Research on Soil Displacement and Adjacent Pile Response Caused by High-Pressure Jet Grouting Pile Construction in Loess Areas
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摘要: 通过对高压旋喷桩施工挤土效应的分析,将施工过程简化为半无限土体中一系列压力控制的球孔扩张的过程,基于压力控制的球孔扩张理论的弹塑性解,提出了高压旋喷桩施工引起土体位移的计算方法,引入桩土非线性接触理论,利用有限差分法求得桩体内力与变形。将提出的方法应用于现场施工实例,与监测结果进行对比,验证了此方法的合理性,并进行了参数化研究。研究表明:单根高压旋喷桩施工挤土效应随深度增加不断递减,且主要发生在浅层土体处;随着水平距离的增加,地表侧向位移先增大后减小,地表隆起则表现为指数型衰减趋势;施工引起的既有桩最大侧向位移发生在桩头,最大弯矩发生在桩体中部,施工时间间隔对邻桩响应的影响最大,建议通过跳孔施工和间隔施工的方式减小挤土效应。Abstract: This study analyzed the soil displacement effect during high-pressure rotary jet pile construction by simplifying the construction process as a series of pressure-controlled spherical cavity expansions in a semi-infinite soil medium. Based on the elastic-plastic solution of pressure-controlled spherical cavity expansion theory, a calculation method was proposed to estimate the soil displacement caused by high-pressure rotary jet pile construction. Nonlinear contact theory between the pile and soil was introduced, and the finite difference method was employed to determine the internal forces and deformations of the pile. The proposed method was applied to field construction cases, and its validity was verified by comparing the results with on-site monitoring data. Additionally, a parametric study was conducted. The research findings revealed that the soil displacement effect decreased with depth and primarily occurred in shallow soil layers during the construction of individual high-pressure rotary jet piles. The lateral displacement at the ground surface increased first and then decreased with the increase in horizontal distance, while the ground uplift exhibited an exponential decay trend. The maximum lateral displacement of existing piles was observed at the pile head, and the maximum bending moment occurred in the middle section of the pile. The construction time interval had the greatest influence on the response of adjacent piles. Therefore, to mitigate soil displacement effects, it is recommended to adopt construction techniques such as skip-hole drilling and spaced pile installation.
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