矩形顶管端头土体加固模型试验与沉降控制研究

Model Test and Settlement Control Research on Soil Reinforcement at the End of Rectangular Pipe Jacking

摘要:

为研究矩形顶管施工过程中工作井端头土体稳定性及其对工程安全的影响,以及端头土体加固不足引发的地表沉降等问题,依托合肥市龙岗路综合管廊项目,制作了几何相似比为1∶20的缩尺矩形顶管模型,开展模型试验和模拟验证。通过模型试验,研究了不同加固长度对土体稳定性的影响。结果表明:对矩形顶管端头土体进行加固可有效控制地表产生的沉降;矩形顶管顶进时,工作井前端地表沉降呈"V"形分布;当加固长度由0.30 m增至0.34 m时,地表沉降最大值仅降低了7.14%,继续增加加固长度效果趋缓;工作井侧向土压力集中在洞口上侧区域,且随顶进距离的增加而增大,在顶进400 mm时达到最大值,即647.435 kPa。研究揭示了加固长度与沉降控制的非线性关系,建议6 m为实际工程经济加固长度。

Abstract:

This study aims to investigate the soil stability at the end of working well during rectangular pipe jacking construction and its impacts on engineering safety, as well as the ground settlement issues induced by insufficient soil reinforcement at the end. Based on the Longgang Road utility tunnel project in Hefei, a scaled model of rectangular pipe jacking with a geometric similarity ratio of 1∶20 was fabricated, and model tests together with simulation verification were carried out to explore the influence of different reinforcement lengths on soil stability. The test results indicate that the soil reinforcement at the end can effectively reduce the ground settlement. The ground settlement at the front of the working well presents a V-shaped distribution during pipe jacking. When the reinforcement length increases from 0.30 m to 0.34 m, the maximum ground settlement is only reduced by 7.14%, and the improvement effect tends to be insignificant with further increase of the reinforcement length. The lateral earth pressure of the working well is concentrated in the upper area of the tunnel opening and increases with the increase of the jacking distance, reaching a maximum value of 647.435 kPa at the jacking distance of 400 mm. This study reveals the nonlinear relationship between reinforcement length and settlement control, and proposes 6 m as the economical reinforcement length for practical engineering applications.