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基坑开挖后的卸载会引起基坑的回弹,基坑开挖越深,则回弹量越大,较大回弹量会造成各种工程问题。现有回弹量计算方法需要进行专门的回弹试验或特定应力路径试验以确定回弹计算所需的模量。为了避免进行专门试验,特研究了应用常规试验所得模量与常用Mindlin解和Boussinesq解相结合,得到一种计算回弹量的简便可行方法。通过对Mindlin解和Boussinesq解计算所得应力,与e-lg p模型和Duncan-Chang模型的变形计算方法进行组合,得到4种计算方法,然后应用分层总和法计算求解基坑的回弹量,通过与实测值对比,比较4种组合计算方法的精度,得出更适合于工程实际应用的、准确性更高的基坑回弹量计算方法。经3个工程实例检验,推荐采用Mindlin解和e-lg p模型分别计算应力和模量,再应用分层总和法累加变形量,可得到与工程实测值非常相近的坑底总回弹量和坑底分层回弹量。
Excavation after foundation excavation will cause the rebound of the foundation pit, the deeper the foundation pit excavation, the greater the rebound amount, the greater the amount of springback will cause a variety of engineering problems. Existing methods for springback calculation require a dedicated springback test or a specific stress path test to determine the modulus required for springback calculations. In order to avoid the special experiment, we studied the combination of the modulus obtained by the routine experiment with the commonly used Mindlin solution and the Boussinesq solution, and obtained a simple and feasible method to calculate the springback. By calculating the stress calculated by Mindlin solution and Boussinesq solution and combining with the deformation calculation method of e-lg p model and Duncan-Chang model, four calculation methods are obtained, then the layered sum method is used to calculate the springback of foundation pit, By comparing with the measured values, the accuracy of the four kinds of combined calculation methods is compared and the calculation method of the foundation pit resilience, which is more suitable for the practical engineering application, is obtained. After three engineering examples, it is recommended to calculate the stress and modulus separately using Mindlin's solution and e-lg p model, and then to calculate the total rebound amount at the bottom of the pit by the cumulative sum of stratified summation method. Bottom layered layered springback.