and non-clay under differrent gradients and ground load, and the idea of the critical width and the calculation formula of reducing coefficient of the earth pressure of the earth-strip are also presented. The total and distributing earth pressure of earth-strip for different soils, different gradients and ground load can be calculated simply by the superposition method, the idea of the critical width and the calculation formula of reducing coefficient of the earth pressure of the earth-strip. Finally, two engineering examples are given to show that the retaining and protection structures generated by the method and the formulas are safe and rational; the method and the formulas can be for reference by similar excavation engineering.